Description:FIELD OF INVENTION

[001] The present invention relates to heterocyclic compounds and pharmaceutically acceptable salts thereof. Particularly, the present invention relates to 2-aryl quinazoline/quinazolinone derivatives as multi-targeting agents for treatment of neurological disorders. More particularly, the present invention relates to 2-aryl quinazoline/quinazolinone derivatives based multi-targeting agents for treating neurological disorders and method for preparation thereof.

BACKGROUND OF THE INVENTION

[002] Neurological disorders are medically defined as disorders that affect the brain as well as the nerves found throughout the human body and the spinal cord. The neurological disorders include such as, but not limited to, Alzheimer’s disease, Parkinson’s disease, depression, Huntington chorea, amyotrophic lateral sclerosis, ageing, cerebral ischaemia, substance-abuse risk and the like. Neurological disorders are multifactorial and multiple cellular pathways need to be simultaneously targeted for the effective treatment/management of the disease state. Single target therapies were not found to be effective enough for the treatment of neurological disorders. Various single targeting agents such as donepezil, rivastigmine, pargyline, clorgiline etc. are in clinical practice, however none of these drugs cure the disease and provide symptomatic relief.
[003] There are several patent applications/non-patent literatures that provide quinazolinone derivatives for the treatment of neurological disorders. One such Taiwanese Patent Application TWI426903BA relates to a series of 2-aryl-4-quinazolinone derivatives that have been synthesized and exhibited potent anti-cancer activity in vitro cancer cells and in vivo animal model.
[004] Another WIPO Patent Application WO2017121388A1 discloses quinazolinone derivative, a preparation method therefor, a pharmaceutical composition, and applications. The cited prior art discloses compound represented by formula I, a pharmaceutically acceptable salt, a solvate, a crystal form, a eutectic crystal, a stereoisomer, an isotope compound, a metabolite, or a prodrug thereof. Generation or activity of a cell factor can be regulated, and accordingly, cancers and inflammatory diseases can be effectively treated.
[005] One such non-patent application titled “Current Progress in Quinazoline Derivatives as Acetylcholinesterase and Monoamine Oxidase Inhibitors” published in July 2021 in chemistry select discloses quinazoline-4-(3H)-one derivatives as centre of attraction of medicinal and synthetic chemists due to their excellent versatility in biological activities that are witnessed by many approved drugs available in the market which contains quinazoline as main pharmacophore unit. The cited non-patent mainly focuses on the recent and current progresses in quinazoline derivatives as an acetylcholinesterase (AChE) and monoamine oxidase (MAO)-B inhibitors. The review has leanings towards the molecular determinants and structure-activity relationships (SAR) of quinazoline derivatives on AChE and MAO inhibitory potencies.
[006] Many newly developed AChE and MAO inhibitors were reported to be under different phases of clinical trials but shown number of adverse effects, for e.g., some of these drugs bind irreversibly with the receptors and permanently disabled them and some of these drugs show hepatotoxicity & severe drug-drug interactions.
[007] In view of the problems associated with the above state of the art, there is a need for effective multi-targeting agents effective against neurological disorders.

OBJECTIVES OF THE INVENTION

[008] The primary objective of the present invention is to provide to a 2-aryl quinazoline/quinazolinone derivatives based multi-targeting agents for treating neurological disorders and method for preparation thereof.
[009] Another objective of the present invention is to provide a 2-aryl quinazoline/quinazolinones derivatives and pharmaceutical salts thereof as multi-targeting agents for the treatment of various neurological disorders such as Alzheimer’s disease, Parkinson’s disease, depression, Huntington chorea, amyotrophic lateral sclerosis, ageing, cerebral ischaemia, substance-abuse risk and the like.
[0010] Another objective of the present invention is to synthesize 2-aryl quinazoline/quinazolinones derivatives through multistep reaction.
[0011] Yet another objective of the present invention is to provide a multipotent 2-aryl quinazoline/quinazolinones derivatives with monoamine oxidase inhibition activities, acetylcholinesterase inhibition activities, beta amyloid aggregation inhibition activities, reactive oxygen species inhibition activities, metal chelation activities, and neuroprotection and neurorescue potential for treating neurological disorder.
[0012] Other objects and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, wherein, by way of illustration and example, the aspects of the present invention are disclosed.

BRIEF DESCRIPTION OF DRAWINGS

[0013] The present invention will be better understood after reading the following detailed description of the presently preferred aspects thereof with reference to the appended drawings, in which the features, other aspects and advantages of certain exemplary embodiments of the invention will be more apparent from the accompanying drawings in which:
[0014] Figure 1 (a) illustrates 1H NMR (400 MHz) of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline;
[0015] Figure 1 (b) illustrates 13C NMR (100) spectra of 2-(3-methoxy-4-(s)phenyl)-4-(piperidin-1-yl)quinazoline;
[0016] Figure 2 (a) illustrates 1H NMR (600 MHz) spectra of 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline; and
[0017] Figure 2 (b) illustrates and 13C NMR (150) spectra of 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline; and
[0018] Figure 3 (a) illustrates 1H NMR (600 MHz) spectra of 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one; and
[0019] Figure 3 (b) illustrates 13C NMR (150) spectra of 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one; and
[0020] Figure 4 (a) illustrates 1H NMR (600 MHz) spectra of 2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine; and
[0021] Figure 4 (b) illustrates 13C NMR (150) spectra of 2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine; and
[0022] Figure 5(a) illustrates1H NMR (600 MHz) of 2-(3-ethoxy-4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine;and
[0023] Figure 5(b) illustrates 13C NMR (150 MHz) spectra of 2-(3-ethoxy-4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine;and
[0024] Figure 6(a) illustrates 1H NMR (600 MHz) of 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one; and
[0025] Figure 6(b) illustrates 13C NMR (150 MHz) spectra of 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one.

SUMMARY OF THE INVENTION

[0026] The present invention relates to 2-aryl quinazoline/quinazolinone derivatives of formula 1 and pharmaceutically acceptable salts thereof used as multi-targeting agents for the treatment of various neurological disorders such as Alzheimer’s disease, Parkinson’s disease, depression, Huntington chorea, amyotrophic lateral sclerosis, ageing, cerebral ischaemia, substance-abuse risk and the like.

Wherein
• R1, R2, R3, R4, R5, R6, R7 are independently selected from a group of, not limiting to, H, F, Cl, Br, I, NO2, CH3, OCH3, CN, NH2, CH2CH3, isopropyl, vinyl, allyl, phenyl and/or Y-(CH2)m-Z wherein,
o Y is selected from a group of, not limiting to, O or N;
o m is a value between 0 to 4; and
o Z is independently selected from a group of, not limited to, morpholine, piperidine, N, N-dimethyl, pyrrolidine, pyrrole and the like.
• at least one of R1, R2, R3, R4, R5, R6, R7 is X-(CH2)n-C=CH wherein,
o X is selected from a group of, not limiting to, O, N, S, or C; and
o n is a value between 0 to 6
• at least one of R1, R2, R3, R4, R5, R6, R7 is selected from a group of, but not limited to, O, morpholine, piperidine, N, N-dimethyl pyrrolidine, pyrrole, piperazine optionally substituted with alkyl or phenyl group.

