Description:FIELD OF INVENTION
[0001] Embodiment of the present invention relates to a novel donepezil inspired coumarin derivatives as potent acetylcholinesterase (AChE) inhibitor for Alzheimer’s disease. More particularly, the present invention relates to hybridizing coumarin structure with substituted alicyclic/aliphatic nitrogen heterocycle functionalities mimicking donepezil drug as potent acetylcholinesterase inhibitor conjugates for Alzheimer’s disease.
BACKGROUND
[0002] In the parlance of symptoms, Alzheimer’s disease (AD) is one of the most widespread and detrimental neurodegenerative disorders. The symptoms appear after mid 50 of life featuring insidious impairment of higher intellectual function like cognition, related behaviour and mood. As the condition passes the span, progressive disorientation, memory loss and aphasia indicate severe cortical dysfunction, and eventually, within a decade, the patient becomes profoundly disabled, mute and immobile (Cummings, J. et al., 2021).
[0003] Exact cause is not known but a few factors are implicated in its etiology which includes positive family history, deposition of Aβ amyloid derived from amyloid precursor protein (APP) forming neuritic senile plaques and neurofibrillary tangles. Till date, Alzheimer’s disease is an incurable ailment and the most prevalent form of dementia among geriatrics that deteriorates self-care, and quality of life, ending in physical, emotional, and economic burdens for caregivers. Additionally, increased life expectancy and ageing of the population has led to higher incidence of age-dependent neurodegenerative disorders. As one of these, Alzheimer's disease (AD) accounts for 60% to 70% of cases of senile dementia. The number of patients with AD worldwide is estimated at around 50 million and nearly 10 million new patients are diagnosed every year (Matthews, D. C. et al., 2021).
[0004] Looking at the complications of the disease and to make the things worse, only four drugs are available for AD management, mainly acetylcholinesterase (AChE) inhibitors donepezil, rivastigmine, and galantamine, and glutamate NMDA receptor antagonist memantine, while some drug candidates are in pipeline. However, tacrine is withdrawn from the major market on account of significant liver toxicity.
[0005] Current clinical therapy mainly alleviates the cognitive and functional symptoms on a temporary basis. Despite enormous research efforts to tackle this neurological ailment, the success rate for drug candidates is only around 0.5%. In addition to classical β-amyloid, apoE4 and Tau protein abnormality, the oxidative stress management and disrupted reverse trans-sulfuration leading to progressive damage to neuroprotective signalling networks is a contributing factor for AD complications. Due to the pathological complexity of AD, advancement in improved therapeutic efficacy could be accomplished by developing multi-target, multi-function new chemical entities (NCEs) enabling fine tuning disease pathology synchronously (Klunk, W. E. et al., 2004, Ono, M. et al. 2009). The clinically approved anti-AD drugs are disclosed below:

[0006] As mentioned in the above paragraph of origin of the problem, very few drugs are available in the market for AD which relies on alleviating the symptoms of the patients rather than curative or disease modifying treatments. The modification of current and future anti-AD drugs keeping unaltered crucial pharmacophore with activity enhancing scaffolds implementing rational drug design not only could sideline the shortcomings of current therapy but also target and fine tune several disease pathological pathways in a positive manner (Hroch, L. et al., 2016, Hroch, L. et al., 2003).
[0007] The coumarin heterocycle is observed as an abundant constituent in several plant species, displays comprehensive range of pharmacological profile comprising anticoagulant, anti-inflammatory, anti-cancer, and antioxidant properties. Recently, considerable synthetic research is attributed to neurological diseases inhibiting AChE, MAO and BACE-1 targets utilizing coumarin backbone. Consequently, coumarin is considered as a promising scaffold in drug design. (Pan, L. et al., 2008, Yan, J-W. et al., 2012).

7-hydroxy coumarin
[0008] Therefore, there is a need hybridizing coumarin structure with nitrogen bearing alicyclic heterocycle mimicking functionalities from Donepezil drug. Donepezil is USFDA approved established AChE inhibitor. The purpose is to extract the multi beneficial effects of the proposed structures, as AD is a complicated disease where numerous targets are involved.

SUMMARY
[0009] The present invention relates to hybridizing coumarin structure with substituted alicyclic/aliphatic nitrogen heterocycle functionalities mimicking donepezil drug as potent acetylcholinesterase inhibitors.
[0010] In accordance with an embodiment of the present invention, donepezil inspired amine conjugated coumarin derivatives as potent acetylcholinesterase inhibitors for Alzheimer’s disease of Formula (I) or pharmaceutically acceptable salts, solvents and prodrugs thereof,

