Seo B, Yun J, Lee S, Kim M, Hwang K, Kim J, Min K R, Kim Y, Moon D
College of Pharmacy, Chungbuk National University, Cheongju, Korea.
Planta Med. 1999 Dec;65(8):683-6. doi: 10.1055/s-1999-14092.
A tyrosinase inhibitor was isolated from the whole plant of Barbarea orthocerus Led. (Brassicaceae) by activity-guided fractionation, and identified as (R)-5-phenyl-2-oxazolidinethione (barbarin) by structural analysis followed by comparison with reported spectral data. The compound exhibited significant inhibitory effects on mushroom and murine tyrosinases at more than 1.6 x 10(-5) M. Barbarin exhibited IC50 values of 4.2 x 10(-5) M on mushroom tyrosinase and of 4.8 x 10(-5) M on murine tyrosinase. Kojic acid as a positive control exhibited IC50 values of 3.4 x 10(-5) M and 6.0 x 10(-5) M on mushroom and murine tyrosinases, respectively. Therefore, barbarin exhibited a similar level of inhibitory potency with kojic acid used as a positive control. In a kinetic study with various concentrations of L-dopa as the substrate, barbarin was identified as an uncompetitive inhibitor and kojic acid as a mixed inhibitor of both mushroom and murine tyrosinases. Barbarin exhibited KEIS values of 3.3 x 10(-5) M and 3.6 x 10(-5) M on mushroom and murine tyrosinases, respectively. Kojic acid exhibited KEIS and KEI values of 2.4 x 10(-5) M and 2.2 x 10(-5) M on mushroom tyrosinase and those of 8.9 x 10(-5) M and 7.2 x 10(-5) M on murine tyrosinase, respectively.
通过活性导向分级分离法从山芥（十字花科）全株中分离出一种酪氨酸酶抑制剂，经结构分析并与已报道的光谱数据比较，鉴定其为（R）-5-苯基-2-恶唑烷硫酮（山芥素）。该化合物在浓度大于1.6×10⁻⁵ M时对蘑菇酪氨酸酶和小鼠酪氨酸酶均表现出显著的抑制作用。山芥素对蘑菇酪氨酸酶的IC50值为4.2×10⁻⁵ M，对小鼠酪氨酸酶的IC50值为4.8×10⁻⁵ M。作为阳性对照的曲酸对蘑菇酪氨酸酶和小鼠酪氨酸酶的IC50值分别为3.4×10⁻⁵ M和6.0×10⁻⁵ M。因此，山芥素与用作阳性对照的曲酸表现出相似水平的抑制效力。在以不同浓度L-多巴为底物的动力学研究中，山芥素被鉴定为非竞争性抑制剂，曲酸为蘑菇酪氨酸酶和小鼠酪氨酸酶的混合型抑制剂。山芥素对蘑菇酪氨酸酶和小鼠酪氨酸酶的KEIS值分别为3.3×10⁻⁵ M和3.6×10⁻⁵ M。曲酸对蘑菇酪氨酸酶的KEIS和KEI值分别为2.4×10⁻⁵ M和2.2×10⁻⁵ M，对小鼠酪氨酸酶的KEIS和KEI值分别为8.9×10⁻⁵ M和7.2×10⁻⁵ M。
