ANTI-OBESITY AND ANTI-DYSLIPIDEMIC EFFECTS OF OIL PALM
PHENOLICS IN PREVENTING ATHEROSCLEROSIS AND CARDIOVASCULAR
DISEASE
FIELD OF THE INVENTION
The present invention provides a method of delaying weight gain or obesity and preventing
the effects of dyslipidemia caused by an atherogenic diet in an animal. It comprises the step
of administering oil palm phenolics in the drinking water to said animal. The aforementioned
properties of oil palm phenolics are attributed to the up-regulation of fatty acid beta oxidation
and down-regulation of cholesterol biosynthesis in the liver, when the said animal was given
a low-fat normal diet. In addition, oil palm phenolics also up-regulated unfolded protein
response in the liver, down-regulated antigen presentation and processing in the spleen as
well as up-regulated antioxidant genes in the heart, when the said animal was given a highfat,
cholesterol-containing, atherogenic diet. Oil palm phenolics may thus confer anti
inflammatory and antioxidative effects for the prevention of atherosclerosis and
cardiovascular disease.
BACKGROUND OF THE INVENTION
Cardiovascular disease, together with atherosclerosis, is the first cause of death in the world.
A variety of risk factors are known to be associated with the pathogenesis of atherosclerosis
and cardiovascular disease. These factors include hypercholesterolemia, hyperlipidemia,
hyperglycemia, hypertension, obesity, elevated levels of plasma homocysteine and
hemostatic factors, family history, the male gender, stress, smoking, lack of exercise, high-fat
diets, infectious agents and aging. People with diabetes usually have more severe debility
from atherosclerotic events over time than non-diabetics.
Atherosclerosis is a disease affecting arterial blood vessels, and it involves the hardening
(calcification) of arteries and the formation of atheromatous plaques within the arteries. As
with other chronic diseases, atherosclerosis is believed to be caused by the accumulation of
harmful free radicals and reactive oxygen species in the body. It is associated with systemic
immune responses and inflammation. Atherosclerosis causes two main problems, infarction
(complete coronary occlusion) and aneurysm (partial coronary occlusion), and it can actually
be viewed as a problem of wound healing and chronic inflammation. Atheroslerosis may
cause brain strokes, heart attacks and peripheral artery occlusive diseases in the lower
extremities.
The pathophysiology of atherosclerosis comprises various important steps, including
enhanced endothelial focal adhesiveness, permeability and pro-coagulation (endothelial
dysfunction), expression of adhesion molecules, monocyte adhesion and immigration,
formation of foam cell and fatty streaks, smooth muscle cell (SMC) migration from the tunica
media into the tunica intima, plaque formation and finally, plaque rupture and thrombus
formation. A prevalent theme in atherosclerosis is thus the presence of oxidative stress and
inflammation, due to the oxidation of LDL.
The oxidation of low-density lipoprotein (LDL) has been accepted as an important initial
event in the development of atherosclerosis. Reactive oxygen species can stimulate the
oxidation of LDL, and oxidized LDL which is not recognized by the LDL receptor is then
taken up by scavenger receptors in macrophages leading to foam cell formation and
atheromatous plaques. In addition, macrophages also possess toll-like receptors which bind
pathogen-like molecules and initiate a signalling cascade which leads to cell activation. These
macrophages produce inflammatory cytokines, chemokines, free radicals, growth-regulating
molecules, metalloproteinases and other hydrolytic enzymes. Apoptosis of foam cells, which
is influenced by cytokine expression and the macrophage activation state also contributes to
the formation of a necrotic core.
Previous studies show that among the genes which have increased expression in the
atherosclerotic vessel wall are those involved in inflammation, such as chemokine and
chemokine receptors, interleukin and interleukin receptors, major histocompatibility complex
(MHC) molecules, endothelial cell adhesion molecules, extracellular matrix and matrix
remodeling proteins, matrix metalloproteinase genes, transcription factors, lipid metabolism
and vascular calcification genes, as well as macrophages and smooth muscle cell specific
genes. On the other hand, among the genes with decreased expression in the atherosclerotic
vessel wall include anti-adhesive, anti-proliferative and anti-inflammatory genes as well as
differentiated muscle markers.
Besides surgical interventions such as angioplasty and bypass surgery, various
pharmacological interventions have been used for the treatment of atherosclerosis and the
associated cardiovascular disease. Medications to lower cholesterol and LDL as well as those
which increase high-density lipoprotein (HDL) are normally utilized to prevent the
occurrence of atherosclerosis. For example, statins are used to inhibit an enzyme called
Hmgcr (3-hydroxy-3-methylglutaryl-coenzyme-A reductase), which is involved in
cholesterol biosynthesis. Yet another therapeutic strategy in the treatment of atherosclerosis is
the use of cell cycle inhibitors which include pharmacological agents, irradiation or gene
therapy, as vascular proliferation is central to atherosclerosis.
Immunosuppressive and anti-inflammatory drugs such as cyclosporine which block the
activation of T cells may also be used as a therapeutic treatment for atherosclerosis. In
addition to its cholesterol-lowering properties, statins also show pleiotropic effects including
immunosuppressive properties. Vaccination with oxidized LDL, bacteria containing modified
phospholipids or heat shock proteins is also an attractive approach to induce protective
immunity against atherosclerosis. Yet other approaches include transfer of anti-inflammatory
interleukins and administration of decoys and antibodies directed against pro-inflammatory
interleukins.
Most of the current approaches however, aim to treat atherosclerosis rather than to prevent it.
With the increase in health awareness among the public, it was realized through
epidemiological and experimental studies that diets containing high amount of
phytochemicals can also provide protection against free radical-induced diseases such as
atherosclerosis and cardiovascular disease, due to their high antioxidant activities. For
example, dietary antioxidants such as vitamin E, vitamin C, carotenoids, polyphenols and
coenzyme Q10 were found to be able to prevent atherogenesis.
Phenolic antioxidants from soy, pomegranate, ginger and red wine were also found to
attenuate atherosclerosis either by LDL-dependent mechanisms such as reducing LDL levels,
inhibiting LDL oxidation and increasing the antioxidant status or via other LDL-independent
mechanisms. Resveratrol, a phenolic phytoalexin found in red wine, was also suggested to
mediate cardioprotection through the preconditioning effect, rather than direct protection.
Preconditioning is achieved by subjecting the heart to a therapeutic amount of stress, thereby
disturbing normal cardiovascular homeostasis and reestablishing a modified homeostatic
condition with increased cardiac defences that can withstand subsequent stress insults.
Resveratrol was also found to increase the lifespan and survival of mice on a high-calorie
diet. Plant phenolics are thus promising candidates for the prevention of atherosclerosis and
related cardiovascular disease.
The oil palm {Elaeis guineensis) contains various phytochemicals which possess significant
antioxidant properties such as carotenoids, tocopherols and tocotrienols. The extraction of
water-soluble phenolics from the palm oil mill effluent (POME) through a completely
solvent-free process recovers another type of antioxidant from the oil palm, designated the
Essence of Palm® which contains various phenolic acids and polyphenols. This discovery
potentiates the two-pronged approach of reducing environment pollution caused by POME
while producing premium products for the pharmaceutical, nutraceutical and cosmeceutical
markets. Oil palm phenolics showed significant biological activities against LDL oxidation,
increased the amounts of HDL in hamsters fed an atherogenic diet and attenuated
atherosclerosis in blood vessels of atherogenic diet-fed rabbits.
In this study, we extended the knowledge that oil palm phenolics can attenuate
atherosclerosis by hypothesizing that the extract might influence certain gene expression
changes. We thus tested this hypothesis by feeding mice with either a low-fat normal diet
(14.6% kcal/kcal energy) or a high-fat (40.5% kcal/kcal energy) atherogenic diet containing
cholesterol (0.15% w/w). Each group was further given either distilled water (control group)
or oil palm phenolics (treatment group). By harvesting major organs such as livers, spleens
and hearts for microarray gene expression profiling analysis, we identified the biological
changes caused by oil palm phenolics in the normal diet fed mice, by the atherogenic diet and
by oil palm phenolics in the atherogenic diet fed mice, as well as discovered how the extract
changed the gene expression profiles caused by the atherogenic diet.
