Prevention of tertiary butyl hydroperoxide induced oxidative impairment and cell death by a novel antioxidant protein molecule isolated from the herb, Phyllanthus niruri

The present study has been designed and carried out to investigate the mechanism of the protective action of a novel antioxidant protein molecule, isolated from the herb, Phyllanthus niruri (PNP), against tertiary butyl hydroperoxide (TBHP) induced cytotoxicity and cell death. Incubation of hepatocytes with PNP prevented TBHP-induced loss in cell viability and enhanced LDH leakage in a dose-dependent manner. Reduction in GSH/GSSG ratio and activities of antioxidant enzymes have also been found to be prevented by this protein. Moreover, TBHP exposure caused injury in cellular mitochondria, disrupted mitochondrial membrane potential, induced reciprocal regulation of Bcl-2 family proteins and facilitated cytochrome c release in the cytosol. In addition, TBHP introduces apoptosis as the primary phenomena of cell death as evidenced by DAPI staining, flow cytometric analyses and studies on the activation of caspases. PNP treatment, however, counteracted these changes and maintains normalcy in hepatocytes. Combining, data suggest that PNP possesses cytoprotective activity against TBHP-induced oxidative cellular damage and prevents hepatocytes from apoptotic death.