Gallic Acid, an Antioxidant, Exhibits Antiapoptotic Potential in Normal Human Lymphocytes: A Bcl-2 Independent Mechanism

Oxidative stress, produced as a consequence of normal metabolism or induced by extraneous stimuli, has been proved to be a mediator of cell death. The inherent antioxidant defense system and exogenous antioxidants can help the body to combat this oxidative stress-induced cell death. In this study, we explored the antiapoptotic potential of gallic acid, a dietary phenolic having antioxidative and anticarcinogenic properties, in normal human peripheral blood lymphocytes (PBLs). Incubation of PBLs with 100 microM H2O2 for 1.5-2.0 h induced phosphatidyl serine externalisation, lipid peroxidation and high molecular weight DNA fragmentation. Pretreatment of lymphocytes with gallic acid for 18 h could effectively inhibit lipid peroxidation and apoptosis induced by oxidative stress. Treatment of PBLs with gallic acid failed to induce any change in the expression of Bcl-2, an antiapoptotic protein. It seems that the protection provided by gallic acid was due to its direct action in the scavenging of free radicals as it was found to be a stronger antiradical than trolox, a water- soluble analogue of vitamin E.