Synthesis and radical scavenging activity of new phenolic hydrazone/hydrazide derivatives: Experimental and theoretical studies

Hydrazone and hydrazone-hydrazide-based compounds represent important classes of compounds that continue to attract increasing interest due to their diverse pharmacological actions. In the present study, a series of new phenolic hydrazone/hydrazide derivatives (1-10) have been successfully synthesized and evaluated for their antiradical activity using experimental and theoretical methods. The hydrazones 1-5 were found to be significantly more reactive than their analogs hydrazone-hydrazide 6-10 via the main antiradical mechanism as well as toward DPPH and ABTS radicals. The NH group of the hydrazone is more reactive than the NH group of the hydrazide and the phenolic OH groups. The carbonyl group of the hydrazide plays a negative role in the antiradical activity of such molecules. Among the studied compounds, compound 4 was found to be the best radical scavenger with SC50 values (concentration causing 50% of DPPH or ABST scavenging) comparable to those of ascorbic acid and Trolox. These findings provide insights on the structure-activity relationship of hydrazone and hydrazone-hydrazide type compounds, as well as open up new perspectives for the development of novel potent antioxidants. (C) 2021 Elsevier B.V. All rights reserved.