Design and Synthesis of Novel Quinoxaline Derivatives as Potential Anticancer Targeting Therapeutics.

Abstract

Cancer is a major problem in human health and remains the second highest cause of mortality worldwide, with millions of cases every year. A total of 1,658,370 new cancer cases and 589,430 cancer deaths are projected to occur in the United States in 2015. Therefore, current efforts to cure cancer have been focusing on drugs, biological molecules and immune mediated therapies. The use of conventional cytotoxic anti-tumor drugs is based on the theory that rapidly proliferating and dividing cells are more sensitive to these compounds than the normal cells. However, Studies have been focusing recently on targeted therapy to overcome traditional chemotherapy’s drawbacks. Targeted therapy refers to a new generation of cancer drugs designed to interfere with a specific target protein that is believed to have a critical role in tumor growth or progression, through targeting one of the six hallmarks of cancer. Sustained tumor angiogenesis is one of the hallmark features of cancer. VEGF is one of the key angiogenic stimulators secreted by the tumor cells to switch on the angiogenic phenotype. Intra-tumor hypoxia, alteration in oncogenes and tumor suppressor genes significantly up regulate VEGF expression. Therefore, targeting VEGFR leading to inhibition of angiogenesis, which further resulted in the arrest of tumor growth.Quinoxaline is a heterocyclic compound containing benzene ring and pyrazine ring. It is proved to be selective ATP competitive inhibitors in many kinases.

2-Rational and Design In an attempt to discover new quinoxalines analogues with promising anti-tumor activity, our study involved the synthesis of new series of quinoxaline derivatives as type II VEGFR-2 inhibitors based on comprehensive SAR studyand structural similarities with Sorafenib as a type II VEGFR-2 inhibitor. Their structures were confirmed by various spectral and micro analytical data (13C NMR, 1H NMR, FT IR, Mass Spectrum, and Elemental Analyses).

3-Chemistry This study comprises the synthesis of the following reported starting materials and intermediates: 1. 3-Methylquinoxalin-2-(1H)-one(I) 2. 2-chloro-3-methylquinoxaline (II) 3. Quinoxaline-2,3(1H,4H)-dione(X) 4. 2, 3-Dichloroquinoxaline(XI) 5. Quinoxalin-2(1H)-one(XIX) 6. 2-chloroquioxaline(XX) Also, it involved the following unavailable reported intermediates: 1. 3-((3-Methylquinoxalin-2-yl) amino) benzoic acid (III). 2. N1-(3-methylquinoxalin-2-yl)benzene-1,4-diamine (IV). 3. 3-((3-Chloroquinoxalin-2-yl) amino) benzoic acid(XII). 4. N1-(3-chloroquinoxalin-2-yl) benzene-1,4-diamine (XIII). 5. 3-(Quinoxalin-2-ylamino)benzoic acid (XXI). 6. N1-(quinoxalin-2-yl)benzene-1,4-diamine(XXII).

Moreover, these new target compounds were synthesized:

1. 3-((3-Methylquinoxalin-2-yl)amino)-N-phenylbenzamide(VIa). 2. N-(4-chlorophenyl)-3-((3-methylquinoxalin-2-yl)amino)benzamide(VIb). 3. N-(4-methoxyphenyl)-3-((3-methylquinoxalin-2-yl)amino)benzamide(VIc). 4. N-(4-((3-methylquinoxalin-2-yl)amino)phenyl) benzamide (VIIa). 5. 4-Chloro-N-(4-((3-methylquinoxalin-2-yl)amino)phenyl)benzamide (VIIb). 6. 4-Methoxy-N-(4-((3-methylquinoxalin-2-yl)amino)phenyl)benzamide(VIIc). 7. 4-Methyl-N-(4-((3-methylquinoxalin-2-yl)amino)phenyl)benzamide(VIId). 8. 1-(4-((3-Methylquinoxalin-2-yl)amino)phenyl)-3-phenylthiourea(VIIIa). 9. 1-(4-((3-Methylquinoxalin-2-yl)amino)phenyl)-3-phenylurea (VIIIb). 10. 1-(4-Chlorophenyl)-3-(4-((3-methylquinoxalin-2-yl)amino)phenyl)urea (VIIIc). 11. 1-(4-((3-Methylquinoxalin-2-yl)amino)phenyl)-3-(m-tolyl)urea (VIIId). 12. 1-(3-Methoxyphenyl)-3-(4-((3-methylquinoxalin-2-yl)amino)phenyl)urea (VIIIe). 13. 4-Methyl-N-(4-((3-methylquinoxalin-2-yl)amino)phenyl)benzenesulfonamide (IXa). 14. N-(4-((3-methylquinoxalin-2-yl)amino)phenyl)-4-nitrobenzenesulfonamide(IXb). 15. 3-((3-Chloroquinoxalin-2-yl) amino)-N-phenylbenzamide(XVa). 16. N-(4-chlorophenyl)-3-((3-chloroquinoxalin-2-yl) amino) benzamide(XVb). 17. 3-((3-Chloroquinoxalin-2-yl) amino)-N-(4-methoxyphenyl) benzamide (XVc). 18. N-(4-((3-chloroquinoxalin-2-yl) amino) phenyl) benzamide(XVIa). 19. 4-Chloro-N-(4-((3-chloroquinoxalin-2-yl) amino) phenyl) benzamide(XVIb). 20. N-(4-((3-chloroquinoxalin-2-yl) amino) phenyl)-4-methoxybenzamide(XVIc). 21. N-(4-((3-chloroquinoxalin-2-yl) amino) phenyl)-4-methylbenzamide (XVId). 22. 1-(4-((3-Chloroquinoxalin-2-yl) amino) phenyl)-3-phenylthiourea(XVIIa). 23. 1-(4-((3-Chloroquinoxalin-2-yl) amino) phenyl)-3-phenylurea(XVIIb). 24. 1-(4-Chlorophenyl)-3-(4-((3-chloroquinoxalin-2-yl) amino) phenyl) urea (XVIIc). 25. 1-(4-((3-Chloroquinoxalin-2-yl) amino) phenyl)-3-(m-tolyl) urea(XVIId). 26. 1-(4-((3-Chloroquinoxalin-2-yl) amino) phenyl)-3-(3-methoxyphenyl) urea (XVIIe). 27. 1-(4-((3-Chloroquinoxalin-2-yl)amino)phenyl)-3-(4-methoxyphenyl)urea(XVIIf). 28. N-(4-((3-chloroquinoxalin-2-yl) amino) phenyl)-4-methylbenzenesulfonamide (XVIIIa). 29. N-(4-((3-chloroquinoxalin-2-yl)amino)phenyl)-4-nitrobenzenesulfonamide (XVIIIb). 30. N-(phenyl)-3-(quinoxalin-2-ylamino)benzamide derivatives(XXIVa). 31. N-(4-methoxyphenyl)-3-(quinoxalin-2-ylamino)benzamides)(XXIVb). 32. 1-(3-Methoxyphenyl)-3-(4-(quinoxalin-2-ylamino) phenyl) urea (XXV).

4-Bilological Evaluation: The targeted compounds were submitted to test their in-vitro anticancer activity by screening against 3 tumor cell linesnamely (HCT-116, HEPG-2 and MCF-7). Out of the titled compounds, 5 showed promising activity (VIId, VIIIa, VIIIc, VIIIe, XVa). The enzymatic activity of the synthesized compounds was assessed against VEGFR-2 tyrosine kinases at Bio Science Corporation (BPS). Unfortunately, our compounds showed weak activity against VEGFR-2 (most of the compounds activities were between 2% and 21%), which couldn’t explain the potent antiproliferative activity of compounds (VIId, VIIIa, VIIIc, VIIIe, XVa).Moreover,VIIIc was selected as the most potent compound and was further selected to investigate its effect on cell cycle progression, induction of apoptosis, and expression of cleaved caspase-3 using Human colon carcinoma cell line (HCT-116).

5-Docking Studies Molecular docking using CDOCKER protocol was attempted for initial design and to investigate the binding mode of the targeted compounds and interpret the biological results.