DETAILED DESCRIPTION OF THE INVENTION

[0027] The following description describes various features and functions of the disclosed system with reference to the accompanying figures. In the figures, similar symbols identify similar components, unless context dictates otherwise. The illustrative aspects described herein are not meant to be limiting. It may be readily understood that certain aspects of the disclosed system can be arranged and combined in a wide variety of different configurations, all of which have not been contemplated herein.
[0028] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
[0029] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
[0030] The terms and words used in the following description are not limited to the bibliographical meanings, but, are merely used to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustrative purpose only and not for the purpose of limiting the invention.
[0031] It is to be understood that the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.
[0032] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, steps, components or groups thereof.
[0033] Accordingly, the present invention relates to novel heterocyclic compounds and pharmaceutically acceptable salt or derivatives thereof. Particularly, the present invention relates to 2-aryl quinazoline/quinazolinone derivatives as multi-targeting agents for the treatment of neurological disorders. More particularly, the present invention relates to 2-aryl quinazoline/quinazolinone derivatives based multi-targeting agents for the treatment of neurological disorders and method for preparation thereof.
[0034] The present invention relates to a heterocyclic compound, preferably 2-aryl quinazoline/quinazolinone derivatives of formula 1 and pharmaceutically acceptable salt thereof (represented as formula 1). The formula 1 is represented a

• R1, R2, R3, R4, R5, R6, R7 are independently selected from a group of, not limiting to, H, F, Cl, Br, I, O, NO2, CH3, OCH3, CN, NH2, CH2CH3, isopropyl, propargyl, vinyl, allyl, phenyl and/or Y-(CH2)m-Z wherein,
o Y is selected from a group of, not limiting to, O or N;
o m is a value between 0 to 4; and
o Z is independently selected from a group of, not limited to, propargyl, morpholine, piperidine, N, N-dimethyl, pyrrolidine, pyrrole and the like, wherein
• at least one of R1, R2, R3, R4, R5, R6, R7 is X-(CH2)n-C=CH wherein,
o X is selected from a group of, not limiting to, O, N, S, or C; and
o n is a value between 0 to 6
• at least one of R1, R2, R3, R4, R5, R6, R7 is selected from a group of, but not limited to, O, morpholine, piperidine, N, N-dimethyl pyrrolidine, pyrrole, piperazine optionally substituted with alkyl or phenyl group.
[0035] In an embodiment, the present invention relates to 2-aryl quinazoline/quinazolinone derivatives of formula 1 and pharmaceutically acceptable salt thereof (represented as formula 1). The formula 1 is represented as

wherein
R1, R2, R3, R4, R5, R6, are independently selected from a group of, not limiting to, H, F, Cl, Br, I, NO2, CH3, OCH3, CN, NH2, CH2CH3, isopropyl, vinyl, allyl, propargyl, phenyl and/or Y-(CH2)m-Z wherein, Y is selected from a group of, not limiting to, O or N;
o m is a value between 0 to 4; and
o Z is independently selected from a group of, not limited to, propargyl, morpholine, piperidine, N, N-dimethyl, pyrrolidine, piperazine, pyrrole and the like.
R7 is selected from a group of, but not limited to, O, morpholine, piperidine, N, N-dimethyl pyrrolidine, pyrrole, piperazine optionally substituted with alkyl or phenyl group, or X-(CH2)n-R6 , wherein
o X is C, N, or O
[0036] The present invention also provides a method of preparation of 2-aryl quinazoline/quinazolinone derivatives of formula 1 or a pharmaceutically acceptable salt thereof.
[0037] In an exemplary embodiment, the present invention relates to 2-aryl quinazoline/quinazolinone derivatives of formula 1 selected from the following compounds:
Compound IUPAC name Compounds of Formula 1
1 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline

2 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl) quinazoline

3 2-(4-(2-morpholino-ethoxy) phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one

4 2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine

5 2-(3-ethoxy-4-(2-morpholino-ethoxy) phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine

6 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one

7 4-(2-(4-(4-chloroquinazolin-2-yl)-2-ethoxyphenoxy) ethyl)morpholine

[0038] The method for preparation of 2-aryl quinazoline/quinazolinone derivatives (formula 1) involves reaction between substituted aldehydes, and substituted 2-aminobenzamide in the presence of a base and a solvent.

[0039] In an embodiment, the method for synthesis of 2-aryl quinazoline/quinazolinone derivatives comprises of the following steps:

a) alkylating substituted benzaldehydes using alkylating agent and a base in a solvent, forming 1-(prop-2-yn-1-yloxy)phenyl)aldehydes;
b) reacting the intermediates obtained in step (a) with a plurality of substituted 2 amino-benzamide using catalyst and a solvent, forming 2-arylquinazolinones and 3-(prop-2-yn-1-yl)-2-(4-alkyloxyphenyl)quinazolin-4(3H)-one;
c) chlorinating the 2-arylquinazolinones/3-(prop-2-yn-1-yl)-2-(4-alkyloxyphenyl)quinazolin-4(3H)-one obtained in step (b) in a chlorinating agent, forming 2-aryl,4-chloroquinazolinones; and
d) alkylating 2-aryl,4-chloroquinazolinones obtained in step (c) using an alklating agent and a base in a solvent, forming 4-(alkyl)-2-(4-(prop-2-yn-1-yloxy)phenyl)quinazoline and N-(prop-2-yn-1-yl)-2-(alkyloxyphenyl)quinazolin-4-amines.
In an exemplary embodiment, the substituted benzaldehydes are selected from the group of hydroxy substituted benzaldehydes such as 3-hydroxy benzaldehyde, 4-hydroxy benzaldehyde, vanillin or substituted vanillin such as, isovanillin, 4-hydroxy vanillin or the like.
[0040] In an exemplary embodiment, the alkylating agent used in the present invention is selected from a group consisting of such as, but not limited to, propargyl bromide, or allyl bromide or acetylene bromide, vinyl bromide, and the like.
[0041] In an exemplary embodiment, the base used in the present invention is selected from a group consisting of such as, but not limited to, sodium carbonate, potassium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide, and the like.
[0042] In an exemplary embodiment, the chlorinating agent is selected from a group consisting of such as, but not limited to, Thionyl chloride, and Phosphorus oxychloride.
[0043] In an exemplary embodiment, the solvent is selected from a group consisting of such as, but not limited to, ethanol, methanol, acetonitrile, dimethylformamide, acetone and the like. In a preferred embodiment, the solvent used in step (b) is ethanol.
[0044] In an exemplary embodiment, the catalyst used in the present invention is selected from a group consisting of, such as, but not limited to, iodine.
[0045] In an embodiment of the present invention, the process of preparation of 2-aryl quinazoline/quinazolinone derivatives comprises the following steps:
a. Alkylation of Substituted benzaldehydes to prepare forming 1-(prop-2-yn-1-yloxy)phenyl)aldehydes:
The substituted benzaldehydes are reacted with an alkylating agent and a base in a solvent at a temperature in the range of 70-80 °C for 6 to 8 h. The ratio of substituted benzaldehyde/base/ alkylating agent is taken in the range of 1:1.1:1.1 to 1:1.5:1.3. The progress of the reaction is monitored through TLC. On the completion of reaction, the reaction mixture is poured on crushed ice to obtain precipitates of 1-(prop-2-yn-1-yloxy)phenyl)aldehydes which are filtered and dried.
b. Reacting 1-(prop-2-yn-1-yloxy)phenyl)aldehydes prepared in step (a) with substituted 2 amino-benzamide to form 2-arylquinazolinones :
The 1-(prop-2-yn-1-yloxy)phenyl)aldehydes prepared in step (a) is reacted with substituted 2 amino-benzamide in the presence of a catalyst and a solvent in a ratio in the range of 1:1:0.1 to 1:1.1:1. The reaction mixture is stirred under reflux and progress of the reaction was monitored through TLC, and on completion of the reaction the solid precipitates of 2-arylquinazolinones and 3-(prop-2-yn-1-yl)-2-(4-alkyloxyphenyl)quinazolin-4(3H)-one are filtered and dried.
c. chlorinating the 2-arylquinazolinones obtained in step (b) to form 2-aryl,4-chloroquinazolinones;
The 3-(prop-2-yn-1-yl)-2-(4-alkyloxyphenyl)quinazolin-4(3H)-one prepared in step (b) is reacted with thionyl chloride in the presence of base and a solvent in a ratio in the range of 1:2:0.1 to 1:5:0.2 . The reaction mixture is stirred under reflux and progress of the reaction was monitored through TLC. The excess thionyl chloride was neutralized with saturated solution of sodium bicarbonate followed by extraction with dichloromethane. The crude solid was purified with column chromatography (EA:PE = 1:5) to obtained pure 2-aryl,4-chloroquinazoline derivatives.
d. alkylating 2-aryl,4-chloroquinazolinones obtained in step (c) to form compounds of formula 1
The 2-aryl,4-chloroquinazolinones prepared in step (c) are reacted with an alkylating agent and a base in a solvent at a temperature in the range of 70-80 °C for 6 to 8 h. The ratio of 2-aryl,4-chloroquinazolinones /base/ alkylating agent is taken in the range of 1:1:1.1 to 1:1.2:1.3; The progress of the reaction is monitored through TLC. On the completion of reaction, the reaction mixture is poured on crushed ice to obtain precipitates of 1-(prop-2-yn-1-yloxy)phenyl)aldehydes which are filtered, dried and purified through column chromatography (EA:PE = 1:3 to 2:5).
[0046] In an embodiment, 2-aryl quinazoline/quinazolinone derivatives synthesized in the present invention serves as multi-targeting agents for the treatment of neurological disorders such as, but not limited to, Alzheimer’s disease, Parkinson’s disease, depression, Huntington chorea, amyotrophic lateral sclerosis, ageing, cerebral ischaemia, and substance-abuse risk. The multi-targeting agents formed in the present invention bind to the multiple targets and receptor activity can be modulated as per requirement.

