Zhang Y H, Fang L H
Planta Med. 2001 Feb;67(1):77-9. doi: 10.1055/s-2001-10634.
The effect of tetrandrine, a bis-benzylisoquinoline alkaloid, on dopamine biosynthesis in PC12 cells was investigated. Tetrandrine at a concentration of 3.0 microM decreased dopamine content by 59.4% (IC50 = 2.4 microM) and intracellular tyrosine hydroxylase (TH) activity was inhibited by the treatment of tetrandrine (49.8% inhibition at 3.0 microM) compared with control. We next examined the effects of tetrandrine on the kinetics of PC12 TH. The PC12 TH was obtained from PC12 cells with minor purification. Tetrandrine inhibited the PC12 TH activity by 40.6% at a concentration of 45 microM and exhibited noncompetitive inhibition on the enzyme using L-tyrosine as a substrate (Ki = 60.8 microM). These results suggest that the inhibition of TH activity by tetrandrine may partially contribute to the decrease in dopamine biosynthesis in PC12 cells.
研究了双苄基异喹啉生物碱粉防己碱对PC12细胞中多巴胺生物合成的影响。浓度为3.0微摩尔的粉防己碱使多巴胺含量降低了59.4%（半数抑制浓度=2.4微摩尔），与对照组相比，粉防己碱处理抑制了细胞内酪氨酸羟化酶（TH）的活性（3.0微摩尔时抑制率为49.8%）。接下来，我们研究了粉防己碱对PC12细胞TH动力学的影响。PC12细胞TH是从PC12细胞中经过少量纯化获得的。浓度为45微摩尔时，粉防己碱抑制PC12细胞TH活性40.6%，以L-酪氨酸为底物时，对该酶表现出非竞争性抑制（抑制常数=60.8微摩尔）。这些结果表明，粉防己碱对TH活性的抑制可能部分导致了PC12细胞中多巴胺生物合成的减少。
