Synthesis and in vitro-anticancer and antimicrobial evaluation of some novel quinoxalines derived from 3-phenylquinoxaline-2(1H)-thione

Two novel series derived from 3-phenylquinoxaline-2(1H)-thione 2 and 2-(hydrazinocarbonylmethylthio)-3-phenylquinoxaline 6 have been synthesized. Eight out of twenty six new compounds were selected at the National Cancer Institute for evaluation of their in vitro-anticancer activity. Among them, compounds 3b, 3c, 4b, and 4c displayed moderate to strong growth inhibition activity against most of the tested sub-panel tumor cell lines with GI(50) 10(-5) to 10(-6) molar concentrations. Compound 4b exhibited a significant value of percent tumor growth inhibition against breast cancer at concentration < 10(-8) M. Compound 4c showed moderate selectivity towards leukemia cell lines with GI(50) of 1.8 to 3.8 mu M (selectivity ratio = 5.7). Preliminary antimicrobial testing revealed that compounds 7a, 7b, 8a, 11a, and 11b were as active as ampicillin against B. subtilis (MIC = 12.5 mu g/mL). Compounds 7b and 8a. were also nearly as active as ampicillin against E. coli (MIC = 12.5 mu g/ml,). In addition, compounds 4a, 7b, 10b, and 11a. were as active as ampicillin against P. aerugenosa (MIC = 50 mu g/mL). However, compounds 7b, 8a, and 10b showed mild activity against C. albicans (MIC = 50 mu g/mL). The values of minimum bactericidal concentrations indicated that compounds 4a and 7b were bactericidal against B. subtilis and P. aerugenosa, respectively, while compound 10b was bactericidal against both organisms. However, compound 11a was bactericidal against E. coli, P. aerugenosa, and S. aureus.