A NOVEL SESQUITERPENE (+) -1-BISABOLONE AND A PROCESS FOR ISOLATION FROM CYBOPOGON FLEXUOSUS
Field of the invention
The present invention relates to a novel sesquiterpene (+)-l-bisabolone and a process for isolation from Cymbopogon flexuosus mainly responsible for the strong anti-microbial/anti-bacterial activity. The present invention particularly relates to antibacterial activity of the essential oil and a pure isolate identified as (+)-l-bisabolone of formula 1 against gram positive bacteria from a strain of a grass identified as ( ymbopogon flexuosus.
(Formula Removed)
Background of the invention
Cymbopgon species (family Poaceae) are native to tropical and subtropical regions of Asia and Africa. The aromatic grasses such as Cymbopogon and Tetiverla zizanioides have been known because of their medicinal and perfumery values. The genus Cymbopogon is well known source of aroma chemicals especially terpenoids. Essential oil derived from Cymbopogon species such as Java citronella (Cymbopogon winterianus). Palmarosa (Cymbopogon martini var. motiu) and Lemongrass (Cymbopogon flexuosus) are very popular and widely consumed in the world market. The chemical compounds present in varying concentrations in the species, varieties, ecotypes and chemotypes of the Cymbopogon grass have a great demand due to their uses in perfumery, flavour and pharmaceutical industry. There are approximately sixty species of Cymbopogon native to tropical and subtropical regions of Africa and Asia. (Corrigan. D 1992, in "Adverse Effects of Herbal Drugs" Vol. 1. Springer verlag. Berlin. 115-123). Out of twenty seven species available in India mainly Cymbopogon flexuosus, C.winterianus and C.martini var. motia have been exploited for commercial cultivation as a source of citral, citronellal and geraniol respectively.
The present invention is based on materials having excellent propert es having microstnicture.
the discovery of a genus of acrylic-based resinous for the fabrication of LMF's and other articles
The invention includes articles wh ch are radiation curable to optical resinous articles
having surfaces with a replicated
nicrostructure comprising a plurality of utilitarian

discontinuities having an optical p irpose, said optical resinous articles having a glass
transition temperature of at least'. articles so prepared.
5°C. Also included are the cured optical resinous
are free from carbocyclic and heterocyclic
Said radiation curable articles polymerizable moieties and comprise:
(A) at least one monofunctiona] a crylic monomer selected from the group consisting of:
at least one monomeric t-aikyf |(meth)acrylate,
at least one monomeric N-sub^tituted or N,N-disubstituted (meth)acrylamide and
(3) at least one C\* primary or secondary alkyl (meth)acrylate;
at least one multifunctional (njieth)acrylate or (meth)acrylamide monomer;
optionally, at least one oligon^eric multifunctional (meth)acrylate; and
at least one photoinitiator.
BRIEF DESCRIPTION OF THE|DRAWINGS
FIGURE 1 is a schematic view o
a LMF in a backlit liquid crystal display.
FIGURE 2 is a plot of the articles prepared according to the
pre fcrred dynamic tensile moduli of illustrative cured invention.
DETAILED DESCRIPTION; PREFERRED EMBODIMENTS
Accordingly the present invention relates to a novel sesquiterpene. (+)-bisabolone of the formula 1 given below

(Formula Removed)

and a process for the isolation of a above said compound from Cymbopogon flexuosu the said process comprising characterized in that hydrodistilling freshly harvested leaves of the grass Cymbopogon flexuosus[RLJCF(HSR)], extracting the distillate with a non-polar solvent such as herein described to obtain concentrate, further hydrodistilling the obtained concentrate and separating the essential oil. followed by separating of the sesquiterpene of formula 1 from the essential oil using conventitional methods.
The present invention also relates to a process for the isolation of a noyel sesquiterpene, (+)-l-bisabolone of the formula I from Cymbopogon flexuosus
(Formula Removed)

said process comprising hydrodistilling freshly harvested leaves of the grass Cymbopogon flexuosus, extracting the distillate with a non-polar solvent to obtain a concentrate, further hydrodistilling the obtained concentrate and separating theessential oil, followed by separating of the sesquiterpene of formula 1 from theessential oil.
