臺灣冷杉葉子抽出物之生物活性

Abstract

本研究利用乙醇萃取法萃取臺灣冷杉 (Abies kawakamii) 葉子，以液相液相分配分離出正己烷可溶部、乙酸乙酯可溶部、正丁醇可溶部及水可溶部等4個分離部，並進行生物活性評估。試驗結果顯示，臺灣冷杉乙醇抽出物及熱水抽出物不具有抗黴菌與木材腐朽菌之能力，亦不具有抗病媒蚊幼蟲之活性。乙醇抽出物在抗氧化活性方面，總酚類與總黃酮類含量分別為94.84 mg of GAE/g及71.10 mg CAE/g，在各分離部中，以乙酸乙酯可溶部具有最高的總酚類與總黃酮類含量，分別為160.90 mg of GAE/g及296.98 mg of CAE/g。在還原力、DPPH自由基捕捉能力及總抗氧化能力測定上，乙酸乙酯可溶部仍具有最佳的效果。以乙醇抽出物及各可溶部餵食秀麗隱桿線蟲 (Caenorhabditis elegans)，測試抽出物延長線蟲壽命的效果;結果顯示以乙酸乙酯及正丁醇2個可溶部具有較佳的效果，約可延長10-20%的線蟲壽命。 以次黃嘌呤與黃嘌呤2種受質測試臺灣冷杉乙醇抽出物及各可溶部對黃嘌呤氧化酶抑制效果，在試驗濃度為100 μg/mL時，乙酸乙酯可溶部具有最好的抑制率，進一步測試IC50，乙酸乙酯可溶部在黃嘌呤作為受質時IC50值為66.70 μg/mL，在次黃嘌呤作為受質時IC50值為48.76 μg/mL。以酵素動力學分析乙酸乙酯可溶部對黃嘌呤氧化酶的抑制型態，顯示以次黃嘌呤為受質時，乙酸乙酯可溶部的抑制型態為競爭型;而以黃嘌呤為受質時，乙酸乙酯可溶部則為混合型的抑制型態。

The goal of this study is evaluating the bioactivities of the leaf ethanolic extract of Abies kawakamii and its 4 fractions, n-hexane-soluble fraction, ethyl acetate-soluble fraction, n-butanol-soluble fraction and water-soluble fraction, all derived from liquid-liquid partition. The results showed that both leaf ethanolic extract and leaf boiled water extract had no inhibition activities on molds, Wood-rotting fungus and mosquito larvae. Ethanolic extract had 94.84 mg GAE/g and 71.10 mg CAE/g in total phenolic contents and total flavonoid contents respectively. Among all fractions, ethyl acetate-soluble fraction had the highest total phenolic contents and total flavonoid contents, 160.90 mg GAE/g and 296.98 mg CAE/g respectively. Ethyl acetate-soluble fraction also had the best effects in reducing power, DPPH free-radical scavenging activity and trolox equivalent antioxidant capacity. Anti-aging effect was tested by feeding Caenorhabditis elegans the ethanolic extract and its fractions. Results showed that ethyl acetate-soluble fraction and n-butanol-soluble fraction had better effects than other fractions, ca. 10 to 20 % mean life span of Caenorhabditis elegans was prolonged. Inhibitory on xanthine oxidase of leaf ethanolic extract of Abies kawakamii and its fractions is tested by using 2 substrates, xanthine and hypoxanthine. Among 4 fractions, the ethyl acetate-soluble fraction had the best inhibitory of xanthine oxidase at a concentration of 100 μg/mL. The IC50 values of ethyl acetate-soluble fraction were 66.70 and 48.76 μg/mL with xanthine and hypoxanthine as the substrate, respectively. The enzyme kinetic analyses showed that the inhibitory of xanthine oxidase by ethyl acetate-soluble fraction was of competitive type with hypoxanthine as a substrate; and the competitive-type inhibition of ethyl acetate-soluble fraction was found with xanthine as a substrate.