Beneficial effects of carnosic acid on dieldrin-induced dopaminergic neuronal cell death.

Carnosic acid (CA) is one of the bioactive polyphenols present in extracts of the herb rosemary (Rosmarinus officinalis). In this study, we examined possible protective effects of CA on neurotoxicity induced by dieldrin, an organochlorine pesticide implicated in sporadic Parkinson's disease, in cultured dopaminergic cells (SN4741). CA (5-10 muM) pretreatment showed potent protective effects in a concentration-related manner and prevented dieldrin (10 muM)-induced caspase-3 activation, Jun N-terminal kinase phosphorylation, and caspase-12 activation. Furthermore, dieldrin-induced downregulation of brain-derived neurotrophic factor production was significantly attenuated by CA. These results suggest that CA may safeguard dopaminergic neuronal cells from environmental neurotoxins by enhancing brain-derived neurotrophic factor and repressing apoptotic molecules.