Lycii fructus extract ameliorates hydrogen peroxide-induced cytotoxicity through indirect antioxidant action.

Unlabelled: Lycii Fructus is the dried ripe fruits of Lycium chinense and L. barbarum, which has long been used as a traditional food material in East Asia. The purpose of this study was to investigate the role of the indirect antioxidative action in the Lycii fructus extract (LFE)-induced cytoprotective effect in vitro.

3,4-Dihydroxyphenylacetic acid is a predominant biologically-active catabolite of quercetin glycosides.

Since dietary flavonoid glycosides, including quercetin 4'-glucoside from onion, are poorly absorbed from the gastrointestinal tract, they are converted into smaller phenolic acids, which can be absorbed into the circulation. The purpose of this study was to compare the effects of the major phenolic acid catabolites of quercetin 4'-glucoside, including 3,4-dihydroxyphenylacetic acid (DOPAC), 3-hydroxyphenylacetic acid, 3,4-dihydroxybenzoic acid (protocatechuic acid) and hippuric acid, on the antioxidant activity and phase II cytoprotective enzyme induction in vitro. Both DOPAC and protocatechuic acid, having a catechol moiety, exhibited both DPPH radical scavenging and superoxide dismutase-like activities, whereas 3-hydroxyphenyl acetic acid and hippuric acid did not.

A novel tag-free probe for targeting molecules interacting with a flavonoid catabolite.

3,4-Dihydroxyphenylacetic acid (DOPAC) is one of the colonic microflora-produced catabolites of quercetin 4'-glucoside (Q4'G). Although the interaction of DOPAC with cellular proteins might be involved in its biological activity, the actual proteins have not yet been identified. In this study, we developed a novel tag-free DOPAC probe to label the targeted proteins by the copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) and verified its efficacy.

Ascorbic acid synergistically potentiates phloxine b-induced photocytotoxicity in human acute promyelocytic leukemia cells.

Ascorbic acid (AsA) is known as an antioxidant but concomitantly possesses a pro-oxidant property. Because the impact of AsA on photodynamic therapy response is unclear, we investigated the effect of AsA on photocytotoxicity induced by phloxine B in human acute promyelocytic leukemia HL-60 cells. AsA synergistically enhanced phloxine B-induced photocytotoxic effects, including inhibition of cell proliferation, DNA ladder formation, and caspase-3 activation, whereas AsA itself showed no photocytotoxicity.