厚葉石斑木葉子抽出物對秀麗隱桿線蟲生命週期與耐熱性之影響

Abstract

本研究評估厚葉石斑木 (Rhaphiolepis umbellata var. integerrima)葉子乙醇抽出物及四個可溶部的抗氧化活性，以及對秀麗隱桿線蟲生命週期與耐熱性的影響。在四個可溶部中，以乙酸乙酯可溶部與正丁醇可溶部含有較高的總酚類及總黃酮類含量；在還原力、DPPH自由基捕捉能力及TEAC總抗氧化能力方面，同樣以乙酸乙酯可溶部與正丁醇可溶部有較佳的抗氧化效果。 乙醇抽出物及可溶部對秀麗隱桿線蟲生命週期的影響，結果顯示乙醇抽出物及乙酸乙酯可溶部可以延長線蟲的壽命，即乙醇抽出物及乙酸乙酯可溶部有顯著的減緩老化能力；線蟲耐高溫試驗方面，乙酸乙酯可溶部與正己烷可溶部對於線蟲的高溫耐受性具有濃度依存的效果，又以正己烷可溶部的效果最佳，顯示正己烷可溶部可大幅增加線蟲對於高溫逆境的抵抗能力。在抑制線蟲體內脂褐素生成的評估方面，以正己烷可溶部及乙醇抽出物處理之線蟲在37℃下的體內脂褐素累積量最低，即正己烷可溶部及乙醇抽出物在致死溫度下，可有效減緩線蟲老化速率。在線蟲基因轉殖種CL4176 阿茲海默症β-Amyloid麻痺試驗中，乙醇抽出物、正己烷可溶部及乙酸乙酯可溶部可大幅減少線蟲麻痺率，皆低於正對照組，顯示乙醇抽出物、正己烷可溶部及乙酸乙酯可溶部可有效抑制阿茲海默症β-Amyloid的毒性。在抑制線蟲體內SOD-3 (Iron/manganese superoxide dismutase) 表現量方面，乙酸乙酯可溶部可以降低線蟲體內SOD-3的表現量，表示乙酸乙酯可溶部可有效降低線蟲體內氧化壓力的含量。綜合上述可知，厚葉石斑木葉子抽出物對秀麗隱桿線蟲具有多元的抗氧化及延緩老化之活性。

The purposes of this study are to evaluate the antioxidant activicity, and the influences of leaf extract from Rhaphiolepis umbellata var. integerrima on lifespan and thermotolerance in Caenorhabditis elegans. In the antioxidant evaluation, results showed the n-butanol-soluble fraction and ethyl acetate-soluble fraction had higher total phenolic and flavonoid content than the other fractions. Moreover, n-butanol-soluble fraction and ethyl acetate-soluble fraction also had better performances in reducing power, DPPH free-radical scavenging activity and trolox equivalent antioxidant capacity. In the lifespan assay of C. elegans, the ethanolic extract and ethyl acetate-soluble fraction could robustly extend the lifespan of C. elegans. It revealed the ethanolic extract and ethyl acetate-soluble fraction had the significant delay-aging activity. In thermotolerance assay, there was concentration-dependent effect of ethyl acetate-soluble fraction and n-hexane-soluble fraction on enhancing the thermotolerance of C. elegans. The n-hexane-soluble fraction had the highest improving effect. That means the n-hexane-soluble fraction could greatly improve the thermaltolerance of C. elegans at the heat stress. Furthermore, the C. elegans treated with n-hexane-soluble and ethanolic extract, respectively, could reduce the lipofuscin accumulation and retard the aging rate of C. elegans in lethal temperature of 37℃. In the β-amyloid paralysis assay of Alzheimer's disease with transgenic worms (CL4176), the ethanolic extract, n-hexane-soluble fraction and ethyl acetate-soluble fraction could notably reduce the paralysis rate of worms, which was even lower than the positive control. These results demonstrated the ethanolic extract, n-hexane-soluble fraction and ethyl acetate-soluble fraction could inhibit the toxicity of β-amyloid and had the potential for alleviating Alzheimer's disease. Additionally, the ethyl acetate-soluble fraction could reduce SOD-3 expression of C. elegans; the ethyl acetate-soluble fraction could reduce the oxidative stress in C. elegans. Based on the above results, the leaf extract of Rhaphiolepis umbellata var. integerrima had multiple antioxidant activities and delay-aging effect in C. elegans.