SUMMARY OF THE INVENTION
The invention relates to a composition useful for providing anti-obesity or anti- dyslipidemics
properties, and thus the prevention of artherosclerosis and cardiovascular diseases related
thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a graph for body and organ weights of mice;
Figure 2 depicts the GenMAPPs showing functions and genes significantly changed by oil
palm phenolics in the liver;
Figure 3 shows the illustration diagram of genes up-regulated by the Atherogenic Diet in the
liver;
Figure 4 shows the illustration diagram of genes down-regulated by the Atherogenic Diet in
the Liver Cholesterol Biosynthesis Pathway;
Figure 5 shows the illustration diagram of genes regulated by the Atherogenic Diet in the
Spleen;
Figure 6 shows the illustration diagram of genes regulated by the Atherogenic Diet in the
heart;
Figure 7 shows the illustration diagram of genes up-regulated by oil palm phenolics in the
liver unfolded protein response network;
Figure 8 shows the illustration diagram of genes down-regulated by oil palm phenolics in the
spleen antigen presentation network;
Figure 9 shows the illustration diagram of genes up-regulated by oil palm phenolics in the
heart antioxidant pathway;
Figure 0 shows a graph diagram of the percentage of genes which showed a change in
direction when regulated by oil palm phenolics as compared to the atherogenic diet;
Figure 11 shows a comparison of genes significantly changed by the atherogenic diet and oil
palm phenolics in terms of the direction of fold changes (liver data as example);
Figure 12 shows the illustration diagram of gene expression fold changes of eight target
genes as determined by microarray and real-time qRT-PCR experiments and their correlation;
Figure 13 shows the graph diagram of results of cytokine profiling on blood serum samples
from mice; and
Figure 14 shows the graph diagram of results of antioxidant analysis on blood serum samples
from mice.
DETAILED DESCRIPTION
All male inbred BALB/c mice n = 40) which were designated for this study were purchased
from the Institute of Medical Research, Kuala Lumpur, Malaysia, at around five weeks of age
just after weaning. All animal procedures were approved by the Animal Care and Use
Committee of the University of Malaya, Kuala Lumpur, Malaysia. The animals were
randomly assigned into cages (n = 5 per cage) and acclimatized for one week, during which a
standard chow diet purchased from the University of Malaya, and distilled water were given.
At the start of the experiment, the diet of the animals was changed to a custom-made low-fat
normal diet (58.2% kcal/kcal carbohydrate, 27.2% kcal/kcal protein and 14.6% kcal/kcal fat,
including cellulose, mineral mix, vitamin mix and DL-methonine) or a custom-made high-fat
atherogenic diet (40.5% kcal/kcal carbohydrate, 19.0% kcal/kcal protein and 40.5% kcal/kcal
fat, including 0.15% w/w cholesterol, as well as cellulose, mineral mix, vitamin mix and DLmethonine).
The normal control group (« = 10) and the atherogenic control group (« = 10)
were supplemented with distilled water while the normal treatment group (n = 10) and the
atherogenic treatment group (n = 10) were supplemented with oil palm phenolics as drinks ad
libitum. The antioxidant content of the oil palm phenolics given was around 1500 ppm gallic
acid equivalent. Food and fluid were changed daily. During the animal feeding process, body
weights were monitored every week. After six weeks, the mice were sacrificed via euthanasia
with diethyl ether and blood samples were collected via cardiac puncture. Six major organs
including livers, spleens, hearts, kidneys, lungs and brains were excised, blotted, weighed,
snap-frozen in liquid nitrogen and stored at -80°C.
The body weights of mice steadily increased every week throughout the six weeks of feeding,
with those on the atherogenic diet showing a higher increase in weight gain compared to
those on the normal diet (Figure 1A). In contrast, mice in the normal treatment group showed
a delay in weight gain throughout the six weeks of feeding (Figure 1A). When the organ
weights from the animals were compared, the atherogenic diet was found to cause an increase
in the weight of mouse livers (Figure IB). On the other hand, oil palm phenolics did not
significantly affect organ weights, both in mice given the normal diet and the atherogenic diet
(Figure IB). These results indicate that the addition of extra fat and cholesterol in the
atherogenic diet increased its energy content. This caused the livers of mice in the two
atherogenic diet groups to enlarge in order to accommodate an increased need for fat and
cholesterol processing, and resulted in a higher weight gain.
A portion (200 ) of whole blood samples obtained from about half of the animals (« = 4)
was aliquoted into a tube containing ethylenediaminetetraacetic acid (EDTA) (Ambion,
Austin, TX) to prevent clotting. These whole blood samples were immediately sent after
dissection of the animals to the Clinical Biochemistry and Hematology Laboratory,
Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine,
University of Putra Malaysia (UPM), Serdang, Selangor, Malaysia, for hematology analysis.
The analysis was carried out using the Animal Blood Counter Vet Hematology Analyzer
(Horiba ABX, France).
In order to obtain sera, the remaining blood samples from all of the animals ( = 10) were
allowed to clot at room temperature for 2 hours before centrifuging them at 3300 rpm for 5
minutes, after which the supernatant layers were collected and stored at -20°C. A portion (100
,) of each serum sample (n = 6 per group) was kept in aliquots for cytokine profiling and
antioxidant analysis. The remaining serum samples (around 200 ΐ per replicate) were then
sent for clinical biochemistry analysis using the Roche/Hitachi 902 Chemistry Analyzer
(Roche/Hitachi, Switzerland) in the Clinical Biochemistry and Hematology Laboratory,
Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine,
UPM. Clinical biochemistry parameters which were examined include alanine
aminotransferase, aspartate aminotransferase, glucose, serum total protein, albumin, globulin,
albumin:globulin ratio, total cholesterol, triglycerides, low-density lipoprotein (LDL) and
high-density lipoprotein (HDL). Two samples in each control group and three samples in
each treatment group were excluded from data analysis due to blood lysis.
In terms of hematology, mice given the atherogenic diet showed a significant increase in the
levels of white blood cells, neutrophils and lymphocytes when compared to those given the
normal diet (Table 1), indicating the presence of an inflammatory response. Oil palm
phenolics did not affect hematology parameters in both modules (Table 1). In terms of
clinical biochemistry, significant changes caused by the atherogenic diet involved the levels
of glucose ( ), albumin ) globulin (†), A:G ( ), total cholesterol (†), LDL-C (†) and HDLC
(†) (Table 2). Oil palm phenolics did not cause significant changes in the clinical
biochemistry parameters measured in each module, except for normalizing glucose levels in
the atherogenic diet module (Table 2).
Table 1: Hematology Parameters Measured Using Mouse Whole Blood Samples
Values shown are Means ± S.E.M.;
Means with different superscript letters are significantly different (P < 0.05).
Table 2 : Clinical Biochemistry Parameters Measured Using Mouse Serum Sampl
Normal Normal Atherogenic Atherogenic
Diet + Diet + Diet + Diet +
Test
Distilled Oil Palm Distilled Oil Palm
Water Phenolics Water Phenolics
Alanine Aminotransferase (ALT) (U L) 34.4 ± 3.3 42.5 ± 6.5 4 1.8 ± 10.7 a 32.2 ± 5.1
Aspartate Aminotransferase (AST) (U/L) 175.2 ± 23.8 240.4 ± 22.3 174.8 ± 29.3 157.2 ± 32.2
Glucose (mmol/L) 6.0 ± 1.1 6.7 ± 0.4 5.3 ± 0.4 7.4 ± 0.4
Serum Total Protein (g/L) 53.8 ± 1.8 53.8 1.1 53.2 ± 0.9 54.8 ± 0.7
Albumin (g L) 34.0 ± 0.9 33. 1± 1.3 29.4 ± 0.7 3 1.0 ± 0.7
Globulin (g/L) 19.8 ± 1.1 20.8 ± 0.8 23.8 ± 0.7 23.7 ± 0.7
A:G 1.8 ± 0.1 1.6 ± 0.1 1.2 ± 0.1 1.3 ± 0.1
Total Cholesterol (mmol/L) 3.46 ± 0.13 3.53 ± 0.19 a 4.77 ± 0.15 4.76 ± 0.19
Triglycerides (mmol/L) 1.05 ± 0.08 1.04 ± 0.1 1 1.13 ± 0.04 1.14 ± 0.15 a
Low-Density Lipoprotein (mmol/L) 0.15 ± 0.02 0.18 ± 0.03 a 0.26 ± 0.03 b 0.30 ± 0.06 b
High-Density Lipoprotein (mmol/L) 2.79 ± 0.1 1 2.83 ± 0.17 4.05 ± 0.11 3.93 ± 0.14
Values shown are Means ± S.E.M.;
Means with different superscript letters are significantly different (P < 0.05).
Microarray Gene Expression Analysis
For gene expression analysis, livers from the normal diet module as well as livers, spleens
and hearts from the atherogenic diet module were used in the total RNA extraction process.
Total RNA isolation from mouse organs was carried out using the RNeasy Mini Kit (Qiagen,
Inc., Valencia, CA) and QIAshredder homogenizer (Qiagen, Inc., Valencia, CA). The total
RNA samples obtained were subjected to NanoDrop 1000A Spectrophotometer for yield and
purity assessment. Integrity of the total RNA samples was then assessed using the Agilent
2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA) and Agilent RNA 6000 Nano Chip
Assay Kit (Agilent Technologies, Palo Alto, CA). Four total RNA samples with the highest
RNA Integrity Numbers and 28S/18S rRNA ratios within each condition were then selected
for microarray studies.