In one embodiment of the invention, the non-polar solvent used for extraction of the distillate is selected from the group consisting of n-hexane, petroleum ether and dichloromethane.
In one embodiment of the invention, the sesquiterpene of the formula 1 is separated from the essential oil using column chromatography.
In yet another embodiment of the invention, the yield of (+)-l-bisabolonc of formula 1 from Cymbopogon flexuosus essential oil is 35-45 %.
designates esters and amides of acrylic and methacrylic acids, the inclusion of both acids being designated by the parenthesized construction "(rneth)acrylic".
Group 1 of component A includes monomeric t-alkyl (meth)acrylates; i.e., alkyl (meth)acryiates having a tertiary carbon atom attached to the alkoxy oxygen atom. For the most part these are €4* alkyl (meth)acrylates, with t-butyl (meth)acrylates being particularly preferred and t-butyl acrylate being most preferred.
Group 2 includes monomeric N-substituted and N,N-disubstituted (meth)acrylamides, especially acrylamides. These include N-alkylacrylamides and N,N-dialkylacrylamides, especially those containing cm alkyl groups. Particularly preferred are N-isopropylacrylamide, N-t-butylacrylamide, N,N-dimethylacrylamide and N,N-diethylacrylamide.
Group 3 includes Q.g primary and secondary alkyl (meth)acrylates which may contain substituents on the alkyl groups. Illustrative unsubstituted compounds are methyl acrylate, methyl methacrylate, ethyl acrylate and 1-propyl acrylate. Illustrative substituted compounds, which may also function as reactive diluents, are the 2-(N-butylcarbamyl)ethyl (meth)acrylates. The €1.3 (meth)acrylates are usually preferred, with methyl acrylate and ethyl acrylate being most preferred. Other suitable reactive diluents are enumerated in the aforementioned US Patent 4,576,850. .
The radiation curable compositions forming the articles of the invention also include component B, which is at least one multifunctional (meth)acrylate or (meth)acrylamide monomer and which serves as a crosslinking agent By "multifunctional (meth)acrylate monomer" is meant a monomeric (i.e., non-polymerized) compound containing more than one (meth)acrylic group.
Compounds suitable for use as component B include polyol poly(meth)acrylates, typically prepared from aliphatic diols, triols and/or tetraols containing 2-10 carbon atoms. Examples of* suitable poly(meth)acrylates are ethylene glycol diacrylate, 1,6-hexanediol diacrylate, 2-ethyl-2-hydroxymethyl-l,3-propanediol triacrylate (trimethylolpropane triacrylate), di(trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, the corresponding methacrylates and the (meth)acrylates of alkoxylated (usually ethoxylated) derivatives of said polyols. Also included are N,N'-
alkylenebisacrylamides, particularly those containing a cm alkylene group. Particularly preferred is N,N'-metl ylenebisacrylamide.
Optional component C, when prei ent, may serve the purposes of affording improved ductility and minimizing shrinkag e upon polymerization. It is at least one oligomeric multifunctional (meth)acrylate, vsually a di(meth)acrylate. Suitable materials for component C include the oligoneric polyether di(meth)acrylates having a glass transition temperature of at mo it 23°C. Examples are poly(ethylene glycol) and poly(propylene glycol) di(meth)a irylates, typically having molecular weights in the range of about 300-1,000. Compounds of this type are commercially available under several trade names. Also incluc led are di(meth)acrylates of polyester polyols and oligomers thereof, as exemplified by such commercially available compounds as "CN-292", a low viscosity polye >ter acrylate oligomer commercially available from Sartomer Co.
Optional component C may alsc
be an oligomeric urethane di(meth)acrylate. Such
materials may be prepared, for ex imple, by the reaction of an alkylene diisocyanate of the formula OCN-R3-NCO with * diol of the formula HO-R4-OH, wherein each of R3 and R4 is independently a Ca-ioo Alkylene group, to form a urethane diol diisocyanate, followed by reaction with a hydroxyalkyl (meth)acrylate. For example, a preferred compound of this type may be prepared from 2,2,4-trimethylhexylene diisocyanate, poly(caprolactone)diol and 2-hydf-oxyethyl methacrylate.
