Design, synthesis, computational and biological evaluation of new benzodiazepines as CNS agents

Shweta Verma; Surendra Kumar; Sushil Kumar

doi:10.1016/j.arabjc.2017.08.005

View/Download PDF

Buy Reprints

PDF

Translate this page into:

Original article

13 (

); 863-874

doi:

10.1016/j.arabjc.2017.08.005

Design, synthesis, computational and biological evaluation of new benzodiazepines as CNS agents

Shweta Verma^{^a,⁎}, Surendra Kumar^{^b}, Sushil Kumar^{^a}

a Faculty of Pharmacy, IFTM University, Moradabad 244001, U.P., India

b College of Pharmacy, Gachon University of Medicine and Science, Hambakmoeiro 191, Yeonsu-gu, Incheon City 21936, South Korea

⁎Corresponding author. shweta_iftm@yahoo.in (Shweta Verma)

Received: 2017-5-14, Accepted: 2017-8-13, Published: 2017-01-01

Disclaimer:
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.

Peer review under responsibility of King Saud University.

Abstract

Two series of new benzodiazepines were synthesized and the target compounds (E1-10 and G1-10) were evaluated for antianxiety and skeletal muscle relaxant activity as CNS agents in albino mice. The chemical structures of the compounds were confirmed on the basis of their TLC, IR, ¹H NMR and ¹³C NMR analysis. In computational studies, the physicochemical similarity of the target compounds was assessed by calculating from a set of physicochemical properties using software programs and test compounds demonstrated moderate physiochemical similarity with respect to diazepam. Log P values of the target compounds indicates good penetration to CNS. Molecular docking studies revealed that the target compounds correctly dock into the binding pocket of the GABA_A receptor, while their bioavailability/drug-likeness was predicted to be acceptable but requires future optimization. The test compounds (E1-10 and G1-10) were screened for antianxiety and skeletal muscle relaxant activity using Elevated plus maze and Rotarod method respectively. Among them, the compounds E10 and G7 showed maximum potency as CNS agents.

Keywords

Benzodiazepines

Phenylpiperazine

Antianxiety

Skeletal muscle relaxant

Computational studies

Show Related Articles from PubMed

1 Introduction

Anxiety is the most common neurological disorder due to number of stress factors (physiological, psychological and sociological) which results in disturbance of daily routine life (Ninan, 2001; Barbee, 1988; Steimer, 2002 ). The etiology of these disorders is the dysfunction of monoamine neurotransmitters in CNS, such as gamma-amino butyric acid (GABA), serotonin (5-HT), dopamine (DA) and norepinephrine (NE) (Nash and Nutt, 2004; Nutt and Malizia, 2001). The ligands like benzodiazepines and arylpiperazines are showed the affinity towards these receptors and reported as CNS agents (Kumar et al., 2016; Kumar et al., 2011; Clayton et al., 2007 ). The GABA_A-benzodiazepine receptor is an important target for several anxiolytic drugs and may therefore play an important role in anxiety-related disorders (Argyropoulos and Nutt, 1999; Park-Chung et al., 1999). The benzodiazepines receptor (BZ) has been classified into several types, based on a subunit isoforms and clinical effects related to each type. The BZ1 receptor contains the α1 isoform. The BZ1 receptor is highly concentrated in the cortex, thalamus, and cerebellum. It is responsible for the BZDs’ sedative effects, anterograde amnesia and for some of the anticonvulsive effects. Sixty percent of GABA_A receptors contain the α1 subunit. BZ2 receptors contain the α2 isoform and highly concentrated in areas such as the limbic system, motor neurons, and the dorsal horn of the spinal cord. BZ2 receptors mediate the anxiolytic and, to a large extent, the myorelaxant effects of BZDs (Griffin et al., 2013). Currently used anxiolytics demonstrated some serious adverse effects. Therefore, to reduce the probability of side effects, there is need to find new anxiolytics, preferably in chemical classes in which such activity has not yet been observed. Here, we designed some new molecules by chemical hybridization of benzodiazepine nucleus with phenylpiperazines (Scheme 1) and evaluated as anxiolytics with GABA_A- benzodiazepine receptor. Newly designed compounds were consist of: a head part (benzodiazepine nucleus), connecting site and a tail part (phenylpiperazine) (Fig. 1). The main structural features explored included changes in the relative position of the substituent group of phenyl piperazine ring. In computational studies, the physicochemical similarity of the target compounds was assessed by calculating from a set of physicochemical properties and molecular modeling was performed by using online software programs. The target compounds (E1-10 and G1-10) were evaluated for antianxiety and skeletal muscle relaxant activity using Elevated plus maze and Rotarod method respectively in albino mice.

Synthetic scheme for the preparation of the target compounds. Reagent and conditions: (i) Toluene, Reflux 4 h. (ii) Hexamine, Formic acid, Ethanol, Reflux 6 h. (iii) POCl3, N,N-Dimethylaniline (iv) DMF, anhyd. K2CO3, KI, Stir 80 °C for 24 h (v) ClCOCH2Cl, Heat 5 h (vi) DMF, anhyd. K2CO3, KI, Stir 80 °C for 24 h.

Chemical hybridization of target compounds consists of: a head (benzodiazepine nucleus), connecting site and a tail (phenyl piperazine ring).

2 Materials and methods

2.1

2.1 Experimental

All the chemicals used were of laboratory grade and procured from CDH&S.D. Fine chemicals (India). Melting points were determined by open tube capillary method and are uncorrected. The IR spectra of synthesized compounds were recorded in potassium bromide discs on Schimadzu FTIR Spectrophotometer 8300. The ¹H NMR and ¹³CNMR spectra of the synthesized compounds were recorded in CDCl₃ using Bruker DRX-300spectrophometer and tetramethylsilane (TMS) as an internal standard. The signals are quoted as follows: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; bs, broad singlet and are expressed in δ ppm. The reactions progress was monitored by thin-layer chromatography (TLC) using silica gel G and spots were visualized in an iodine chamber.

2.2

2.2 Synthesis of compounds

Synthetic scheme for the preparation of target compounds (E1-10) and (G1-10) is summarized in Scheme 1.The nature of substituent is given in Table 1. 2-Amino-5-chlorbenzophenone (A) was converted to N-(2-benzoyl-4-chlorophenyl)-2-chloroacetamide (B) by refluxing with chloroacetylchloride in toluene according to the reported procedure (Sternbach et al., 1962; Sternbach, 1971). The synthesized compound (B) was further treated with hexamine and formic acid in ethanol to yield 1, 4-benzodiazepine (C) according to reported procedure (Singh et al., 2013). The oxo group of 1, 4-benzodiazepine (C) was replaced by chloro group to form 2, 7-dichloro-5-phenyl-3H-benzo[e][1, 4] diazepine(D) (Jain and Surana, 2013; Kaur and Kishore, 2014) which was further treated with aryl substituted piperazines obtained the target compounds (E1-10). For another series the NH group of 1,4-benzodiazepine (C) was chloroacetylated afforded 7-chloro-1-(2-chloroacetyl)-5-phenyl-1H-benzo[e][1,4]diazepin-2(3H)-one (F) which was further reacted with aryl substituted piperazines obtained target compounds (G1-10).

Table 1 Substituent of compounds for E1-10 and G1-10.

Cpd. No.		R
1	E1, G1	H
2	E2, G2	3-Cl
3	E3, G3	4-Cl
4	E4, G4	4-Br
5	E5, G5	4-F
6	E6, G6	4-NO₂
7	E7, G7	4-CH₃
8	E8, G8	2-OCH₃
9	E9, G9	3-OCH₃
10	E10, G10	4-OCH₃

2.2.1

2.2.1 Synthesis of N-(2-benzoyl-4-chlorophenyl)-2-chloroacetamide (B)

2-Amino-5-chlorbenzophenone (A) (2.31 g, 0.01 mol) was dissolved in 50 ml of toluene in a 250 ml round bottom flask and chloroacetylchloride (1.59 ml, 0.02 mol) was added. The reaction mixture was refluxed for 4 h. The solution was then cooled, washed with ice cold dilute aqueous ammonia solution, dried with anhydrous sodium sulfate, filtered and concentrated in vacuo. The crude residue was recrystallized in ethanol.