Amplification of total RNA samples which were of high yield, purity and integrity was
carried out using the Illumina TotalPrep RNA Amplification Kit (Ambion, Inc., Austin, TX).
The cRNA produced was then hybridized to the Illumina MouseRef-8 Expression BeadChip
Version 1 (Illumina, Inc., San Diego, CA), using the Direct Hybridization Kit (Illumina, Inc.,
San Diego, CA). Illumina MouseRef-8 Expression BeadChips contained 50-mer genespecific
probes for over 24000 genes which were designed based on the Mouse Exonic
Evidence Based Oligonucleotide (MEEBO) set, the RIKEN FANTOM 2 database and the
National Center for Biotechnology Information (NCBI) RefSeq (Release 5) transcript
database. Microarray hybridization, washing and scanning were carried out according to the
manufacturer's instructions.
In brief, cRNA was added with a hybridization buffer, and the hybridization mixture was then
briefly heated and hybridized to an Illumina BeadChip. The hybridized microarray then
underwent a series of washes using the wash buffers provided and 100% ethanol (Merck,
Darmstadt, Germany). Non-specific hybridization was blocked before incubating the
microarray with the Amersham Fluorolink Streptavidin Cy-3 dye (GE Healthcare Bio-
Sciences, Little Chalfont, UK) for detection, followed by a final wash with the wash buffer.
The microarray was then dried and scanned with the Illumina BeadArray Reader confocal
scanner and Illumina BeadScan software (Illumina, Inc., San Diego, CA), available at the
Malaysia Genome Institute, National University of Malaysia.
Quality control of the hybridization, microarray data extraction and initial analysis were
carried out using the Illumina BeadStudio software (Illumina, Inc., San Diego, CA). Outlier
samples were removed via hierarchical clustering analysis provided by the Illumina
BeadStudio software and also using the TIGR MeV software, via different distance metrics.
A minimum of three replicates per condition (with outliers removed) was then considered for
further analysis.
It should be noted that four comparisons of the microarray data obtained were made in this
study, with the first comparison to find out gene expression changes caused by oil palm
phenolics in the normal diet module (Normal Diet + Oil Palm Phenolics : Normal Diet +
Distilled Water). The second comparison was made to find out gene expression changes
caused by the atherogenic diet (Atherogenic Diet + Distilled Water: Normal Diet + Distilled
Water). The third comparison was made to identify gene expression changes caused by oil
palm phenolics in the atherogenic diet module (Atherogenic Diet + Oil Palm Phenolics :
Atherogenic Diet + Distilled Water). The fourth comparison was carried out to identify genes
which were regulated differently by the atherogenic diet and oil palm phenolics, by
comparing results from the second and third comparison. The first three comparisons were
carried out separately before the fourth comparison was made.
For the first three comparisons, gene expression values were normalized using the rank
invariant method and genes which had a Detection Level of more than 0.99 in either
condition (control or treatment) were considered significantly detected. To filter the data for
genes which changed significantly in terms of statistics, the Illumina Custom error model was
used and genes were considered significantly changed at a (Differential Score| of more than
20, which was equivalent to a P Value of less than 0.01. The stringency of this filtering
criterion was lowered to a (Differential Score| of more than 13, which was equivalent to a P
Value of less than 0.05, should less than 100 genes were considered significantly changed.
Since the results of this statistical analysis would be used for functional analysis, it would be
relevant to include more genes by using a lower threshold to give statistical power to the
functional analysis, in which functional significance could be assessed.
The genes and their corresponding data were then exported into the Microsoft Excel software
for further analysis. To calculate fold changes, an arbitrary value of 10 was given to
expression values which were less than 10. Fold changes were then calculated by dividing
means of Signal Y (treatment) with means of Signal X (control) if the genes were upregulated
and vice versa if the genes were down-regulated. Two-way (gene and sample)
hierarchical clustering of the significant genes was then performed using the TIGR MeV
software to ensure that the replicates of each condition were clustered to each other. The
Euclidean distance metric and average linkage method were used to carry out the hierarchical
clustering analysis.
For the first three comparisons, changes in biological pathways and gene ontologies were also
assessed via functional analysis, using the GenMAPP and MAPPFinder softwares. The
MAPPFinder software ranks GenMAPPs (pathways) and gene ontologies based on
hypergeometric distribution. GenMAPPs and gene ontologies which had Permuted P Values
of less than 0.01, Numbers of Genes Changed of more than or equal to 2 and Z Scores of
more than 2 were considered significant. A Permuted P Value of less than 0.05 was used
when genes were selected using a (Differential Score| of more than 13, in order to identify
more GenMAPPs and gene ontologies affected.
It should be noted that the MAPPFinder software clusters multiple probes for a distinct gene
into a single gene grouping in order to calculate the number of distinct genes which meet the
user-defined criteria, not the probes. In this study, up- and down-regulated genes were
analyzed separately in the functional enrichment analysis but were viewed together in each
GenMAPP. Boxes coloured yellow indicate genes which were up-regulated while those
coloured blue indicate genes which were down-regulated. The fold changes are indicated next
to the boxes. Individual boxes which have different shadings within them indicate the
presence of multiple probes (splice transcripts) within a single gene.
Changes in regulatory networks were also analyzed through the use of Ingenuity Pathways
Analysis software (Ingenuity® Systems, Redwood City, CA) [36] for the first three
comparisons. A data set containing differentially expressed genes and their corresponding
fold changes was uploaded into the application. Analysis of up- and down-regulated genes
were carried out separately. Each gene identifier was mapped to its corresponding gene object
in the Ingenuity Pathways Knowledge Base. These genes were overlaid onto a global
molecular network developed from information contained in the Ingenuity Pathways
Knowledge Base. Networks of these focus genes were then algorithmically generated based
on their connectivity.
A network is a graphical representation of the molecular relationships between genes or gene
products. Genes or gene products were represented as nodes, and the biological relationship
between two nodes was represented as an edge (line). The intensity of the node color
indicates the degree of up- (red) or down- (green) regulation. Nodes were displayed using
various shapes that represented the functional class of the gene product. Edges were
displayed with various labels that described the nature of the relationship between the nodes.
Gene descriptions which were not referenced emanated directly from the Ingenuity Pathways
Analysis software.
Oil Palm Phenolics Up-Regulated Fatty Acid Beta Oxidation Genes and Down-
Regulated Cholesterol Biosynthesis Genes in the Liver (Normal Diet Module)
Oil palm phenolics up-regulated 196 genes and down-regulated 54 genes in the livers of mice
on a normal diet, with the lists of genes and functions significantly changed supplemented in
Additional Files 1 and 2 respectively. Functional analysis on the microarray data from the
liver showed that oil palm phenolics up-regulated the fatty acid beta oxidation pathway
(Figure 2A). Among the fatty acid beta oxidation genes up-regulated were those encoding
sterol carrier protein (Sep), lysophospholipase (Lyplal), monoglyceride lipase (Mgll), acetylcoA
dehydrogenase (Acadt), acyl-coA dehydrogenases (Acads, AcadS), hydroxyacyl-coA
dehydrogenases (Hadhb, Hadhsc), acetyl-coA acetyltransferases (Acat2, Acat3) and acetylcoA
acyltransferase (Acaa2).
The liver is known as an organ active in fatty acid beta oxidation, and thus up-regulation of
hepatic fatty acid beta oxidation might contribute to the suppression of liver fat and visceral
fat accumulation. Up-regulated fatty acid beta oxidation may also contribute to the prevention
of diabetes, which is known to be caused by obesity and insulin resistance. Up-regulation of
genes involved in lipid catabolism has also been found to be caused by the catechins of green
tea and the chlorogenic acid of coffee. In addition, removal of lipids from the body through
fatty acid beta oxidation may prevent lipid peroxidation, which contributes to atherosclerosis.
Interestingly, enhanced hepatic fatty acid synthesis and reduced fatty acid oxidation have also
been implied in the development of an alcohol-induced fatty liver. Thus, we postulate that oil
palm phenolics may also be able to prevent alcohol-induced liver damage by up-regulating
hepatic fatty acid beta oxidation.
