College of Pharmacy, Pusan National University, Busan 46241, South Korea.
College of Pharmacy and Inje Institute of Pharmaceutical Sciences and Research, Inje University, Gimhae, Gyeongnam 50834, South Korea.
Bioorg Med Chem. 2018 Aug 7;26(14):3882-3889. doi: 10.1016/j.bmc.2018.05.047. Epub 2018 May 31.
Thirteen (Z)-4-(substituted benzylidene)-3-phenylisoxazol-5(4H)-ones were designed to confirm the geometric effect of the double bond of the β-phenyl-α, β-unsaturated carbonyl scaffold on tyrosinase inhibitory activity. Compounds 1a-1m, which all possessed the (Z)-β-phenyl-α, β-unsaturated carbonyl scaffold, were synthesized using a tandem reaction consisting of an isoxazolone ring formation and a Knoevenagel condensation, and three starting materials, ethyl benzoylacetate, hydroxylamine and benzaldehydes. Some of the compounds showed inhibitory activity against mushroom tyrosinase as potent as compounds containing the "(E)"-β-phenyl-α, β-unsaturated carbonyl scaffold. Compounds 1c and 1m showed greater inhibitory activity than kojic acid: IC = 32.08 ± 2.25 μM for 1c; IC = 14.62 ± 1.38 μM for 1m; and IC = 37.86 ± 2.21 μM for kojic acid. A kinetic study indicated that 1m inhibited tyrosinase in a competitive manner and that it probably binds to the enzyme's active site. In silico docking simulation supported binding of 1m (-7.6 kcal/mol) to the active site of tyrosinase with stronger affinity than kojic acid (-5.7 kcal/mol). Similar results were obtained using cell-based assays, and in B16F10 cells, compound 1m dose-dependently inhibited tyrosinase activity and melanogenesis. These results indicate the anti-melanogenic effect of compound 1m is due to the inhibition of tyrosinase and (Z)-isomer of the β-phenyl-α, β-unsaturated carbonyl scaffold can, like its congener the (E)-isomer, act as an excellent scaffold for tyrosinase inhibition.
设计了十三（Z）-4-（取代苄叉基）-3-苯基异噁唑-5（4H）-酮以确认β-苯基-α，β-不饱和羰基支架的双键对酪氨酸酶抑制活性的几何影响。使用由异噁唑啉环形成和Knoevenagel缩合组成的串联反应合成了具有（Z）-β-苯基-α，β-不饱和羰基支架的化合物 1a-1m，该反应使用了三种起始原料，即苯甲酰基乙酸乙酯，羟胺和苯甲醛。一些化合物表现出对蘑菇酪氨酸酶的抑制活性，与含有（E）-β-苯基-α，β-不饱和羰基支架的化合物一样有效。化合物 1c 和 1m 显示出比曲酸更强的抑制活性：IC 为 32.08 ± 2.25 μM 对于 1c；IC 为 14.62 ± 1.38 μM 对于 1m；IC 为 37.86 ± 2.21 μM 对于曲酸。动力学研究表明，1m 以竞争性方式抑制酪氨酸酶，并且它可能与酶的活性位点结合。基于计算机的对接模拟支持 1m（-7.6 kcal/mol）与酪氨酸酶的活性位点结合，亲和力强于曲酸（-5.7 kcal/mol）。使用基于细胞的测定获得了相似的结果，在 B16F10 细胞中，化合物 1m 剂量依赖性地抑制酪氨酸酶活性和黑色素生成。这些结果表明，化合物 1m 的抗黑色素生成作用归因于酪氨酸酶的抑制，并且（Z）-异构体的β-苯基-α，β-不饱和羰基支架可以像其同种异构体（E）-异构体一样，作为酪氨酸酶抑制的极好支架。
