alexa Synthesis, Anticancer and Molecular Docking Studies of 2-(4-chlorophenyl)-5-aryl-1,3,4-Oxadiazole Analogues | OMICS International
ISSN: 2161-0444
Medicinal Chemistry
Like us on:
Make the best use of Scientific Research and information from our 700+ peer reviewed, Open Access Journals that operates with the help of 50,000+ Editorial Board Members and esteemed reviewers and 1000+ Scientific associations in Medical, Clinical, Pharmaceutical, Engineering, Technology and Management Fields.
Meet Inspiring Speakers and Experts at our 3000+ Global Conferenceseries Events with over 600+ Conferences, 1200+ Symposiums and 1200+ Workshops on
Medical, Pharma, Engineering, Science, Technology and Business

Synthesis, Anticancer and Molecular Docking Studies of 2-(4-chlorophenyl)-5-aryl-1,3,4-Oxadiazole Analogues

Mohamed Jawed Ahsan1*, Vikram Pratap Singh Rathod1, Monika Singh1, Ramdayal Sharma1, Surender Singh Jadav2, Sabina Yasmin2, Salahuddin3 and Pradeep Kumar1

1Department of Pharmaceutical Chemistry, Maharishi Arvind College of Pharmacy, Jaipur, Rajasthan 302 023, India

2Department of Pharmaceutical Sciences, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835 215, India

3Department of Pharmaceutical Technology, Noida Institute of Engineering and Technology, Knowledge Park II, Greater Noida, Uttar Pradesh 201 306, India

*Corresponding Author:
Mohamed Jawed Ahsan
Department of Pharmaceutical Chemistry
Maharishi Arvind College of Pharmacy
Jaipur, Rajasthan 302 023, India
Tel: +91 9694087786
Fax: +91 144 5121120
E-mail: [email protected]

Received date: November 19, 2013; Accepted date: December 19, 2013; Published date: December 21, 2013

Citation: Ahsan MJ, Singh Rathod VP, Singh M, Sharma R, Jadav SS, et al. (2013) Synthesis, Anticancer and Molecular Docking Studies of 2-(4-chlorophenyl)-5- aryl-1,3,4-Oxadiazole Analogues. Med chem 3:294-297. doi:10.4172/2161- 0444.1000154

Copyright: © 2013 Ahsan MJ, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Visit for more related articles at Medicinal Chemistry

Abstract

Among a series of ten, 2-(4-chlorophrnyl)-5-aryl-1,3,4-oxadiazole analogs, 4c showed maximum activity on various cancer cell lines, with average growth percent of 95.37%. The molecular docking studies for the compounds 4a & 4c showed that the residue Cys797 is present near to the para substitution of phenyl group while the five member oxadiazole ring of ligandswas lying near to Leu792 and Met 793 of EGFR tyrosine kinase active

Keywords

Anticancer; Oxadiazole; Single-dose assay; Molecular docking studies

Introduction

About 13 percent of all the death worldwide is due to cancer, surpassing cardiovascular disease and taking number one place [1,2]. Chemotherapy of cancer is associated with various adverse effects viz. bone marrow depression, alopecia, drug induced caner, etc. and is often associated with cytotoxicity, genotoxicity to normal cells together with the development of resistance [3]. Medicinal chemists have great perseverance in research and development (R & D) for the search of newer and safer anticancer agents. EGFR family of Tyrosine Kinases (TK) play a vital role in cancer proliferation and it is suggested that any agent which would inhibit the TK activity may have substantial role in the cancer treatment [4]. So we selected EGFR family of TK and explore the binding mode of the our compounds to EGFR tyrosine kinase active site. Imatinib (gleevec) an anticancer drug is TK inhibitor (TKI), inhibits TK encoded by the bcr-abl oncogene as well as receptor TKs encoded by the c-kit and platelet-derived growth factorreceptor (PDGFR) oncogenes [5]. Oxadiazole derived compounds are known to display wide range of biological and pharmacological activities including anticancer, antitubercular, antibacterial, antifungal, anti- HIV, anti-inflammatory, and insecticidal activities [6-12]. There are nearly 2577 publications from 2002 to 2012 involving 1,3,4-oxadiazoles [13]. Some of the marketed oxadiazole drugs include raltegravir (antiretroviral), zibotentan (anticancer), etc. We have earlier reported the anticancer activity of some novel oxadiazole analogues [6,14].