(I)
[0011] In another embodiment of the present invention, a pharmaceutical composition comprising is provided. The pharmaceutical composition comprises the donepezil inspired amine conjugated coumarin derivatives of Formula (I), and the pharmaceutically acceptable salts, solvents and prodrugs thereof, and a pharmacologically acceptable excipient.
[0012] In another embodiment of the present invention, a process for the preparation of the donepezil inspired amine conjugated coumarin derivatives of Formula (I) or a pharmaceutically acceptable salts, solvents and prodrugs thereof is provided. The process comprises the steps of reacting a solution of substituted oxarinyl coumarins (2.29 mmol) and appropriate secondary amine (3.43 mmol) in 15 mL absolute ethanol was refluxed at 80-90 °C for 2-3 hours. The reaction progress was monitored by thin-layer chromatography (TLC) in intervals with mobile phase chloroform and methanol. Upon reaction completion, the solvent was evaporated by rotary evaporator. The resulting crude product was purified by column chromatography using a mobile phase of 2% methanol in chloroform, to obtain amine conjugated coumarin derivatives inspired from donepezil drug of Formula (I).
[0013] Therefore, in the present invention, novel amine conjugated coumarin derivatives inspired from donepezil drug are designed, synthesized and evaluated for AChE inhibition potential for Alzheimer`s disease. As hypothesized, the synthesized derivatives showed promising in-silico interactions with the targets AChE involved in Alzheimer`s disease. Further, to support, the hybrids were screened for AChE inhibition study. Compounds 3, 8, 13 and 18 showed good AChE inhibition activity.
[0014] To further clarify the advantages and features of the present invention, a more particular description of the invention will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the invention and are therefore not to be considered limiting in scope. The invention will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0001] FIG. 1 depicts a schematic representation of a process for synthesis of novel amine conjugated coumarin derivatives inspired from donepezil drug as potent acetylcholinesterase (AChE) inhibitors for Alzheimer’s disease of Formula (I) or pharmaceutically acceptable salts, solvents and prodrugs thereof, in accordance with an embodiment of the present disclosure;
[0002] FIG. 2 depicts two-dimensional (2D) visualisation of binding interactions of compound 3 with 4EY7 enzyme, in accordance with an embodiment of the disclosure;
[0003] FIG. 3 depicts three-dimensional (3D) visualisation of binding interactions of compound 3 with 4EY7 enzyme, in accordance with an embodiment of the disclosure;
[0004] FIG. 4 depicts three-dimensional (3D) visualisation of binding interactions of compound 13 with 4EY7 enzyme, in accordance with an embodiment of the disclosure;
[0005] FIG. 5 depicts three-dimensional (3D) visualisation of binding interactions of compound 13 with 4EY7 enzyme, in accordance with an embodiment of the disclosure;
[0006] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
[0007] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures, and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations, further modifications in the illustrated online platform, and further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.
[0008] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or subsystems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, subsystems, elements, structures, components, additional devices, additional subsystems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0009] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0010] In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
[0011] FIG. 1 depicts a schematic representation of a process for synthesis of amine conjugated coumarin derivatives inspired from donepezil drug as potent AChE inhibitor for Alzheimer’s disease of Formula (I) or pharmaceutically acceptable salts, solvents and prodrugs thereof, in accordance with an embodiment of the present disclosure.
[0012] Embodiment of the present invention relates to a novel amine conjugated coumarin derivatives inspired from donepezil drug as potent AChE inhibitor for Alzheimer’s disease. The present invention relates to hybridizing coumarin structure with piperidine, 4-methyl piperidine, 4-benzyl piperidine, ethyl isonipecotate, ethyl nipecotate, 1-methyl piperazine, 1-ethyl piperazine, N-benzyl piperazine and N-benzyl-N-methyl piperazine functionalities mimicking donepezil drug side chain as potent AChE inhibitor ligands for Alzheimer’s disease.
[0013] In accordance with an embodiment of the present invention, an amine conjugated coumarin derivatives inspired from donepezil drug as potent AChE inhibitor for Alzheimer’s disease of Formula (I) or pharmaceutically acceptable salts, solvents and prodrugs thereof,

(I)
wherein,

[0014] In an embodiment of the present invention, the amine conjugated coumarin derivatives of Formula (I) are selected from a group comprising one of
Compound
Code X Y Z R R1
1 N CH2 H --- H
2 N CH H CH3 H
3 N CH H Bn H
4 N CH H COOEt H
5 N CH COOEt H H
6 N N H CH3 H
7 N N H CH2CH3 H
8 N N H Bn H
9 --- H --- H
10 N CH2 H --- Me
11 N CH H CH3 Me
12 N CH H Bn Me
13 N CH H COOEt Me
14 N CH COOEt H Me
15 N N H CH3 Me
16 N N H CH2CH3 Me
17 N N H Bn Me
18 --- H --- Me

