Design and synthesis of chalcone mediated novel pyrazoline scaffolds: Discovery of benzothiophene comprising antimicrobial inhibitors

Abstract

Nitrogen and sulphur containing heterocyclic moieties have been found to possess extensive studies owing to their biological properties. Reporting herein the design, synthesis and spectral characterization of novel benzothiophene substituted pyrazolines. Combination of benzothiophene and pyrazoline rings has been achieved through synthesis of chalcones followed by cyclization with phenyl hydrazine in the presence of acetic acid. The structures of all the synthesized compounds were confirmed by NMR, HRMS, UV–Vis and FT-IR spectral techniques. All the newly prepared compounds along with standard drugs were investigated for their anti-microbial activities against different bacteria and fungi species. As a result, most of the molecules have shown consistent toxicity to kill the studied pathogens. Study presents the effect of variation in substitution at position 5 of pyrazoline ring on their biological activities. Among all these molecules, 3i exhibited outstanding activity against the studied microbial pathogens, almost like reference drugs. Additionally, molecules 3a, 3b and 3c showed prominent anti-microbial activity. Molecules 3f, 3 g and 3 h with poly-nuclear substitution have exhibited reasonably low bioactivities. Overall, this study has proven that prepared biologically active molecules can be exploited as leads for preclinical studies with the aim of rising novel antimicrobial drugs.