Component D of the radiation photoinitiator effective to promdte ultraviolet radiation. Suitable materials aforementioned US Patent 4,576 Polymer Technology. Examples ketones, thioalkylphenyl morj holinoalkyl Particularly useful in many instances "Darocur 4265", comprising a (2,4,6-trimethylbenzoyl)diphen
curable articles of this invention is at least one polymerization of said articles upon exposure to for use as photoinitiators are identified in the 850 and in such reference works as Encyclopedia of ire benzoin ethers, hydroxy- and alkoxyalkyl phenyl ketones and acylphosphine oxides, is a commercially available material designated mixture of 2-hydroxy-2-propyl phenyl ketone and y phosphine oxide.
Other important features of the articles formed by curing. These
invention are the properties of the optical resinous include a glass transition temperature (Tg) of at least
35°C, preferably at least 40°C. Cured articles having glass transition temperatures lower than 35°C are not within the scope of the invention.
Other preferred properties include a tensile strength in the range of about 70-700 kg/cm2, a modulus of elasticity in the range of about 140-14,000 kg/cm2, an elongation to break in the range of about 5-300%, an optical homogeneity of at least about 91% transmission, a haze value of less than about 5%, a birefringence of less than about 0.002 and a dynamic tensile modulus, E', that falls within the boundary of the area A-B-C-D in FIGURE 2. Said figure is a modified version of Figure 1 of the aforementioned US Patent 4,576,850, converting dynamic shear modulus (G1) in dynes/cm2 to dynamic tensile modulus in Pascals.
The proportions of the components forming the curable articles of this invention may be widely varied, subject only to the Tg limitation and, preferably, one or more of the other preferred property profiles described hereinabove. Most often, components A and B each constitute about 1-98% by weight and component C, when present, about 5-75% of the article, based on total polymerizable components (usually the total of components A, B and C). Component D, the photoinitiator, is present in a minor amount effective to promote polymerization upon exposure to ultraviolet radiation, generally in the range of about 0.005-3.0% and preferably about 0.005-1.0% based on total polymerizable components.
The radiation curable articles of mis invention may be prepared by simply blending the components thereof, with efficient mixing to produce a homogeneous mixture. It is often preferred to remove air bubbles by application of vacuum or the like, with gentle heating if the mixture is viscous, and casting or otherwise creating a film of the resulting blend on a desired surface. The film can then be charged to a mold bearing the microstructure to be replicated and polymerized by exposure to ultraviolet radiation, producing cured optical resinous articles of the invention having the aforementioned properties. If polymerized on a surface other than the one on which it is to be used, the optical resinous article can be transferred to another surface.
Such a polymerization process lends itself to rapid, mass production of articles with no adverse environmental impact because no or only a minor amount of solvent or
other volatiles are evolved and
he polymerization can be carried out at ambient
temperatures and pressures. The p rocess also lends itself to replication of articles with microstructure comprising utili arian discontinuities, such as projections and depressions, which are readily rel< tased from the mold without loss of the detail of the
thermal dimensional stability, rei istance to abrasion and impact, and integrity even when the articles are bent.
mold and with retention of the conditions during use. The artic properties, such as toughness, resistance to common solvents,
replication of such detail under a wide variety of
es can be formed with a wide variety of desired
flexibility, optical clarity and homogeneity, and
the microstructure of such articles having high
The invention is illustrated by th by weight unless otherwise indicated photoinitiator are based on total all examples fell within the regioi
: following examples. All parts and percentages are . Percentages of monomeric constituents and of •nonomeric constituents. Dynamic tensile moduli in A-B-C-D of FIGURE 2.