Materials and Methods

Chemistry

All chemicals were supplied by E. Merck, and S. D. Fine Chemicals. Melting points were determined by open tube capillary method and are uncorrected. Purity of the compounds was checked by elemental analysis and the progress of reactions was monitored by TLC plates (silica gel G) using mobile phase, chloroform: methanol (9:1), and acetone: n-hexane (8:2) and the spots were identified by iodine vapours or UV light. IR spectra were recorded on a Schimadzu 8201 PC, FTIR spectrometer (KBr pellets). 1H NMR spectra were recorded on a Bruker AC 300 MHz spectrometer using TMS as internal standard in DMSO d6. Mass spectrawere recorded on a Bruker Esquire LCMS using ESI and elemental analyses were performed on Perkin-Elmer 2400 Elemental Analyzer.

General method for the synthesis of 4-chlorobenzohydrazide (3): 4-Chlorobenzoic acid (1) (7.84 g, 0.05 mol) was dissolved in excess of ethanol (50 ml) the reaction mixture was acidified and refluxed for 8-10 h. The layer of ester is separated by filtrationflask and neutralizedwith sodium bicarbonate to obtain ethyl-4-chlorobenzoate (2). Equimolar mixture of ethyl-4-chlorobenzoate (2) and hydrazine hydrate was refluxed for 12 h and the excess solvent removed under vacuumand poured into the crushed ice to obtain 4-chlorobenzohydrazide (3).

General method for the synthesis of 2-(4-chlorophenyl)-5-aryl- 1,3,4-oxadiazole analogues(4a-j): 4-Chlorobenzohydrazide (0.85 g, 0.005 mol) (3) and aromatic aldehydes was refluxed 10-12 h using 20 mol% NaHSO3 and ethanol-water system (1:2, v/v) solvent [15]. After completion of reaction the mixture the excess solvent removed and the concentrate was poured into crushed ice washed with water, dried and recrystallized with absolute ethanol. The reaction was monitored throughout by TLC using chloroform-methanol (9:1) and acetone: n-hexane (8:2) as mobile phase.

2-(4-Chlorophenyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole (4a) Yield 70%, IR (KBr) 1521, 1112, 789, 745 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 7.02-7.03 (2H, d, J=3.2 Hz, ArH), 7.36-7.38 (2H, d, J=6.1 Hz, ArH), 7.39-7.41 (2H, d, J=6.0 Hz, ArH), 7.43-7.45 (2H, d, J=6.2 Hz, ArH). 13C NMR (75 MHz, DMSO-d6): δ 116.1, 121.9, 124.5, 128.7, 129.2, 129.7, 134.7, 162.6, 164.8; m/z=274 (M+), 275 (M+1)+1, 276 (M+2)+. Cal/Ana: [C (61.12) 61.22 H (2.92) 2.94 N (10.08) 10.20].

2-(4-Chlorophenyl)-5-(4-chlorophenyl)-1,3,4-oxadiazole (4b) Yield 74%, IR (KBr) 1531, 1131, 742 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 7.28-7.30 (4H, dd, J=6.1 Hz ArH), 7.39- 7.41 (4H, dd, J=6.2 Hz ArH); m/z=290 (M+), 292 (M+2)+. Cal/Ana: [C (57.62) 57.76 H (2.79) 2.77 N (9.59) 9.62].

2-(4-Chlorophenyl)-5-(4-methoxyphenyl)-1,3,4-oxadiazole (4c) Yield 82%, IR (KBr) 1526, 1121, 749 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 3.79 (3H, s, OCH3), 7.32-7.34 (2H, d, J=6.1 Hz, ArH), 7.35-7.37 (2H, d, J=6.1 Hz, ArH), 7.39-7.41 (2H, d, J=6.0 Hz, ArH), 7.81- 7.83 (2H, d, J=6.1 Hz ArH); m/z=286 (M+), 288 (M+2)+. Cal/ Ana: [C (62.79) 62.84 H (3.89) 3.87 N (9.57) 9.77].

2-(4-Chlorophenyl)-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole (4d) Yield 79%, IR (KBr) 1528, 1127, 694 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 3.81 (6H, s, OCH3), 7.31-7.33 (2H, d, J=6.1 Hz, ArH), 7.42-7.44 (2H, d, J=6.2 Hz, ArH), 7.89-7.92 (3H, m, ArH); m/z=316 (M+), 318 (M+2)+. Cal/Ana: [C (60.47) 60.67 H (4.19) 4.14 N (8.77) 8.84].