[0015] In another embodiment of the present invention, a pharmaceutical composition comprising is provided. The pharmaceutical composition comprises the amine conjugated coumarin derivatives of Formula (I), and the pharmaceutically acceptable salts, solvents and prodrugs thereof, and a pharmacologically acceptable excipient. The amine conjugated coumarin derivatives inspired from donepezil drug of Formula (I) are selected from a group comprising one of
[0016] In another embodiment of the present invention, the pharmacologically acceptable excipient is selected from the group consisting of binders, diluents, disintegrants, lubricants, glidants, fillers, colouring agents, flavouring agents, and combinations thereof. The composition is administered by one of route selected from oral, rectal, cutaneous, pulmonary, nasal, sublingual, the parenteral route, in particular intradermic, subcutaneous, intramuscular, intravenous, intra-arterial, intra-rachidial, intra-articular, intra-pleural, intraperitoneal, ocular, inhalation, transdermic, epidural, intrabronchial, intramural, intracardiac, intracerebral, intracerebroventricular, intragastric, intratympanic, intraspinal, intrathecal, intratracheal, intraduodenal, intra-uterine, intravaginal, intravesical, intravitreal, rectal, subconjunctival, and intertumoral administration. The composition is in one of the forms as a tablet, capsule, pill, syrup, suspension, powder, granule, emulsion, microsphere, injectable solution, and solid liquid nanoparticles.
[0017] In another embodiment of the present invention, a process for the preparation of the amine conjugated coumarin derivatives inspired from donepezil drug as potent AChE inhibitor derivatives of Formula (I) or a pharmaceutically acceptable salts, solvents and prodrugs thereof is provided. The process comprises the steps of reacting oxirane substituted coumarin (0.5 g, 2.29 mmol) and appropriate secondary amine (3.43 mmol) in 15 mL absolute ethanol was refluxed at 80-90 °C temperature for 2-3 hours. The reaction progress was monitored by thin-layer chromatography (TLC) in intervals with mobile phase chloroform and methanol (5:0.5). Upon reaction completion, the solvent was evaporated by rotary evaporator. The resulting crude product was purified by column chromatography using a mobile phase of 2% methanol in chloroform, affording the desired compounds in excellent yields to obtain novel amine conjugated coumarin derivatives of Formula (I).
[0018] In another embodiment of the present invention, the process for synthesizing oxirane substituted coumarin is provided. The process comprising the steps of reacting appropriate hydroxycoumarin (6.169 mmol) and epichlorohydrin (162.5 mmol) (1:26 molar ratio) was dissolved in 15 mL of absolute ethanol. To this solution, a 0.5 M ethanolic solution of potassium hydroxide (15 mL) was added dropwise at room temperature. The reaction mixture was then subjected to reflux for 3 hours. The mixture was allowed to cool to room temperature, and the solvent was removed under reduced pressure using a rotary evaporator. The resulting orange semi-solid was extracted with chloroform (3 X 50 mL) and distilled water (3 X 50 mL). The organic (chloroform) layer, which retained the orange colour, was separated and washed twice with water, then dried over anhydrous magnesium sulphate (MgSO4). The dried organic layer was concentrated under reduced pressure, yielding faint orange solid. Recrystallization from ethanol and activated charcoal yielded oxirane substituted coumarin.
[0019] The present invention is explained further in the following specific examples, which are only by way of illustration and are not to be construed as limiting the scope of the invention.
Examples
[0020] EXPERIMENTAL STUDIES
[0021] Step 1: Synthesis of oxirane substituted coumarin
[0022] A mixture of appropriate hydroxycoumarin (6.169 mmol) and epichlorohydrin (162.5 mmol) (1:26 molar ratio) was dissolved in 15 mL of absolute ethanol and transferred to a 50 mL round-bottom flask. To this solution, a 0.5 M ethanolic solution of potassium hydroxide (15 mL) was added dropwise at room temperature. The reaction mixture was then subjected to reflux for 3 hours. The progress of the reaction was monitored using thin-layer chromatography (TLC). Once the reaction was complete, the mixture was allowed to cool to room temperature, and the solvent was removed under reduced pressure using a rotary evaporator. The resulting orange semi-solid was extracted with chloroform (3 X 50 mL) and distilled water (3 X 50 mL). The organic (chloroform) layer, which retained the orange colour, was separated and washed twice with water, then dried over anhydrous magnesium sulphate (MgSO₄). The dried organic layer was concentrated under reduced pressure, yielding faint orange solid. This crude product was then recrystallized from ethanol and activated charcoal, yielding white solid as the final product.
[0023] Step-3: Synthesis of novel amine conjugated coumarin derivatives (Compound 1 – 18)
A solution of oxirane substituted coumarin (2.29 mmol) and appropriate secondary amine (3.43 mmol) in 15 mL absolute ethanol was refluxed at 80-90 °C temperature for 2-3 hours. The reaction progress was monitored by thin-layer chromatography (TLC) in intervals with mobile phase chloroform and methanol (5:0.5). Upon reaction completion, the solvent was evaporated by rotary evaporator. The resulting crude product was purified by column chromatography using a mobile phase of 2% methanol in chloroform, affording the desired compounds in excellent yields.
[0024] RESULTS AND DISCUSSION
[0025] DOCKING STUDY
The main goal of this investigation was synthesis of new amine conjugated coumarin derivatives and the assessment of their acetylcholinesterase activity. The compounds were initially evaluated for drug-like properties using Lipinski's rule of five. Docking study was performed to gain knowledge about protein and ligand interaction, and to evaluate which compound had greatest binding energy and has the greatest number of interactions with protein. Main interactions which were involved are hydrogen bond interaction, hydrophobic and van der waals interactions.
[0026] Targets- Acetylcholinesterase (AChE), Protein Code- 4EY7
[0027] FIG. 2 depicts 2D visualisation of binding interactions of compound 3, in accordance with an embodiment of the disclosure.
[0028] FIG. 3 depicts 3D visualisation of binding interactions of compound 3, in accordance with an embodiment of the disclosure.
[0029] FIG. 4 depicts 2D visualisation of binding interactions of compound 13, in accordance with an embodiment of the disclosure.
[0030] FIG. 5 depicts 2D visualisation of binding interactions of compound 13, in accordance with an embodiment of the disclosure.
[0031] Table No. 1: Docking profile of 7-(3-(4-benzylpiperidin-1-yl)-2-hydroxypropoxy)-2H-chromen-2-one (Compound 3), ethyl 1-(2-hydroxy-3-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)propyl)piperidine-4-carboxylate (Compound 13) and Donepezil drug with protein 4EY7.
Compound structure Docking score
(Kcal/mol) Distance (Å) Amino acid residue Type of interactions
Compound code 3

