Parkinson's disease (PD) is a progressive neurodegenerative disorder with a prevalence of 1-2% in people over the age of 50. Mitochondrial dysfunction occurred in PD patients showing a 15-30% loss of activity in complex I. Asiatic acid (AA), a triterpenoid, is an antioxidant and used for depression treatment, but the effect of AA against PD-like damage has never been reported. In the present study, we investigated the protective effects of AA against H(2)O(2) or rotenone-induced cellular injury and mitochondrial dysfunction in SH-SY5Y cells. Mitochondrial membrane potential (MMP) and the expression of voltage-dependent anion channel (VDAC) were detected with or without AA pretreatment following cellular injury to address the possible mechanisms of AA neuroprotection. The results showed that pre-treatment of AA (0.01-100 nM) protected cells against the toxicity induced by rotenone or H(2)O(2). In addition, MMP dissipation occurred following the exposure of rotenone, which could be prevented by AA treatment. More interestingly, pre-administration of AA inhibited the elevation of VDAC mRNA and protein levels induced by rotenone(100 nM) or H(2)O(2) (300 microM).These data indicate that AA could protect neuronal cells against mitochondrial dysfunctional injury and suggest that AA might be developed as an agent for PD prevention or therapy.