EXAMPLES 1-5
To a 3-necked flask equipped mechanical stirrer was charged 3 50 mg of dibutyltin dilaurate. Th polycaprolactone dioj (Mn. 530) 60°C. The mixture was then stirred 55°C and a mixture of 18.7 hydroquinone monomethyi ether range of 54-58°C. The mixture i of the reaction was verified by oligomeric urethane dirnethacri'late, dimethacrylate".
with an.addition funnel, temperature probe and .2 ml of 2,2,4-trimethylhexane 1,6-diisocyanate and 5 addition funnel was charged with 39.75 g of warm which was added to the contents of the flask at 55-at 65°C for 14 hours. The flask was then cooled to ml of 2-hydroxyethyl methacrylate and 100 mg was added while maintaining the temperature in the vas stirred at 55°C for 10-12 hours until completion nfrared spectroscopy. The product was the desired , hereinafter sometimes designated "oligomer
In each example, a mixture of some examples, pentaerythritol into a scintillation vial and 3°A components were mixed with placed in a vacuum oven and
o igomer dimethacrylate, methyl methacrylate and, in riacrylate in a total dmount of 5-10 g were weighed of "Darocur 4265" photoinitiator was added. The vortex mixer. The uncapped scintillation vial was oven evacuated to remove air bubbles from the
ine
solution. If the coating mixture was highly viscous, the temperature of the vacuum oven was increased to 50°C to facilitate the removal of air bubbles. Approximately one gram of the mixture was then poured into an aluminum pan 5 cm in diameter. The pan was tilted to spread the mixture across the entire bottom of the pan. If the mixture was viscous, the pan was placed in a circulating air oven set at 80°C to heat the mixture, which allowed for easier spreading of the mixture across the bottom of the pan. The spread and leveled solution was then polymerized by ultraviolet radiation in an ultraviolet processor. Two 600-watt bulbs were used with a belt speed of 12 ft./min, lamp to belt distance of 4 inches, and the coating was passed 10 times through the processor. A culture dish was placed upside down over the aluminum pan containing the coating in order to prevent the pan from being blown around on the belt.
The product films were analyzed for glassy plateau modulus (G), rubbery plateau modulus (R) and glass transition temperature (Tg) using a Rhcometrics Solids Analyzer. The results are given in Table 1.
(Table Remove)
EXAMPLES 6-14
The polymerization procedure of of t-butyl acrylate with, in tetraethyJene g]ycol diacrylate, trimethylolpropane triacrylate am given in Table II.
(Table Remove)
Examples 1-5 was performed on a series of mixtures
various examples, "CN-292" polyester acrylate,
trimethylolpropane triacrylate and ethoxylated
employing 0.01% of photoinitiator. The results are
EXAMPLES 15-24
The polymerization procedure oF Examples 6-14 was perfonned on a series of mixtures of N,N-dimethylacryte nide or N,N-diethylacrylamide with, in various examples, N.N-methylenebisacryl imide and 1,6-hexanediol diacrylate. The results are given in Table III.
(TableRemove)
'Second Tg at 232°C.
EXAMPLES 25-31
The polymerization procedure mixtures of t-butyl acrylate and poly(propyJene glycol Mn 540] Example 1. The results are given i
qf Examples 6-14 was performed on a series of ,6-hexanediol diacrylate and, in various examples, diacrylate and the oligomer dimethacrylate of ft> Table IV.
(Table Remove)EXAMPLES 32-38
The polymerization procedure or Examples 6-14 was performed on a series of mixtures of N,N-dimethylacrylamJde, 1,6-hexanediol diacrylate and, in various examples, polypropylene glycol Mn 540) diacrylate and the oligomer dimethacrylate of Example 1. The results are given in Table V.
(Table Remove)
EXAMPLES 39-42
The polymerization procedure c mixtures of N,N-dimethylacryJarr polypropylene glycol Mn 540) diacryl
TABLE VI
f Examples 6-14 was performed on a series of ide, t-butyl acrylate, 1,6-hexanediol diacrylate and ate. The results are given in Table VI
(Table Remove)

What is claimed is:
1. An article which is radiation curable to an optical resinous article having a surface
with a replicated microstructure comprising a plurality of utilitarian discontinuities
having an optical purpose, said optical resinous article having a glass transition
temperature of at least 35°C;
said radiation curable article being free from carbocyclic and heterocyclic polymerizable moieties and comprise:
(A) at least one monofunctional acrylic monomer selected from the group consisting
of:
at least one monomeric t-alkyl (meth)acrylate,
at least one monomeric N-substituted or N,N-disubstituted (meth)acrylamide and
at least one d^ primary or secondary alky! (meth)acrylate;

at least one multifunctional (meth)acrylate or (meth)acrylamide monomer;
optionally, at least one oligomeric multifunctional (meth)acrylate; and
at least one photoinitiator.