Genes involved in cholesterol biosynthesis on the other hand, such as those encoding
lanosterol synthase (Lss), sterol-C4-methyl oxidase-like (Sc4mol), farnesyl diphosphate
synthetase (Fdps), NAD(P) dependent steroid dehydrogenase-like (Nsdhl) and 3-hydroxy-3-
methylglutaryl-Coenzyme A synthase 1 (Hmgcsl) were down-regulated in this study (Figure
2B). It should be noted that the fold changes for most of the genes in the GenMAPP were
negative, indicating down-regulation, even for genes which were not selected as significantly
different based on the selection criteria used. Hmgcr which encodes for 3-hydroxy-3-
methylglutaryl-coenzyme-A reductase, an enzyme inhibited by cholesterol-lowering statins,
showed a negative fold change as well, although the value was not significantly different.
Cholesterol is an important constituent of cellular membranes and serves as a precursor in the
formation of bile acids and steroid hormones. Excessive cholesterol however, is involved in
atherosclerotic lesion and gallstone formation. The results obtained suggest that cholesterol
biosynthesis in the livers of these mice was reduced, and further imply that oil palm phenolics
may help to prevent atherosclerosis and cardiovascular disease. These results (up-regulated
fatty acid beta oxidation and down-regulated cholesterol biosynthesis in the liver) also
support earlier findings that oil palm phenolics were able to improve vascular health and
reduce atherosclerosis.
Gene Expression Changes in the Liver, Spleen and Heart (Atherogenic Diet Module)
The number of genes significantly changed by the atherogenic diet was highest in the liver
(2593 up-regulated and 451 down-regulated), followed by the spleen (990 up-regulated and
534 down-regulated) and the heart (1441 up-regulated and 991 down-regulated). The number
of genes significantly changed by oil palm phenolics was highest in the spleen (327 upregulated
and 249 down-regulated), followed by the liver (35 up-regulated and 84 downregulated)
and the heart (19 up-regulated and 13 down-regulated). In the latter comparison, as
the heart showed the least number of genes significantly changed (32 genes) which would not
give much information in further functional analysis, we further reduced this stringency by
filtering for significantly changed genes with a (Differential Score| of more than 13, which
was equivalent to a P Value of less than 0.05. This yielded 132 significantly changed genes in
the heart (79 up-regulated and 53 down-regulated). The lists of genes significantly changed
by the atherogenic diet and oil palm phenolics in these mouse organs, together with the fold
changes, are supplemented in Additional Files 3 and 4 respectively. The lists of GenMAPPSs
and gene ontologies significantly changed by the atherogenic diet and oil palm phenolics in
the major organs analyzed are given in Additional Files 5 and 6 respectively.
Increased Intake of Dietary Fat and Cholesterol Up-Regulated Liver Regeneration and
Down-Regulated Hepatic Cholesterol Biosynthesis
Administration of the atherogenic diet increased the turnover of metabolites in the liver, as
shown by an up-regulation of genes involved in the generation of precursor metabolites
(anabolism) and energy (catabolism). It was also evident that genes involved in fatty acid
beta oxidation, the tricarboxylic acid cycle and the electron transport chain were upregulated,
thus suggesting an increase in energy production due to the utilization of extra fat.
In addition, the turnover of liver tissues was also evident, due to the up-regulation of nuclear
receptors which stimulate hepatocyte growth such as Hnf4a (Figure 3A) as well as
cytochrome c oxidases, complement genes and caspases involved in cell death (Figure 3B).
Up-regulation of the fatty acid beta oxidation process would increase the metabolism of extra
fatty acids obtained from the atherogenic diet. This eventually results in an increased energy
production through the tricarboxylic acid cycle and electron transport chain. When
challenged with the atherogenic diet, the liver thus adjusts its metabolic processes in relation
to lipid metabolism and energy production. Interestingly, mitochondrial metabolism has been
implicated in the production of free radicals and degenerative diseases. It is thus possible that
the increase in energy production caused an increase in the production of free radicals in the
liver as well, thus resulting in oxidative stress.
As a result of this oxidative insult, nuclear receptors involved in tissue growth and genes
involved in cell death were up-regulated, thus suggesting that the atherogenic diet triggered
hepatic inflammatory reprogramming and liver regeneration in the mice. This also explains
the enlargement of livers which was observed in these animals. An example of a nuclear
receptor up-regulated is the hepatocyte nuclear factor 4-alpha {Hnf4a), which was also found
to be up-regulated when ApoE3Leiden (E3L) mice (which have lipid profiles resembling
those of humans) were fed an atherogenic diet. Hnf4a is central to the maintenance of
hepatocyte differentiation and is a major in vivo regulator of genes involved in the control of
lipid homeostasis. The up-regulation of this gene and other genes associated with it suggests
the important role of Hnf4a in maintaining the proper function of the liver when challenged
by oxidative stress.
Among the genes involved in cell death include those encoding cytochrome c oxidases
belonging to the mitochondrial electron transport chain, complement genes and caspases. The
up-regulation of these genes suggests that cell death occurred via apoptosis as a result of
complement-mediated cell damage. Activation of the terminal pathway of the complement
system leads to insertion of terminal complement complexes (C5b-9) into the cell membrane,
which may induce cytolysis. Recent data also indicate that the terminal complement pathway
(C5b-9) is involved in the induction of apoptosis via a caspase-dependent pathway.
Incidentally, besides being involved in the electron transport chain, cytochrome c oxidases
are essential in the apoptotic process. The up-regulation of these three groups of genes in the
same network thus implies that the atherogenic diet caused complement activation, resulting
in cell death via apoptosis. Interestingly, induction of the complement pathway in the liver
has also been associated with lesion development in atherosclerosis-prone LDL receptordeficient
(LDLr ) mice when they were fed a high-fat Western-style diet.
As expected, genes involved in cholesterol biosynthesis were down-regulated by the
atherogenic diet (Figure 4). Plasma or serum cholesterol levels are determined by inputs from
both diets and de novo biosynthesis, utilization of cholesterol especially in the liver and
steroidogenic tissues, as well as excretion of either cholesterol or bile acids. As the
atherogenic diet provided dietary cholesterol which further increased cholesterol levels in the
blood circulation, genes involved in hepatic cholesterol biosynthesis were down-regulated in
this study. This observation is expected due to the fact that de novo cholesterol biosynthesis is
down-regulated when cholesterol is available from dietary intake, and partly validates the
microarray gene expression data obtained.
A Heightened Production and Turnover of Immune Cells was Caused by the
Atherogenic Diet in the Spleen
The immune system has long been implicated in atherosclerosis, which is caused by an
inflammatory response. This response is mediated by endothelial cells, platelets, monocytederived
macrophages, dendritic cells, mast cells and specific subtypes of T lymphocytes or T
cells. Advanced human atheromas also contain a heterogeneous population of T cell
receptors. Some dendritic cells cluster with T cells directly within atherosclerotic lesions,
while others migrate to lymphoid organs to activate T cells. Macrophages, endothelial cells
and smooth muscle cells appear to be activated based on their expression of MHC class II
molecules and numerous inflammatory products. In addition, bone-marrow cells including
hematopoietic stem cells, also contribute to the pathological remodelling in atherosclerosis by
differentiating into smooth muscle cells. Non-bone marrow-derived circulating progenitor
cells in the adventitia of atherosclerotic lesions might also be a source for smooth muscle
cells, macrophages and endothelial cells in these lesions, besides the migration of these cells
from the tunica media.
In this study, genes involved in the immune response were up-regulated by the atherogenic
diet in the spleen, such as those regulated by tumour necrosis factor-alpha {Tnfa) and signal
transducer and activator of transcription 3 (Stat3) (Figure 5A). In addition, the apoptotic
process was also found to be up-regulated. On the other hand, genes down-regulated by the
atherogenic diet include those regulated by the tumour suppressor Tp53 (Figure 5B) and
transforming growth factor-beta (Tgfbl). Tp53 is anti-proliferative while Tgfbl is anti¬
inflammatory. The up-regulation of Tnfa and Stat3, coupled with the down-regulation of
Tp53 and Tgfbl, suggests the up-regulation of an inflammatory response towards the
atherogenic diet.
It is interesting to note that Stat3 was discovered because of its role in the acute phase
response, and that this is the only capacity in which its function in vivo can be clearly
ascribed to its activity as a transcription factor. Stat3 is important for hematopoietic
homeostasis as it plays a critical role in mediating cellular responses involved in the
production of immature and committed hematopoietic progenitors. In addition, Stat3 has been
implicated in many human lymphoproliferative and myeloproliferative diseases, including
multiple myeloma, non-Hodgkin lymphoma and acute myeloid leukemia, that display
deregulated Stat3 activation. In support of the observation that the Stat3 network was upregulated,
the B cell receptor pathway was also up-regulated in this study, further advocating
the role of Stat3 in encouraging the proliferation of immune cells. Together with the upregulation
of the Stat3 network, B cell receptor pathway and apoptosis, the down-regulation
of the tumour suppressor Tp53 implies that the atherogenic diet caused an increased turnover
of immune cells in the spleen, and thus explains the increased production and deployment of
immune cells in the blood circulation, which may further excerbate the in vivo inflammatory
effects of the atherogenic diet in this study.