2.2.2

2.2.2 Synthesis of 7-chloro-5-phenyl-1H-benzo[e] [1, 4] diazepin-2(3H)-one (C)

N-(2-benzoyl-4-chlorophenyl)-2-chloroacetamide (B) (9.74 g, 0.036 mol), hexamine (7.58 g, 0.072 mol) and formic acid (3.6 ml, 99%) are suspended in 0.5 L of absolute ethanol. The reaction mixture was refluxed for 6 h till the completion of reaction and mixture was concentrated to dryness. Distilled water was added and the resulting suspension was stirred at 60 °C for 0.5 h. The suspension was cooled to 20 °C and filtered. The crude product was recrystallized from ethanol to obtained compound (C).

2.2.3

2.2.3 Synthesis of 2, 7-dichloro-5-phenyl-3H-benzo[e] [1, 4] diazepine (D)

7-Chloro-5-phenyl-1H-benzo[e] [1, 4] diazepin-2(3H)-one (C) (14.55 g, 0.05 mol) was added in a portion to a mixture of POCl₃ (19.2 ml) and N, N-Dimethylaniline (10.3 ml) over a period of 15–20 min with continuous stirring. After completion of addition, the reaction mixture was refluxed for 7–8 h, cooled and kept in a refrigerator overnight. The reaction mixture was poured into ice cooled water and the product was extracted with diethyl ether. The organic layer was collected and dried over MgSO₄, removal of the solvent afforded the compound D.

2.2.4

2.2.4 General procedure for the synthesis of E1-10

2, 7-dichloro-5-phenyl-3H-benzo[e] [1, 4] diazepine (D) (0.001 mol) was dissolved in dimethylformamide (20 ml) in a 250 ml round bottom flask, anhydrous K₂CO₃ (0.002 mol), catalytic amount of potassium iodide and appropriate phenylpiperazine (0.001 mol) was added. The above reaction mixture was stirred at 70–80 °C for 24 h. After completion of reaction, the reaction mixture was poured in ice cold water and kept overnight for precipitation. The obtained product was filtered, washed with water and recrystallized from ethanol afforded the target compounds (E1-10).

2.2.4.1

2.2.4.1 7-Chloro-5-phenyl-2-(4-phenylpiperazin-1-yl)-3H-benzo[e][1, 4] diazepine(E1)

IR (KBr, cm⁻¹): 3051 (str, CH arom), 2921 (str, CH alip), 2243 (str, C⚌N arom), 1463 (C⚌C arom), 1319 (str, C—N), 681 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.17–3.67 (m, 8H, pip ring), 6.81–7.80 (m, 13H, Ar—H), 4.33 (s, 2H, CH₂, Bzd ring). ¹³C NMR (CDCl₃ δ): 168.61 (C⚌N), 149.59 (C—N, ter amine), 139.32, 134.59, 134.19, 131.60, 131.51, 129.72, 129.71, 129.30, 129.25, 129.24, 128.74, 128.73, 124.31, 119.98, 118.74, 114.54, 114.35 (arom carbon), 56.02 (CH₂, Bzd ring), 51.35, 51.36, 49.14, 49.17 (pip ring). Mp: 146–148 °C. Yield: 79%.

2.2.4.2

2.2.4.2 7-Chloro-2-(4-(3-chlorophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine(E2)

IR (KBr, cm⁻¹): 3054 (CH, arom), 2920 (CH, alip), 2244 (C⚌N, aromatic), 1465 (C⚌C aromatic), 1321 (C—N arom), 687 (C—Cl). ¹H NMR (300 MHz; CDCl3 δ): 2.64–3.77 (m, 8H, pip ring), 6.30–7.92 (m, 12H, Ar—H), 4.33 (s, 2H, CH2, Bzd ring). ¹³C NMR (CDCl3 δ): 168.65 (C⚌N), 149.60 (C—N ter amine), 139.31, 135.51, 134.19, 131.60, 131.31, 131.04, 130.10, 130.11, 129.30, 129.25, 129.24, 128.74, 128.73, 124.31, 122.31, 112.39, 110.37 (arom carbon), 56.32 (CH2, Bzd ring), 51.61, 51.62, 49.18, 49.19 (pip ring). Mp: 150–152 °C. Yield: 67%.

2.2.4.3

2.2.4.3 7-Chloro-2-(4-(4-chlorophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E3)

IR (KBr, cm-1): 3058 (CH, arom), 2929 (CH, alip), 2240 (C⚌N, aromatic), 1459 (C⚌C aromatic), 1319 (C—N arom), 677 (C—Cl). ¹H NMR (300 MHz; CDCl3 δ): 2.67–3.83 (m, 8H, pip ring), 6.31–7.75 (m, 12H, Ar—H), 4.33 (s, 2H, CH2 Bzd ring). ¹³C NMR (CDCl3 δ): 168.84 (C⚌N), 149.42 (C—N ter amine), 139.32, 134.59, 134.59, 134.19, 133.23, 131.53, 129.10, 128.95, 128.77, 128.34, 127.73, 119.98, 118.74, 117.54, 117.35, 117.22 (arom carbon), 56.02 (CH2, Bzd ring), 51.13, 51.36, 49.14, 49.17 (pip ring). Mp: 156–158 °C. Yield: 69%.

2.2.4.4

2.2.4.4 7-Chloro-2-(4-(4-bromophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E4)

IR (KBr, cm⁻¹): 3057 (CH, arom), 2928 (CH, alip), 2239 (C⚌N, aromatic), 1460 (C⚌C aromatic), 1318 (C—N arom), 679 (C—Cl). ¹H NMR (300 MHz; CDCl3 δ): 2.65–3.87 (m, 8H, pip ring), 6.39–7.90 (m, 12H, Ar—H), 4.33 (s, 2H, CH2, Bzd ring). ¹³C NMR (CDCl3 δ): 168.68 (C⚌N), 149.35, 149.72 (C—N ter amine), 139.10, 134.16, 133.23, 131.50, 130.21, 129.08, 129.07, 128.94, 128.31, 127.12, 119.96, 118.83, 118.45, 117.32, 117.19 (arom carbon), 55.31 (CH2, Bzd ring), 51.35, 51.36, 49.17, 49.18 (pip ring). Mp: 170–172 °C. Yield: 55%.

2.2.4.5

2.2.4.5 7-Chloro-2-(4-(4-fluorophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E5)

IR (KBr, cm⁻¹): 3048 (CH, arom), 2919 (CH, alip), 2244 (C⚌N, aromatic), 1471 (C⚌C aromatic), 1317 (C—N arom), 676 (C—Cl). ¹H NMR (300 MHz; CDCl3 δ): 2.70–3.14 (m, 8H, pip ring), 6.67–7.55 (m, 12H, Ar—H), 4.33 (s, 2H, CH2Bzd ring). ¹C NMR (CDCl3 δ): 168.84 (C⚌N), 149.42 (C—N ter amine), 139.32, 134.59, 134.59, 134.19, 133.23, 131.53, 129.10, 128.95, 128.77, 128.34, 127.73, 119.98, 118.74, 117.54, 117.35, 117.22 (arom carbon), 56.02 (CH2, Bzd ring), 51.13, 51.36, 49.14, 49.17 (pip ring). Mp: 160–162 °C. Yield: 71%.

2.2.4.6

2.2.4.6 7-Chloro-2-(4-(4-nitrophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E6)

IR (KBr, cm⁻¹): 3059 (str, CH arom), 2931 (str, CH alip), 2247 (str, C⚌N arom), 1469 (C⚌C arom), 1321 (str, C—N), 658 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.67–3.83 (m, 8H, pip ring), 6.31–7.75 (m, 12H, Ar—H), 4.33 (s, 2H, CH₂, Bzd ring). ¹³C NMR (CDCl₃ δ): 168.84 (C⚌N), 149.42 (C—N, ter amine), 139.32, 134.59, 134.59, 134.19, 133.23, 131.53, 129.10, 128.95, 128.77, 128.34, 127.73, 119.98, 118.74, 117.54, 117.35, 117.22 (arom carbon), 56.02 (CH₂, Bzd ring), 51.13, 51.36, 49.14, 49.17 (pip ring). Mp: 202–204 °C. Yield: 81%.

