The effects of 4-hydroxyphenyl α-glucopyranoside (α-arbutin) and 4-hydroxyphenyl β-glucopyranoside (arbutin) on the activity of tyrosinase from human malignant melanoma cells were examined. The inhibitory effect of α-arbutin on human tyrosinase was stronger than that of arbutin. The Ki value for α-arbutin was calculated to be 1/20 that for arbutin. We then synthesized arbutin-α-glycosides by the transglycosylation reaction of cyclomaltodextrin glucanotransferase using arbutin and starch, respectively, as acceptor and donor molecules. The structural analyses using 13C- and 1H-NMR proved that the transglycosylated products were 4-hydroxyphenyl β-maltoside (β-Ab-α-G1) and 4-hydroxyphenyl β-maltotrioside (β-Ab-α-G2). These arbutin-α-glycosides exhibited competitive type inhibition on human tyrosinase, and their Ki values were calculated to be 0.7 mM and 0.9 mM, respectively. These arbutin-α-glycosides posessed stronger inhibitory activity than arbutin, but less activity than α-arbutin. These results suggested that the α-glucosidic linkage of hydroquinone-glycosides plays an important role in the inhibitory effect on human tyrosinase.
研究了 4-羟基苯基 α-吡喃葡萄糖苷(α-熊果苷)和 4-羟基苯基 β-吡喃葡萄糖苷(熊果苷)对人类恶性黑色素瘤细胞酪氨酸酶活性的影响。α-熊果苷对人类酪氨酸酶的抑制作用强于熊果苷。经计算,α-熊果苷的 Ki 值是熊果苷的 1/20。然后,我们分别以熊果苷和淀粉为受体分子和供体分子,通过环麦芽糊精葡聚糖转移酶的转糖基化反应合成了熊果苷-α-糖苷。利用 13C- 和 1H-NMR 进行的结构分析证明,转糖基化产物为 4-羟基苯基 β-麦芽糖苷(β-Ab-α-G1)和 4-羟基苯基 β-麦芽三糖苷(β-Ab-α-G2)。这些熊果苷-α-糖苷对人类酪氨酸酶具有竞争型抑制作用,其 Ki 值分别为 0.7 mM 和 0.9 mM。这些熊果苷-α-糖苷的抑制活性强于熊果苷,但低于α-熊果苷。这些结果表明,对苯二酚糖苷中的α-葡萄糖苷键在对人类酪氨酸酶的抑制作用中起着重要作用。