-9.2 2.21 ALAB:526 Hydrogen bond

2.88 ARGB:525
2.50 GLNB:527
3.37 HISB:381
2.85 GLYB:523
5.37 ALAB:528 Hydrophobic
bond
3.97 HISA:381
Compound code 13

-9.7 2.93 HISA:381 Hydrogen bond

2.91 HISB:381
1.87 ALAA:528
2.84 GLNA:527
2.64 TYRA:510
2.57 ARGA:525
4.74 VALA:408 Hydrophobic
bond
4.50 LEUA:524
5.29 VALA:330
4.43 VALA:429
Donepezil (Standard) -9.3 2.44 HISB:381 Hydrogen
bond
2.88 HISA:381
2.16 GLNB:527
3.41 THRB:383
4.47 LEUA:380 Hydrophobic bond
5.24 TRPA:385
5.04 ARGB:393
[0032] From the above results, by analysing parameter like docking score, distance, type of interaction like hydrogen bond, hydrophobic bond, it is observed that the derivatives show better interaction with acetylcholinesterase. They also obey Lipinski rule, cross the blood brain barrier.
[0033] PHYSICOCHEMICAL DATA
[0034] Table No. 2. Physicochemical data of synthesized derivatives (1–18)
Compound
Code Molecular Formula Molecular
Weight Colour and Nature Melting
Point 0C Mobile
Phase Rf Value % Yield
Code 1
UMB-PIP C17H21NO4
303.35 g/mol Off white solid 92-94 Chloroform: Methanol
(5:0.5) 0.6
56%

Code 2
UMB-4MP C18H23NO4
317.38 g/mol Colourless
Transparent crystal 78-80 Chloroform: Methanol
(5:0.5) 0.5
55%

Code 3
UMB-4BP C24H27NO4

393.48 g/mol White crystalline solid 98-100 Chloroform: Methanol
(5:0.4) 0.5 76%

Code 4
UMB-ISO C20H25NO6
375.42 g/mol White solid 90-92 Chloroform: Methanol
(5:0.5) 0.6 75%
Code 5
UMB-ETN C20H25NO6
375.42 g/mol White pale yellow solid 58-60 Chloroform: Ethanol
(5:0.4) 0.6 59%
Code 6
UMB-1MP C17H22N2O4
318.37 g/mol Off white solid 110-112 Chloroform: Methanol
(5:0.5) 0.5 50%
Code 7
UMB-1EP C18H24N2O4

332.39 g/mol White solid 108-110 Chloroform: Methanol
(5:0.5) 0.5 72%
Code 8
UMB-1BP C23H26N2O4
394.46 g/mol White crystalline solid 100-102 Chloroform: Methanol
(5:0.6) 0.6 65%
Code 9
UMB-NBA C20H21NO4
339.39 g/mol White needle shaped crystals 70-72 Chloroform: Methanol
(5:0.8) 0.6 51%
Code 10
COU-PIP C18H23NO4 317.16 White solid 60-62 Chloroform: methanol
(5:1.5) 0.5 62%
Code 11
COU-4MP C19H25NO4 331.41 White solid 108-110 Chloroform: methanol
(5:0.2) 0.6 80%
Code 12
COU-4BP C25H29NO4 407.50 White solid 60-62 Chloroform: methanol
(5:0.2) 0.5 62%
Code 13
COU-ISO C21H27NO6 389.18 Light Brown solid 70-72 Chloroform: methanol
(5:0.5) 0.6 84%
Code 14
COU-ETN C21H27NO6 389.44 White solid 76-78 Chloroform: methanol
(5:1) 0.6 70%
Code 15
COU-1MP C18H24N2O4 332.39
White solid 100-102 Chloroform: methanol
(5:0.5) 0.6 84%
Code 16
COU-1EP C19H26N2O4 346.42 White solid 108-110 Chloroform: methanol
(5:0.5) 0.5 89%
Code 17
COU-1BP C24H28N2O4 408.49 Off sticky Solid 120-122 Chloroform: methanol
(5:0.5) 0.6 78%
Code 18
COU-NBA C21H23NO4 353.41 White solid 86-88 Chloroform: methanol
(5:0.5) 0.5 88%