The Atherogenic Diet Triggered an Inflammatory Response in the Heart
In the heart, the atherogenic diet increased the expression of genes involved in fatty acid beta
oxidation, proteasomal degradation, heme biosynthesis as well as inflammation including
those regulated by Tnfa, CREB (cyclic adenosine monophosphate response element binding)
binding protein (Crebbp) and Jun oncogene which is part of activator protein- 1 (Ap-1)
(Figure 6A). Down-regulated genes were found to be involved in glycolysis, circadian
rhythm, muscle development and anti-inflammatory networks such as those regulated by
sirtuin 1 (Sirtl) and Tgfbl (Figure 6B).
The Jun protein forms part of the transcription factor AP-1, which is pro-inflammatory as it
has been implicated in oxidative stress. Binding sites of the redox-regulated transcription
factor AP-1 are located in the promoter region of a large variety of genes that are directly
involved in the pathogenesis of diseases, including atherosclerosis. Activation of Jun via Jun
amino-terminal kinase (Jnk) in response to various forms of stress causes arterial injury and
heart disease. In addition, heme biosynthesis was also up-regulated by the atherogenic diet in
the heart, and this suggests increased turnover of red blood cells, most probably caused by
oxidative stress brought about by the diet.
On the other hand, Tgfb has been suggested to be anti-inflammatory in atherosclerosis, as it
plays an important role in the maintenance of normal blood vessel structure, while defects in
this superfamily of genes have been linked to a range of cardiovascular syndromes including
loss of healthy vessel architecture and aneurysm. Microarray profiling carried out on the
aortas from apolipoprotein E-deficient (apoE^ ) mice on a high-fat diet compared with control
C57B1/6J and C3H mice across time also showed a decreased expression of an isoform of
Tgfb. The down-regulation of the Tgfbl gene in this study thus implies a pro-inflammatory
response to the atherogenic diet in the heart.
The Unfolded Protein Response was Up-Regulated by Oil Palm Phenolics in the Liver
In livers of mice belonging to the atherogenic diet treatment group, genes involved in the
unfolded protein response were up-regulated (Figure 7) by oil palm phenolics compared to
the atherogenic diet control group. Down-regulation of genes involved in endogenous antigen
presentation, fatty acid metabolism, arylsulfatase activity, NADH dehydrogenase
(ubiquinone) activity and oxidoreductase activity were also observed, indicating a downregulation
of the inflammatory response and energy production.
Up-regulated genes involved in the unfolded protein response include Herpudl, Tral and
Vcp. Unfolded protein response can be promoted by the buildup of unfolded proteins in the
endoplasmic reticulum and constitutes a mechanism to reduce this burden. It acutely reduces
translation of new proteins, followed by increased expression of chaperones to aid folding of
existing proteins and enhanced elimination of proteins that cannot be refolded. Endoplasmic
reticulum stress responsive genes have been suggested to be a protective response to protein
unfolding or protein damage resulting from cellular stress signals. Accordingly, decreased
expression of Herpudl were reported to be found in prostate cancer patient specimens. Thus,
oil palm phenolics may help to reduce the amount of damaged proteins caused by the
atherogenic diet in the liver and thus lessen its turnover and metabolic burden.
Another interesting gene found regulated was Keapl, which was down-regulated by the
atherogenic diet but up-regulated by oil palm phenolics. Keapl is an inhibitor of Nrf2, which
normally sequesters Nrf2 in the cytoplasm. Under oxidative stress, the cysteine residues of
Keapl are oxidized and Nrf2 migrates to the nucleus to activate phase II antioxidant
enzymes. Of particular interest, KIAA0132, a human homolog of Keapl, was up-regulated by
rt-butylhydroquinone (tBHQ), a strong inducer of phase II detoxification enzymes via
activation of the antioxidant responsive element (ARE). Putative Nrf2 binding sites in the 5'-
flanking region of KIAA0132 also indicate that transcription of KIAA0132 can be increased
by the transcription factor that it sequesters, and thus this feedback effect may aim to keep in
balance the expression of ARE-driven genes.
Down-regulation of genes involved in endogenous antigen presentation such as H2-T23, H2-
T10, Cd59a and Mugl may be a mechanism by which oil palm phenolics reduce
inflammation brought about by the atherogenic diet. Genes involved in fatty acid metabolism
were also down-regulated, including Cpt2, Peer, Acas2, Fads2, Abcd3 and Abcg2. Fads2
encodes the rate-limiting enzyme in the synthesis of long-chain polyunsaturated fatty acids.
This function includes the synthesis of arachidonic acid that is needed for synthesis of the
eicosanoid biomediators that play central roles in cell signalling, cardiovascular regulation,
inflammation and blood coagulation.
Down-Regulation of Antigen Presentation in the Spleen Implies that Oil Palm Phenolics
Attenuated the Inflammatory Response
Compared to the atherogenic diet control group, genes up-regulated in spleens of mice in the
atherogenic diet treatment group are those involved in carbohydrate metabolism, glucose
metabolism, glutathione metabolism as well as cytoskeleton organization and biogenesis.
Genes down-regulated by oil palm phenolics in spleens of mice are involved in antigen
presentation (Figure 8), apoptosis, B cell receptor signalling, defence response, genes specific
to blood and lymph tissues, heme biosynthesis, immune response, regulation of apoptosis, T
cell activation and differentiation as well as T cell receptor signalling.
Transketolase (Tkt), which controls the nonoxidative branch of the pentose phosphate
pathway, provides NADPH for biosynthesis and reducing power for several antioxidant
systems [82]. It was up-regulated in the spleen by oil palm phenolics, together with glucose-
6-phosphate dehydrogenase (X-linked) (G6pdx) and phosphogluconate dehydrogenase (Pgd),
all of which are involved in the pentose phosphate pathway. The products of the pentose
phosphate pathway are important for the biosynthesis of purine and for stimulating
antioxidant response pathways in conjunction with the action of dietary phenolic
antioxidants. This may also explain the up-regulation of antioxidant genes including Mgstl,
Mgst2, Gsr and Gstml in the spleen by oil palm phenolics. Additionally, genes encoding
stefins {Stfal, Stfal) were up-regulated as well. These cystatins are natural inhibitors of
cysteine cathepsins, which have been implicated in antigen presentation and inflammation. In
addition, Anxa2, a phospholipase inhibitor, was up-regulated. Annexin A2 is a pleiotropic
protein which has been proposed to function inside the cell in sorting of endosomes and
outside the cell in anti-coagulant reactions.
Genes encoding MHC molecules such as H2-Abl and H2-Ebl which have been implicated in
atherosclerosis, were down-regulated in the spleen, thus suggesting that oil palm phenolics
were able to attenuate the inflammatory response brought about by the atherogenic diet.
Other MHC genes down-regulated include H2-Aa, H2-Bf H2-Dma, H2-DMb2, H2-Ea, H2-
Q6, H2-Q7, H2-T9, H2-T10, H2-T17 and H2-T23. Activated macrophages and smooth
muscle cells express MHC II antigens such as HLA-DR that allow them to present antigens
to T cells, which cause atherosclerosis. In addition, MHC II expression is also central to the
immune regulation in T cell-mediated autoimmune diseases.
The gene expression of MHC II molecules are transcriptionally regulated by the class II
transcriptional activator (CIITA or C2ta). CIITA activates the expression of MHC II in all
types of professional antigen-presenting cells (macrophages, dendritic cells, B lymphocytes),
of which dendritic cells are the most potent among the three. Interferon-represses collagen
synthesis and increases the expression of MHC II molecules in aortic smooth muscle cells
through CIITA, contributing to atherosclerosis. In line with the down-regulation of major
histocompatibility complexes, the C2ta gene was down-regulated in this study (Figure 8).
This is similar to the effects of statins, which are largely used in the treatment of
cardiovascular disease not only because of their therapeutic effect in lowering cholesterol
levels but also in decreasing the expression of MHC II genes, in which C2ta has been
demonstrated as a target.
The Ccr7 receptor present on the surface of secondary lymphoid cells, functions to attract
dendritic cells which migrate to secondary lymphoid organs to present antigens to activate
naive T cells. A mechanism of anti-inflammation by antioxidants is through the modulation
of cytokine induction during inflammation. In line with this, cytokines and cytokine receptors
such as Ccl5, Cell 9 and Ccr7 were down-regulated by oil palm phenolics in this study.
