Synthesis and evaluation of new chalcones, derived pyrazoline and cyclohexenone derivatives as potent antimicrobial, antitubercular and antileishmanial agents

A series of chalcones (1-8) were prepared by Claisen-Schmidt condensation of 3-nitroacetophenone with various aldehydes. These chalcones on cyclization with hydrazine hydrate in the presence of glacial acetic acid, hydrazine hydrate in absolute ethanol and ethyl acetoacetate in the presence of barium hydroxide gave corresponding N-acetyl pyrazolines (9-16), N-unsubstituted pyrazolines (17-19) and cyclohexenone derivatives (20-22). All the synthesized compounds were evaluated for their in vitro antibacterial and antifungal activity by using broth microdilution method, and many compounds showed promising activity against various tested bacteria and fungi. Among various tested compounds, 16 and 19 exhibited strongest activities against Streptococcus pyogenes and Pseudomonas aeruginosa; both have MIC value of 25 mu g/mL, which is fourfold greater than the standard drug. Many compounds showed good activity against Candida albican. Analogs 11, 12, 15-17 and 19 displayed two- to fivefold greater activity against C. albican as compared to the standard drug. Results of antitubercular evaluation revealed that compounds 4 and 19 displayed strong antimycobacterial activity against H(37)Rv having MIC of 25 and 62.5 mu g/mL, respectively. All analogs were found to be inactive against Leishmania braziliensis except analogs 4 and 5 which exhibited strong leishmanicidal activity against Leishmania promastigotes with IC50 values of 9.3 and 8.9 mu g/mL, respectively.