[0035] Table No. 3. Spectral data of all synthesized derivatives (1–18).
Compd
Code IR spectral data (KBr) (cm−1) 1H NMR (400 MHz) (ppm values) 13C NMR (125 MHz) (ppm) Mass (gram)
1 3424.96, 3100.97, 2938.98, 1728.07, 1482.03, 1231.33, 1125.12 7.648 (d, 1H), 7.382 (d, 1H), 6.901-6.869 (dd, 1H), 6.840 (d, 1H), 6.264 (d, 1H), 4.122-4.099 (m, 1H), 4.038-4.018 (t, 2H), 2.643-2.403 (m, 7H), 1.631-1.457 (m, 6H) 161.917, 161.067, 155.631, 143.341, 143.295, 128.689, 128.629, 112.975, 112.778, 112.558, 101.452, 70.897, 64.975, 60.67, 54.575, 25.941, 24.043 304.70
2 3435.56, 3141.47, 2972.73, 1731.76, 1457.92, 1278.58, 1172.22 7.647 (d, 1H), 7.381 (d, 1H), 6.902-6.880 (dd, 1H), 6.842 (d, 1H), 6.267 (d, 1H), 4123-4.005 (m, 3H), 2.994 (d, 1H), 2.817 (d, 1H), 2.555-1.963 (m, 4H), 1.643 (d, 2H), 1.395-1.186 (m, 3H), 0.994 (d, 3H) 161.962, 161.112, 155.692, 143.341, 128.689, 113.097, 112.846, 112.611, 101.497, 70.935, 65.097, 60.299, 55.539, 52.510, 34.504, 34.177, 30.556, 21.758 318.15
3 3323.71, 3022.87, 2911.99, 1722.12, 1556.27, 1295.93, 1154.12 7.639 (d, 1H), 7.374 (d, 1H), 7.302-7.136 (m, 6H), 6.894-6.830 (m, 2H), 4.120-3.797 (m, 4H), 3.004-1.525 (m, 12H), 1.389-1.231 (m, 2H) 161.909, 161.074, 155.669, 143.379, 143.242, 140.411, 129.122, 128.872, 128.673, 127.976, 125.888, 125.638, 113.19, 112.968, 112.74, 102.22, 101.52, 101.39, 71.07, 70.86, 65.11, 60.24, 55.38, 52.51, 43.01, 42.86, 37.67, 32.06 394.53
4 3451.96, 3046.98, 2959.23, 1731.76, 1613.16, 1285.32, 1160.22 7.638 (d, 1H), 7.375 (d, 1H), 6.888-6.866 (dd, 1H), 6.829 (d, 1H), 6.261 (d, 1H), 4.162-3.407 (m, 6H), 3.016-2.994 (m, 7H), 2.121-1.701 (m, 6H), 1.271-1.180 (m, 3H) 174.788, 161.857, 161.091, 155.680, 143.325, 128.717, 113.153, 112.781, 112.667, 101.512, 70.71, 62.15, 60.23, 54.21, 51.86, 40.74, 28.32, 28.11, 14.14 376.3
5 3424.96, 3073.98, 2938.98, 1728.87, 1509.03, 1231.33, 1195.05 7.638 (d, 1H), 7.373 (d, 1H), 6.883-6.826 (m, 2H), 6.259 (d, 1H), 4.168-3.993 (m, 5H), 3.476 (d, 1H), 3.067-1.543 (m, 11H), 1.274-1.179 (m, 3H) 173.759, 161.902, 161.135, 155.722, 143.409, 128.819, 128.636, 113.294, 112.907, 112.778, 101.596, 101.482, 70.63, 65.36, 60.51, 60.38, 54.76, 41.33, 26.54, 24.56, 14.22 376.73
6 3233.07, 3067.23, 2941.88, 1725.01, 1613.13, 1152,04, 1120.44 7.647 (d, 1H), 7.385 (d, 1H), 6.899-6.878 (dd, 1H), 6.846 (d, 1H), 6.272 (d, 1H), 4.142-4.004 (m, 3H), 3.488 (d, 1H), 2.739-2.512 (m, 10H) 161.910, 161.982, 155.771, 143.356, 128.755, 113.274, 112.91, 101.56, 70.70, 65.08, 60.03, 55.09, 45.99 319.2
7 3424.96, 3073.98, 2938.98,1728.87, 1509.03, 1231.33, 1112.01 7.650 (d, 1H), 7.386 (d, 1H), 6.900-6.879 (dd, 1H), 6.844 (d, 1H), 6.271 (d, 1H), 4.150-4.002 (m, 3H), 2.756-2.424 (m, 11H), 1.124-1.088 (t, 3H) 161.932, 161.150, 155.783, 143.341, 128.743, 113.271, 112.922, 112.740, 101.558, 70.77, 65.15, 60.07, 53.20, 52.82, 11.98 333.2
8 3424.96, 3100.97, 2948.63, 1731.76, 1509.03, 1150.45, 1120.44 7.642 (d, 1H), 7.378 (d, 1H), 7.328-7.263 (m, 4H), 6.893-6.871 (dd, 1H), 6.837 (d, 1H), 6.267 (d, 1H), 4.047-4.018 (t, 3H), 2.595-2.508 (m, 8H) 161.879, 161.089, 155.760, 143.310, 137.837, 129.122, 128.705, 127.065, 113.188, 112.846, 112.679, 101.505, 70.73, 65.10, 62.88, 60.01, 52.97 395.37
9 3462.56, 3080.73, 2935.13, 1704.76, 1509.03, 1107.20, 1100.19 7.646 (d, 1H), 7.378-7.262 (m, 6H), 6.875-6.853 (dd, 1H), 6.819 (d, 1H), 6.271 (d, 1H), 4.160-4.136 (t, 1H), 4.054-3.976 (m, 2H), 3.728 (d, 1H), 3.563 (d, 1H), 2.700-2.669 (t, 1H), 2.557-2.526 (dd, 1H) 161.880, 161.136, 155.703, 143.341, 137.892, 129.013, 128.710, 127.382, 113.168, 112.811, 101.53, 70.76, 65.80, 62.46, 59.11, 42.16 340.3
