Effects of (1 R,9 S)-β-hydrastine on l-DOPA-induced cytotoxicity in PC12 cells

Abstract

(1 R,9 S)-β-Hydrastine in lower concentrations of 10–50 μM inhibits dopamine biosynthesis in PC12 cells (Planta Med. 57 (2001) 609). In this study, the effects of (1 R,9 S)-β-hydrastine on l-DOPA ( l-3,4-dihydroxyphenylalanine)-induced cytotoxicity in PC12 cells were investigated. (1 R,9 S)-Hydrastine at concentrations up to 250 μM did not reduce cell viability. However, at concentrations higher than 500 μM it caused cytotoxicity in PC12 cells, as determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, TUNEL (terminal deoxynucleotidyltransferase dUTP nick-end labeling) method and flow cytometry. Exposure of PC12 cells to cytotoxic concentrations of (1 R,9 S)-β-hydrastine (500 and 750 μM) in combination with l-DOPA (20, 50 and 100 μM) after 24 or 48 h resulted in a significant decrease in cell viability compared with the effects of (1 R,9 S)-β-hydrastine or l-DOPA alone, and apoptotic cell death was observed. However, the decrease in cell viability induced by (1 R,9 S)-β-hydrastine was not prevented by the antioxidant N-acetyl- l-cysteine, indicating that it is not mediated by membrane-based oxygen free radical damage. These data suggest that (1 R,9 S)-β-hydrastine has a mild cytotoxic effect and at higher concentration ranges aggravates l-DOPA-induced cytotoxicity in PC12 cells.