Effect of Quercetin and Epicatechin on the Transcript Expression and Activity of Antioxidant Enzymes in Tobacco Seedlings

The aim of this study was to evaluate the effect of flavonoids quercetin and epicatechin on the transcript expression and activity of antioxidant enzymes. Tobacco seedlings were exposed to 50 and 100 µM quercetin and epicatechin. The transcript expression level and the activity analysis of various antioxidant enzymes were monitored in their root and shoot. Interestingly, 50 µM epicatechin and 100 µM quercetin exposures were found to increase the expression of genes encoding antioxidant enzymes in shoot. In tobacco root, only GST and GPx expression were increased with 50 µM epicatechin and 100 µM quercetin exposures. Activity assay of all the enzymes showed similar trend to that of the transcript expression in shoot tissue. While in root, except CAT and SOD other enzymes activity also showed similar trend to that of expression pattern. Results have suggested the possible regulation of antioxidant enzymes by these two flavonoids at transcriptional and post-transcriptional level. Additionally, appropriate levels of such flavonoids seem to be essential for such regulations.