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.