Oyama Takahiro, Yoshimori Atsushi, Takahashi Satoshi, Yamamoto Tetsuya, Sato Akira, Kamiya Takanori, Abe Hideaki, Abe Takehiko, Tanuma Sei-Ichi
Hinoki Shinyaku Co., Ltd., 9-6 Nibancho, Chiyoda-ku, Tokyo 102-0084, Japan.
Institute for Theoretical Medicine, Inc., 4259-3 Nagatsuda-cho, Midori-ku, Yokohama, Kanagawa 226-8510, Japan.
Bioorg Med Chem Lett. 2017 Jul 1;27(13):2868-2872. doi: 10.1016/j.bmcl.2017.04.074. Epub 2017 Apr 26.
So far, many inhibitors of tyrosinase have been discovered for cosmetic and clinical agents. However, the molecular mechanisms underlying the inhibition in the active site of tyrosinase have not been well understood. To explore this problem, we examined here the inhibitory effects of 4'-hydroxylation and methoxylation of phenylbenzoic acid (PBA) isomers, which have a unique scaffold to inhibit mushroom tyrosinase. The inhibitory effect of 3-PBA, which has the most potent inhibitory activity among the isomers, was slightly decreased by 4'-hydroxylation and further decreased by 4'-methoxylation against mushroom tyrosinase. Surprisingly, 4'-hydroxylation but not methoxylation of 2-PBA appeared inhibitory activity. On the other hand, both 4'-hydroxylation and methoxylation of 4-PBA increased the inhibitory activity against mushroom tyrosinase. In silico docking analyses using the crystallographic structure of mushroom tyrosinase indicated that the carboxylic acid or 4'-hydroxyl group of PBA derivatives could chelate with cupric ions in the active site of mushroom tyrosinase, and that the interactions of Asn260 and Phe264 in the active site with the adequate-angled biphenyl group are involved in the inhibitory activities of the modified PBAs, by parallel and T-shaped π-π interactions, respectively. Furthermore, Arg268 could fix the angle of the aromatic ring of Phe264, and Val248 is supposed to interact with the inhibitors as a hydrophobic manner. These results may enhance the structural insight into mushroom tyrosinase for the creation of novel tyrosinase inhibitors.
到目前为止，已经发现了许多用于化妆品和临床药物的酪氨酸酶抑制剂。然而，酪氨酸酶活性位点抑制作用的分子机制尚未得到充分理解。为了探究这个问题，我们在此研究了苯基苯甲酸（PBA）异构体的4'-羟基化和甲氧基化的抑制作用，这些异构体具有独特的骨架来抑制蘑菇酪氨酸酶。在这些异构体中具有最强抑制活性的3-PBA，其对蘑菇酪氨酸酶的抑制作用在4'-羟基化后略有降低，在4'-甲氧基化后进一步降低。令人惊讶的是，2-PBA的4'-羟基化而非甲氧基化表现出抑制活性。另一方面，4-PBA的4'-羟基化和甲氧基化均增加了对蘑菇酪氨酸酶的抑制活性。使用蘑菇酪氨酸酶的晶体结构进行的计算机对接分析表明，PBA衍生物的羧酸或4'-羟基可以与蘑菇酪氨酸酶活性位点中的铜离子螯合，并且活性位点中的Asn260和Phe264与角度合适的联苯基团的相互作用分别通过平行和T形π-π相互作用参与了修饰后的PBA的抑制活性。此外，Arg268可以固定Phe264芳香环的角度，并且Val248应该以疏水方式与抑制剂相互作用。这些结果可能会增强对蘑菇酪氨酸酶的结构认识，以开发新型酪氨酸酶抑制剂。