10 3451.97, 3077.83, 2939.95, 1725.98, 1509.99, 1195.65 7.506 (d, 1H), 6.920-6.898 (dd, 1H), 6.838 (d, 1H), 6.139 (d, 1H), 4.143-4.021 (m, 3H), 2.558-2.396 (m, 10H), 1.641-1.462 (m, 6H) 161.757, 161.196, 155.054, 152.481, 125.471, 113.643, 112.505, 111.981, 111.875, 101.490, 70.859, 65.006, 60.701, 54.606, 25.963, 24.073, 18.607, 18.569 318.70
11 3427.85, 3081.69 2955.38, 1718.26, 1610.27, 1072.23 7.505 (d, 1H), 6.920-6.898 (dd, 1H), 6.859 (d, 1H), 6.153 (d, 1H), 4141-3.922 (m, 3H), 3.002 (d, 1H), 2.827 (d, 1H), 2.565-2.291 (m, 6H), 2.035-2.005 (t, 1H), 1.666 (d, 2H), 1.425-0.930 (m, 6H) 161.765, 161.218, 155.077, 152.496, 125.547, 125.380, 113.666, 112.596, 112.452, 112.292, 112.072, 111.848, 101.558, 101.444, 71.048, 70.859, 70.654, 65.195, 64.998, 60.458, 60.329, 60.193, 55.600, 55.433, 52.609, 52.442, 34.473, 34.154, 30.556, 21.735, 18.660, 18.562 332.54
12 3420.14, 3023.84, 2939.95, 1725.90, 1449.24, 1025.94 7.502 (d, 1H), 7.304-7.137 (m, 5H), 6.912-6.890 (dd, 1H), 6.832 (d, 1H), 4.123 (d, 1H), 4.043-4.010 (t, 2H), 3.035 (d, 1H), 2.864 (d, 1H), 2.582-2.262 (m, 9H), 2.004-1.949 (t, 1H), 1.686-1.210 (m, 6H) 161.742, 161.241, 155.107, 152.496, 140.426, 129.046, 128.158, 125.820, 125.494, 113.719, 112.550, 111.996, 101.520, 70.821, 65.135, 60.329, 55.339, 52.480, 43.021, 37.692, 32.310, 32.006, 18.630 408.38
13 3265.86, 3077.86, 2939.95, 1728.87, 1614.13, 1068.37 7.509 (d, 1H), 6.917-6.895 (dd, 1H), 6.837 (d, 1H), 4.175-4.122 (dd, 3H), 4.044-4.026 (t, 2H), 2.573-2.342 (m, 7H), 1.964 (d, 2H),1.283-1.247 (t, 3H) 174.777, 161.689, 161.211, 155.107, 152.473, 125.516, 113.765, 112.490, 12.057, 101.558, 70.669, 65.173, 60.398, 60.299, 54.226, 51.895, 40.713, 28.294, 28.089, 18.630, 14.174 390.18
14 3400.85, 2924.52, 1722.12, 1610.27, 1103.08 7.509 (d, 1H), 6.913 (d 1H), 6.840 (d, 1H), 4.163-4.006 (m, 5H), 3.091 (d, 1H), 2.784-2.239 (m, 10H), 1.937-0.835 (m, 8H) 173.711, 161.713, 161.235, 155.134, 152.477, 125.515, 113.775, 112.523, 112.067, 101.572, 70.618, 65.644, 60.540, 60.328, 55.755, 54.811, 54.112, 53.445, 41,606, 41.500, 26.550, 26.414, 24.478, 24.251, 18.650, 14.196 390.21
15 3227.29, 3075.08, 2936.06, 1718.26, 1606.41, 1456.96. 7.510 (d, 1H), 6.918-6.896 (dd, 1H), 6.842 (d, 1H), 4.145-4.002 (m, 3H), 2.735-2.305 (m, 15H) 161.689, 161.241, 155.092, 152.504, 125.501, 113.742, 112.550, 112.019, 101.505, 70.676, 65.188, 60.049, 55.046, 53.049, 45.921, 18.623 333.19
16 3439.42, 2839.67, 1718.26, 1610.27, 1157.08 7.507 (d, 1H), 6.912-6.890 (t, 1H), 4.151-4.001 (m, 4H), 2.755-2.398 (m, 15H), 1.123-1.088 (t, 3H) 161.698, 161.212, 155.088, 152.485, 125.492, 113.729, 112.538, 112.007, 101.496, 76.681, 70.694, 65.169, 60.062, 52.731, 52.192, 18.620, 11.881 347.3
17 3233.39, 3067.27, 2941.88, 2800.13, 1725.05, 1120.44 7.497 (d, 1H), 7.326-7.294 (q, 4H), 7.257 (d, 1H), 6.909-6.887 (dd, 1H), 6.828 (d, 1H), 4.139-3.989 (m, 3H), 3.528-3.486 (q, 3H), 2.730-2.388 (m, 13H), 1.224-1.189 (t, 1H) 161.713, 161.258, 155.118, 152.500, 137.884, 129.043, 128.421, 127.412, 125.500, 113.752, 112.515, 112.045, 101.565, 70.717, 65.837, 62.490, 59.166, 42.160, 18.650 409.3
18 3477.03, 3081.69, 3027.69, 2951.52, 1718.26, 1610.27, 1157.08. 7.499 (d, 1H), 7.360-7.265 (m, 5H), 6.892-6.870 (dd 1H), 6.812 (d, 1H), 6.138 (d, 1H), 4.170-4.146 (q, 1H), 4.055-3.977 (m, 2H), 3.735 (d, 1H), 3.577 (d, 1H), 2.711-2.680 (q, 1H), 2.572-2.541 (dd, 1H) 161.713, 161.258, 155.118, 152.500, 137.884, 129.043, 128.421, 127.412, 125.500, 113.752, 112.515, 112.045, 101.565, 70.717, 65.837, 62.490, 59.166, 42.160, 18.650 354.5

