Depending on their structures, polyphenols (. tea polyphenols) could also act by chelating prooxidant transition metal ions such as Fe2+, which are involved in reactions eliciting free radical production, including hydroxyl radicals (OH•) and alkoxyl radicals (RO•) (Dufresne & Farnworth, 2001). Polyphenols that are able to scavenge lipid peroxyl (LOO•) and lipid alkoxyl (LO•) radicals or act as singlet oxygen quenchers (1O2) are effective inhibitors of lipid peroxidation processes, owing to the recognized role of these reactive species to initiate or to propagate free radical lipid peroxidation in cell membranes. The polarity of polyphenols is variable, ranging from water-soluble polyphenols.
