大汕二品山藥(Dioscorea alata)果皮與果肉抗氧化活性之探討

Studies on antioxidative activity of yam (Dioscorea alata) peel and meat portion

魏吉宏(Ji-hung Wei)

指導教授 ： 許成光

亞洲大學/健康學院/生物科技學系碩士班/碩士(2005年)

摘要

本論文主要是探討殺菁，乾燥，萃取方式對大汕二品山藥果皮的抗氧化活性之影響，並進一步探討大汕二品山藥果皮與果肉對細胞的抗氧化活性。在本研究中體外抗氧化的測定方法包括以下三種:總多酚類含量，還原力以及DPPH自由基清除能力(Diphenyl-pricryl-hydrazyl)。細胞試驗則是以不同濃度的tert-butyl hydroperoxide (t-BHP)處理小鼠肝細胞(FL83B)與肝癌細胞(Hepa 1-6)，測試山藥果皮與果肉之酒精與水萃物對細胞存活率、細胞內過氧化氫含量、細胞內脂質過氧化物及細胞內抗氧化酵素(catalase、Superoxide dismutase、Glutathione peroxidase)含量之影響。在抗氧化活性試驗中的結果顯示，山藥果皮的50%乙醇，熱水和水萃取液之總多酚含量、還原力及DPPH自由基清除能力皆遠高於山藥果肉之萃取液。在三種萃取方式之山藥皮萃取液的抗氧化能力以50%乙醇的萃取液最高，但是熱水萃取方式則較適合山藥果肉。將山藥皮浸置於85℃之熱水中30秒以達到殺菁之目的，此項處理則明顯地降低了山藥果皮萃取物之抗氧化能力。大體而言，冷凍乾燥比熱風乾燥保留了較高的山藥果皮抗氧化能力。在細胞試驗中，山藥果皮酒精萃取物對受到氧化傷害之細胞具有較佳的保護效能。山藥果皮與果肉皆不能降低以25與50 mM t-BHP所誘導的細胞過氧化氫之含量。山藥果皮與果肉皆能降低sodium nitroprusside (SNP)所誘導的Hepa 1-6細胞內脂質過氧化物丙二醛之含量，但果肉降低FL83B脂質過氧化物丙二醛之含量之能力卻比果皮佳。在細胞內抗氧化酵素試驗中，果皮與果肉降低Hepa 1-6細胞內catalase之活性，但都能提升SOD與GPx之活性。對於提升FL83B細胞內GPx和SOD之活性則以果皮之酒精萃取物為最佳；似乎只有維生素C能提升FL83B細胞內catalase抗氧化酵素之活性，果皮與果肉則無提升catalase抗氧化酵素之活性。

關鍵字

山藥 ； 果皮 ； 細胞抗氧化 ； 殺菁

並列摘要

The purposes of this study were to evaluate the antioxidant abilities of ethanol and water extracts from one kind of Taiwanese yam peel and flesh, Darson (Dioscorea alata), and to evaluate the effects of blanching, drying and extraction methods on the antioxidant activities. The antioxidant measurements included total phenolic content, reducing power, and Diphenyl-pricryl-hydrazyl (DPPH) radical scavenging activity. Mouse liver cell (FL83B) and liver caner cell (Hepa 1-6) were used as the cell models to evaluate the influence of ethanol and water extracts from yam flesh and peel on the survival of the cells, the levels of hydrogen peroxide and malondialdehye (MDA), as well as the activities of antioxidant enzymes, such as catalase, Superoxide dismutase (SOD) and Glutathione peroxidase (GPx). The results showed that all the 50% ethanolic, hot water and water extracts from the peel had much higher total phenolic content, reducing power and DPPH radical scavenging activity than the extracts from the flesh. Among three extraction methods, 50% ethanolic extraction resulted in the highest antioxidant activity in the peel, while hot water extraction was more appropriate for the flesh. Blanching by immersing the peel in 85 oC water for 30 sec caused significant reductions in the antioxidant activities of all the extracts from the peel. Generally speaking, freeze-dried peel maintained higher antioxidant activities than hot-air dried peel did. In the cellular antioxidant evaluations, the ethanolic extract from the peel showed great protective ability toward FL83B and Hepa 1-6. However, the extracts from the flesh and peel did not decrease the levels of 25 and 50 mM tert-butyl hydroperoxide (t-BHP) induced hydrogen peroxide. The SNP induced lipid peroxidation in Hepa 1-6 decreased by the extracts from both yam flesh and peel, but the extract from the flesh showed higher inhibitory effect on the level of MDA in FL83B than the extract from the peel. For cellular antioxidant enzymes measurement, both ethanol and water extracts from Darson yam peel and flesh increased SOD and GPx activities in Hepa 1-6 cells, but they decreased the catalase activity. In FL83B, the ethanol extract from Darson yam peel showed the highest increase in the activities of SOD and GPx; however, all the extracts would not increase the catalase activity.

並列關鍵字

yam ； peel ； cell antioxidant activity ； blanching

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