EXPERIMENTAL APPROACH The following examples provide different products synthesized in the present invention and should not be construed to limit the scope of the present invention.
[0047] Example 1:
2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline

The compound 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline was prepared from 4-chloro-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline intermediate.

Methodology:
1. To a 50 ml RBF, 4-hydroxy-3-methoxybenzaldehyde (4.09 mmol) was dissolved in DMF and K2CO3 (4.5 mmol) was added along with propargyl bromide (5.3 mmol). The reaction mixture was heated at 80 °C for 6 to 8 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of 3-methoxy-4-(prop-2-yn-1-yloxy)benzaldehyde (8) were filtered out and dried in vacuum oven. Further the precipitates were crystallized in ethanol and used for further reactions.
2. To a solution of 2-aminobenzamide (2 mmol) in ethanol (10 ml), variously 3-methoxy-4-(prop-2-yn-1-yloxy)benzaldehyde (2 mmol) and iodine (0.3 mmol) were added in 50 ml RBF. The reaction mixture was stirred under reflux and progress of the reaction was monitored through TLC. On the completion of reaction excess solvent was evaporated under vacuum using rotary evaporator. The crude solid was further diluted with saturated solution of sodium thiosulfate to neutralize any excess iodine. The solid precipitates of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazolin-4(3H)-one were filtered under vacuum and dried in vacuum oven. Further, the precipitates were crystallized in ethanol and used in the next reaction.
3. To the suspension of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazolin-4(3H)-one (4 mmol) and dichloromethane (25 ml) in 50 ml RBF the catalytic amount of DMF was added followed by the addition of thionyl chloride (6 mmol) in ice cold conditions. The reaction mixture was refluxed until clear solution formed in the RBF. The progress of the reaction was monitored through TLC. On the completion of the reaction, the reaction mixture was poured over crushed ice in a 200 ml beaker. The excess thionyl chloride was neutralized with saturated solution of sodium bicarbonate followed by extraction with dichloromethane (3 X 20 ml). The combined organic layer was washed with water, brine, and dried over anhydrous sodium sulphate. The organic layer was evaporated under vacuum using rotary evaporator to obtain the crude solid. The crude solid was purified with column chromatography (5% EA in PE) to obtained pure 4-chloro-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline.
4. To a 25 ml RBF, 4-chloro-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline (1.5 mmol) was dissolved in DMF and K2CO3 (1.6 mmol) was added along with piperidine (1.6 mmol). The reaction mixture was heated at 80 °C for 6 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of crude final products were filtered out and dried in vacuum oven. The crude solid was purified with column chromatography (20-30% EA in PE) to obtain desired products.
[0048] Figure 1 (a) illustrates 1H NMR (400 MHz) of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline and Figure 1 (b) illustrates and 13C NMR (100) spectra of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline.
[0049] IC50 MAO-A: 989.33 ± 12.43 nM, MAO-B: 2671.79 ± 48.51 nM, AChE: 5272.41 ± 30.54 nM. Aß42 inhibition at 5 µM: 43.76 ± 3.1 %; Off white powder, melting point: 183-186 oC; Yield 78%, 1H NMR (CDCl3, 500 MHZ, d with TMS=0): 8.18-8.15 (2H, m), 7.94-7.92 (1H, m), 7.87 (1H, d, J= 10Hz), 7.71-7.67 (1H, m) 7.38-7.32 (5H, m) 7.30-7.23 (1H, m), 7.12 (1H, d, J= 15Hz), 4.84-4.82 (2H, m), 4.02-4.00 (3H, m) 3.87-3.84 (4H, m), 3.60-3.58 (2H, m), 2.70-2.68 (4H, m), 2.63-2.52 (1H, m); 13C NMR (CDCl3, 125 MHZ, d with TMS=0) d: 164.84, 159.08, 152.90, 149.48, 149.37, 148.71, 137.95, 137.94, 132.87, 132.44, 129.31, 128.89, 128.44, 127.35, 125.03, 115.36, 113.30, 111.56, 78.46, 75.94, 63.21, 56.68,56.07, 56.05, 56.02, 53.10, 49.87.
[0050] Example 2: 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl) quinazoline

[0051] The compound was prepared from 4-chloro-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline intermediate.
Methodology:
1. To a 50 ml RBF, 4-hydroxy-3-methoxybenzaldehyde (4.09 mmol) was dissolved in DMF and K2CO3 (4.5 mmol) was added along with propargyl bromide (5.3 mmol). The reaction mixture was heated at 80 °C for 6 to 8 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of 3-methoxy-4-(prop-2-yn-1-yloxy)benzaldehyde were filtered out and dried in vacuum oven. Further the precipitates were crystallized in ethanol and used for further reactions.
2. To a solution of 2-aminobenzamide (2 mmol) in ethanol (10 ml), variously 3-methoxy-4-(prop-2-yn-1-yloxy)benzaldehyde (2 mmol) and iodine (0.3 mmol) were added in 50 ml RBF. The reaction mixture was stirred under reflux and progress of the reaction was monitored through TLC. On the completion of reaction excess solvent was evaporated under vacuum using rotary evaporator. The crude solid was further diluted with saturated solution of sodium thiosulfate to neutralize any excess iodine. The solid precipitates of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazolin-4(3H)-one were filtered under vacuum and dried in vacuum oven. Further, the precipitates were crystallized in ethanol and used in the next reaction.
3. To the suspension of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazolin-4(3H)-one (4 mmol) and dichloromethane (25 ml) in 50 ml RBF the catalytic amount of DMF was added followed by the addition of thionyl chloride (6 mmol) in ice cold conditions. The reaction mixture was refluxed until a clear solution formed in the RBF. The progress of the reaction was monitored through TLC. On the completion of the reaction, the reaction mixture was poured over crushed ice in a 200 ml beaker. The excess thionyl chloride was neutralized with saturated solution of sodium bicarbonate followed by extraction with dichloromethane (3 X 20 ml). The combined organic layer was washed with water, brine, and dried over anhydrous sodium sulphate. The organic layer was evaporated under vacuum using rotary evaporator to obtain the crude solid. The crude solid was purified with column chromatography (5% EA in PE) to obtained pure 4-chloro-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline.
4. To a 25 ml RBF, 4-chloro-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline (1.5 mmol) was dissolved in DMF and K2CO3 (1.6 mmol) was added along with benzylpiperidine (1.6 mmol). The reaction mixture was heated at 80 °C for 6 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of crude final products were filtered out and dried in vacuum oven. The crude solid was purified with column chromatography (20-30% EA in PE) to obtain desired products.

