Spinosin is a flavonoid in the seed of Ziziphus jujuba that prevents skin pigmentation in a human skin model

Abstract

Abstract Because tyrosinase catalyzes essential steps in melanin synthesis, tyrosinase inhibitors are widely used for skin–lightening. To reduce the side effects of synthetic compounds, safer tyrosinase inhibitors isorated from natural products have gained attention. Here, we examined the anti-melanogenic effect of the seed of Ziziphus jujuba and identified eight major compounds, of which spinosin exhibited the strongest tyrosinase inhibitory activity (IC50 = 47 µM). When further examined, spinosin suppressed αMSH- or UVB-induced melanogenesis in B16F10 cells without cytotoxicity. The anti-melanogenic effect was also shown in a human skin model. As an underlying mechanism, in silico analysis showed that spinosin may bind to and suppress tyrosinase activity by forming multiple hydrogen bonds and hydrophobic interactions with the binding pocket of tyrosinase. Lineweaver-Burk and Dixon plots further revealed that spinosin acts as a competitive inhibitor of tyrosinase (Vmax, 11.61 × 103, 11.63 × 103, and 11.62 × 103, Km, 0.139, 0.185, and 0.239 for the con, 10 µM, 50 µM of spinosin, respectively). In conclusion, spinosin, a major compound in the seed of Ziziphus jujuba, could be a novel additive for treating pigmentation disorders or skin-lightening cosmetics.