A series of semicarbazones, thiosemicarbazones, 1,3,4-oxadiazoles/thiadiazoles bearing pyrazole scaffold were designed and synthesized. All the synthesized new compounds were characterized by 1H NMR, 13C NMR, MS and elemental analysis. The synthesized compounds were screened to probe their in vitro antimicrobial activity against bacteria and fungi species. The structure-activity relationship of the synthesized compounds was studied. The compounds displayed good to excellent potency against tested microorganisms. The in vitro antioxidant activities of the 1,3,4-oxadiazoles/thiadiazoles were evaluated by DPPH, hydroxyl and nitric oxide radical scavenging assay. Among the tested compounds, compound with chloro substitution showed good antioxidant potential.
A series of new Schiff bases of 4-(methylthio)benzaldehyde derivatives 3(a-i) were synthesized by the reaction of 4-(methylthio)benzaldehyde with various amines 2(a-i). Newly synthesized compounds were characterized by elemental analyses, UV-visible, FT-IR, Mass and 1H NMR spectral studies. All compounds were evaluated for their in vitro antibacterial activity against clinically isolated strains i.e., E. Coli, P. Fluorescence, M. Luteus and B. Subtilis. These compounds were screened for their antioxidant activity by 2,2-diphenyl-1-picryl-hydrazyl (DPPH•) and ferrous ion chelating assay (Fe2+) methods. The cytotoxicity assay was performed by tryphan blue dye exclusion method. Compounds 3g, 3h and 3i exhibited good antibacterial activity when compared with other compounds in the series against tested pathogenic bacterial strains. All the compounds showed antioxidant activity, where compound 3b was the best radical scavenger and Fe2+ ion scavenger. These findings showed that the Schiff bases of 4-(methylthio)benzaldehyde derivatives possess antioxidant activity with different mechanism of actions towards the different free radicals tested. Among these derivatives, 3b and 3h had the strongest activity against human peripheral lymphocytes.
Imines of six new quinolin-5-ylamine derivatives 3(a-c) and 5(a-c) were synthesized by the reaction of quinolin-5-ylamine (1) with different aldehydes 2(a-c) and ketones 4(a-c). The chemical structures of the compounds were confirmed by UV-visible, FT-IR and 1H NMR spectral study. New compounds were screened for the antioxidant activity by DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Butylated Hydroxytoluene (BHT) was used as standard. All the compounds showed DPPH radical scavenging activity, where compound 3c was the best radical scavenger.