Zinc Oxide Nanoparticles Catalyzed Synthesis of Chalcone and Chalcone-sulfonamide Hybrids and Screening their Antibacterial Activities

Abstract

Chalcone is an aromatic ketone and an enone that forms the central core for a variety of important biological compounds, which are known collectively as chalcones or chalconoids. Alternative names for chalcone include benzylideneacetophenone, phenyl styryl ketone benzalacetophenone, β-phenylacrylophenone,γ-oxo-α,γ-diphenyl-α-propylene and α-phenyl-β benzoylethylene. Chalcones are 1,3-diphenyl-2-propene-1-one, in which two aromatic rings are linked by a three carbon α, β unsaturated carbonyl system. They are a major class of natural products characterized by an open ring structure and often considered as flavonoid family derivatives. Chalcone derivatives containing different substituents to A and B ring of the skeleton at different positions reported with broad spectrum biological activities including antibacterial, antifungal, antioxidant, anti-inflammatory and antiviral activity attributable to the presence of double bond in conjugation with carbonyl functionality. In this work, two 4’-amino substituted chalcone derivatives and two chalcone-sulfonamide hybrids were synthesized by both conventional and zinc oxide nanoparticles. The zinc oxide nanoparticle catalyzed reaction were obtained with good to excellent yields of 76.3-98.6 %. The structures of the compounds were fully characterized using spectroscopic techniques (UV Vis, 1H, 13C and DEPT-135 NMR). The synthesized 4’-amino substituted chalcones and chalcone-sulfonamide hybrid were screened for their antibacterial activities against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhimurium and the result revealed that chalcone-sulfonamide hybrid 18b showed potent activity against B. subtilis and E. coli with 17, 20 and 13, 14 mm zone of inhibitions at 50 and 100 mg/mL concentrations compared to standard drug ciprofloxacin (25 mm). Compound 18a also showed higher activity against E.coli (18 mm) and B. subtilis (15 mm) at 100 mg/mL. Compound 91 showed vague activity on S. aureus and active on against E.coli with 16 mm zone of inhibition.