2.2.4.7

2.2.4.7 7-Chloro-2-(4-(4-methylphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E7)

IR (KBr, cm⁻¹): 3050 (str, CH arom), 2920 (str, CH alip), 2241 (str, C⚌N arom), 1462 (C⚌C arom), 1310 (C—N arom), 673 (C—Cl).¹H NMR (300 MHz; CDCl₃ δ): 2.66–3.67 (m, 8H, pip ring), 6.81–8.39 (m, 12H, Ar—H), 4.33 (s, 2H, CH₂, Bzd ring), 3.22 (s, 3H, CH₃). ¹³C NMR (CDCl₃ δ): 168.84 (C⚌N), 149.42 (C—N, ter amine), 139.32, 134.59, 134.59, 134.19, 133.23, 131.53, 129.10, 128.95, 128.77, 128.34, 127.73, 119.98, 118.74, 117.54, 117.35, 117.22 (arom carbon), 56.02 (CH₂, Bzd ring), 51.13, 51.36, 49.14, 49.17 (pip ring). Mp: 135–137 °C. Yield: 79%.

2.2.4.8

2.2.4.8 7-Chloro-2-(4-(2-methoxyphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E8)

IR (KBr, cm⁻¹): 3053 (str, CH arom), 2918 (str, CH alip), 2237 (C⚌N arom), 1458 (C⚌C arom), 1318 (str, C—N), 677 (C—Cl).¹H NMR (300 MHz; CDCl₃ δ): 2.18–3.87 (m, 8H, pip ring), 6.10–9.38 (m, 12H, Ar—H), 4.88 (s, 2H, CH₂, Bzd ring), 4.88 (s, 3H, OCH₃). ¹³C NMR (CDCl₃ δ): 168.84 (C⚌N), 149.42 (C—N, ter amine), 139.32, 134.59, 134.59, 134.19, 133.23, 131.53, 129.10, 128.95, 128.77, 128.34, 127.73, 119.98, 118.74, 117.54, 117.35, 117.22 (arom carbon), 56.31 (OCH₃), 56.02 (CH₂, Bzd ring), 51.13, 51.36, 49.14, 49.17 (pip ring). Mp: 177–180 °C. Yield: 80%.

2.2.4.9

2.2.4.9 7-Chloro-2-(4-(3-methoxyphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E9)

IR (KBr, cm⁻¹): 3045 (str, CH arom), 2917 (str, CH alip), 2246 (str, C⚌N arom), 1452 (C⚌C arom), 1312 (str, C—N), 669 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.17–3.68 (m, 8H, pip ring), 6.45–7.85 (m, 12H, Ar—H), 4.36 (s, 2H, CH₂, Bzd ring) 3.68 (s, 3H, OCH₃). ¹³C NMR (CDCl₃ δ): 168.84 (C⚌N), 149.42 (C—N, ter amine), 139.32, 134.59, 134.59, 134.19, 133.23, 131.53, 129.10, 128.95, 128.77, 128.34, 127.73, 119.98, 118.74, 117.54, 117.35, 117.22 (arom carbon), 56.31 (OCH₃), (CH₂, Bzd ring), 51.13, 51.36, 49.14, 49.17 (pip ring). Mp: 165–167 °C. Yield: 81%.

2.2.4.10

2.2.4.10 7-Chloro-2-(4-(4-methoxyphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E10)

IR (KBr, cm⁻¹): 3046 (str, CH arom), 2928 (str, CH alip), 2243 (str, C⚌N arom), 1461 (C⚌C arom), 1318 (str, C—N), 671 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.67–3.83 (m, 8H, pip ring), 6.31–7.75 (m, 12H, Ar—H), 4.33 (s, 2H, CH₂, Bzd ring), 3.65 (s, 3H, OCH₃). ¹³C NMR (CDCl₃ δ): 168.84 (C⚌N), 149.42 (C—N, ter amine), 139.32, 134.59, 134.59, 134.19, 133.23, 131.53, 129.10, 128.95, 128.77, 128.34, 127.73, 119.98, 118.74, 117.54, 117.35, 117.22 (arom carbon), 56.31 (OCH₃), 56.02 (CH₂, Bzd ring), 51.13, 51.36, 49.14, 49.17 (pip ring). Mp: 185–187 °C. Yield: 82%.

2.2.5

2.2.5 Synthesis of 7-chloro-1-(2-chloroacetyl)-5-phenyl-1H-benzo[e] [1, 4] diazepin-2(3H)-one (F)

7-Chloro-5-phenyl-1H-benzo[e] [1, 4 ] diazepin-2(3H)-one (C) (0.01 mol) and chloroacetyl chloride (0.08 mol) was taken in a 250 ml of round bottom flask. The reaction mixture was refluxed for 5 h. After completion of reaction, the reaction mixture was cooled and precipitate was filtered, washed with ether and dried. The product was recrystallized to afford the compound (F).

2.2.6

2.2.6 General procedure for the synthesis of G1-10

7-Chloro-1-(2-chloroacetyl)-5-phenyl-1H-benzo[e] [1, 4] diazepin-2(3H)-one (F) (0.001 mol) was dissolved in dimethylformamide (20 ml) in a 250 ml round bottom flask, anhydrous K₂CO₃ (0.002 mol), catalytic amount of potassium iodide and appropriate phenylpiperazine (0.001 mol) was added. The above reaction mixture was stirred at 70–80 °C for 24 h. After completion of reaction, the reaction mixture was poured in ice cold water and kept overnight for precipitation. The obtained product was filtered, washed with water and recrystallized from ethanol afforded the target compounds (G-10).

2.2.6.1

2.2.6.1 7-Chloro-5-phenyl-1-(2-(4-phenylpiperazin-1-yl) acetyl)-1H-benzo[e][1, 4]diazepin-2(3H)-one (G1)

IR (KBr, cm⁻¹): 3151 (str, CH arom), 2923 (str, CH alip), 2243 (str, C⚌N arom), 1632 (str, C⚌O amide), 1465 (str, C⚌C arom), 1284 (str, C—N), 665 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.73–3.33 (m, 8H, pip ring), 3.36 (s, 2H,CH₂CO), 6.84–8.66 (m, 13H, Ar—H), 4.14 (s, 2H, CH₂, Bzd ring),¹³C NMR (CDCl₃ δ): 166.21 (C⚌N), 149.35, 149.72 (C—N ter amine), 139.10, 134.16, 133.23, 131.50, 130.21, 129.08, 129.07, 128.94, 128.31, 127.12, 119.96, 118.83, 118.45, 117.32, 117.19 (arom carbon), 55.31 (CH₂, Bzd ring), 51.35, 51.36, 49.18, 49.17 (pip ring). Mp: 88–92 °C. Yield: 59%.

2.2.6.2

2.2.6.2 7-Chloro-1-(2-(4-(3-chlorophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4]diazepin-2(3H)-one (G2)

IR (KBr, cm⁻¹): 3153 (str, CH arom), 2930 (str, CH alip), 2249 (str, C⚌N arom), 1638 (C⚌O amide), 1458 (C⚌C aromatic), 1291 (C—N arom), 669 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.73–3.36 (m, 8H, pip ring), 3.33 (s, 2H,CH₂CO), 6.68–8.18 (m, 12H, Ar—H), 4.11 (s, 2 H, CH₂, Bzd ring).¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 185–187 °C. Yield: 67%.

2.2.6.3

2.2.6.3 7-Chloro-1-(2-(4-(4-chlorophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4]diazepin-2(3H)-one (G3)

IR (KBr, cm⁻¹): 3160 (str, CH arom), 2928 (str, CH alip), 2247 (str, C⚌N arom), 1636 (str, C⚌O amide), 1468 (str, C⚌C aromatic), 1289 (str, C—N), 671 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.73–3.33 (m, 8H, pip ring), 3.33 (s, 2H,CH₂CO), 6.67–7.56 (m, 12H, Ar—H), 4.00 (s, 2H, CH₂, Bzd ring), ¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 191–194 °C. Yield: 65%.

2.2.6.4

2.2.6.4 7-Chloro-1-(2-(4-(4-bromophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G4)

IR (KBr, cm⁻¹): 3159 (CH, arom), 2929 (CH alip), 2247 (C⚌N aromatic), 1640 (C⚌O amide), 1469 (C⚌C aromatic), 120 (C—N arom), 672 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.16–3.31 (m, 8H, pip ring), 3.55 (s, 2 H,CH₂CO), 6.67–7.56 (m, 12H, Ar—H), 4.00 (s, 2H, CH₂Bzd ring). ¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 169–171 °C. Yield: 53%.