Additionally, antigenic markers such as Cd3d, Cd24a, Cd59b, Cd72, Cd79a, Cd79b, Cd83
and Cd86 were down-regulated. These markers are present on dendritic cells and interact
with counter-receptors on T cells to enhance co-stimulation and adhesion. Cd83 and Cd86 are
specific markers of mature dendritic cells, which are up-regulated by oxidative stress through
a NF-KB-dependent mechanism. The down-regulation of MHC II genes and genes encoding
antigenic markers thus suggests that oil palm phenolics suppressed the inflammatory
response associated with the atherogenic diet, and this may represent a mechanism by which
oil palm phenolics ameliorate atherosclerosis.
Antioxidant Genes were Up-Regulated by Oil Palm Phenolics in the Heart
In hearts of mice, genes up-regulated by oil palm phenolics include those involved in
oxidative stress (Figure 9), circadian exercise and nucleosome assembly. Down-regulated
genes on the other hand, are involved in electron transport and signalling as well as cell
proliferation and migration.
Up-regulated genes involved in antioxidant activities include Mgstl and Gpxl. These
antioxidant genes are essential in the detoxification of carcinogens and scavenging of reactive
oxygen species. Fstll or TSC-36, which has been shown to inhibit the proliferation of
vascular smooth muscle cells in vitro and in vivo following stimulation of TGF-, was upregulated
as well. Down-regulated genes on the other hand, are involved in electron transport
and signalling. Genes involved in cell proliferation and migration (which have been
implicated in atherosclerosis), such as Egf, Ltbp4, Smtn, Vtn and Lgals4 were down-regulated
as well. Alas2, a gene which is red cell specific, was also down-regulated. This is in contrast
with the observation that the atherogenic diet up-regulated genes involved in heme
biosynthesis, which further indicates that oil palm phenolics decreased heme turnover caused
by the atherogenic diet and thus functioned to reduce oxidative stress in the heart.
Comparison of Genes Significantly Changed by the Atherogenic Diet and Oil Palm
Phenolics
In order to assess how oil palm phenolics affected genes changed by the atherogenic diet,
genes significantly changed by the atherogenic diet were intersected with genes significantly
changed by oil palm phenolics in the atherogenic diet module to obtain a set of genes which
were significantly regulated by both factors (atherogenic diet and oil palm phenolics). This
comparison is given in Additional File 7. The percentages of genes which were differentially
regulated by both factors in terms of direction were then calculated, with the results shown in
Figure 10. A majority (> 50%) of the genes regulated by oil palm phenolics in the different
organs showed a difference in direction of regulation when compared to the atherogenic diet.
The highest percentage of change was found in the liver while the lowest percentage of
change was found in the spleen. Figure 11 shows a diagram to compare the fold change
direction of genes significantly changed by the atherogenic diet and oil palm phenolics, using
the liver as an example.
Unchanged changes are genes which show a similar direction of regulation by the
atherogenic diet and oil palm phenolics while changed genes showed an opposite direction of
regulation by the two factors. The percentage of changed genes was calculated by dividing
the amount of genes which changed in terms of direction of regulation with the total number
of genes significantly changed by both factors.
ND + DW indicates Normal Diet + Distilled Water, AD + DW indicates Atherogenic Diet +
Distilled Water and AD + OPP indicates Atherogenic Diet + Oil Palm Phenolics. Values of
fold changes are represented using a blue-black-yellow (negative to positive) colour scheme.
The |Differential Score| for all genes is more than 20, equivalent to a P Value of less than
0.01.
Real-Time qRT-PCR Validation
To confirm the microarray results, the expression levels of eight target genes (Table 3) were
measured using real-time quantitative reverse transcription-polymerase chain reaction (qRTPCR).
The first two target genes were found to be changed by oil palm phenolics in the
normal diet module (first comparison). For the atherogenic diet module, as the focus of this
study was more to identifying the changes caused by oil palm phenolics rather than the
atherogenic diet, the remaining six target genes chosen for real-time qRT-PCR were from the
third comparison (Atherogenic Diet + Oil Palm Phenolics : Atherogenic Diet + Distilled
Water). The genes were chosen based on their differential scores, in which the most
significantly up-regulated and down-regulated genes in each of the organ tested were
selected.
Table 3: Genes Selected for the Real-Time qRT-PCR Validation Experiments
* Housekeeping gene.
These genes were also present in the GenMAPPs and gene ontologies identified as
significantly changed by the GenMAPP software. These genes also showed detection levels
of 1.0000 in both the control and treatment groups, which indicate that they were
significantly expressed in both groups. In addition, the genes chosen were also present as
single splice transcripts in the microarrays used. The reason for this selection criterion was to
minimize discordance between the two gene expression profiling techniques as differences in
probe designs between microarrays and TaqMan assays might result in detection of additional
splice variants. Finally, all of the TaqMan assays selected had suffixes of ml, which indicate
that the probes were designed across splice junctions, and would avoid the detection of
genomic DNA.
Expression levels of target genes were normalized to the geometric mean of three
housekeeping genes, Sfrs9, Gukl and Hnrpab. These genes were chosen as they were shown
to be stable across the previously obtained microarray data. Eukaryotic 18S rRNA
Endogenous Control was also tested together with the three housekeeping genes in
preliminary experiments, and their stabilities were determined using the geNorm software.
However, this gene was found to be the least stable of the four housekeeping genes tested and
was thus further dropped as an endogenous control (data not shown).
Expression fold changes for each gene quantitated by the qBase software based on the real¬
time qRT-PCR data obtained, together with those determined by the previous microarray
experiments, are shown in Figure 12A. The direction and magnitude of fold changes obtained
from the real-time qRT-PCR technique were comparable to those obtained from the
microarray technique. As shown in Figure 12B, correlation of fold changes obtained by the
two gene expression profiling techniques was high (R2 = 0.9877), thus validating the
microarray data obtained.
Serum Cytokine Profiling Supported In Vivo Anti-Inflammatory Effects of Oil Palm
Phenolics
Multiplex cytokine profiling on serum samples was carried out using the Bio-Plex
Suspension Array System (Bio-Rad Laboratories, Hercules, CA), which is a microbead and
flow-based protein detection system based on the Luminex xMAP technology, available at
the Medical Biotechnology Center, Faculty of Medicine, University of Malaya. The Bio-Plex
Mouse Cytokine 23-Plex Cytokine Panel (Bio-Rad Laboratories, Hercules, CA), which
included antibody-conjugated beads for 23 types of mouse cytokines, was also utilized. The
cytokines present in this panel include IL-la, IL- , IL-2, IL-3, IL-4, IL-5, IL-6, IL-9, IL-10,
IL-12 (p40), IL-12 (p70), IL-13, IL-17, Eotaxin, G-CSF, GM-CSF, IFN-, KC, MCP-1
(MCAF), MIP- 1a , MIP- 1, RANTES and TNF-a.
The experiment was carried out according to manufacturer's instructions. Each serum sample
{n ~ 6) was tested in duplicates. The data were analyzed using the Bio-Plex Manager Version
4.0 software (Bio-Rad Laboratories, Hercules, CA). Generation of standard curves, averaging
of duplicate fluorescence readings of each serum sample, background subtraction with the
blank and calculation of concentration for each cytokine were carried out by the Bio-Plex
Manager software. The averaged concentration readings were exported into Microsoft Excel
for statistical analysis, in which the two-tailed unpaired Student's t-test was used. Differences
with t-test p-values of less than 0.05 were considered statistically significant.
For serum cytokine profiling, the amounts of eotaxin were surprisingly high for all animals in
the three groups (Figure 13A). This may be caused by the exposure of the animals to the nonsterile
environment as they were not maintained in a specific pathogen-free facility. In the
normal diet module, RANTES was significantly reduced in the treatment group compared to
the control group (Figure 13B). This may be a sign of lowered inflammation as RANTES had
been implied in inflammation, obesity and cerebral microvascular dysfunction. For those on
the atherogenic diet, there was a significant decrease in interleukin-12 (p40 subunit) (IL-12
(p40)) and a significant increase in interleukin-13 (IL-13) in the group given oil palm
phenolics when compared to the atherogenic control group (Figure 13B).
As a component of the immune response, cytokines too play an important role in mediating
the inflammatory response in atherosclerosis. Atherosclerotic lesions normally contain
cytokines that promote a Thl cellular immune response (interferon- , interleukin-1,
inter leukin-2, TNF-a and TNF-) rather than a Th2 humoral immune response (interleukin-4,
interleukin-5 and interleukin-10) [99]. In mice belonging to the atherogenic diet treatment
group, a decrease in the pro-inflammatory IL-12 (p40) cytokine and an increase in the anti¬
inflammatory IL-13 cytokine in the sera were observed when compared to the atherogenic
diet control group. This is believed to be an attenuation of the inflammatory response towards
atherosclerosis.
