Antioxidant/prooxidant effects of bioactive polyphenolics

Abstract

Pine, grape and witch hazel byproducts are rich sources of polyphenols. From extracts (OW) soluble in both ethyl acetate and water we have generated a collection of fractions differing in percentage of pyrogallol groups. The mixtures were highly active as free radical scavengers against DPPH. The phenolics protected red blood cells from free radical induced hemolysis and were mildly cytotoxic to HaCat keratinocytes. They also inhibited the proliferation of tumoral SK-Mel 28 melanoma cells. Our results show that there is a relationship between percentage of pyrogallol groups, scavenging efficiency, cell antioxidant effect, cytotoxicy and antiproliferation. Interestingly, the most effective antioxidants were also the most cytotoxic and effective antiproliferative agents. This could be due to a dual antioxidant/prooxidant effect of polyphenols.