2.2.6.5

2.2.6.5 7-Chloro-1-(2-(4-(4-fluorophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G5)

IR (KBr, cm⁻¹): 3166 (CH, arom), 2928 (CH alip), 2250 (C⚌N aromatic), 1634 (C⚌O amide), 1463 (C⚌C aromatic), 1291 (C—N arom), 656 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.11–3.36 (m, 8H, pip ring), 3.37 (s, 2H,CH₂CO), 6.85–8.10 (m, 12H, Ar—H), 4.19 (s, 2H, CH₂Bzd ring). ¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 176–178 °C. Yield: 71%.

2.2.6.6

2.2.6.6 7-Chloro-1-(2-(4-(4-nitrophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G6)

IR (KBr, cm⁻¹): 3149 (CH, arom), 2928 (CH alip), 2247 (C⚌N aromatic), 1630 (C⚌O amide), 1460 (C⚌C aromatic), 1282 (C—N arom), 664 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.07–3.33 (m, 8H, pip ring), 3.34 (s, 2H,CH₂CO), 6.86–8.68 (m, 12H, Ar—H), 4.14 (s, 2H, CH₂Bzd ring). ¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 180–182 °C. Yield: 83%.

2.2.6.7

2.2.6.7 7-Chloro-1-(2-(4-(4-methylphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G7)

IR (KBr, cm⁻¹): 3151 (CH, arom), 2923 (CH alip), 2243 (C⚌N aromatic), 1632 (C⚌O amide), 1465 (C⚌C aromatic), 1284 (C—N arom), 1238 (C—N ali), 665 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.16–3.42 (m, 8 H, pip ring), 3.58 (s, 2H,CH₂CO), 6.31–8.42 (m, 12H, Ar—H), 4.17 (s, 2H, CH₂ Bzd ring), 3.98 (s, 3H CH₃). ¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 183–185 °C. Yield: 72%.

2.2.6.8

2.2.6.8 7-Chloro-1-(2-(4-(2-methoxyphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G8)

IR (KBr, cm⁻¹): 3147 (CH, arom), 2921 (CH alip), 2250 (C⚌N aromatic), 1631 (C⚌O amide), 1463 (C⚌C aromatic), 1280 (C—N arom), 659 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.31–3.462 (m, 8H, pip ring), 3.59 (s, 2H,CH₂CO), 6.32–8.52 (m, 12 H, Ar—H), 4.19 (s, 2H, CH₂Bzd ring), 3.84 (s, 3H, OCH₃). ¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 190–192 °C. Yield: 79%.

2.2.6.9

2.2.6.9 7-Chloro-1-(2-(4-(3-methoxyphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G9)

IR (KBr, cm⁻¹): 3149 (CH, arom), 2919 (CH alip), 2241 (C⚌N aromatic), 1637 (C⚌O amide), 1463 (C⚌C aromatic), 1289 (C—N arom), 672 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.17–3.32 (m, 8H, pip ring), 3.55 (s, 2 H,CH₂CO), 6.32–8.48 (m, 12H, Ar—H), 4.14 (s, 2H, CH₂Bzd ring), 3.78 (s, 3H, OCH₃). ¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂,Bzd ring), 53.51, 48.92 (pip ring). Mp: 193–195 °C. Yield: 73%.

2.2.6.10

2.2.6.10 7-Chloro-1-(2-(4-(4-methoxyphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G10)

IR (KBr, cm⁻¹): 3144 (CH, arom), 2926 (CH alip), 2244 (C⚌N aromatic), 1629 (C⚌O amide), 1465 (C⚌C aromatic), 1284 (C—N arom), 1238 (C—N ali), 656 (C—Cl). ¹H NMR (300 MHz; CDCl₃ δ): 2.77–3.39 (m, 8 H, pip ring), 3.65 (s, 2H,CH₂CO), 6.81–8.68 (m, 12H, Ar—H), 4.15 (s, 2H, CH₂ Bzd ring), 3.76 (s, 3H, OCH₃).¹³C NMR (CDCl₃ δ): 196.47 (C⚌O ketone), 169.89 (CONH), 151.14 (C—N, ter amine), 137.50 (C—N sec amine), 133.17, 133.02, 131.77, 130.09, 129.10, 128.50, 127.52, 126.31, 123.06, 119.66, 116.11 (arom carbon), 62.28 (CH₂, Bzd ring), 53.51, 51.36, 49.17, 48.92 (pip ring). Mp: 197–199 °C. Yield: 80%.

2.3

2.3 Computational evaluation

A set of molecular parameters was computed for the target compounds as well as standard drug diazepam using Chem 3D Ultra version, 8.0 & 11.0, and Schrodinger software are shown in Table 2. The important molecular parameters for CNS agents are blood brain barrier (BBB), log P and topological polar surface area (TPSA). Literature review suggested that TPSA is a measure of a molecule’s hydrogen bonding capacity and its value should not exceed certain limit if the compound is intended to be CNS active. Two differing limits have been proposed: (Waterbeemed et al., 1998) suggested a limit of 90 A², where, (Kelder et al., 1999) suggested 60–70 A². The TPSA value for most of the test compounds were well within these limits. The log BB values and log P values for the test compounds were noted and suggesting that these have an excellent potential for CNS activity.

Table 2 Calculation of molecular, pharmacokinetic and toxicity parameters for target compounds (E1-10, G1-G10) and standard drug.

Cpd. code	Log BB^j	Log P	M.W^a	MR^b	SAS^c	MSA^d	SEV^e	TPSA^f	MTI^g	WI^h	Ovⁱ	CAR	MUT	RE	SI
E1	0.526	5.71	414.93	124.41	687.07	371.84	338.31	31.2	19347	2532	1.5780	Non-toxic	Non-toxic	Non-toxic	toxic
E2	0.691	6.26	449.37	129.01	711.62	386.67	352.65	31.2	20575	2791	1.6018	Non-toxic	Non-toxic	Non-toxic	toxic
E3	0.691	6.25	449.37	129.01	711.68	386.65	352.65	31.2	20688	2815	1.6018	Non-toxic	Non-toxic	Non-toxic	toxic
E4	0.735	6.53	493.83	132.1	720.24	392.02	358.39	31.2	20688	2815	1.6066	Non-toxic	Non-toxic	Non-toxic	toxic
E5	0.633	5.86	432.92	124.81	693.43	375.25	337.93	31.2	20688	2815	1.5993	Non-toxic	Non-toxic	Non-toxic	toxic
E6	−0.626	4.17	459.93	129.30	711.68	386.65	352.65	83.01	24839	3445	1.6018	Non-toxic	Non-toxic	Non-toxic	toxic
E7	0.514	6.19	428.96	130.31	718.32	390.57	355.2	31.2	21540	2815	1.6100	Non-toxic	Non-toxic	Non-toxic	toxic
E8	0.526	5.58	444.96	131.66	710.82	389.39	360.58	40.43	22758	3033	1.5893	Non-toxic	Non-toxic	Non-toxic	toxic
E9	0.454	5.58	444.96	131.66	732.05	397.58	361.36	40.43	23080	3081	1.6204	Non-toxic	Non-toxic	Non-toxic	toxic
E10	0.454	5.58	444.96	131.06	735.78	399.82	362.85	40.43	23402	3129	1.6251	Non-toxic	Non-toxic	Non-toxic	toxic
G1	0.042	4.34	472.97	135.63	728.30	402.2	369.75	56.22	26711	3580	1.6144	Non-toxic	Non-toxic	Non-toxic	toxic
G2	0.198	4.89	507.41	140.24	752.86	417.03	384.10	56.22	28238	3909	1.6320	Non-toxic	Non-toxic	Non-toxic	toxic
G3	0.162	4.89	507.41	140.24	752.86	417.03	384.10	56.22	28367	3937	1.6320	Non-toxic	Non-toxic	Non-toxic	toxic
G4	0.171	5.16	551.86	143.32	761.49	422.39	389.80	56.22	28367	3937	1.6366	Non-toxic	Non-toxic	Non-toxic	toxic
G5	0.114	4.49	490.95	136.04	734.50	405.84	372.97	56.22	28367	3937	1.6196	Non-toxic	Non-toxic	Non-toxic	toxic
G6	−1.114	2.19	517.96	140.20	762.10	423.68	389.71	108.03	33480	4723	1.6420	Non-toxic	Non-toxic	Non-toxic	toxic
G7	0.016	4.82	486.99	141.53	759.58	420.90	386.66	56.22	29441	3937	1.6398	Non-toxic	Non-toxic	Non-toxic	toxic
G8	−0.057	4.21	502.99	142.88	671.16	387.30	380.75	65.45	30980	4217	1.5245	Non-toxic	Non-toxic	Non-toxic	toxic
G9	−0.043	4.21	502.99	142.88	643.66	360.63	352.58	65.45	31350	4273	1.5613	Non-toxic	Non-toxic	Non-toxic	toxic
G10	−0.08	4.21	502.99	142.88	644.44	360.52	352.26	65.45	31720	4329	1.5661	Non-toxic	Non-toxic	Non-toxic	toxic
Diazepam	0.205	2.84	284.74	80.88	475.24	246.15	214.21	32.67	5393	726	1.4217	toxic	toxic	toxic	Non-toxic

a Molecular weight.