IL-12 is a cytokine of innate immunity which is secreted by activated macrophages and
dendritic cells, and is a key inducer of cell-mediated immunity as it stimulates the production
of IFN-, stimulates the differentiation of CD4+ helper T lymphocytes into THI cells as well
as enhances cytolytic functions of activated NK cells and CD8+ cytolytic T lymphocytes. It
has been implicated in atherosclerosis and other inflammatory diseases, and have been found
to be attenuated by several antioxidative plant compounds such as catechins, curcumin,
apigenin and silibinin. IL-13 is a cytokine of adaptive immunity which is secreted by CD4+
helper T lymphocytes (TH2 cells), and it inhibits macrophages and antagonizes IFN-. The
anti-inflammatory effects observed in the serum samples were consistent with the gene
expression changes seen in the spleens of mice given oil palm phenolics, which indicate
attenuation of the inflammatory response.
Serum Antioxidant Analysis Confirmed In Vivo Antioxidant Effects of Oil Palm
Phenolics
The basic mechanism for the antioxidant assays used in this study involves the transfer of an
electron from the antioxidant to the probe, which is normally an oxidant. This results in the
formation of an oxidized antioxidant and a reduced probe. Antioxidant analysis on serum
samples was carried out using four assays including the total phenolics content by Folin-
Ciocalteu reagent (TP-FCR) assay, the ferric reducing ability of plasma (FRAP) assay, the
2,2-diphenyl-l-picrylhydrazyl (DPPH) scavenging activity assay and the Trolox equivalent
antioxidant capacity (TEAC) assay. All these assays were carried out using the Infinite M200
microplate reader (Tecan, Austria). Each serum sample n = 6) was tested in duplicates.
Measurement settings and data acquisition were carried out using the Magellan Version 6.2
software (Tecan, Austria). Generation of standard curves, averaging of duplicate absorbance
readings of each sample, background subtraction with the blank, calculation of concentration
and statistical analysis for each assay were carried out in Microsoft Excel. Statistical analysis
was carried out by using the two-tailed unpaired Student's t-test. Differences with t-test pvalues
of less than 0.05 were considered statistically significant.
For the TP-FCR assay, gallic acid was prepared in a range of 0 to 2000 mg/mL to generate
the standard curve. For serum analysis, 15 of 100% ethanol was added to 15 of each
serum sample in order to precipitate macromolecules out. The mixture was then vortexed for
two minutes and centrifuged at 1100 xg for five minutes. The clear supernatant was then
collected for analysis. A master mix containing 40 of distilled water and 4 of FolinCiocalteu
reagent for each reaction to be carried out was prepared. This master mix was then
aliquoted into a clear 96-well flat bottom microplate. The microplate was read at an
absorbance of 765 nm. 2 of sample or gallic acid standard diluent was then pipetted into
each well, followed by 20 of 15% w/v disodium carbonate (Na2C0 3) . The microplate was
then shaken at maximum intensity for 10 seconds and incubated at room temperature for 2
hours. Absorbance was read at 765 nm. The 765and concentration of gallic acid
equivalent for each sample were calculated based on the standard curve obtained.
For the FRAP assay, ferrous sulphate heptahydrate (FeS0 4.7H20 ) was prepared in a range of
0 to 2000 /L to generate the standard curve. Solutions A, B and C were then prepared.
Solution A comprised of 300 mM acetate (C2H3Na0 2.3H20 ) buffer pH 3.6 in 16% v/v acetic
acid (C2H 0 2) . Solution B comprised of 10 mM 2,4,6,-tri(2-pyridyl)-s-triazine (TPTZ)
solution in 40 mM hydrochloric acid (HC1). Solution C comprised of 20 mM ferric chloride
hexahydrate (FeCl3.6H20 ) solution in distilled water. The straw coloured FRAP reagent was
then prepared by mixing 25 mL of Solution A, 2.5 mL of Solution B and 2.5 mL of Solution
C. It was then kept in a water bath at 37°C. 180 of FRAP reagent was then aliquoted into a
clear 96-well flat bottom microplate. The microplate was read at an absorbance of 593 nm. 8
of sample or FeS0 4.7H20 standard diluent was then pipetted into each well. The
microplate was then shaken at maximum intensity for 10 seconds and incubated at 37°C for
10 minutes. Absorbance was read at 593 nm. The 593and concentration of Trolox
equivalent for each sample were calculated based on the standard curve obtained.
For the DPPH assay, Trolox was prepared in a range of 0 to 500 /L to generate the
standard curve. For serum samples, 15 of 100% ethanol was added to 15 of each
serum sample in order to precipitate macromolecules out. The mixture was then vortexed for
2 minutes and centrifuged at 1100 xg for 5 minutes. The clear supernatant was then collected
for analysis. 0.2 mmol/L DPPH was prepared in 50% v/v ethanol. 95 ΐ of this DPPH
solution was then aliquoted into a clear 96-well flat bottom microplate. The microplate was
read at an absorbance of 515 nm. 5 of sample or Trolox standard diluent was then pipetted
into each well. The microplate was then shaken at maximum intensity for 10 seconds and
incubated at room temperature for 10 minutes. Absorbance was read at 515 nm. The
AA515nm and concentration of Trolox equivalent for each sample were calculated based on
the standard curve obtained.
For the TEAC assay, a 7 mM 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS)
solution and a 2.45 mM dipotassium persulfate (K 0 S2) solution were first prepared in
distilled water each. The ABTS reagent was then prepared by mixing 25 mL of ABTS
solution with 12.5 mL of K20gS2 solution and held in darkness for 16 hours at room
temperature to produce a dark green coloured solution. The following day, Trolox was
prepared in a range of 0 to 200 /L to generate the standard curve. 180 ί of ABTS
reagent was then aliquoted into a clear 96-well flat bottom microplate. The microplate was
read at an absorbance of 734 nm. 18 ΐ sample or Trolox standard diluent was then
pipetted into each well. The microplate was then shaken at maximum intensity for 10 seconds
and incubated at 37°C for 6 minutes. Absorbance was read at 734 nm. The AA734nm and
concentration of Trolox equivalent for each sample were calculated based on the standard
curve obtained.
For serum antioxidant analysis, the standard curves obtained for the four assays carried out
had R values > 0.9 (data not shown). No significant changes were caused by oil palm
phenolics in the normal diet module (Figure 14), and this was quite unexpected. However, it
should be noted that the administration of a commercially available source of olive phenolics
(Olivenol Livin') derived from olive mill wastewater also did not increase plasma total
antioxidant status although blood was drawn one hour after ingestion of the preparation for
analysis, similar to previous studies carried out on olive oil wastewater extract and olive leaf
supplements. The lack of effect on the total antioxidant capacity observed was interpreted in
terms of lower attainable concentrations of olive phenolics as compared to endogenous
antioxidants. This may also be the case for oil palm phenolics.
The antioxidant analysis carried out on the serum samples showed that for the atherogenic
diet control group, there was a significant decrease in antioxidant capacity when compared to
mice given the normal diet, which indicates a higher oxidative stress in mice given the
atherogenic diet (Figure 14). This is similar to the observations carried out by previous
studies. The atherogenic diet treatment group on the other hand, showed almost similar
antioxidant capacity when compared to mice given the normal diet, thus indicating that the
antioxidant resistance of mice supplemented with oil palm phenolics was still high although
they were also given the atherogenic diet. This further implies that oil palm phenolics
restored the antioxidant capacity of mice given the atherogenic diet, and is in line with the
gene expression changes observed in the major organs of mice, in which antioxidant genes
were up-regulated.
As a summary, it was found that oil palm phenolics up-regulated fatty acid beta oxidation and
down-regulated cholesterol biosynthesis in livers of mice given the normal diet. This might
explain the slight delay in weight gain caused by the extract, and further imply the application
of oil palm phenolics in promoting weight loss and preventing obesity. The administration of
the atherogenic diet increased cellular proliferation and turnover in the major organs of mice
studied, including the liver, spleen and heart. An increased intake of fat and cholesterol
caused an increased circulation and utilization of the respective metabolites in these organs,
which further induced oxidative stress, inflammation, injury, cellular proliferation and tissue
regeneration to compensate for the increased metabolic burden, especially in the liver.
Among the genes found to be regulated by the atherogenic diet, it was most apparent that
those linked to the pro-inflammatory Tnfa were up-regulated, while those linked to the anti
inflammatory Tgfb were down-regulated, especially in the spleen and heart.
On the other hand, oil palm phenolics showed signs of attenuating the effects of the
atherogenic diet. This extract increased unfolded protein response in livers of mice, which is
important in getting rid of misfolded proteins, while attenuated antigen presentation and
processing in spleens of mice, similar to the effects of statins. Oil palm phenolics also
increased the expression of antioxidant genes in the hearts of these mice. A majority (> 50%)
of the genes regulated by oil palm phenolics in the different organs showed a difference in the
direction of regulation when compared to the atherogenic diet.
