麵包樹之美白成分及抗氧化成分的研究

由於酪胺酸酶抑制劑及抗氧化劑能夠預防色素不均和老化的問題，因此在化粧品及藥品產業中的使用日趨重要。植物中廣泛存在並廣為研究的黃酮類，經常被報導具有抑制酪胺酸酶的活性且具有抗氧化能力的一群。因此，本研究試圖對從麵包樹中純化出的黃酮類化合物進行抑制酪胺酸酶及清除自由基的評估實驗。從麵包樹心材及栓皮部份分離得到的八個化合物分別為artocarpin (1)、norartocarpetin (2)、artogomezianone (3)、artoepoxycommunone(4)、cyclocomuunol (5)、artocommunol CG (6)、artocommunol CI (7)及artocommunol CJ (8)，其中化合物4、6、7與8為新化合物。在抑制酪胺酸酶活性試驗中，化合物1-3及5-7具有抑制酪胺酸酶活性，特別是化合物2顯示出具有很強的活性，其IC50值於反應30分鐘後為0.42 μM，且化合物2及3為競爭型抑制模式。在DPPH自由基清除試驗中，化合物7展現出很強的清除活性，IC50值於反應30分鐘後為33.85 μM；在ABTS陽離子自由基清除試驗中，化合物1、2、3、6及7具有活性，其中化合物2、3及7也顯示出優於正相對照組抗壞血酸2到22倍不等的清除能力；而在清除超氧陰離子試驗中，化合物1、2、5及6顯示出具有清除超氧陰離子自由基之能力。上述由麵包樹分離出之黃酮類化合物具有能發展成為化粧品中酪胺酸酶抑制劑與抗氧化劑之潛能。

關鍵字

麵包樹；黃酮類；酪胺酸酶抑制劑；抗氧化劑

並列摘要

Use of tyrosinase inhibitors and antioxidants is becoming increasingly important in the cosmetic and medicinal industries due to their preventive effect on pigmentation disorders and aging. As far as we know, flavonoids are one of the most numerous and best-studied groups of plant. Some flavonoids have been shown to have the inhibitory activity of tyrosinase as well as radical scavenging activity. For this purpose, we evaluated the compounds isolated from Artocarpus communis whether display the tyrosinase inhibition and the antioxidative ability. There are 8 compounds including 4 new prenylated flavonoids, artoepoxycommunone (4), artocommunol CG (6), artocommunol CI (7) and artocommunol CJ (8), along with 4 known compounds, artocarpin (1), norartoparpetin (2), artogomezianone (3) and cyclocommunol (5) were isolated from the heartwood and cortex of Artocarpus communis. In tyrosinase inhibitory activity experiment, compounds 1-3 and 5-7 presented antiytrosinase activities, especially compound 2 showed the strongest inhibitory potential with an IC50 value of 0.42 μM at 30 min. Among the test compounds, compunds 2 and 3 manifested a competitive inhibition mode in the Lineweaver-Burk plot evaluation. In this study, DPPH•(1,1-diphenyl-2-picrylhydrazyl), ABTS＋˙(2,2'-azinobis-ethyl- benzothi-azoline-6-sulfonic acid) and O2-˙(superoxide anion) free radical scavenging methods were applied for free radical scavenging effects. Of the compounds tested, compound 7 had strong DPPH• scavenging activity with an IC50 value of 33.85μM, compounds 2, 3 and 7 showed more effective ABTS＋˙ scavenging effects than ascorbic acid, and compounds 1, 2, 5 and 6 exhibited potent inhibitions of superoxide anion, respectiviely. Consequently, these compounds showed great potential for becoming antityrosinase and antioxidative agents in cosmetics.