High Molecular Weight Plant Polyphenolics (Tannins) as Biological Antioxidants

TLDR

The study assessed condensed and hydrolyzable tannins and related phenolics as antioxidants via cyclic voltammetry, metmyoglobin, and deoxyribose assays. Tannins exhibited redox potentials comparable to simple phenolics but were 15–30 × more effective at quenching peroxyl radicals, and, for example, polygalloyl glucose reacted an order of magnitude faster with hydroxyl radicals, indicating that plant tannins are potent biological antioxidants. Keywords: tannins, plant phenolics, antioxidant, total antioxidant activity, oxidative damage, dietary antioxidant.

Abstract

Representative condensed and hydrolyzable tannins and related simple phenolics were evaluated as biological antioxidants using cyclic voltammetry, the metmyoglobin assay, and the deoxyribose assay. The redox potentials of the tannins were similar to those of structurally related simple phenolics. However, the tannins were 15−30 times more effective at quenching peroxyl radicals than simple phenolics or Trolox. One of the tannins, polygalloyl glucose, reacted an order of magnitude more quickly with hydroxyl radical than mannitol. These results suggest that tannins, which are found in many plant-based foods and beverages, are potentially very important biological antioxidants. Keywords: Tannins; plant phenolics; antioxidant; total antioxidant activity; oxidative damage; dietary antioxidant