Abstract
Catechin absorption, bioavailability, and distribution in human tissue and excretion were low. Colonic bacteria degrade catechin and few studies suggest that biotransformed metabolites may increase or decrease biological activities. However, the antioxidant potential of biotransformed metabolites is still unexplored. Hence, it is necessary to investigate the antioxidant potential of colonic bacterial transformed catechin metabolites.
The In vitro antioxidant potential of biotransformed catechin metabolites was assessed by DPPH, Hydrogen peroxide, and ABTS assay. Cytotoxic effect of biotransformed catechin metabolites on human mesenchymal stem cells and their response to antioxidant genes GPX1 and POR expression in human peripheral blood mononuclear cells (PBMC) were evaluated.
Free radical scavenging activity of partially purified bacterial transformed catechin metabolites was low compared to pure catechin. The results revealed that variations in the antioxidant potential of pure catechin and colonic bacterial altered catechin metabolites. The IC50 value of partially purified biotransformed catechin metabolites exhibits free radical scavenging activity at high concentrations, while pure catechins act as a potent inhibitor at lower concentrations. The expression of GPX1 and POR gene increased four folds in a concentration dependent manner in pure catechin-treated cells. In contrast, partially purified biotransformed catechin metabolites treated cells expressed the downregulation of GPX1 and upregulation of POR gene.
Therefore, it can be concluded that the functional group alteration in biotransformed catechin metabolites may reduce the hydrogen donating ability, thus In vitro antioxidant potential of biotransformed catechin metabolites was low compared to pure catechin. Hence, GPX1 and POR exhibit different expression patterns in treated peripheral blood mononuclear cells. These findings suggest that pure catechin and colonic bacterial transformed catechin metabolites differed functionally.