本研究目的為評估柳杉（Cryptomeria japonica D. Don）不同徑級枝條樹皮乙醇抽出物
之抗氧化活性，抗氧化活性試驗包括DPPH 自由基清除試驗、超氧自由基捕捉試驗、還原力測
定、總抗氧化能力試驗等；此外，並測定其總酚類含量和原花青素含量。結果顯示徑級4-5 cm
（TBL）及徑級2-3 cm（TBS）抽出物的總酚類含量分別為121.63 及134.03 mg GAE/g，以TBS乙醇抽出物之總酚類含量較高；另外測定原花青素（Proanthocyanidins）含量，TBS 乙醇抽出物之含量（38.57 mg CAE/g）亦較TBL 乙醇抽出物之含量（33.49 mg CAE/g）為高；而評估兩者之抗氧化活性，結果顯示TBS 乙醇抽出物之自由基捕捉能力與還原能力都較TBL 乙醇抽出物為佳。另將TBS 乙醇抽出物進一步細分為正己烷分離部、乙酸乙酯分離部及水分離部，並進行抗氧化活性評估。在多酚類含量測定試驗中，以乙酸乙酯分離部含有較多的總酚類含量（389mg GAE/g）及原花青素含量（135 mg CAE/g）；而抗氧化能力試驗結果亦顯示，乙酸乙酯分離部抗氧化能力在3 個分離部中最佳，與多酚類含量多寡結果一致。本研究結果得知柳杉枝條樹皮乙醇抽出物具有抗氧化物質，並顯示良好之抗氧化活性，可做為後續利用之價值。

The objective of this study is to assess the antioxidant activity of different diameters (2-3cm, TBS, and 4-5 cm TBL) from Cryptomeria japonica twig bark ethanolic extracts. The antioxidant activities were carried out using various antioxidant assays, including DPPH free radical, superoxide radical scavenging assays, reducing power assay, and trolox equivalent anti-oxidant capacity (TEAC).In addition, total phenolic contents and proanthocyanidin contents of these extracts were also determined.Results revealed that the total phenolic contents of TBL and TBS ethanolic extracts were 121.63 and 134.03 mg GAE / g,
respectively. The result indicate that ethanolic extracts from TBS revealed more phenolic contents than TBL one. Also, the proanthocyanidin contents of TBS ethanolic extract (38.57 mg CAE /g) is higher than TBL ethanolic extract (33.49 mg CAE /g). In addition, TBS ethanolic extract exhibited the best DPPH radical scavenging activity and reducing power than TBL.Therefore, TBS ethanolic extract was separated into n-hexane fraction (HEF), ethyl acetate fraction (EAF), and water fraction (WAF) by using liquid-liquid partition. Of these three fractions, EAF contained
highest content of total phenolic contents (389 mg GAE/g) and proanthocyanidins contents (135 mg CAE/g). Also, the order of three fractions by their antioxidant activities was EAF > WAF >HEF. This order is related to total phenolic contents, and might be used as an index for pre-evaluating research. Result revealed twig bark extracts from C. japonica possess antioxidant activities and are of interest for further research.