Inhibitory Effect of the Root of Coptis japonica on Catecholamine Biosynthesis in PC12 Cells

The effect of the root of Coptis japonica (COPT), both dichloromethane soluble $(CH_2Cl_2)$ and insoluble $(H_2O)$ fractions, on catecholamine contents and tyrosine hydorxylase (TH) activity in PC12 cells was investigated. $(CH_2Cl_2){\;}and{\;}H_2O$ fractions showed 21 and 53% inhibitions on dopamine content, respectively, at a ocncentraction of 40 .mu.g/ml in medium : the $(H_2O)$ fraction proveided a grateer inhibitory effect. The TH activity was reduced by the treatment of COPT ($(H_2O)$ fraction). These results suggest that COPT has an inhibitory effect on the catecholamine biosynthesis by the reduction of TH activity in PC12 cells.