Effects of the antioxidants in pomegranate juice on DNA‐protein crosslinking via guanine oxidation

Abstract

DNA‐protein cross‐linking is a direct result of oxidative damage. Here we investigated effects of antioxidants from pomegranate juice on DNA‐protein crosslinking via guanine oxidation. Cross‐linking was detected by gel shift assay. After flash quench treatment, pUC19 exhibited a drop in mobility and highly cross‐linked DNA remained in the wells. With addition of POM brand pomegranate juice to samples, the plasmid runs as a single band even after oxidation via the flash‐quench technique. Significant inhibition of cross‐linking is evident at a 1:500 dilution of the juice, a concentration that has physiological relevance. Individual compounds found in the juice (gallic acid, quercetin, catechin, cyanin, ellagic acid, and p‐coumaric acid ) were investigated. These compounds were active down to concentrations of 1μM. Transient absorption spectroscopy results showed a decay of guanine radical concomitant with the formation of phenoxy radical, suggesting that the phenolic components repair guanine radical by reduction.