[0036] BIOLOGICAL ACTIVITY
[0037] Acetylcholinesterase Activity
The inhibitory activities of the compounds against AChE were determined in 96-well plates by a modified spectrophotometric method reported by Ellman et al. using donepezil as reference drug. Initially, the synthesized compounds 1–18 were prepared at two concentrations (10−3 and 10−4 M) using 2% DMSO and inhibition potencies were measured. All synthesized compounds were found to possess satisfactory % inhibition rate. Synthesized “Compound 3, 8, 13, 18 showed promising acetylcholinesterase activity.
[0038] Table No. 4: Inhibitory Effects of the Synthesized coumarin derivatives and the Positive Controls on AChE (4EY7).
% inhibition
Compound Code 10–3 M 10–4 M
1 54.23 ± 1.76 41.84 ± 0.97
2 59.58 ± 0.95 51.77 ± 1.84
3 93.04 ± 1.03 88.25 ± 1.63
4 65.94 ± 1.85 52.17 ± 2.04
5 74.77 ± 0.81 60.59 ± 1.29
6 81.21 ± 2.17 76.35 ± 1.38
7 75.65 ± 1.86 64.17 ± 1.30
8 90.24 ± 1.31 86.41 ± 1.83
9 75.94 ± 1.15 68.13 ± 0.97
10 36.96 ± 0.35 17.16 ± 1.07
11 43.32 ± 1.17 29.63 ± 1.07
12 81.54 ± 1.82 77.17 ± 0.73
13 94.18 ± 0.39 87.06 ± 0.56
14 56.27 ± 0.84 48.68 ± 1.09
15 44.83 ± 1.34 33.04 ± 0.86
16 45.83 ± 0.87 33.54 ± 0.14
17 73.51 ± 0.64 51.51 ± 0.07
18 91.30 ± 0.39 73.60 ± 1.34
Standard
Donepezil 98.06 ± 0.73 96.27 ± 0.98