[0052] Figure 2 (a) illustrates 1H NMR (600 MHz) of 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline and Figure 2 (b) illustrates Figure 2 (b) illustates 13C NMR (150) spectra of 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline.

[0053] IC50 MAO-A: 3456.62 ± 87.22 nM, MAO-B: 4347.82 ± 72.31 nM, AChE: 177.05 ± 7.58 nM. Aß42 inhibition at 5 µM: 37.12 ± 6.7 %; Pale yellow powder; melting point: 195-198 oC; Yield 69%, 1H NMR (DMSO d6, 400 MHZ, d with TMS=0): 8.04-8.02 (2H, m), 7.89 (1H, d, J=10Hz), 7.81-7.79 (1H, m), 7.73 (1H, t, J=10Hz), 7.43 (1H, t, ¬J¬=10Hz), 7.12 (1H, d, J=10Hz), 4.83 (2H, m), 3.84 (3H, s), 3.73 (4H, bs) 3.58-3.56 (1H, t, J=5Hz), 1.71-1.69 (6H, m); 13C NMR (DMSO d6, 100 MHZ, d with TMS=0), 164.71, 158.38, 152.67, 149.34, 149.03, 133.32, 132,30, 128.66, 125.84, 125.36, 121.40, 115.11, 113.76, 111.65, 79.67, 79.03, 56.49, 55.96, 50.88, 26.03, 24.80

[0054] Example 3
2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one

[0055] The compound was prepared from 2-(4-(2-morpholinoethoxy)phenyl)quinazolin-4(3H)-one by alkylation.
Methodology:
1. To a 50 ml RBF, 4-hydroxybenzaldehyde (4.09 mmol) was dissolved in DMF and K2CO3 (10.6 mmol) was added along with 4-(2-chloroethyl)morpholine hydrochloride (5.3 mmol). The reaction mixture was heated at 80 °C for 6 to 8 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of 4-(2-morpholinoethoxy)benzaldehyde were filtered out and dried in vacuum oven. Further the precipitates were crystallized in ethanol and used for further reactions.
2. To a solution of 2-aminobenzamide (2 mmol) in ethanol (10 ml), variously 4-(2-morpholinoethoxy)benzaldehyde (2 mmol) and iodine (0.3 mmol) were added in 50 ml RBF. The reaction mixture was stirred under reflux and progress of the reaction was monitored through TLC. On the completion of reaction excess solvent was evaporated under vacuum using rotary evaporator. The crude solid was further diluted with saturated solution of sodium thiosulfate to neutralize any excess iodine. The solid precipitates of 2-(4-(2-morpholinoethoxy)phenyl)quinazolin-4(3H)-one were filtered under vacuum and dried in vacuum oven. Further, the precipitates were crystallized in ethanol and used in the next reaction.
3. To a 25 ml RBF, substituted 2-(4-(2-morpholinoethoxy)phenyl)quinazolin-4(3H)-one (0.16 mmol), caesium carbonate (0.16 mmol) was added and solubilized in DMF as solvent. The reaction mixture was then heated at 60 ? for 10 minutes followed by addition of propargyl bromide (0.19 mmol) at 0 ? and reaction mixture was kept at stirring at room temperature. The reaction was monitored by TLC and GC-MS. After the completion of reaction to the reaction mixture (15ml) water was added and aqueous phase was extracted with ethyl acetate (20 ml×3), washed with brine, dried over sodium sulphate and the organic solvent was evaporated under vacuum using rotary evaporator. The crude solid was purified with column chromatography (50-70% EA in PE) to obtain desired products.

[0056] Figure 3 (a) illustrates 1H NMR (600 MHz) of 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one and Figure 3 (b) illustrates and 13C NMR (150 MHz) spectra of 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one.

[0057] IC50 MAO-A: 5563.56 ± 45.78 nM, MAO-B: 1357.62 ± 55.90 nM, AChE: 978.13 ± 45.21 nM. Aß42 inhibition at 5 µM: 34.87 ± 4.2 %; Light brown powder, melting point: 170-174 oC; Yield 69%, 1H NMR (CDCl3, 600 MHZ, d with TMS=0): 8.34 (2H, d, J = 6 Hz), 7.77 (1H, m), 7.76-7.50 (3H, m), 7.49-7.48 (1H, m), 7.05 (2H, d, J= 6Hz), 4.70 (2H, d, J= 6Hz), 4.22 (2H, t, J = 6Hz), 3.77-3.76 (4H, m), 2.87 (2H, t, J = 6Hz), 2.63 (4H, s), 2.35-2.34 (1H, m); 13C NMR (CDCl3 d6, 150 MHZ, d with TMS=0), 161.92, 160.33, 155.36, 147.33, 134.71, 130, 129.93, 127.65, 127.50, 127.20, 127.12, 126.89, 120.60, 115.04, 114.87, 78.70, 72.79, 72.77, 72.66, 66.85,66.06, 57.53, 54.14, 36.56