b Molar refractivity.

c Connolly solvent accessible surface area.

d Connolly molecular surface area.

e Connolly solvent excluded volume.

f Topological polar surface area.

g Molecular topological index.

h Wienner index.

i Ovality.

j QikProp prediction; OSIRIS prediction: CAR: Carcinogencity; MUT: Mutagenicity; RE: Reproductive effects; SI: Skin irritant.

2.3.1

2.3.1 Screening through in silico pharmacokinetic and toxicity parameters

Pharmacokinetic (PK) and toxicity properties depends on physicochemical descriptors of drugs, which determines its absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties, that makes them to be therapeutically effective. Pharmacokinetic and toxicity parameters were calculated using the Chemoffice, Schrodinger and OSIRIS property explorer. The toxicity parameters accessed includes carcinogenicity, mutagenicity, reproductive/developmental toxicity, and skin irritant effects (CS Chem office; Schrodinger; Osiris Property Explorer ). The predicted pharmacokinetic and toxicity parameters are summarized in Table 2.

2.3.2

2.3.2 Molecular modeling

The test compounds were explored for their binding affinity and interaction towards the GABA_A receptor through molecular docking using Molecular Operating Environment. The target protein structure was taken from the reported work of (Richter et al., 2012). The modeled target protein structure with bound Diazepam was taken as starting coordinates for reference and test compounds docking. The protein structure was prepared by “Protein Preparation Wizard” of Schrodinger suite with default options. The test compounds were structurally drawn and energy minimized using MMFF94× force field followed by conformational search with Low Mode MD. The reference and test compounds were docked into GABA_A receptor using rigid receptor docking protocol. The “triangle matcher” was used for placing the molecule into the binding pocket, which were ranked by London dG scoring function followed by structure refinement with GBVI/WSA dG. The predicted docking score for all the test compounds are shown in Table 3.

Table 3 Comparison of predicted binding affinities of (E1-10), (G1-10) and Diazepam against GABA_A receptor.

	Amino acid residues involved with in 5 Å	H-bond interaction	Π-Π interaction	Cation-Π interaction	Halogen bonding	Docking Score
E1	Asn60, Phe77, His101, Asn 102, Met130, Glu137, Leu140, Thr142, Lys155, Tyr159, Ala160, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Glu189	Tyr209	–	Asn102	−4.9703
E2	Asn60, Phe77, His101, Asn 102, Thr142, Lys155, Ser158, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	Tyr209	Lys155	–	−4.7753
E3	Asn60, Phe77, His101, Asn 102, Met130, Leu140, Thr142, Lys155, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Gln203 Thr206	–	–	–	−5.2317
E4	Asn60, Phe77, His101, Asn 102, Met130, Leu140, Thr142, Lys155, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Gln203 Thr206	His101	–	–	−6.0010
E5	Asn60, Phe77, His101, Asn 102, Met130, Leu140, Thr142, Lys155, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Gln203	Tyr209	–	–	−5.0977
E6	Asn60, Phe77, His101, Asn 102, Met130, Arg132, Leu140, Tyr141, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Gln203 Thr206	–	–	–	−5.7405
E7	Asn60, Phe77, His101, Asn 102, Met130, Tyr141, Thr142, Lys155, Tyr159, Ala160, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Gln203 Thr206	Tyr209	Lys155	–	−5.4246
E8	Asn60, Phe77, His101, Met130, Leu140, Lys155, Ser158, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	Tyr209	–	–	−5.5697
E9	Asn60, Phe77, His101, Asn102, Leu140, Thr142, Lys155, Ser158, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	–	–	–	−5.5661
E10	Asn60, Phe77, His101, Asn102, Met130, Arg132, Leu140, Tyr141, Thr142, Tyr159, Ala160, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Gln203 Glu189 Thr206	Tyr209	–	–	−5.7163
G1	Asn60, Phe77, His101, Asn102, Met130, Leu140, Thr142, Lys155, Ser158, Tyr159, Ala160, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Gln203 Ser204	His101	–	–	−5.732
G2	Phe77, His101, Asn102, Thr142, Lys155, Ser158, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	Tyr209	–	–	−5.622
G3	Phe77, His101, Asn102, Leu140, Thr142, Lys155, Ser158, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Thr206	Tyr209	Lys155	–	−5.771
G4	Phe77, His101, Asn102, Leu140, Thr142, Lys155, Ser158, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	Tyr209	Lys155	–	−5.847
G5	Phe77, His101, Asn102, Thr142, Lys155, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	Tyr209	–	–	−5.680
G6	Phe77, His101, Asn102, Met130, Leu140, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Gly207	Tyr209	Lys155	–	−5.968
G7	Phe77, His101, Asn102, Met130, Leu140, Thr142, Lys155, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	Tyr209	–	–	−5.976
G8	Asn60, Phe77, His101, Asn102, Met130, Leu140, Thr142, Lys155, Tyr159, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189 Thr206	–	Lys155	–	−5.125
G9	Phe77, His101, Asn102, Met130, Leu140, Thr142, Lys155, Tyr159, Ala160, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Glu189	–	Lys155	–	−5.816
G10	Phe77, Ala79, His101, Asn102, Met130, Leu140, Thr142, Lys155, Tyr159, Ala160, Glu189, Val190, Val202, Gln203, Ser204, Thr206, Tyr209	Tyr159 Glu189	Tyr209	Lys155	–	−6.020
Diazepam	Asn60, Phe77, His101, Met130, Thr142, Arg144, Gly157, Ser158, Tyr159, Glu189, Val202, Ser204, Thr206, Tyr209, Val211	Thr209	His101 Tyr209	–	–	−5.238

2.3.3

2.3.3 Similarity calculation

The physicochemical similarity of the target compounds with respect to standard drug was calculated from a set of 7 physicochemical properties computed using software programs (Kumar et al., 2011) and is shown in Table 4. Firstly, the distance d_i of a particular target compound j to drug molecules e.g., diazepam was calculated by the formula; ${di}^{2} = \sum_{j = 1}^{n} {\frac{(\frac{1 - X_{i,j}}{X_{i,std}})}{n}}^{2}$ where, Xi, j is the value of molecular parameter ‘i’ for compound ‘j’, Xi, std is the value of the same molecular parameter for the standard drug, e.g., Diazepam. Then, the similarity of compound ‘j’ to the standard drug was calculated as: Similarity (%) = (1 − R) × 100. Where R = √d² is the quadratic mean (root mean square), a measure of central tendency. The target compounds showed good similarity with respect to standard drug (13–106%).

Table 4 Similarity of target compounds (E1-10 and G1-G10) with respect to the standard drug.

Cpd. code	Similarity^a,b (in %) to diazepam	Cpd. code	Similarity^a,b (in %) to diazepam
E1	13	G1	60
E2	25	G2	73
E3	26	G3	74
E4	29	G4	76
E5	25	G5	72
E6	46	G6	106
E7	31	G7	81
E8	36	G8	88
E9	39	G9	90
E10	41	G10	92

a (1 − R) × 100 where R = quadratic mean (root mean square mean).

b Calcd. from physicochemical properties: Molecular weight; Molar refractivity; Connolly solvent accessible surface area; Connolly molecular surface area; Connolly solvent excluded volume; Topological polar surface area; Molecular topological index.