[0039] Therefore, in the present invention novel amine conjugated coumarin hybrids inspired from donepezil are designed, synthesized and evaluated for multi-target potential for Alzheimer`s disease. As hypothesized, the synthesized derivatives showed promising in-silico interactions with the targets AChE involved in Alzheimer`s disease. Further, to support, the hybrids were screened for acetylcholinesterase inhibition study. Compounds 3, 8, 13 and 18 showed promising acetylcholinesterase inhibition activity. In summary, the hybridization strategy of combining bioactive functionalities of existing drugs acting on neurodegenerative conditions proved successful at least in the initial stage. Further exploration of more designed synthetic derivatives could prove beneficial to support the hypothesis.
[0040] While specific language has been used to describe the invention, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[0041] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of processes described herein may be changed and is not limited to the manner described herein. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.

, Claims:WE CLAIM:
1. Amine conjugated coumarin derivatives inspired from donepezil drug as potent acetylcholinesterase inhibitors for Alzheimer’s disease of Formula (I) or pharmaceutically acceptable salts, solvents and prodrugs thereof,

(I)
wherein,
Structure
Code X Y Z R R1
1 N CH2 H --- H
2 N CH H CH3 H
3 N CH H Bn H
4 N CH H COOEt H
5 N CH COOEt H H
6 N N H CH3 H
7 N N H CH2CH3 H
8 N N H Bn H
9 --- H --- H
10 N CH2 H --- Me
11 N CH H CH3 Me
12 N CH H Bn Me
13 N CH H COOEt Me
14 N CH COOEt H Me
15 N N H CH3 Me
16 N N H CH2CH3 Me
17 N N H Bn Me
18 --- H --- Me

2. Amine conjugated coumarin derivatives inspired from donepezil drug as potent acetylcholinesterase inhibitors for Alzheimer’s disease of Formula (I) as claimed in claim 1, wherein the Amine conjugated coumarin derivatives of Formula (I) are selected from a group comprising one of
Structure
Code X Y Z R R1
1 N CH2 H --- H
2 N CH H CH3 H
3 N CH H Bn H
4 N CH H COOEt H
5 N CH COOEt H H
6 N N H CH3 H
7 N N H CH2CH3 H
8 N N H Bn H
9 --- H --- H
10 N CH2 H --- Me
11 N CH H CH3 Me
12 N CH H Bn Me
13 N CH H COOEt Me
14 N CH COOEt H Me
15 N N H CH3 Me
16 N N H CH2CH3 Me
17 N N H Bn Me
18 --- H --- Me

3. A pharmaceutical composition comprising:
the amine conjugated coumarin derivatives inspired from donepezil drug derivatives of Formula (I) as claimed in claim 1 or in claim 2, and the pharmaceutically acceptable salts, solvents and prodrugs thereof; and a pharmacologically acceptable excipient.
4. The pharmaceutical composition as claimed in claim 3, wherein the amine conjugated coumarin derivatives of Formula (I) are selected from a group comprising one of
Structure
Code X Y Z R R1
1 N CH2 H --- H
2 N CH H CH3 H
3 N CH H Bn H
4 N CH H COOEt H
5 N CH COOEt H H
6 N N H CH3 H
7 N N H CH2CH3 H
8 N N H Bn H
9 --- H --- H
10 N CH2 H --- Me
11 N CH H CH3 Me
12 N CH H Bn Me
13 N CH H COOEt Me
14 N CH COOEt H Me
15 N N H CH3 Me
16 N N H CH2CH3 Me
17 N N H Bn Me
18 --- H --- Me

5. The pharmaceutical composition as claimed in claim 3, wherein the pharmacologically acceptable excipient is selected from the group consisting of binders, diluents, disintegrants, lubricants, glidants, fillers, colouring agents, flavouring agents, and combinations thereof.
6. The pharmaceutical composition as claimed in claim 3, wherein the composition is in one of the forms as a tablet, capsule, pill, syrup, suspension, powder, granule, emulsion, microsphere, injectable solution, and solid liquid nanoparticles.
7. A process for the preparation of the amine conjugated coumarin derivatives inspired from donepezil drug derivatives of Formula (I) or a pharmaceutically acceptable salts, solvents and prodrugs thereof as claimed in claim 1, said process comprising the steps of:
reacting a solution of substituted oxarinyl coumarin (2.29 mmol) and appropriate secondary amine (3.43 mmol) in 15 mL absolute ethanol was refluxed at 80-90 °C for 2-3 hours. The reaction progress was monitored by thin-layer chromatography (TLC) in intervals with mobile phase chloroform and methanol (5:0.5). Upon reaction completion, the solvent was evaporated by rotary evaporator. The resulting crude product was purified by column chromatography using a mobile phase of 2% methanol in chloroform, affording the desired compounds in excellent yields to obtain amine conjugated coumarin derivatives inspired from donepezil derivatives of Formula (I).
8. The process for the preparation of the amine conjugated coumarin derivatives inspired from donepezil derivatives of Formula (I) as claimed in claim 7, wherein the aminating agents is selected from one of piperidine, 4-methyl piperidine, 4-benzyl piperidine, ethyl isonipecotate, ethyl nipecotate, 1-methyl piperazine, 1-ethyl piperazine, N-benzyl piperazine and N-benzyl-N-methyl piperazine.
The process for the preparation of the amine conjugated coumarin derivatives inspired from donepezil drug derivatives of Formula (I) as claimed in claim 7, wherein the process for synthesizing coumarin comprising the steps of:
reacting A mixture of appropriate hydroxycoumarin (6.169 mmol) and epichlorohydrin (162.5 mmol) (1:26 molar ratio) was dissolved in 15 mL of absolute ethanol and transferred to a 50 L round-bottom flask equipped with a magnetic stirrer, addition funnel, condenser, and a calcium guard tube.
To this solution, a 0.5 M ethanolic solution of potassium hydroxide (15 mL) was added dropwise at room temperature. The reaction mixture was then subjected to reflux for 3 hours. The mixture was allowed to cool to room temperature, and the solvent was removed under reduced pressure using a rotary evaporator. The resulting orange semi-solid was extracted with chloroform and distilled water. The organic layer, which retained the orange colour, was separated and washed twice with water, then dried over anhydrous magnesium sulphate (MgSO4). The dried organic layer was concentrated under reduced pressure, yielding faint orange solid. This crude product was then recrystallized from ethanol and activated charcoal to yield oxiranyl coumarin as a yellow solid.