[0058] Example 4:
2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine

[0059] The compound was prepared from 4-(2-(4-(4-chloroquinazolin-2-yl)phenoxy)ethyl)morpholine by substitution reaction.
Methodology:
1. To a 50 ml RBF, 4-hydroxybenzaldehyde (4.09 mmol) was dissolved in DMF and K2CO3 (10.6 mmol) was added along with 4-(2-chloroethyl)morpholine hydrochloride (5.3 mmol). The reaction mixture was heated at 80 °C for 6 to 8 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of 4-(2-morpholinoethoxy)benzaldehyde were filtered out and dried in vacuum oven. Further the precipitates were crystallized in ethanol and used for further reactions.
2. To a solution of 2-aminobenzamide (2 mmol) in ethanol (10 ml), variously 4-(2-morpholinoethoxy)benzaldehyde (2 mmol) and iodine (0.3 mmol) were added in 50 ml RBF. The reaction mixture was stirred under reflux and progress of the reaction was monitored through TLC. On the completion of reaction excess solvent was evaporated under vacuum using rotary evaporator. The crude solid was further diluted with saturated solution of sodium thiosulfate to neutralize any excess iodine. The solid precipitates of 2-(4-(2-morpholinoethoxy)phenyl)quinazolin-4(3H)-one were filtered under vacuum and dried in vacuum oven. Further, the precipitates were crystallized in ethanol and used in the next reaction.
3. To the suspension of 2-(4-(2-morpholinoethoxy)phenyl)quinazolin-4(3H)-one (4 mmol) and dichloromethane (25 ml) in 50 ml RBF the catalytic amount of DMF was added followed by the addition of thionyl chloride (6 mmol) in ice cold conditions. The reaction mixture was refluxed until a clear solution formed in the RBF. The progress of the reaction was monitored through TLC. On the completion of the reaction, the reaction mixture was poured over crushed ice in a 200 ml beaker. The excess thionyl chloride was neutralized with saturated solution of sodium bicarbonate followed by extraction with dichloromethane (3 X 20 ml). The combined organic layer was washed with water, brine, and dried over anhydrous sodium sulphate. The organic layer was evaporated under vacuum using rotary evaporator to obtain the crude solid. The crude solid was purified with column chromatography (5% MeOH in CHCl3) to obtained pure 4-(2-(4-(4-chloroquinazolin-2-yl)phenoxy)ethyl)morpholine.
4. To a 25 ml RBF, 4-(2-(4-(4-chloroquinazolin-2-yl)phenoxy)ethyl)morpholine (1.5 mmol) was dissolved in DMF and K2CO3 (1.6 mmol) was added along with propargyl amine (1.6 mmol). The reaction mixture was heated at 80 °C for 6 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of crude final products were filtered out and dried in vacuum oven. The crude solid was purified with column chromatography (20-30% EA in PE) to obtain desired products.
Figure 4 (a) illustrates 1H NMR (600 MHz) of 2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine and Figure 4 (b) illustrates and 13C NMR (150 MHz) spectra of 2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine.
[0060] IC50 MAO-A: 7421.92 ± 49.30 nM, MAO-B: 2721.61 ± 32.19 nM, AChE: 1129.75 ± 32.12 nM. Aß42 inhibition at 5 µM: 39.52 ± 1.8 %; Light brown powder, melting point: 170-174 oC; Yield 78%, 1H NMR (CDCl3, 600 MHZ, d with TMS=0): 8.53 (2H, d, J = 6Hz), 7.91 (1H, d, J = 12Hz), 7.73-7.69 (2H, m), 7.39 (1H, t, J = 6Hz), 7.01 (2H, d, J = 6Hz), 5.80 (1H, m), 4.60-4.59 (2H, m), 4.19 (2H, t, J = 6Hz), 3.75 (4H, t, J = 6Hz), 2.84 (2H, t, J = 6Hz), 2.61-2.60 (4H, m), 2.33-2.32 (1H, m); 13C NMR (CDCl3 d6, 150 MHZ, d with TMS=0), 160.66, 159.98, 158.71, 150.71, 132.73, 131.58,130.05, 128.78, 125.29, 120.51, 114.27, 113.35, 80.19, 71.81, 66.97, 65.88, 57.67, 54.17, 31.06

[0061] Example 5:
2-(4-(3-ethoxy-2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine

[0062] The compound was prepared from 4-(2-(4-(4-chloroquinazolin-2-yl)-2-ethoxyphenoxy)ethyl)morpholine by substitution reaction.
Methodology:
1. To a 50 ml RBF, 3-ethoxy-4-hydroxybenzaldehyde (4.09 mmol) was dissolved in DMF and K2CO3 (10.6 mmol) was added along with 4-(2-chloroethyl)morpholine hydrochloride (5.3 mmol). The reaction mixture was heated at 80 °C for 6 to 8 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of 3-ethoxy-4-(2-morpholinoethoxy)benzaldehyde were filtered out and dried in vacuum oven. Further the precipitates were crystallized in ethanol and used for further reactions.
2. To a solution of 2-aminobenzamide (2 mmol) in ethanol (10 ml), variously 3-ethoxy-4-(2-morpholinoethoxy)benzaldehyde (2 mmol) and iodine (0.3 mmol) were added in 50 ml RBF. The reaction mixture was stirred under reflux and progress of the reaction was monitored through TLC. On the completion of reaction excess solvent was evaporated under vacuum using rotary evaporator. The crude solid was further diluted with saturated solution of sodium thiosulfate to neutralize any excess iodine. The solid precipitates of 2-(3-ethoxy-4-(2-morpholinoethoxy)phenyl)quinazolin-4(3H)-one were filtered under vacuum and dried in vacuum oven. Further, the precipitates were crystallized in ethanol and used in the next reaction.
3. To the suspension of 2-(3-ethoxy-4-(2-morpholinoethoxy)phenyl)quinazolin-4(3H)-one (4 mmol) and dichloromethane (25 ml) in 50 ml RBF the catalytic amount of DMF was added followed by the addition of thionyl chloride (6 mmol) in ice cold conditions. The reaction mixture was refluxed until a clear solution formed in the RBF. The progress of the reaction was monitored through TLC. On the completion of the reaction, the reaction mixture was poured over crushed ice in a 200 ml beaker. The excess thionyl chloride was neutralized with saturated solution of sodium bicarbonate followed by extraction with dichloromethane (3 X 20 ml). The combined organic layer was washed with water, brine, and dried over anhydrous sodium sulphate. The organic layer was evaporated under vacuum using rotary evaporator to obtain the crude solid. The crude solid was purified with column chromatography (5% MeOH in CHCl3) to obtained pure 4-(2-(4-(4-chloroquinazolin-2-yl)-2-ethoxyphenoxy)ethyl)morpholine.
4. To a 25 ml RBF, 4-(2-(4-(4-chloroquinazolin-2-yl)-2-ethoxyphenoxy)ethyl)morpholine (1.5 mmol) was dissolved in DMF and K2CO3 (1.6 mmol) was added along with propargyl amine (1.6 mmol). The reaction mixture was heated at 80 °C for 6 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of crude final products were filtered out and dried in vacuum oven. The crude solid was purified with column chromatography (20-30% EA in PE) to obtain desired products.
[0063] Figure 5 (a) illustrates 1H NMR (600 MHz) of 2-(3-ethoxy-4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine and Figure 5 (b) illustrates 13C NMR (150 MHz) spectra of 2-(3-ethoxy-4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine.
[0064] IC50 MAO-A: 3874.51± 32.44 nM, MAO-B: 1984.62 ± 61.65 nM, AChE: 888.74 ± 23.82 nM. Aß42 inhibition at 5 µM: 23.65 ± 3.2 %; Light brown powder, melting point: 170-174 oC; Yield 71% 1H NMR (600 MHz, CHLOROFORM-D) d 8.17-8.16 (2H, m), 7.92 (1H, d, J = 8.4Hz), 7.74-7.71 (2H, m), 7.41 (1H, t, J = 7.2Hz), 7.00 (2H, d, J = 9Hz) 5.86-5.85 (1H, m), 4.59- 4.57 (2H, m), 4.27, 4.26-4.23 (4h, m), 3.76 (4H, t, J = 4.8Hz), 2.88 (2H, t, J= =6Hz), 2.66-2.64 (4H, m), 2.32-2.31 (1H, m), 1.49 (3H, t, J = 7.2Hz); 13C NMR (CDCl3 d6, 150 MHZ, d with TMS=0) 159.95, 158.71, 150.65, 150.56, 148.67, 132.74, 132.16, 128.78, 125.37, 121.81, 120.56, 113.41, 113.38, 113.14, 80.19, 77.25, 77.04, 76.83, 71.73, 66.95, 66.92, 64.51, 57.52, 54.11, 31.93, 31.09, 29.67, 22.70, 14.95, 14.12

