大黄蒽醌衍生物对酪氨酸酶的抑制作用

大黄素对酪氨酸酶有显著的竞争性抑制作用,K_i值为1.51×10~(-4)mol,50％抑制的药物浓度为36.6μg/ml;大黄酸的抑制作用较弱,芦荟大黄素几乎无抑制作用。氯化铜(3.3×10~(-7)mol/L)、半胱氨酸(3.3×10~(-7)mol/L)和牛血清白蛋白(1.0mg/ml)对大黄素抑制酪氨酸酶有较强的拮抗作用,恢复率分别为60.0％、45.7％和61.1％。大黄素能与牛血清白蛋白非特异性结合形成复合物,引起吸收光谱红移55毫微米。大黄蒽醌衍生物对酪氨酸酶的抑制作用可能是大黄抗黑色素瘤的作用机制之一。

Inhibitory Effects of Anthraquinone Derivatives of Chinese Rhub Arb on Tyrosinase

The effects of anthraquinone derivatives on tyrosinase were investigated.Tyrosinase was markedly inhibited by emodin with IC5036.6μg/ml. But rhein and aloe-emodin showed no significant effects on tyrosinase.The inhibition of emodin on tyrosinase was competitive with ki value of 1.51×10-4mol/L and could be reversed by the addition of copper chloride, cysteine and bovine serum albumin (BSA) . The percentage of recovery of copper chloride(3.3×10-7mol)/L, cysteine (3.3×10-7mol/L) and BSA (1.0mg/ml) was 60.0%, 45.7% and 61.1%, respectively. The absorption spectrum of emodin was changed by adding BSA. The shift of 55 nm in the absorption spectrum of emodin indicated the formation of a complex of emodin and BSA.The inhibition of anthraquinone derivatives, especially emodin, on tyrosinase may be one of the mechanisms of their anti-melanoma.