| 摘要: | 背景與目的：扁桃斑鳩菊是一種珍貴的藥用植物，被稱為苦葉。扁桃斑鳩菊除了可作為蔬菜用外，亦可被用於瘧疾，糖尿病、腹瀉、性病、肝炎、腸胃病、皮膚病和傷口的治療。而從自然界找尋有效的高抗氧化之天然物質，以降低生物體內之氧化性傷害，是值得進行研究。 研究方法：扁桃斑鳩菊葉及莖以三種不同溶劑(水、酒精、乙酸乙酯)萃取，並進行萃取物的活性測試，以瞭解何種溶劑能萃取出較高的抗氧化活性物質。抗氧化活性的測試包括DPPH自由基清除能力、螯合亞鐵離子能力、還原力及清除超氧陰離子能力；對不同萃取物進行類黃酮、總酚、花青素及胺基酸等活性成分含量及血管收縮素轉化酶抑制活性評估。 研究結果：1. 葉及莖提取物的收率以水萃物含量最高，分別為24.9及27.2 %。2. 抗氧化試驗中，DPPH自由基清除能力以酒精萃取物最高（莖優於葉萃取物，EC50各為0.52及0.78 mg/mL），其次為乙酸乙酯萃取物，水萃物最弱。亞鐵離子螯合能力顯示酒精萃取層效果最強（葉優於莖萃取物EC50各為0.77及0.90 mg/mL），葉乙酸乙酯層抗氧化力最弱。還原力測定中以酒精萃取物還原力最好。超氧陰離子清除能力各萃取物皆以莖比葉強，以莖乙酸乙酯萃取物最好（EC50為0.94 mg/mL）。3. 抗氧化活性成分含量試驗中，花青素含量主要存在於葉及莖水萃物，尤以葉的萃取物最多（1.51 μmole/g）。總酚含量（葉比莖多）依序為水萃物（687.31 μg/mg），其次酒精萃取物（111.15 μg/mg），最少為乙酸乙酯萃取物（49.62 μg/mg）。類黃酮在各萃取物中，酒精及乙酸乙酯萃取物含量差不多，其中以莖的乙酸乙酯萃取物所含的類黃酮含量最高（29.26 μg/mg），而在水萃物含量最少。胺基酸含量中明顯看到葉及莖的水萃物含量最為豐富，乙酸乙酯萃取物含量最少。4. 血管收縮素轉化酶抑制活性中，以葉及莖水層萃取物抑制能力最強(IC50分別為0.19 mg/mL及0.82 mg/mL)，而莖的酒精萃取物最不具活性。 結論：扁桃斑鳩菊抗氧化試驗中，DPPH、亞鐵離子清除率及還原力主要以酒精萃取物為主，在葉及莖都有不錯抗氧化力；抗氧化有關的活性成分如花青素及總酚主要分佈於葉的水萃取物，類黃酮含量在酒精及乙酸乙酯萃取物分佈差不多；胺基酸組成在水萃取物較多樣且普遍含量較多；血管收縮素轉化酶抑制活性中，以水萃取物最強。綜合上述研究，證實扁桃斑鳩菊葉及莖皆具有不錯的抗氧化力及抗氧化活性成分。
Background and Purpose: Vernonia amygdalina (VA), known as bitter leaf, is a valuable medicinal plant. Besides its use as a vegetable, the plant is also used in the treatment of malaria, diabetes, diarrhea, venereal diseases, hepatitis, gastrointestinal problems, skin diseases and wounds. The aim of this study is to investigate the antioxidative properties of V. amygdalina and how it could be used to reduce oxidative damage in the body. Methods: V. Amygdalina leaves and stems were extracted using three different solvents: water, ethanol and ethyl acetate. The following antioxidative activity assays were conducted: α,α-diphenyl- β-picrylhydrazyl (DPPH) radical scavenging ability, Fe2+ chelating ability, relative reducing power, and superoxide anion scavenging ability. The different extracts were evaluated for angiotensin I-converting enzyme inhibitory (ACEi) activities and active ingredient contents, which included flavonoids, total phenolics, anthocyanins and amino acids. The results:1. The aqueous extracts from VA leaves and stems had the highest content (24.9 and 27.2 %, respectively). 2. The antioxidant activities for the VA extracts obtained were as follows: the ethanolic extract (stem higher than leaf, EC50 values were 0.52 and 0.78 mg/mL, respectively) had the highest DPPH radical scavenging ability compared to the ethyl acetate and water extracts. The ethanolic extract had the highest Fe2+ chelating ability (leaf higher than stem, EC50 values were 0.77 and 0.90 mg/mL, respectively), and the ethyl acetate extract from the leaves had the lowest antioxidant capacity. The highest reducing power was detected in the ethanolic extract. Results showed that stems had better ability than leaves in all extractions, with the ethyl acetate extract of stems showing the best superoxide anion scavenging ability (EC50 value was 0.94 mg/mL). 3. The active ingredient content of VA extracts obtained was as follows: the aqueous extracts from VA leaves and stems contained high level of anthocyanins, with the highest concentration found in the leaf extracts (1.51 μmole/g). The aqueous extract had the highest total phenolics content (687.31 μg/mg) (leaf higher than stem), followed by the ethanol and ethyl acetate extracts (111.15 and 49.62 μg/mg, respectively). Similar flavonoid content was detected in the ethanol and ethyl acetate extracts (the highest concentration (29.26 μg/mg) was detected in the ethyl acetate extract of stems), and the lowest content was found in the aqueous extract. The highest amount of amino acids was detected in the aqueous extract of leaves and stems, while the ethyl acetate extract had the least content.4. ACE-inhibitory activity of the aqueous extract from the leaves and stems had strong inhibitory activity (0.19 and 0.82 mg/mL, respectively) and the ethanol stem extract had the lowest activity. Conclusion: The ethanolic extract had the highest antioxidant activity, including DPPH, ferrous ion chelating and reducing power. In addition, both the leaves and stems extracts were found to have good antioxidative capacities. The aqueous extract of VA leaves contained the highest levels of anthocyanins and total phenolics. Flavonoid contents in the ethanolic and ethyl acetate extracts were almost the same. A variety of amino acids was present in the aqueous extract, and its concentration was higher than the other extracts. Aqueous extracts were found to have strong ACEi activities. In summary, leaf and stem extracts of VA showed antioxidant activities. In all the solvents that were used to extract VA, the aqueous and ethanolic extracts were found to have the highest antioxidant activities and active components. |