2-(4-Chlorophenyl)-5-(4-hydroxy-3-methoxyphenyl)-1,3,4- oxadiazole (4e) Yield 65%, IR (KBr) 3397, 1525, 1132, 699 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 3.83 (3H, s, OCH3), 7.31-7.33 (2H, d, J=6.0 Hz, ArH), 7.42-7.44 (2H, d, J=6.1 Hz, ArH), 7.84-7.87 (3H, m, ArH), 10.27 (1H, s, OH); m/z=302 (M+), 304 (M+2)+. Cal/Ana: [C (59.47) 59.52 H (3.59) 3.66 N (9.22) 9.25].

2-(4-Chlorophenyl)-5-(2-hydroxyphenyl)-1,3,4-oxadiazole (4f) Yield 81%, IR (KBr) 3409, 1521, 1271, 697 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 7.33-7.35 (2H, d, J=6.0 Hz, ArH), 7.41-7.43 (2H, d, J=6.1 Hz, ArH), 7.81-7.84 (3H, m, ArH), 10.02 (1H, s, OH); m/z=272 (M+), 274 (M+2)+. Cal/Ana: [C (66.57) 61.66 H (3.39) 3.33 N (10.25) 10.27].

2-(4-Chlorophenyl)-5-(4-hydroxyphenyl)-1,3,4-oxadiazole (4g) Yield 80%, IR (KBr) 3401, 1527, 1121, 699 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 6.79-6.81 (2H, s, ArH), 7.27-7.29m (2H, d, J=6.0 Hz, ArH), 7.34-7.36 (2H, d, J=6.0 Hz, ArH), 7.41-7.43 (2H, d, J=6.1 Hz, ArH), 7.81-7.84 (3H, m, ArH), 10.12 (1H, s, OH); m/z=302 (M+), 304 (M+2)+. Cal/Ana: [C (59.45) 59.52 H (3.65) 3.66 N (9.28) 9.25].

2-(4-Chlorophenyl)-5-phenyl-1,3,4-oxadiazole (4h) Yield 66%, IR (KBr) 1529, 1137, 702 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 7.31- 7.33 (2H, d, J=6.0 Hz, ArH), 7.41-7.43 (2H, d, J=6.1 Hz, ArH), 7.67- 7.71 (5H, m, ArH); m/z=256 (M+), 258 (M+2)+. Cal/Ana: [C (65.47) 65.51 H (3.59) 3.53 N (10.82) 10.91].

2-(4-Chlorophenyl)-5-(4-methylphenyl)-1,3,4-oxadiazole (4i) Yield 13%, IR (KBr) 1519, 1139, 714 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 2.32 (3H, s, CH3), 7.14-7.16 (2H, d, J=6.0 Hz, ArH), 7.32-7.34 (2H, d, J=6.1 Hz, ArH), 7.35-7.37 (2H, d, J=6.0 Hz, ArH), 7.41- 7.43 (2H, d, J=6.0 Hz, ArH); m/z=270 (M+), 272 (M+2)+. Cal/ Ana: [C (66.47) 66.55 H (4.19) 4.10 N (10.31) 10.35].

2-(4-Chlorophenyl)-5-(furan-2-yl)-1,3,4-oxadiazole (4j) Yield 69%, IR (KBr) 1525, 1124, 731 cm-1; 1H NMR (300 MHz, DMSO-d6): δ 6.98-7.01 (3H, s, Furan), 7.32-7.34 (2H, d, J=6.0 Hz, ArH), 7.39-7.41 (2H, d, J=6.1 Hz, ArH); m/z=246 (M+), 248 (M+2)+. Cal/Ana: [C (58.37) 58.43 H (2.81) 2.86 N (11.32) 11.36].

Anticancer activity

The compounds (4a and 4c) submitted to the NCI 60 cell screen were tested initially at a single high dose (10-5 M) on leukemia, melanoma, lung, colon, CNS, ovarian, renal, prostate, and breast cancers cell lines, nearly 60 in number. The one-dose data was reported as a mean graph of the percent growth of treated cells. The number reported for the onedose assay is growth relative to the no-drug control, and relative to the time zero number of cells. The anticancer screening was carried out as per the NCI US protocol reported elsewhere [16-19]. We have discussed the anticancer screening method in our previous work [6,14,20].

