Hofstra University

Evaluating the Antioxidant Activities of Synthetic Flavonoids.

Bioflavonoids are gaining recognition as an important class of natural products capable of scavenging various oxidizing species. We are conducting a systematic study of the antioxidant properties of synthetic heteroaromatic chalcones (1) and 3-hydroxyflavones (2). A variety of 2'-hydroxy-, 2',4'-dihydroxy-, and 2',4',6'- trihydroxychalcones have been prepared by base-catalyzed condensation of various arylcarboxaldehydes with either 2'-hydroxy-, 2',4'-dihydroxy-, or 2',4',6'- trihydroxyacetophenone (3), respectively. Oxidative cyclization of the hydroxychalcones yields the desired 3-hydroxyflavones.

Scheme 1

Our goal is to investigate the effectiveness with which each of the compounds synthesized scavenge hydroxyl and peroxyl radicals. The ability of antioxidants to inhibit the autoxidation of linoleic acid has been shown to be a versatile kinetic technique, and the oxidation of methyl linoleate is the simplest model for studying the oxidation of polyunsaturated fatty acids. In these systems, the rate of oxidation is given by the rate of production of hydroperoxides. Similarly, in collaboration with members of Hofstra University's Biology Department, we are investigating the ability of synthetic flavonoids to prevent oxidative stress in E. coli strains that have promoters that are either H2O2 or oxygen- stress inducible (e.g. katF, soxS).

(Partial support for this work is provided by a Merck/AAAS Undergraduate Science Research Program Award.)