Division of General Science, Faculty of Education, Buriram Rajabhat University, Buriram 31000, Thailand.
Bureau of Drug Control, Food and Drug Administration, Ministry of Public Health, Nonthaburi 11000, Thailand.
Molecules. 2018 Jun 9;23(6):1403. doi: 10.3390/molecules23061403.
Twenty-seven flavonoids isolated from with vast structural diversity were screened for inhibitory activity against mushroom and murine tyrosinases using l-DOPA as the substrate. Among the flavonoids tested, only four—khrinone (), cajanin (), (3)-3′-hydroxy-8-methoxy vestitol (), and (6a,11a)-3,8-dihydroxy-9-methoxy pterocarpan ()—reacted with mushroom tyrosinase, with IC values of 54.0, 67.9, 67.8, and 16.7 μM, respectively, and only compound showed inhibitory activity against murine tyrosinase. With cell-based assays, only compounds and effectively inhibited melanogenesis in B16-F10 melanoma cells (by 34% and 59%, respectively), at a concentration of 15 μM, without being significantly toxic to the cells. However, the crude extract of and some of the flavonoid constituents appeared to increase melanin production in B16-F10 cells, suggesting that there are flavonoids with both inhibitory and stimulatory melanogenesis in the crude extract. Studies on the correlation between the enzyme-based and cell-based assays showed that only the flavonoids with IC values below 50 μM against mushroom tyrosinase could inhibit the mammalian tyrosinase, and thus, reduce melanogenesis in B16-F10. Flavonoids with the IC values greater than 50 μM, on the other hand, could not inhibit the mammalian tyrosinase, and had either no effect or enhancement of melanogenesis. In conclusion, the tyrosinase enzyme from mushroom is not as selective as the one from mammalian source for the enzyme-based melanogenesis inhibitory screening, and the mammalian cell-based assay appears to be a more reliable model for screening than the enzyme-based one.
从 中分离得到的 27 种具有广泛结构多样性的类黄酮，以 l-DOPA 为底物，筛选其对蘑菇和鼠源酪氨酸酶的抑制活性。在所测试的类黄酮中，只有 4 种——khirone()、cajanin()、(3)-3′-羟基-8-甲氧基vestitol()和(6a,11a)-3,8-二羟基-9-甲氧基紫檀烷()——与蘑菇酪氨酸酶反应，IC 值分别为 54.0、67.9、67.8 和 16.7 μM，只有化合物 对鼠源酪氨酸酶表现出抑制活性。通过细胞试验，只有化合物 和 能有效抑制 B16-F10 黑素瘤细胞的黑色素生成（分别为 34%和 59%），在 15 μM 浓度下，对细胞的毒性不明显。然而， 的粗提物和一些类黄酮成分似乎增加了 B16-F10 细胞中的黑色素生成，表明粗提物中既有抑制黑色素生成的类黄酮，也有刺激黑色素生成的类黄酮。基于酶和细胞的相关性研究表明，只有对蘑菇酪氨酸酶的 IC 值低于 50 μM 的类黄酮才能抑制哺乳动物酪氨酸酶，从而减少 B16-F10 中的黑色素生成。另一方面，IC 值大于 50 μM 的类黄酮不能抑制哺乳动物酪氨酸酶，对黑色素生成没有影响或增强。总之，蘑菇酪氨酸酶不如哺乳动物来源的酪氨酸酶对基于酶的黑色素生成抑制筛选具有选择性，哺乳动物细胞试验似乎比基于酶的试验更可靠。