Molecular docking studies

X-ray crystal structure of EGFR tyrosine kinase (PDB: 2J5F) was downloaded from www.rcsb.org. The active site of 2J5F is well established with hydrophobic active site containing irreversible inhibitor and molecular dockingsimulations were performed in order to distinguish the basic receptor-ligand interactions. The X-ray crystal structure of EGFR tyrosine kinase domain had the resolution of 3.00Å. The protein was prepared by using the Protein Preparation Wizard, pre-processed and heterostate for co-crystallized ligand was generated using Epik; protonation state and optimizationof H bonding of the protein side chains were assigned using Protassign, energy minimized (impref minimization) using OPLS2001 force field. Receptor grid has been prepared with default parameters and without any constrains. Site was specified around the reference ligands N-[4- (3- bromophenylamino)quinazolin-6-yl]acrylamide of EGFR tyrosine kinase. The three dimensional structures of ligands were drawn by using the Maestro 8.5. The ligands were prepared by using Ligprep utility of Schrodinger Suite with default parameters, the ligandenergy minimized by using OPLS 2005 (Macromodel multiple minimization) and water as solvent. The ligands did not show the formation of any tautomers or isomers after ligprep and macromodel multiple energy minimizations. The ligands’ docking was performed with Xtra precision mode (XP) which is employed in GLIDE 5.0 module implemented in the Schrodinger LLC.

Results and Discussion

Chemistry

In the first step 4-chlorobenzoic acid (1) in excess of ethanol was refluxed for 8-10 h in acidic medium to obtain ethyl-4-chlorobenzoate (2). In the subsequent step compound (2) was refluxed with hydrazine hydrate in ethanol for 12 h to obtain 4-chlorobenzohydrazide (3). In the final step 4-chlorobenzohydrazide (3) and aromatic aldehydes was refluxed 10-12 h using 20 mol% NaHSO3 and ethanol-water system (1:2, v/v) solvent to obtain oxadiazole analogues (4a-n). The reaction was monitored throughout by thin layer chromatography (TLC) using chloroform-methanol (9:1) and acetone: n-hexane (8:2) as mobile phase and the purity of the compounds was checked by elemental analysis. The reaction sequence is shown in Scheme 1. The synthesized compounds were characterized by spectral analysis and all the compounds were in full harmony with the proposed structures. In general the IR spectra afforded absorption 1519-1531 cm-1 band due to C=N and 1112- 1271 cm-1 due to oxadiazole stretching. In 1H NMR the signals of the respective protons of the synthesized title compounds were verified on the basis of their chemical shifts and multiplicities in DMSO d6. The spectra showed a singlet at δ 3.79-3.83 ppm corresponding to OCH3; a doublet or multiplet at δ 6.79-7.92 ppm corresponding to aromatic protons.

medicinal-chemistry-oxadiazole-analogues

Scheme 1: Protocol for the synthesis of 2-(4-chloro)-5-aryl-1,3,4-oxadiazole analogues (4a-j).

Anticancer activity

2-(4-chlorophenyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole (4a) showed growth percent (GP) of 87.27 (SF-295; CNS cancer) and 89.12 (MCF7; Brest Cancer) while 2-(4- chlorophenyl)-5-(4-methoxyphenyl)- 1,3,4-oxadiazole (4c) showed GP of 71.70 (PC-3; Prastate cancer) and 74.14 (SR; Leukemia). The compound 4c (mean GP; 95.37) was found to be more active than the compound 4a (mean GP; 98.74). The in vitro anticancer activity of the compounds is given in Table 1. The compound 4c with 4-methoxyphenyl at the 5 position of the oxadiazole ring showed more anticancer activity than the compound 4a with 4-fluorophenyl at the 5 position of oxadiazole nucleus.

Comp. 60 cell lines assay in 1 dose 10-5M conc.
  NSC Code Mean
GP
Range of GP The most sensitive cell line GP of the most
sensitive cell line
4a 776718 98.74 87.26 to
112.87
SF-295 (CNS Cancer) 87.26
MCF7 (Brest Cancer) 89.12
UO-31 (Renal Cancer) 89.93
HCT-15 (Colon cancer) 90.55
NCI-H522 (Non-Small Cell
Lungs cancer)
91.27
4c 776717 95.37 71.70 to
110.76
PC-3 (Prostate Cancer) 71.70
SR (Leukemia) 74.14
UO-31 (Renal Cancer) 80.62
NCI-H522 (Non-Small Cell
Lungs cancer)
82.58
SK-OV-3 (Ovarian Cancer) 83.34

Table 1: Anticancer activity of the selected oxadiazole analogues.

