Synthesis and Biological Evaluations of Prop-2-enone and Penta-1, 4-dien-3-one Chalcones and their Hydrazone Derivatives

Abstract

Chalcones are naturally coloured compounds found in plants, characterized by a distinctive chemical structure with two aromatic rings linked by a three-carbon α, β-unsaturated carbonyl bridge. Chalcones synthesis was achieved via modified Claisen-Schmidt condensation utilizing aromatic aldehydes and ketones, giving a yield of 80 – 98 % and was then combined with 2, 4-dinitrophenyl hydrazine (2, 4-DNPH) to form hydrazones yielding 58 – 86 %. Products formed were characterized accordingly using 1H-NMR, FTIR, UV, and elemental analysis. The biochemical assay involving antimicrobial activity by employing the agar well diffusion method indicated that the chalcones exhibited no activity against the selected isolates (E. coli, S. aureus, P. aeruginosa, and B. subtilis), while the compounds showed good analgesic properties as well as good antioxidant properties as indicated in the  DPPH radical scavenging assay with one of the products  BE6  showing (IC50=11.68 µM)  and the Nitric Oxide bioavailability of  BE1A  indicating high activity. The total antioxidant determination indicated that the chalcones were better than the hydrazones with BE7 giving a value of TAC=8724.02. This indicates that coupled chalcones may exhibit good analgesic and antioxidant properties but still not a good antimicrobial properties.