2.4

2.4 Pharmacological evaluation

The anxiolytic activity was performed by Elevated plus maze method and skeletal muscle relaxant activity was carried out by Rotarod method in Swiss albino mice (Parle et al., 2010, Kulkarni and Reddy, 1996; Sinoriya et al., 2011 ). Prior permission of the Animal Ethics Committee was obtained and all experiments were conducted according to the approved protocol. Diazepam was employed as a standard (positive control). Statistical analysis of the results in the test group was done by comparison with the results in the control group employing one way ANOVA. Level of significance was fixed at p < 0.05.

2.4.1

2.4.1 Anxiolytic activity (Elevated plus maze method)

Swiss albino mice, weighing 20–24 g each, were selected from the stock colony maintained in the central animal facility with free access to food and water. Animals were maintained in an air-conditioned room. The room was maintained at 25 ± 2 °C with natural daytime. Concentration of each compound (5 mg/kg) was used in the form of freshly prepared suspensions in 1% tween 80. All solutions were prepared freshly on test days and given intraperitoneally (i.p.) in a volume of 0.5 ml/20–24 g body weight of mice. The experimental animals were treated with diazepam (2 mg/kg, n = 6), or the test compounds (5 mg/kg) 60 min before evaluation in the maze. The control group was given saline with 1% tween 80. Elevated plus maze apparatus consisted of two open (16 × 5 cm²) and two closed arms (16 × 5 × 12 cm³) facing each other with an open roof (Moser, 1989; Pellow et al., 1985; Rabbani et al., 2004 ). The entire maze is elevated to a height of 25 cm. In the test group, mice were individually examined in 5 min sessions in this apparatus. Each mouse was placed in the central platform facing one open arm. The numbers of entries into open and closed arms and the time spent in open arms were recorded during a 5 min period. The percentage of number of entries into open arms [(open/open + closed) × 100] was calculated for each mouse. The results of EPM have been summarized in Tables 5 and 6.

Table 5 Anti anxiety activity of the target compounds (E1-10) in elevated plus maze method.

Cpd. code	Spent time (open arm)	Number of entries (open arms)	% Number of entries (open arms)
E1	66.48 ± 1.71	7.14 ± 0.41	46.99
E2	68.46 ± 1.14	7.97 ± 0.35	47.72
E3	69.25 ± 1.93*	8.44 ± 0.53*	50.38
E4	63.17 ± 1.82	6.71 ± 0.53	42.12
E5	49.97 ± 4.89	3.05 ± 0.74	28.38
E6	65.48 ± 3.12	4.29 ± 0.63	41.81
E7	55.76 ± 2.98	3.81 ± 0.23	36.72
E8	75.13 ± 1.68*	9.87 ± 0.68*	57.34
E9	81.23 ± 1.74*	10.29 ± 0.74*	58.56
E10	86.58 ± 0.91*	9.14 ± 0.76*	61.48
Diazepam	91.83 ± 2.33	10.89 ± 0.76	63.46
Vehicle	42.12 ± 3.42	2.84 ± 0.91	20.24

* Data represent the mean ± SEM; n= 6; P*< 0.05 compared with vehicle.

Table 6 Anti anxiety activity of the target compounds (G1-10) in elevated plus maze method.

Cpd. code	Spent time (open arm)	Number of entries (open arms)	% Number of entries (open arms)
G1	70.91 ± 1.68*	8.57 ± 0.73*	50.59
G2	77.14 ± 1.29*	10.41 ± 0.99*	57.87
G3	81.89 ± 0.58*	9.28 ± 0.34*	59.28
G4	69.45 ± 1.48	7.99 ± 0.12	47.98
G5	66.54 ± 1.91	7.82 ± 0.29	47.12
G6	64.91 ± 1.82	6.94 ± 0.39	43.79
G7	87.12 ± 0.81*	9.93 ± 0.48*	61.99
G8	50.24 ± 4.98	3.06 ± 0.48	29.11
G9	57.14 ± 3.48	3.97 ± 0.98	36.88
G10	58.91 ± 2.12	4.31 ± 1.09	41.89
Diazepam	91.83 ± 2.33	10.89 ± 0.76	63.46
Vehicle	42.12 ± 3.42	2.84 ± 0.91	20.24

* Data represent the mean ± SEM; n= 6; P*< 0.05 compared with vehicle.

2.4.2

2.4.2 Skeletal muscle relaxant activity (Rotarod Method)

Skeletal muscle relaxant activity of target compounds was carried out by Rotarod method. Mice were placed on a horizontal wooden rod rotating at a speed of 25 rpm. The mice capable of remaining on the top for 1 min or more, in three successive trials were selected for the study. The selected animals were divided into 12 groups (n = 6). The stock solutions of all the test samples and standard were prepared by suspending in 1% tween 80. Tween 80 (1%) and diazepam (2 mg/kg, i.p.) were given to group control and standard. Test sample 5 mg/kg (i.p.) was injected into test groups. Each group of animals was then placed on the rod at an interval of 30 min. The animals that failed more than once on the Rotarod for 1 min were considered as passed the test. The results of skeletal muscle relaxant activity have been summarized in Tables 7 and 8.

Table 7 Skeletal muscle relaxant activity of target compounds (E1-10) by Rotarod method.

Cpd. code	Dose	Rotarod test
E1	5 mg/kg	54.14 ± 1.23
E2	5 mg/kg	51.08 ± 1.04
E3	5 mg/kg	47.54 ± 2.12*
E4	5 mg/kg	55.34 ± 1.22
E5	5 mg/kg	80.33 ± 4.10
E6	5 mg/kg	71.77 ± 1.63
E7	5 mg/kg	75.89 ± 1.84
E8	5 mg/kg	46.55 ± 1.44*
E9	5 mg/kg	42.35 ± 3.48*
E10	5 mg/kg	41.21 ± 2.14*
Diazepam	2 mg/kg	37. 50 ± 1.33
Vehicle	1% Tween 80	85.06 ± 1.98

* Data represent the mean ± SEM; n= 6; P*< 0.05 compared with vehicle.

Table 8 Skeletal muscle relaxant activity of target compounds (G1-10) by Rotarod test.

Cpd. code	Dose	Rotarod test
G1	5 mg/kg	46.91 ± 2.42*
G2	5 mg/kg	45.14 ± 1.90*
G3	5 mg/kg	41.68 ± 3.16*
G4	5 mg/kg	50.78 ± 1.42
G5	5 mg/kg	53.89 ± 1.78
G6	5 mg/kg	54.97 ± 1.48
G7	5 mg/kg	40.87 ± 3.29*
G8	5 mg/kg	80.84 ± 4.16
G9	5 mg/kg	74.98 ± 1.48
G10	5 mg/kg	71.63 ± 1.54
Diazepam	2 mg/kg	37. 50 ± 1.33
Vehicle	1% Tween 80	85.06 ± 1.98

* Data represent the mean ± SEM; n= 6; P*< 0.05 compared with vehicle.