Molecular docking studies

The EGFR tyrosine kinase was reported several times as target for the inhibition of cancer cells. It contains the bound ligand N-[4- (3-bromophenylamino) quinazolin-6-yl] acrylamide and is well established by the presence of hydrophobic cavity at active site. Redocking of bound or reference ligand 34-JAB with EGFR tyrosine kinase exhibited the hydrophobic interactions with the residues Thr790, Met793 and Cys797. The amino acid residues Lys745, Glu762, Met766, Leu788, Met793 and Thr854 make the receptor hydrophobic in nature. The most important residue Cys797 is present near to the para substitution of phenyl group. The five member oxadiazole ring of ligands was lying near to Leu792 and Met 793. It was observed that the presence of methoxy functional group at para position may become more selective towards the EGFR tyrosine kinase [14]. In order to predict the binding affinity and pre eminent docked structures, the combined ligand docking and energy-grid scores were ranked by using E model and Glide scores. The ligand docking and E model scores were provided in the Table 2. The docking scores of compounds 4a and 4c were -5.251 and -5.433 respectively. The molecular docking and binding of ligands 4a and 4c is shown in Graphical abstract, while the 2D pose of the ligand 4c and the active site EGFR tyrosine kinase is shown in Figures 1 and 2.

S. No. Compound Docking score E-model score
1 Reference [21] -8.288 -68.491
2 4a -5.251 -37.778
3 4c -5.433 -38.804

Table 2: The docking score and E model score of reference ligand and selected ligands (4a and 4c).

medicinal-chemistry-Superimposed-diagram

Figure 1: Superimposed diagram of the two ligands 4a and 4c (ball and stick model).

medicinal-chemistry-tyrosine-kinase-active

Figure 2: (A) ligand 4c was shown in ball and stick model and remaining were EGFR tyrosine kinase active site residues; (B) 2D pose view diagram of the ligand 4c and EGFR tyrosine kinase active site residues.

Conclusion

A series of 10 oxadiazole analogues were synthesized in satisfactory yield and two compounds were evaluated for their in vitro anticancer activity at single-dose assay. The oxadiazole analogues showed moderate anticancer activity on various cell lines and molecular docking studies showed that the residue Cys797 is present near to the para substitution of phenyl group while the five member oxadiazole ring of ligands was lying near to Leu792 and Met 793 of EGFR tyrosine kinase active site. The oxadiazole analoguesreported in this study may be further modified to increase their anticancer activity.

Conflict of Interests

The authors confirm that this article content has no conflicts of interest.

Acknowledgements

Anticancer data were provided by National Cancer Institute, Bethesda, MD, USA. We are grateful for all help provided by Prof. Doug Smallwood and Dr. Mohammed Nayel. The management of Maharishi Arvind College of Pharmacy, Jaipur, Rajasthan, India is acknowledged for providing research facilities.

References

Select your language of interest to view the total content in your interested language
Post your comment

Share This Article

Recommended Conferences

Article Usage

  • Total views: 12378
  • [From(publication date):
    November-2013 - Feb 22, 2018]
  • Breakdown by view type
  • HTML page views : 8447
  • PDF downloads : 3931
 

Post your comment

captcha   Reload  Can't read the image? click here to refresh

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2018-19
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

Agri & Aquaculture Journals

Dr. Krish

[email protected]

1-702-714-7001Extn: 9040

Biochemistry Journals

Datta A

[email protected]

1-702-714-7001Extn: 9037

Business & Management Journals

Ronald

[email protected]

1-702-714-7001Extn: 9042

Chemistry Journals

Gabriel Shaw

[email protected]

1-702-714-7001Extn: 9040

Clinical Journals

Datta A

[email protected]

1-702-714-7001Extn: 9037

Engineering Journals

James Franklin

[email protected]

1-702-714-7001Extn: 9042

Food & Nutrition Journals

Katie Wilson

[email protected]

1-702-714-7001Extn: 9042

General Science

Andrea Jason

[email protected]

1-702-714-7001Extn: 9043

Genetics & Molecular Biology Journals

Anna Melissa

[email protected]

1-702-714-7001Extn: 9006

Immunology & Microbiology Journals

David Gorantl

[email protected]

1-702-714-7001Extn: 9014

Materials Science Journals

Rachle Green

[email protected]

1-702-714-7001Extn: 9039

Nursing & Health Care Journals

Stephanie Skinner

[email protected]

1-702-714-7001Extn: 9039

Medical Journals

Nimmi Anna

[email protected]

1-702-714-7001Extn: 9038

Neuroscience & Psychology Journals

Nathan T

[email protected]

1-702-714-7001Extn: 9041

Pharmaceutical Sciences Journals

Ann Jose

[email protected]

1-702-714-7001Extn: 9007

Social & Political Science Journals

Steve Harry

[email protected]

1-702-714-7001Extn: 9042

 
© 2008- 2018 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version