[0065] Example 6: 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one

[0066] The compound was prepared from 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)quinazolin-4(3H)-one by alkylation.
Methodology
1. To a 50 ml RBF, 4-hydroxybenzaldehyde (4.09 mmol) was dissolved in DMF and K2CO3 (10.6 mmol) was added along with 1-(2-chloroethyl)piperidine hydrochloride (5.3 mmol). The reaction mixture was heated at 80 °C for 6 to 8 h. The progress of the reaction was monitored through TLC (EA/PE 1:3). On the completion of reaction, the reaction mixture was poured on crushed ice in beaker and precipitates of 4-(2-(piperidin-1-yl)ethoxy)benzaldehyde were filtered out and dried in vacuum oven. Further the precipitates were crystallized in ethanol and used for further reactions.
2. To a solution of 2-aminobenzamide (2 mmol) in ethanol (10 ml), variously 4-(2-(piperidin-1-yl)ethoxy)benzaldehyde (2 mmol) and iodine (0.3 mmol) were added in 50 ml RBF. The reaction mixture was stirred under reflux and progress of the reaction was monitored through TLC. On the completion of reaction excess solvent was evaporated under vacuum using rotary evaporator. The crude solid was further diluted with saturated solution of sodium thiosulfate to neutralize any excess iodine. The solid precipitates of 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)quinazolin-4(3H)-one were filtered under vacuum and dried in vacuum oven. Further, the precipitates were crystallized in ethanol and used in the next reaction.
3. To a 25 ml RBF, substituted 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)quinazolin-4(3H)-one (0.16 mmol), caesium carbonate (0.16 mmol) was added and solubilized in DMF as solvent. The reaction mixture was then heated at 60 ? for 10 minutes followed by addition of propargyl bromide (0.19 mmol) at 0 ? and reaction mixture was kept at stirring at room temperature. The reaction was monitored by TLC and GC-MS. After the completion of reaction to the reaction mixture (15ml) water was added and aqueous phase was extracted with ethyl acetate (20 ml×3), washed with brine, dried over sodium sulphate and the organic solvent was evaporated under vacuum using rotary evaporator. The crude solid was purified with column chromatography (50-70% EA in PE) to obtain desired products.

[0067] Figure 6 (a) illustrates 1H NMR (600 MHz) of 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one and Figure 6 (b) illustrates 13C NMR (150 MHz) spectra of 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one.
[0068] IC50 MAO-A: 9353.38 ± 52.49 nM, MAO-B: 1595.58 ± 49.38 nM, AChE: 1117 ± 42.23 nM. Aß42 inhibition at 5 µM: 21.88 ± 3.1 %; Light brown powder, melting point: 170-174 oC; Yield 71% 1H NMR (600 MHz, CHLOROFORM-D); 8.34 (1H, d, J = 6Hz), 7.77-7.72 (2H, m), 7.70-7.68 (2H, m), 7.51-7.48 (1H, t, J = 10Hz), 7.04-7.03 (2H, m), 4.69 (2H, s), 4.22-4.21 (2H,m), 2.84 (2H, t, J = 6Hz), 2.57 (4H, m), 2.35 (1H, s), 1.65-1.63 (4H, m), 1.48-1.46 (2H, m); 13C NMR (CDCl3 d6, 150 MHZ, d with TMS=0) 161.96, 160.47, 155.45, 147.34, 134.71, 129.94, 129.90, 127.64, 127.28, 127.14, 126.98, 120.58, 115.03, 114.96, 114.90, 78.70, 72.69, 66.17, 57.75, 55.10, 36.60, 25.81, 24.12
Biological Investigations

[0069] Biological investigations of 2-arylquinazoline/quinazolinone derivatives synthesized in the present invention was performed to evaluate the biological activity of the synthesized compound for the treatment of neurological disorders such as, but not limited to, Alzheimer’s disease, Parkinson’s disease, depression, Huntington chorea, amyotrophic lateral sclerosis, ageing, cerebral ischaemia, and substance-abuse risk. The potential of the synthesized compounds for monoamine oxidase enzyme, acetylcholinesterase enzyme, beta amyloid aggregation, reactive oxygen species inhibition, neurorescue and neuroprotective potential, metal chelating, and cytotoxic effects of the synthesized compound was assessed.
[0070] The MAO inhibition potential of the 2-arylquinazoline/quinazolinone derivatives was evaluated on recombinant human MAO-A and MAO-B enzymes. All the tested compounds showed enhanced inhibition activities for the MAO-A and MAO-B isoform with IC50 values ranging from micro molar to sub nano molar range 40-60% . Different compounds displayed selectivity for MAO-A and MAO-B isoform depending upon the substituents attached to the biaryl rings. Presently, none of currently available quinazoline derivatives inhibit AChE, MAO and Amyloid beta simultaneously. The table hereinbelow provides IC50 values for AChE and MAO.

IC50 Values are in nanomolar units
Name AChE (IC50) MAO-A (IC50) MAO-B (IC50)
2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline 5272.41 ± 30.54 989.33 ± 12.43 2671.79 ± 48.51
4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline 177.05 ± 7.58 3456.62 ± 87.22 4347.82 ± 72.31
2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one 1357.62 ± 55.90 5563.56 ± 45.78 978.13 ± 45.21
2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine 1129.75 ± 32.12 7421.92 ± 49.30 2721.61 ± 32.19
4-(2-(4-(4-chloroquinazolin-2-yl)-2-ethoxyphenoxy)ethyl)morpholine 888.74 ± 23.82 3874.51± 32.44 1984.62 ± 61.65
2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one 1117 ± 42.23 9353.38 ± 52.49 1595.58 ± 49.38
Table 1
[0071] Method: The hMAO inhibitory activity of target compounds (as shown in Table 1) was evaluated using Amplex® Red assay kit as reported in the literature. In this assay, 100 µl of drugs and reference compounds with sufficient amount of MAO-A/B (Dissolved in sodium phosphate buffer 0.05 M, pH 7.4) was taken in flat-black-bottom 96-well plates (Tarsons) and incubated for 30 min at 37 °C in an incubator (n = 3). After 30 min interval, reaction was initiated by addition of Amplex Red working solution containing Amplex® Red reagent, HRP and p-tyramine. The mixture was incubated in dark for 30 min again and amount of H2O2 produced was determined using fluorescence detection (excitation at 545 nm, and emission at 590 nm) using multi-detection microplate fluorescence reader (SynergyHI, Bio-Tek® Instruments). For control studies, the test or reference compounds were replaced by vehicle while any interference due to reaction of compounds with Amplex® Red reagent was subtracted using non-enzymatic reaction. For final calculations, background activity was eliminated which was determined via reactions of test compounds with all components except hMAO enzymes.
[0072] The acetylcholinesterase inhibition activities were determined using Ellman methodology. The tested compounds displayed high potency with IC50 values varying from micro molar to low nano molar range.
[0073] Method: For determination of AChE and BuChE inhibitory potential of the ligands, Ellman et al. protocol was employed. All experiments were performed in tris-HCl buffer of pH-8 using standard inhibitor donepezil. For determination of IC50 concentrations (0.001 – 20 µm) of test compounds and donepezil were used. For each assay 50 µl (0.2 Uml-1 of AChE and 0.6 Uml-1 of BuChE) of enzyme and 20 µl of ligands or reference compounds were taken in 96 well plates and incubated for 30 min. After 30 min interval, 100 µl (1.5 mM) of DTNB was added to it followed by addition of BTCI (30 mM, 10 µl) substrate for initiation of reaction. The absorbance was measured immediately at 415 nm for 20 min at 1 min interval using multi-detection microplate fluorescence reader (SynergyHI, Bio-Tek® Instruments). The absorbance recorded was used for calculating IC50 values. All assays and control studies were done in triplicate and in three independent runs (Table 1).
[0074] In vitro inhibition and disaggregation of self-induced Aß1-42 (Amyloid ß-Protein) aggregation was measured using a ThT-binding assay (Euro J Med Chem, 2012, 58, 84-97)(Table 2).

