The in vitro antioxidant activities of the bromophenols from the red alga Tichocarpus crinitus and phenolic derivatives

A series of bromophenols and corresponding debrominated phenolic compounds was prepared by isolation from red alga Tichocarpus crinitus and by structural modification of natural bromophenols. Their structures were determined by extensive NMR analysis and the antioxidant activities were established through the determination of their abilities to inhibit free radicals using DPPH as the stable radical. The most active free radical scavengers were the debrominated phenolic derivatives 3,4-dihydroxybenzyl alcohol and 3,3',4,4'-tetrahydroxydiphenylmethane.