Antioxidant and cytotoxic activities of naturally occurring phenolic and related compounds: a comparative study

The antioxidant (DPPH radical and superoxide anion scavenging activities), and cytotoxic (in tumor, Jurkat, PC-3, Colon 205, HepG2, and normal PBMCs cells) activities of 16 plant phenolic or related compounds were evaluated in vitro. Different categories compounds corresponding to 10 flavonoids, three lignans, two phenolic acids, and a catechin showed significant mean differences in antioxidant and cytotoxic activities. Particularly, the flavonols, quercetin (3) and tiliroside (11) possess significant antioxidant activity, as well as cytotoxic activity against Jurkat; and Jurkat and HepG2 cells, respectively. In contrast, the flavanone, 5,7-dimethoxy-3',4'-methylenedioxyflavanone (7), and homoisoflavonoid, isobonducellin (10) shown to have no significant antioxidant activity, but exhibited potent cytotoxic activity in Jurkat and HepG2 cells, while moderate growth inhibition against Colon205 cells. Interestingly, none of these derivatives shown to have toxicity toward normal peripheral blood mononuclear cells, over the concentration range tested (5-200 microM). Cytotoxic activities of some natural flavonoids identified in the medicinal plants were evaluated for the first time.