Silybin Derivatives Produced by γ-Irradiation and Their Tyrosinase Inhibitory Activities.

Silybin, which belongs to the flavonolignan group, is the major component of the fruit extract of (common name: milk thistle). Silybin is a medicinal compound with hepatoprotective, antioxidant, and anticancer properties. In this study, silybin derivatives were produced through γ-radiolysis, and their tyrosinase inhibitory activities were evaluated to explore the enhanced activities of silybin derivatives compared to silybin (). Isosilandrin () and 2,3-dehydrosilybin () were obtained from a silybin sample irradiated at 300 kGy. The optimal dose showed significant changes in radiolysis product content. Compounds and exhibited an IC of 274.6 and 109.5 μM, respectively, which are more potent than that of (IC > 500 μM). In addition, a molecular docking simulation revealed the binding affinity of these compounds to tyrosinase and their mechanisms of inhibition. Thus, γ-irradiation is an effective method for structural modification of silybin. We also demonstrated that 2,3-dehydrosilybin is a potential tyrosinase inhibitor.