中藥牛至(Origanum vulgare L.)的乾燥全草用95 %乙醇提取後，再以不同極性的有機溶媒分配萃取，分別得到正己烷層、乙酸乙酯層及水層三部分。此三部分經由抑制酪氨酸酶及掃除DPPH自由基之活性測試，發現在乙酸乙酯層有較明顯之活性作用。因此，本研究將以有效部分之乙酸乙酯層以分子篩LH-20、矽膠(Silica gel)、低壓 Lobar、及高壓 HPLC等層析方法進行純化分離，共得到6個化合物，為Protocatechuic acid (1)、Vanillin (2)、Vanillin acid (3)、Apigenin (4)、4-(3,4-Dihydroxybenzoyloxymethyl)phenyl-O-β-D-glucopyranoside (5)及Origanoside (6)。上述化合物是經各種光譜分析而確認其結構式。2、3、4及6為首次自此植物中分離得到，其中化合物6為新化合物。
從上述牛至純化得到之成分的生物活性顯示化合物1、3及5有明顯清除DPPH自由基之作用，化合物5及6有抑制酪氨酸酶之作用。 Chinese herb Origanum vulgare L. The dried powder of Chinese herb Origanum vulgare L. was extracted with 95 % alcohol, concentrated, and partitioned with different solvents to obtains hexane, ethyl acetate and water extracts. The extracts were tested by the assay of inhibition tyrosinase activity and DPPH scavenging activity to show that ethyl acetate extract has good bioactivities. The ethyl acetate extract was further purfied by sephadex LH-20, silica gel, Lobar RP-8 or HPLC phenyl to get 6 pure compounds, protocatechuic acid (1)、vanillin (2)、Vanillin acid (3)、apigenin (4)、4-(3,4-Dihydroxybenzoyloxymethyl)phenyl-O-β-D-glucopyranoside (5), and origanoside (6). Of these isolated compound 2、3、4and 6 are the first time from Origanum valgar. In addition, 6 is a new compound.
In bioassay, Compounds 1, 3, 5, and 6 were identified with free radical activity and compound 5 and 6 was confirmed to inhibit mushroom tyrosinase.