An article according to claim 1 which is radiation curable to an optical resinous
article having a glass transition temperature of at least 40°C.
An article according to claim 1 having a dynamic tensile modulus that falls within
the boundary of the area A-B-C-D in FIGURE 2.
An article according to claim 1 comprising component A-l.
An article according to claim 4 wherein component A-l is a t-butyl (meth)acrylate.
An article according to claim 1 comprising component A-2.
An article according to claim 6 wherein component A-2 is N-isopropylacrylamide,
N-t-butylacrylamide, N,N-dimethylacrylamide or N,N-diethylacrylamide.
An article according to claim 1
An article according to claim !
mcthacrylatc, ethyl acrylate,
(meth)acrylate.
comprising component A-3.
wherein component A-3 is methyl acrylate, methyl -propyl acrylate or a 2-(N-butylcarbamyl)ethyl
An article according to claim 1 wherein component B is at least one polyol
poly(meth)acrylate.
An article according to claim 10 wherein component B is ethylene glycol
di(meth)acrylate, 1,6-hexanedicl di(meth)acrylate, 2-ethyl-2-hydroxymethyl-l,3-
propanediol tri(meth)acrylate, pentaerythritol tetra(meth)acrylat
di(trimethylolpropane) tetra(meth)acrylate or
12. An article according to cla|m 1 wherein component B is at least one N,N'-
alkylenebisacrylamide.
13. An article according | to claim 12 wherein component B is
N.N'-methylenebisacrylamide.
An article according to claim 11 comprising component C.
An article according to claim] 14 wherein component C is an oligomeric polyether
di(meth)acrylate having a glass transition temperature of at most 23°C.
An article according to claim! 14 wherein component C is a di(meth)acrylate of a
polyester polyol or an oligomer thereof.
An article according to clahfo 16 wherein component C is polyethylene glycol)
di(meth)acrylate or poly(propylehe glycol) di(meth)acrylate.
An article according to clainf 14 wherein component C is an oligomeric urethane
di(meth)acrylate.
An article according to claim IS wherein component C is a reaction product of
2,2,4-trimethylhexane 1 ,6-diisocyanate, polycaprolactone diol and 2-hydroxyethyl
methacrylate.
An article according to claim 1 wherein component A constitutes about 10-98%
by weight based on total polymerizable components.
An article which is radiation curable to an optical resinous article having a surface
with a replicated microstructure comprising a plurality of utilitarian discontinuities
having an optical purpose, said optical resinous article having a glass transition
temperature of at least 40°C;
said. radiation curable article being free from carbocyclic and heterocyclic polymerizable moieties and comprising:
(A) at least one monofunctional acrylic monomer selected from the group consisting
of:
t-butyl (meth)acrylate,
N-isopropylacrylamide, N-t-butylacrylamide, N,N-dimethylacrylamide or N,N-
diethylacrylamide, and
methyl acrylate, methyl methacrylate, ethyl acrylate, 1-propyl acrylate or a 2-(N-
burylcarbamyl)ethyl (meth)acrylate,

at least one multifunctional (meth)acrylate or (meth)acrylamide monomer selected
from the group consisting of ethylene glycol di(meth)acrylate, 1,6-hexanediol
di(meth)acrylate, 2-ethyl-2-hydroxymethyl-l,3-propanediol tri(meth)acrylate,
di(trimethylolpropane) tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate and
N.N'-methylenebisacrylamide, and
optionally, at least one oligomeric multifunctional (meth)acrylate selected from
the group consisting of oligomeric polyether di(meth)acry)ates having a glass
transition temperature of at most 23°C, di(meth)acrylates of polyester polyols and
oligomers thereof, and oligomeric urethane di(meth)acrylates; and
at least one photoinitiator.
An article according to claim 21 wh -in compone'V C is a reaction product of
2,2,4-trimethylhexane 1 ,6-diisodyanate, polycaprolactoi.3 diol and 2-hydroxyethyl
methacrylate.
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim I.
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim 4.
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim 6.
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim 8. .
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim 10.
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim 12.
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim 14.
An optical resinous article formed by ultraviolet radiation curing of an article
according to claim 21.