3 Results and discussion

Two series of benzodiazepines were designed and synthesized in an effort to obtain the drugs with improved biological activities. Our synthetic route to target compounds is outlined in Scheme 1. The target compounds E1-10 and G1-10 have been synthesized by reaction of 2-amino-5-chlorobenzophenone (A) with chloroacetylchloride in toluene to afford N-(2-benzoyl-4-chlorophenyl)-2-chloroacetamide (B) which was further reacted with hexamine, formic acid in ethanol afforded 7-chloro-5-phenyl-1H-benzo[e] [1, 4] diazepin-2(3H)-one (C). The oxo group of compound C was replaced by chloro group to form 2, 7-dichloro-5-phenyl-2, 3-dihydro-1H-benzo[e] [1, 4] diazepine (D) which was further treated with aryl substituted piperazines obtained the target compounds (E1-10). For the synthesis of target compounds (G1-10), the NH group of compound C was chloroacetylated afforded 7-chloro-1-(2-chloroacetyl)-5-phenyl-1H-benzo [e] [1,4] diazepin-2(3H)-one (F)which was further reacted with aryl substituted piperazines obtained target compounds (G1-10). All the target compounds were characterized by analytical and spectroscopic methods. From antianxiety and skeletal muscle relaxant activity, some target compounds have shown significant CNS activity. Compound bearing 4-OCH₃ group in phenyl piperazine ring (E10) has shown the highest antianxiety and muscle relaxant activity than 3-OCH₃ (E9) 2-OCH₃ analogs (E8). However, the compounds containing Cl group (E3 and E2) on phenylpiperazine also produced statistically significant antianxiety and muscle relaxant activity. In another series, the compounds posses 4- CH₃group (G7) was showed maximum potency over chloro analogs (G2 and G3). However, the compound having no substitution on phenyl piperazine ring (G1) also produced statistically significant antianxiety and muscle relaxant activity. In computational study, the TPSA values for most of the test compounds were well within these limits (31.2–108.03) which shows that these compounds have a potential to effectively cross the blood-brain barrier. The log BB values (−1.14 to 0.73) and log P values (2.19–6.53) for the test compounds were noted and suggesting that these have an excellent potential for CNS activity. The target compounds also shows mild to moderate similarity with respect to standard drug. Among the compounds, the compound E6, E10, E9, G6, G10, G9, G8 and G7 showed maximum similarity with respect to diazepam. The in silico toxicity risk assessment results for the test compounds (E1-E10 and G1-G10) were scanned to find moderate to good compared with reference compound at high doses or long term therapeutic use. The results of predicted toxicity parameters corroborated with reference compound. In molecular docking, the reference binding mode of diazepam was predicted with same docking protocol and a docking score of -5.328 with an RMSD of 0.2595 was found. The binding interaction of diazepam shows H-bond with polar amino acid (Thr₂₀₆) and π- π interaction with hydrophobic residues of His₁₀₁ and Tyr₂₀₉ (Fig. 2).

Binding interaction of diazepam as reference drug.

Furthermore, to explore the binding orientation and affinity of all test compounds in GABA_A receptor was predicted by molecular docking simulation. All the test compounds were further docked and their docking scores were predicted (Table 3). For test compounds (E1-E10) a common binding mode was observed, where binding site is comprised of Asn₆₀, Phe₇₇, His₁₀₁, Asn₁₀₂, Met₁₃₀, Glu₁₃₇, Leu₁₄₀, Thr₁₄₂, Lys₁₅₅, Ser₁₅₈, Tyr₁₅₉, Ala₁₆₀, Glu₁₈₉, Val₁₉₀, Val₂₀₂, Gln₂₀₃, Ser₂₀₄, Thr₂₀₆, Tyr₂₀₉ amino acid residues with diverse properties of amino acid within a radius of 5 Å (Fig. 3). All the test compounds were found to make H-bond interaction with backbone of Tyr₁₅₉, Glu₁₈₉, Gln₂₀₃ and Thr₂₀₆ amino acid residues, whereas Π- Π interaction was observed for Tyr₂₀₉ and His₁₀₁ residues, which was similar to reference diazepam drug. Moreover, Compound E1 has shown a halogen bond interaction with Asn102 and Lys155 amino acid residues. Among, all the test compounds, Compound E10 have exhibited a comparable anti-anxiety activity to reference compound. The binding interaction diagram for compound E10 and GABA_A protein receptor revealed a common amino acid binding residues with a total docking score of −5.7163. The compound E10 has made some H-bond network with Glu₁₈₉, Gln₂₀₃ and Thr₂₀₆ and Π-Π Interaction with Tyr₂₀₉ key amino acid residues. Moreover, compounds G1-10, also binds to the same binding pocket in similar binding mode even with some structural variability in these molecules as compared to compounds E1-10. These compounds share the same binding site amino acid residues viz; Phe₇₇, His₁₀₁, Asn₁₀₂, Met₁₃₀, Leu₁₄₀, Thr₁₄₂, Lys₁₅₅, Ser₁₅₈, Tyr₁₅₉, Ala₁₆₀, Glu₁₈₉, Val₁₉₀, Val₂₀₂, Gln₂₀₃, Ser₂₀₄, Thr₂₀₆, Tyr₂₀₉ for GABA_A protein receptor (Fig. 4). Test compounds G1-G10 makes H-bond network with backbone of Tyr₁₅₉ and Glu₁₈₉, whereas Π- Π and Π-cation Interaction was observed with Tyr₂₀₉ and Lys₁₅₅ amino acid residues respectively. Among all the test compounds, G7 has exhibited potent anti-anxiety activity as compared to standard diazepam. Moreover, in silico molecular docking was predicted with total docking score of −5.976, which is comparatively better with reference drug. The ligand binding interaction diagram reveals the similar binding interaction as well as H-bond network and Π-Π interaction with key amino acid residues. Such interactions may have stabilized the test compounds inside the GABA_A receptor binding pocket and total docking score predicted to be a comparable to reference diazepam.

(A) Docked poses of test compounds (E1-E10) in GABAA receptor protein and (B) binding interaction for compound E10.

(A) Docked poses of test compounds (G1-G10) in GABAA receptor protein and (B) binding interaction for compound G7.

4 Conclusion

In conclusion, we have described the synthesis, computational studies and their evaluation for antianxiety and skeletal muscle relaxant activity of new benzodiazepines. The target compounds were successfully synthesized and well characterized by molecular docking studies revealed good binding interactions of target molecules with the GABA_A receptor. The target compounds also showed mild to moderate similarity with respect to standard drug. The pharmacokinetic and toxicity corroborate with standard compound and suggests its potential being drug-like candidates. From antianxiety and skeletal muscle relaxant activity, some of the target compounds have shown significant CNS activity. However, further optimization might be beneficial in the future research and development of the target compounds for the refinement of the CNS activity.

Acknowledgement

The authors are grateful to Vice chancellor, Prof. R.M. Dubey, IFTM University, Moradabad, for the support of this project. This work is a part of work done for Ph.D. degree of IFTM University, Moradabad.

References

Argyropoulos S.V., Nutt D.J., . Eur. Neuropsychopharmacol.. 1999;9:S407-S412.
Barbee J.G., . Ann. Clin. Psychiatry. 1988;10:15-29.
Clayton T., Chen J.L., Ernst M., Richter L., Cromer B.A., Morton C.J., Ng H., Kaczorowski C.C., Helmstetter F.J., Furtmüller R., Ecker G., Parker M.W., Sieghart W., Cook J.M., . Curr. Med. Chem.. 2007;14:2755-2775.
CS Chem office version 8.0, Cambridge Soft Corporation, software publishers association, 1730 M street, Ninan, P. T., 2001. Am. J. Manage. Care 7, S367–S376.
Griffin C.E., Kaye A.M., Bueno F.R., Kaye D.A., . The. Ochsner Journal.. 2013;13:214-223.
[Google Scholar]
Jain, S.M., Surana, J.S., 2013. Arab. J Chem.
Kaur N., Kishore D., . An Int. J. Rapid Commun. Syn. Org. Chem.. 2014;44:2789-2796.
[Google Scholar]
Kelder J., Grootenhuis P.D.J., Bayada D.M., Delbressine L.P.C., Ploemen J.P., . Pharm. Res.. 1999;16:1514-1519.
Kulkarni, S.K., Reddy D.S., 1996. 18, 240.
Kumar S., Wahi A.K., Singh R., . Arab. J. Chem.. 2016;9:S1450-S1457.
Kumar S., Wahi A.K., Singh R., . Eur. J. Med. Chem.. 2011;46:4753-4759.
Moser P.C., . Psychopharmacology.. 1989;99:53.
Nash J., Nutt D., . J. Psychiatry.. 2004;3:11.
Nutt D.J., Malizia A.L., . Br. J. Psychiatry. 2001;179:390-396.
Osiris Property Explorer. http:// www.organic-chemistry.org/prog/peo.
Park-Chung M., Malayev A., Purdy R.H., Gibbs T.T., Farb D.H., . Brain Res.. 1999;830:72-87.
Parle M., Devi S., Verma S., . Ann. Pharmacy Pharmaceut. Sci.. 2010;2:128.
Pellow S., Chopin P., File S.E., Briley M., . J. Neurosci.. 1985;14:167.
Rabbani M., Sajjadi S.E., Vaseghi G., Jafarian A., . Fitoterapia. 2004;75:464.
Richter L., Graaf C.D., Sieghart W., Varagic Z., Morzinger M., Esch I.J.P., Ecker G.F., Ernst M. Nat, . Chem. Biol.. 2012;8:455-464.
Schrodinger Suite, 2010, QikProp, version 3.3, Schrödinger, LLC, New York, NY.
Singh, R.K., Prasad, D.N., Bhardwaj, T.R., 2013, J. Saudi Chem. Soc.
Sinoriya P., Irchhaiya R., Sharma B., Sahu G., Kumar S., . Indian J Pharmacol.. 2011;6:713.
Sternbach L.H., Fryer R.I., Metlesics W., Reeder E., Sach G., Saucy G., Stempel A., . J. Org. Chem.. 1962;27:3796.
Sternbach L.H., . Angew. Chem. Int. Ed.. 1971;10:34-40.
Steimer T., . Clin. Neurosci.. 2002;4:231-249.
Waterbeemed H., Camenishch G., Folkers G., Chretien J.R., Raevsky O.A., . J. Drugs Target.. 1998;6:165.

