Tyrosinase catalyzes hydroxylation of L-tyrosine and dehydrogenation of L-DOPA in the melanin biosynthesis pathway. Tyrosinase inhibitors have potential use as cosmetic whitening agents and for preventing seafood deterioration. In this report, tyrosinase inhibitors extracted from brown alga Colpomenia bullosa (Scytosiphonaceae, Scytosiphonales) were investigated. Inhibitory principles were isolated from the extract and identified as phlorotannins, phloroglucinol (1), diphlorethol (2), triphlorethol C (3), which have not been isolated in a free form previously, and fucophlorethol C (4). Compounds 3 and 4 have not been reported previously as tyrosinase inhibitors. Triphlorethol C (3) was the most potent tyrosinase inhibitor among the phlorotannins isolated, whereas isomeric fucophlorethol C (4) displayed the weakest inhibitory activity. The results suggest that molecular structures of phlorotannins strongly affect their tyrosinase inhibitory activity.

酪氨酸酶在黑色素生物合成途径中催化 L-酪氨酸的羟基化和 L-多巴的脱氢。酪氨酸酶抑制剂具有作为化妆品增白剂和防止海鲜变质的潜在用途。在本报告中，研究了从褐藻Colpomeniabulosa（Scytosiphonaceae，Scytosiphonales）中提取的酪氨酸酶抑制剂。从提取物中分离出抑制性成分，并鉴定为间苯三酚 ( 1 )、间苯二酚 ( 2 )、三叶草酚 C ( 3 )，它们之前没有以游离形式分离出来，以及岩藻酚 C ( 4 )。化合物3和4以前没有报道过作为酪氨酸酶抑制剂。Triphlorethol C ( 3 ) 是分离出的根皮单宁中最有效的酪氨酸酶抑制剂，而异构岩藻酚C ( 4 ) 的抑制活性最弱。结果表明，根皮单宁的分子结构强烈影响其酪氨酸酶抑制活性。