Antioxidant potential of dimethyl lithospermate isolated from Salvia miltiorrhiza (red sage) against peroxynitrite

Peroxynitrite (ONOO-) is a reactive oxidant formed from superoxide and nitric oxide that can readily oxidize cellular components, including essential protein, non-protein thiols, and DNA. ONOO- has contributed to the pathogenesis of diseases such as stroke, heart disease, Alzheimer's disease, and atherosclerosis. In this study, the ability of dimethyl lithospermate (DML), isolated from Salvia miltiorrhiza, to scavenge ONOO- and to protect cells against reactive species and ONOO- was investigated. The data obtained show that DML can efficiently scavenge native ONOO- as well as ONOO- derived from the ONOO- donor 3-morpholinosydnonimine hydrochloride. Spectrophotometric analysis revealed that DML led to decreased ONOO-- mediated nitration of tyrosine through electron donation. DML significantly inhibited nitration of bovine serum albumin by ONOO- in a dose-dependent manner. DML also manifested cytoprotection from cell damage induced by ONOO-. The present study suggests that DML is an effective ONOO- scavenger and promotes cellular defense activity in the protection against ONOO-- involved diseases.