Synthesis, characterization and in vitro antibacterial activity of new steroidal thiazolo quinoxalines

Herein, we report the synthesis of different steroidal thiazolo quinoxaline derivatives as antibacterial agents against Escherichia coli. Steroidal ketone thiosemicarbazones (4–6) were obtained from corresponding ketones (1–3) by refluxing with thiosemicarbazide. The thiosemicarbazones on reaction with 2,3-dichloroquinoxalines at 80 °C gives 3β-acetoxy-5α-cholestan-6-[thiazolo(4,5-b)quinoxaline-2-yl-hydrazone] (7), 3β-chloro-cholestan-6-[thiazolo(4,5-b)quinoxaline-2-yl-hydrazone] (8), and 5α-cholestan-6-[thiazolo(4,5-b)quinoxaline-2-yl-hydrazone] (9). The structures of the compounds were evident by elemental, IR, 1H NMR and FAB mass spectral analyses. The antibacterial activities of these compounds were evaluated by disk diffusion method against the culture of E. coli and the results were compared with the standard drug amoxicillin. The results reveal that the compounds are better antibacterial agents as compared to amoxicillin. Among all the three compounds (7–9), compound 8 showed better zone of inhibition.

Different thiazolo quinoxaline derivatives were synthesized by the reaction of steroidal thiosemicarbazones with 2,3-dichloroquinoxalines. The antibacterial activity of these compounds was evaluated by disk diffusion method against Escherichia coli culture and the results were compared with the standard drug amoxicillin. The results reveal that the compounds are better antibacterial agents as compared to amoxicillin. Among all the compounds (7, 8, and 9), compound 8 showed better zone of inhibition.