Introduction

Materials and methods

Experimental
Synthesis of compounds
Computational evaluation
Pharmacological evaluation

Results and discussion

Conclusion

Fulltext Views
3,266

PDF downloads
633

View/Download PDF
Download Citations

BibTeX
RIS

Show Sections

[1] Argyropoulos S.V., Nutt D.J., . Eur. Neuropsychopharmacol.. 1999;9:S407-S412.

[2] Barbee J.G., . Ann. Clin. Psychiatry. 1988;10:15-29.

[3] Clayton T., Chen J.L., Ernst M., Richter L., Cromer B.A., Morton C.J., Ng H., Kaczorowski C.C., Helmstetter F.J., Furtmüller R., Ecker G., Parker M.W., Sieghart W., Cook J.M., . Curr. Med. Chem.. 2007;14:2755-2775.

[4] CS Chem office version 8.0, Cambridge Soft Corporation, software publishers association, 1730 M street, Ninan, P. T., 2001. Am. J. Manage. Care 7, S367–S376.

[5] Griffin C.E., Kaye A.M., Bueno F.R., Kaye D.A., . The. Ochsner Journal.. 2013;13:214-223.
[Google Scholar]

[6] Jain, S.M., Surana, J.S., 2013. Arab. J Chem.

[7] Kaur N., Kishore D., . An Int. J. Rapid Commun. Syn. Org. Chem.. 2014;44:2789-2796.
[Google Scholar]

[8] Kelder J., Grootenhuis P.D.J., Bayada D.M., Delbressine L.P.C., Ploemen J.P., . Pharm. Res.. 1999;16:1514-1519.

[9] Kulkarni, S.K., Reddy D.S., 1996. 18, 240.

[10] Kumar S., Wahi A.K., Singh R., . Arab. J. Chem.. 2016;9:S1450-S1457.

[11] Kumar S., Wahi A.K., Singh R., . Eur. J. Med. Chem.. 2011;46:4753-4759.

[12] Moser P.C., . Psychopharmacology.. 1989;99:53.

[13] Nash J., Nutt D., . J. Psychiatry.. 2004;3:11.

[14] Nutt D.J., Malizia A.L., . Br. J. Psychiatry. 2001;179:390-396.

[15] Osiris Property Explorer. http:// www.organic-chemistry.org/prog/peo.

[16] Park-Chung M., Malayev A., Purdy R.H., Gibbs T.T., Farb D.H., . Brain Res.. 1999;830:72-87.

[17] Parle M., Devi S., Verma S., . Ann. Pharmacy Pharmaceut. Sci.. 2010;2:128.

[18] Pellow S., Chopin P., File S.E., Briley M., . J. Neurosci.. 1985;14:167.

[19] Rabbani M., Sajjadi S.E., Vaseghi G., Jafarian A., . Fitoterapia. 2004;75:464.

[20] Richter L., Graaf C.D., Sieghart W., Varagic Z., Morzinger M., Esch I.J.P., Ecker G.F., Ernst M. Nat, . Chem. Biol.. 2012;8:455-464.

[21] Schrodinger Suite, 2010, QikProp, version 3.3, Schrödinger, LLC, New York, NY.

[22] Singh, R.K., Prasad, D.N., Bhardwaj, T.R., 2013, J. Saudi Chem. Soc.

[23] Sinoriya P., Irchhaiya R., Sharma B., Sahu G., Kumar S., . Indian J Pharmacol.. 2011;6:713.

[24] Sternbach L.H., Fryer R.I., Metlesics W., Reeder E., Sach G., Saucy G., Stempel A., . J. Org. Chem.. 1962;27:3796.

[25] Sternbach L.H., . Angew. Chem. Int. Ed.. 1971;10:34-40.

[26] Steimer T., . Clin. Neurosci.. 2002;4:231-249.

[27] Waterbeemed H., Camenishch G., Folkers G., Chretien J.R., Raevsky O.A., . J. Drugs Target.. 1998;6:165.

Design, synthesis, computational and biological evaluation of new benzodiazepines as CNS agents

Abstract

Keywords

Benzodiazepines

Phenylpiperazine

Antianxiety

Skeletal muscle relaxant

Computational studies

1 Introduction

2 Materials and methods

2.1 Experimental

2.2 Synthesis of compounds

2.2.1 Synthesis of N-(2-benzoyl-4-chlorophenyl)-2-chloroacetamide (B)

2.2.2 Synthesis of 7-chloro-5-phenyl-1H-benzo[e] [1, 4] diazepin-2(3H)-one (C)

2.2.3 Synthesis of 2, 7-dichloro-5-phenyl-3H-benzo[e] [1, 4] diazepine (D)

2.2.4 General procedure for the synthesis of E1-10

2.2.4.1 7-Chloro-5-phenyl-2-(4-phenylpiperazin-1-yl)-3H-benzo[e][1, 4] diazepine(E1)

2.2.4.2 7-Chloro-2-(4-(3-chlorophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine(E2)

2.2.4.3 7-Chloro-2-(4-(4-chlorophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E3)

2.2.4.4 7-Chloro-2-(4-(4-bromophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E4)

2.2.4.5 7-Chloro-2-(4-(4-fluorophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E5)

2.2.4.6 7-Chloro-2-(4-(4-nitrophenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E6)

2.2.4.7 7-Chloro-2-(4-(4-methylphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E7)

2.2.4.8 7-Chloro-2-(4-(2-methoxyphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E8)

2.2.4.9 7-Chloro-2-(4-(3-methoxyphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E9)

2.2.4.10 7-Chloro-2-(4-(4-methoxyphenyl)piperazin-1-yl)-5-phenyl-3H-benzo[e][1,4]diazepine (E10)

2.2.5 Synthesis of 7-chloro-1-(2-chloroacetyl)-5-phenyl-1H-benzo[e] [1, 4] diazepin-2(3H)-one (F)

2.2.6 General procedure for the synthesis of G1-10

2.2.6.1 7-Chloro-5-phenyl-1-(2-(4-phenylpiperazin-1-yl) acetyl)-1H-benzo[e][1, 4]diazepin-2(3H)-one (G1)

2.2.6.2 7-Chloro-1-(2-(4-(3-chlorophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4]diazepin-2(3H)-one (G2)

2.2.6.3 7-Chloro-1-(2-(4-(4-chlorophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4]diazepin-2(3H)-one (G3)

2.2.6.4 7-Chloro-1-(2-(4-(4-bromophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G4)

2.2.6.5 7-Chloro-1-(2-(4-(4-fluorophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G5)

2.2.6.6 7-Chloro-1-(2-(4-(4-nitrophenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G6)

2.2.6.7 7-Chloro-1-(2-(4-(4-methylphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G7)

2.2.6.8 7-Chloro-1-(2-(4-(2-methoxyphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G8)

2.2.6.9 7-Chloro-1-(2-(4-(3-methoxyphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G9)

2.2.6.10 7-Chloro-1-(2-(4-(4-methoxyphenyl)piperazin-1-yl)acetyl)-5-phenyl-1H-benzo[e][1,4] diazepin-2(3H)-one (G10)

2.3 Computational evaluation

2.3.1 Screening through in silico pharmacokinetic and toxicity parameters

2.3.2 Molecular modeling

2.3.3 Similarity calculation

2.4 Pharmacological evaluation

2.4.1 Anxiolytic activity (Elevated plus maze method)

2.4.2 Skeletal muscle relaxant activity (Rotarod Method)

3 Results and discussion

4 Conclusion

Acknowledgement

References

Suggested read for related articles: