Ethyl 3,4-dihydroxy benzoate, a unique preconditioning agent for alleviating hypoxia-mediated oxidative damage in L6 myoblasts cells

Charu Nimker, Gurpreet Kaur, Anshula Revo, Pooja Chaudhary, Anju Bansal

The importance of hypoxia inducible factor (HIF) as the master regulator of hypoxic responses is well established. Oxygen-dependent prolyl hydroxylase domain enzymes (PHDs) negatively regulate HIF directing it to the path of degradation under normoxia and are, consequently, attractive therapeutic targets. Inhibition of PHDs might upregulate beneficial HIF-mediated processes. In this study, we have examined the efficacy of PHD inhibitor ethyl 3,4-dihydroxy benzoate (EDHB) in affording protection against hypoxia-induced oxidative damage in L6 myoblast cells. L6 cells were exposed to hypoxia (0.5 % O2) after preconditioning with EDHB for different times. Levels of HIF-1α, oxidative stress and antioxidant status were measured after hypoxia exposure. Preconditioning with EDHB significantly improved cellular viability, and the diminished levels of protein oxidation and malondialdehyde indicated a decrease in oxidative stress when exposed to hypoxia. EDHB treatment also conferred enhanced anti-oxidant status, as there was an increase in the levels of glutathione and antioxidant enzymes like superoxide dismutase and glutathione peroxidase. Further, augmentation of the levels of HIF-1α boosted protein expression of antioxidative enzyme heme-oxygenase I. There was enhanced expression of metallothioneins which also have antioxidant, anti-inflammatory properties. These results thus accentuate the potential cytoprotective efficacy of EDHB against hypoxia-induced oxidative damage.