Method: The samples were resuspended in 50 µL of DMSO, and the monomers were solubilized through sonication for 10 min. Native Buffer (940 µL; 50 mM Tris•HCl at pH 7.4 and 150 mM NaCl) was added, and the samples were divided in four parts (247.5 µL). Finally, 2.5 µL of each compound at 1 mM in DMSO (obtaining a final concentration of 5 µM) or DMSO without compound (positive control) was added. The final concentration of Aß40 was 5 µM. The samples were incubated at 37 °C. At 24 h, 135 µL of sample were mixed with 15 µL of ThT at 250 µM, obtaining a final ThT concentration of 25 µM. Finally, the aggregation was tracked by detecting ThT fluorescence (?exc = 445 nm; ?em = 480 nm).
Name Aß1-42 percentage inhibtion (5µM concentration)
2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline 43.76 ± 3.1 %
4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline 37.12 ± 6.7 %
2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one 34.87 ± 4.2 %
2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine 39.52 ± 1.8 %
4-(2-(4-(4-chloroquinazolin-2-yl)-2-ethoxyphenoxy)ethyl)morpholine 23.65 ± 3.2 %
2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one 21.88 ± 3.1 %
Table 2

[0075] The neuroprotective potential of compounds was determined against 6-OHDA neurotoxin using MTT assay. For this, SH-SY5Y cells were plated in 96 wells, at 106 cells/well density. The cells were cultured for 24 hours in DMEM/F-12 media containing 10% FBS and horse serum supplemented 1% penicillin antibiotic solution. The cells were then treated with target compounds (at concentrations of 1-25?m), 4 hours before 6-OHDA (12.5 µM). After 24 hours of incubation in the oven, at 37°C and a 5% CO2, 95% O2 atmosphere, the tested compounds were replaced with 80 mL of medium and 20 mL of MTT in PBS (0.5 mg/mL, final concentration). The cells were incubated for another 4 hours. After the removal of MTT, the formazan crystals were dissolved in DMSO. The amount of formazan was measured using a microculture plate reader with a test wavelength of 570 nm.

[0076] Results for Neuroprotective effects: Synthesized compounds were evaluated for their neuroprotective potential against 6-hydroxydopamine (6-OHDA) neurotoxin in SH-SY5Y cells. These compounds showed mild to moderate neuroprotective potential against 6-OHDA. Maximum cell viability of 74.54 ± 5.1 %, 63.6 ± 7.8 %, 78.43 ± 6.1 % was observed for 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline, 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline, 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one respectively as compared to the 6-OHDA treated cells (49.98 ± 6.3%).
S.No. Compounds Maximum cell viability
1 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline (Example 1) 74.54 ± 5.1 %
2 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline(Example 2) 63.6 ± 7.8 %,
3 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one (Example 3) 78.43 ± 6.1 %
4 6-hydroxydopamine (6-OHDA)(reference compound) 49.98 ± 6.3%

[0077] The metal chelating studies were performed with UV-vis spectrophotometer. The absorption spectra of each compound (50 µM, final concentration) alone or in the presence of CuSO4, FeSO4, and FeCl3 (50 µM, final concentration) for 30 minutes in 20% (v/v) methanol/buffer (20 mM HEPES, 150 mM NaCl, pH = 7.4) were recorded at room temperature.
[0078] Method: UV-vis spectrophotometer was used to evaluate the metal chelation properties of most potent compounds with CuSO4, FeSO4, and FeCl3 salts at final concentration of 50 µM. For each compound, at 1:1 concentration, absorption spectra were recorded alone or in the presence of metal salts after 30 min incubation in 20% (v/v) methanol/buffer (20 mM HEPES, 150 mM NaCl, pH = 7.4)
Results for metal chelation: All the synthesized compounds were found unable to form chelates with any of the metal ions.
[0079] For reversibility studies (Bioorg Med Chem Lett, 2015, 25, 5270-5276) the test inhibitors were incubated with the MAO enzymes at concentrations of 10 × IC50 and 100 × IC50 at 37 °C for of 30 min (negative control performed in the absence of inhibitor), and 4% DMSO was added as co-solvent to all incubations. All the compounds were found reversible with respect to MAO enzyme.
[0080] Method: For reversibility inhibition studies, briefly, the test inhibitors were incubated with the MAO enzymes at concentrations of 10 × IC50 and 100 × IC50 at 37 °C for 30 min (negative control performed in the absence of inhibitor), and 4% DMSO was added as cosolvent to all incubations. After a 30 min incubation period, the samples were subsequently diluted to 100-fold with the addition of tyramine substrate to achieve final inhibitor concentrations of 0.1 × IC50 and 1 × IC50 value, respectively. As positive controls, MAO-A and MAO-B were incubated with theirreversible inhibitors, clorgyline and pargyline, respectively, at 10 × IC50 concentrations and then diluted 100-fold to achieve final inhibitor concentrations of 0.1 × IC50. The residual MAO activities after dilutions were measured (n = 3), and the residual enzyme activities were expressed as mean ± SD.
[0081] Results for reversibility studies: At IC50 concentration of 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline, 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline, 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one, shows 57.43 ± 3.2 %, 52.92 ± 4.5 %, and 53.87 ± 7.0 %, MAO-B activity respectively. While, 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline, 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline, 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one, shows 45.30 ± 2.2 %, 55.27 ± 4.3 % and 49.32 ± 3.2 % activity for MAO-A respectively. Inhibition was decreased by increasing to the concentrations to 10 × IC50 and 100 × IC50. The maximum inhibition was achieved at 100 × IC50 where only 70 % to 80 % activity were observed for the synthesized compounds respective to both the isoforms of MAO. We can conclude that synthesized compounds are found to be reversible inhibitors of MAO enzymes.
S.No Compounds MAO-A activity at
IC50 MAO-B activity at IC50
1 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline (Example 1) 45.30 ± 2.2 % 57.43 ± 3.2 %
2 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline(Example 2) 55.27 ± 4.3 % 52.92 ± 4.5 %
3 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one (Example 3) 49.32 ± 3.2 % 53.87 ± 7.0 %

[0082] Intracellular ROS level of SH-SY5Y cells were determined using non-fluorescent compound 2,7-dichlorofluorescein diacetate (DCF-DA). These compounds are permeable and oxidized by ROS to a fluorescent compound 2,7-DCF. Most of the compounds have reduced the ROS levels.
Method: Intracellular levels of ROS were determined by using non-fluorescent compound 2,7-dichlorofluorescein diacetate (DCF-DA) that is permeable to the cell membrane where it is hydrolyzed by intracellular esterases and oxidized by ROS to a fluorescent compound 2,7-DCF. The human neuroblastoma (SH-SY5Y) cells (approximately 10,000 cells/well) were seeded of 96 well plate in DMEM/F-12 media containing 10% FBS and horse serum supplemented 1% penicillin antibiotic solution for 24h in a humidified atmosphere containing 5% CO2. The
media was removed, washed with PBS and cells were treated with test compounds (without FBS) for 24 h at different concentrations (1 mM, 5 mM and 25 mM). Thereafter, cells were rinsed with PBS three times and treated with H2DCF-DA (50 mM) and incubated for 30 min at 37 oC. Following incubation, cells were rinsed with PBS and fluorescence was detected at a wavelength of 478 nm excitation and 518 nm emission.
Results: ROS levels were reduced to 81.22 ± 3.0 %, 85.73 ± 5.2 %, 79.76 ± 4.9 % and 42.91 ± 3 %, 45.41 ± 6.2 % and 59.71 ± 2.6 % at for 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline, 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline, 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one at 1 mM and 5mM concentrations, respectively in the SH-SY5Y cells . Thus, from these observations, it is apparent that synthesized compounds may protect the neuronal cells from ROS.

