A novel cytoprotective antioxidant: 4-Hydroxyisophthalic acid

The antioxidant and cytoprotective properties of 4-hydroxyisophthalic acid (4-HIPA) isolated from the Decalepis hamiltonii roots was examined. 4-HIPA is a potent scavenger of superoxide (O2−), hydroxyl (OH), nitric oxide (NO), and lipid peroxide (LOO) physiologically relevant free radicals with IC50 values in the nanomolar (2–187) range. 4-HIPA also exhibits a concentration dependent secondary antioxidant activities like reducing power, metal chelating activity, and inhibition of protein carbonylation. Further, 4-HIPA at nanomolar concentration prevented CuSO4-induced human LDL oxidation. 4-HIPA demonstrated cytoprotective activity in primary hepatocytes and Ehrlich Ascites tumour (EAT) cells against oxidative stress inducing xenobiotics apart from the in vitro free radical scavenging activity. The mechanism of cytoprotective action involved maintaining the intracellular glutathione (GSH), scavenging of reactive oxygen species (ROS), and inhibition of lipid peroxidation (LPO). Thus, 4-HIPA is a novel bioactive molecule with potential health implications.