Despite that fact that oil palm phenolics did not significantly alter the body and liver weights
as well as the clinical biochemistry and hematology parameters of mice on the atherogenic
diet, further cytokine profiling and antioxidant analysis on mouse blood serum samples
managed to confirm the in vivo anti-inflammatory and antioxidant effects of the extract. In
contrast with the effects of oil palm phenolics which down-regulated cholesterol biosynthesis
genes in mice fed the normal diet, the extract did not cause a further reduction in this group
of genes. This made sense as administration of the atherogenic diet already down-regulated
cholesterol biosynthesis, and thus further down-regulation of the pathway would be futile to
prevent atherosclerosis. On the other hand, oil palm phenolics acted as an anti-inflammatory
agent and an antioxidant in mice given the atherogenic diet to prevent oxidative stress caused
by the diet. These findings suggest that oil palm phenolics can be used to overcome the
effects of an atherogenic diet and further imply the potential of this extract as a
chemopreventive agent for atherosclerosis and cardiovascular disease.
Generally, the composition in accordance with the present invention may be prepared in
various suitable forms for direct or oral administration for the health purposes as discussed
earlier in the preceding sections.
For instance, the compositions of the present invention may be provided in the following
forms, but no limiting to, suitable for oral administration containing a pre-determined amount
of the extract; a solution or a suspension in an aqueous or non-aqueous liquid, tablets,
capsules and the likes.
The compositions of the invention may also be administered to a human in a dietary
supplement form. Dietary supplements incorporating the active composition can be prepared
by adding the composition to a food in the process of preparing the food. The composition is
added to the food in an amount selected to deliver a desired dose of the composition to the
consumer of the food.
The composition comprising the compounds in accordance with the present invention may be
prepared for use in a pharmaceutically effective or nutraceutically effective amount, solely on
its own or in combination with other agents or compounds deemed appropriate by a person
skilled in the art.
In one embodiment the compositions may be administered in form of doses, within a
predetermined period of time, whereby it may be administered for example but not limiting to
daily, weekly or monthly.
In another embodiment the compositions may be provided in conventional treatment forms,
pharmaceutical formulations or as nutritional supplement.
In one embodiment the composition of the present invention may be provided in a
nutraceutical form.
Those skilled in the art will appreciate that the invention described herein is susceptible to
variations and modifications other than those specifically described. It is to be understood
that the invention includes all such variations and modifications. The invention also includes
all of the steps, features, compositions and compounds referred to or indicated in this
specification, individually or collectively, and any and all combinations of any two or more
of said steps or features.
CLAIMS
1. A composition useful for providing anti-obesity or anti- dyslipidemics properties,
wherein said composition comprising oil palm phenolics.
2. A composition useful for providing anti-obesity or anti-dyslipidemics properties,
wherein said composition comprising extracts from oil palm.
3. The composition as claimed in Claim 2 wherein the extracts comprise oil palm
phenolics.
4. The composition as claimed in Claim 1 wherein the composition is useful for
prevention of artherosclerosis and cardiovascular diseases and diseases related thereto.
5. The composition as claimed in Claim 1 wherein composition is useful for reducing
the inflammatory effects of an atherogenic diet.
6. The composition as claimed in Claims 1 to 5 wherein the composition prevents
oxidative stress caused by the atherogenic diet.
7. The composition as claimed in anyone of Claims 1 to 5 wherein the composition
delays the onset of obesity and attenuates the inflammatory response of atherogenic diet,
whereby the composition aids to suppress the inflammatory response thereby ameliorating
artherosclerosis.
8. The composition as claimed in Claim 1 wherein the composition delays weight gain
or obesity thereby preventing the effects of dyslipidemia.
9. The composition as claimed in Claim 1 wherein the composition is further useful to
induce reduction of cholesterol biosynthesis.
10. The composition as claimed in Claim 1 wherein the composition is further useful in
up-regulating fatty acid beta oxidation.
11. The composition as claimed in Claim 1 wherein the composition is further useful in
suppression of liver fat and visceral fat accumulation by way of up-regulating the fatty acid
beta oxidation.
12. The composition as claimed in Claim 1 wherein the composition is further useful in
preventing diabetes.
13. The composition as claimed in Claim 1 wherein the composition is further useful in
preventing alcohol-induced liver damage.
14. The composition as claimed in Claim 1 wherein the composition is further useful in
up-regulating unfolded protein response, thus eliminating the proteins that cannot be refolded.
15. The composition as claimed in Claim 1 wherein composition is further useful in
down-regulating antigen presentation.
16. The composition as claimed in Claim 1 wherein the composition is further useful in
reducing damaged proteins caused by artherogenic diet.
17. The composition as claimed in Claim 1 wherein the extract is obtained from any part
of palm oil.
18. The composition as claimed in Claim 1 wherein the extract is obtained from palm oil
mill vegetation liquor.
19. Use of a pharmaceutically acceptable amount of a composition comprising an extract
containing oil palm phenolics in the preparation of a medicament for the treatment and
prevention of atherosclerosis and cardiovascular diseases related thereto in a patient in need
thereof.
20. The composition as claimed in Claim 19 wherein the composition is provided in solid
dosage form.
2 1. The composition as claimed in Claim 19 wherein the composition is provided in
liquid dosage form.
22. The composition as claimed in Claim 19 wherein the composition is provided in
solution form.
23. The composition as claimed in Claim 19 wherein the composition is provided in a
pharmaceutically effective form.
24. The composition as claimed in Claim 19 wherein the composition is provided in
nutraceutical form.
25. The composition as claimed in Claim 19 wherein the composition is in nutritional
supplementary form.
26. The composition as claimed in Claim 19 wherein the composition is provided in a
form suitable for oral administration.
AMENDED CLAIMS
received by the International Bureau on 15 June 2011 (15.06.2011)
. A composition comprising extracts containing oil palm phenolics in an amount effective for use
in a method of reducing cholesterol biosynthesis and thus preventing obesity.
2. The composition as claimed in Claim 1 wherein the composition up regulates fatty acid beta
oxidation and down regulates cholesterol biosynthesis in livers,
3. The composition as claimed in Claim 1 wherein the composition is useful for prevention of
obesity associated diseases.
4. The composition as claimed in Claim 1 wherein composition is useful for preventing oxidative
stress caused by atherogenic diet and thus reducing the inflammatory effects of an atherogenic diet,
5. The composition as claimed in Claim in 5 wherein the composition delays the onset of obesity
and attenuates the inflammatory response of atherogenic diet, whereby the composition aids to
suppress the inflammatory response thereby ameliorating artherosclerosis.
6. The composition as claimed in Claim 1 wherein the composition delays weight gain or obesity
thereby preventing the effects of dyslipidemia.
7. The composition as claimed in Claim 1 wherein the composition is further useful in suppression
of liver fat and visceral fat accumulation by way of up-regulating the fatty acid beta oxidation.
8. The composition as claimed in Claim 1 wherein the composition is further useful in preventing
alcohol-induced liver damage.
9. The composition as claimed in Claim 1 wherein the composition is further useful in upregulating
unfolded protein response, thus eliminating the proteins that cannot be re-folded.
1 . The composition as claimed in Claim 1 wherein composition is further useful in down-regulating
antigen presentation.
11. The composition as claimed in Claim 1 wherein the composition is further useful in reducing
damaged proteins caused by artherogenic diet.
12. The composition as claimed in Claim 1 wherein the extracts are extract is obtained from any
part of palm oil.
13. The composition as claimed in Claim 1 wherein the extract is obtained from palm oil mill
vegetation liquor.
14. Use of a pharmaceutically acceptable amount of a composition comprising extracts containing
oil palm phenolics in the preparation of a medicament for preventing obesity and reducing cholesterol
biosynthesis in a patient in need thereof.
15. The use as claimed in Claim 19, effective for up regulating fatty acid beta oxidation and down
regulating cholesterol biosynthesis in livers.
16. The use as claimed in Claim 19, effective for attenuating the effects of atherogenic diet.
17. The use as claimed in Claim 1 , effective for providing anti-dyslipidemic properties.
18. The use as claimed in Claim 19 wherein the medicament is provided in solid dosage form.
19. The use as claimed in Claim 19 wherein the medicament is provided in liquid dosage form.
20. The use as claimed in Claim 19 wherein the medicament is provided in solution form.
21. The use as claimed in Claim 19 wherein the medicament is provided in a pharmaceutically
effective form.
22. The use as claimed in Claim 19 wherein the is provided in nutraceutical form.
23. The use as claimed in Claim 19 wherein the medicament is in nutritional supplementary form.
The use as claimed in Claim 19 wherein the medicament is provided in a form suitable for oral administration.