[0083] The cytotoxic effects of the compounds were evaluated against human neuro-blastome cell line SH-SY5Y because of their similarity to dopaminergic neurons. The compounds were incubated at 1 µM, 5 µM and 25 µM concentrations and were analysed after 24h treatment time. The percentage of cell viability was measured using MTT assay. The compounds were found non-toxic against the tested cells.

Method:
Results: The compounds were found to be non-toxic at lower concentrations. 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline, 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)quinazoline, 2-(4-(2-morpholinoethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one, shows 87.54 ± 7.1 %, 78.23 ± 6.5 %, and 79.32 ± 9.3 %, cell viability at 25 µM concentration respectively. Whereas it shows 91.36 ± 6 %, 89.9 ± 7.6 % and 83.6 ± 8.3 % cell viability at 0.1 µM concentration respectively. So, the lower micromolar range IC50 of the synthesized compounds confirms the non-toxic nature of the compounds to the cells.

[0084] Advantages of the Invention

The present invention exhibits following advantages:
1. The present invention provides a compound and pharmaceutical salts or derivatives thereof to which is effective in treating neurological disorders.
2. The product formed in the present invention possess potential for monoamine oxidase enzyme, acetylcholinesterase enzyme, beta amyloid aggregation, reactive oxygen species inhibition, neurorescue and neuroprotective potential, metal chelating, and cytotoxic effects.
3. The product formed in the present invention exhibits minimal or no side effects.
4. The product formed in the present invention is reversible in nature and receptor activity can be modulated as per requirement.
5. The present invention provides multi-targeting single drug molecule, thereby eliminating possibility of drug-drug interaction.
6. Activities displayed by the 2-aryl quinazoline/quinazolinone derivatives of
formula I
1. acetylcholinesterase inhibition activities
2. beta amyloid aggregation inhibition activities
3. reactive oxygen species inhibition activities
4. multipotent ligands for the treatment of neurological disorders wherein neurological disorder is Alzheimer’s disease, Parkinson’s disease and/or depression
5. multipotent ligands for the treatment of neurological disorders wherein neurological disorder is substance abuse
6. multipotent ligands for the treatment of neurological disorders Huntington chorea, amyotrophic lateral sclerosis, ageing, cerebral ischaemia and the like.

[0085] While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

, Claims:WE CLAIM:

1. A 2-aryl quinazoline/quinazolinone compound of Formula 1 for the Treatment of neurological Disorders :

wherein
• R1, R2, R3, R4, R5, R6, R7 are independently selected from a group of, not limiting to, H, F, Cl, Br, I, NO2, CH3, OCH3, CN, NH2, CH2CH3, isopropyl, vinyl, allyl, phenyl and/or Y-(CH2)m-Z wherein,
o Y is selected from a group of, not limiting to, O or N;
o m is a value between 0 to 4; and
o Z is independently selected from a group of, not limited to, morpholine, piperidine, N, N-dimethyl, pyrrolidine, pyrrole and the like.
• at least one of R1, R2, R3, R4, R5, R6, R7 is X-(CH2)n-C=CH wherein,
o X is selected from a group of, not limiting to, O, N, S, or C; and
o n is a value between 0 to 6
• at least one of R1, R2, R3, R4, R5, R6, R7 is selected from a group of, but not limited to, O, morpholine, piperidine, N, N-dimethyl pyrrolidine, pyrrole, piperazine optionally substituted with alkyl or phenyl group.

2. The compound as claimed in claim 1, wherein the compound of Formula 1 is selected from the group comprising of:
I. 2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)-4-(piperidin-1-yl)quinazoline
II. 4-(4-benzylpiperazin-1-yl)-2-(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl) quinazoline
III. 2-(4-(2-morpholino-ethoxy) phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one
IV. 2-(4-(2-morpholinoethoxy)phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine
V. 2-(4-(2-morpholino-ethoxy) phenyl)-N-(prop-2-yn-1-yl)quinazolin-4-amine
VI. 2-(4-(2-(piperidin-1-yl)ethoxy)phenyl)-3-(prop-2-yn-1-yl)quinazolin-4(3H)-one
VII. 4-(2-(4-(4-chloroquinazolin-2-yl)-2-ethoxyphenoxy) ethyl)morpholine

3. A method for preparation of 2-aryl quinazoline/quinazolinone derivatives (formula 1) as claimed in claim 1, wherein the method comprising the steps of:
a) alkylating hydroxy substituted benzaldehydes using alkylating agent and a base in a solvent, forming 1-(prop-2-yn-1-yloxy)phenyl)aldehydes;
b) reacting the intermediates obtained in step (a) with substituted 2-amino-benzamide using catalyst and a solvent, forming 2-arylquinazolinones and 3-(prop-2-yn-1-yl)-2-(4-alkyloxyphenyl)quinazolin-4(3H)-one;
c) chlorinating the 2-arylquinazolinones/3-(prop-2-yn-1-yl)-2-(4- alkyloxyphenyl) quinazolin-4(3H)-one obtained in step (b) in a chlorinating agent, forming 2-aryl, 4- chloroquinazolinones; and
d) alkylating 2-aryl,4-chloroquinazolinones obtained in step (c) using an alkylating agent and a base in a solvent, forming 4-(alkyl)-2-(4- (prop-2-yn-1- yloxy) phenyl) quinazoline and N-(prop-2-yn-1- yl)-2-(alkyloxyphenyl)quinazolin-4-amines.

4. The method as claimed in claim 3, wherein the substituted benzaldehydes are selected from the group of hydroxy substituted benzaldehydes such as 3-hydroxy benzaldehyde, 4-hydroxy benzaldehyde, vanillin or substituted vanillin such as, isovanillin, 4-hydroxy vanillin or the like.

5. The method as claimed in claim 3, wherein the alkylating agent used in the present invention is selected from a group consisting of such as, but not limited to, propargyl bromide, or allyl bromide or acetylene bromide, vinyl bromide, and the like.

6. The method as claimed in claim 3, wherein the base is selected from a group of sodium carbonate, potassium carbonate, caesium carbonate, sodium hydroxide, potassium hydroxide and the like.

7. The method as claimed in claim 3, wherein the chlorinating agent is selected from a group of POCl3, SOCl2 and the like.

8. The method as claimed in claim 3, wherein the solvent is selected from group of ethanol, methanol, acetonitrile, dimethylformamide, acetone and the like.

9. The 2-aryl quinazoline/quinazolinone derivatives of formula I as claimed in claim 1, wherein the compounds display activities including monoamine oxidase inhibition activities, acetylcholinesterase inhibition activities, beta amyloid aggregation inhibition activities, reactive oxygen species inhibition activities and metal chelation activities.

10. The 2-aryl quinazoline/quinazolinone derivatives of formula I as claimed in claim 1, as multipotent ligands for the treatment of neurological disorders wherein neurological disorder are Alzheimer’s disease, Parkinson’s disease and/or depression, substance abuse, Huntington chorea, amyotrophic lateral sclerosis, ageing, cerebral ischemia and the like.