石蓮與山藥對大鼠初代肝細胞抗氧化能力之研究

Study on the antioxidative activity of Graptopetalum paraguayense E. Walther and Discorea alata L. in rat primary hepatocytes

陳威帆(Wei-Fan Chen)

指導教授 ： 李宗貴

中山醫學大學/健康管理學院/營養學研究所/碩士(2005年)

https://doi.org/10.6834/CSMU.2005.00023

摘要

生物醫學研究顯示，多種慢性疾病的發生與體內氧化壓力的發生有關。不少蔬果含有豐富的多酚化合物(polyphenols)、類胡蘿蔔素、有機硫化物等植物性化合物(phytochemicals)，已知它們具有良好的抗氧化活性，此一特性也因此被用來解釋為何多食蔬果有助於預防慢性疾病的發生。本研究主要目的乃探討石蓮(Graptopetalum paraguayense E. Walther)與山藥(Discorea alata L.)之水(GW；DW)、50%乙醇(GE50；DE50)和乙酸乙酯(GEA；DEA)連續萃之萃出物出或沸水萃出物(GWH；DWH)對大鼠初代肝細胞抗氧化能力之影響。結果顯示，石蓮與山藥萃出物中，50%乙醇萃出物之總酚含量最高(GE: 530.88 ± 2.46 mg/g；DE: 26.00 ± 0.52 mg/g)；然而在增加肝細胞glutathione (GSH)含量上，均以乙酸乙酯(GEA)萃出物的效果最佳，且呈現劑量依賴關係，而且石蓮效果優於山藥(p<0.05)，除乙酸乙酯萃出物外，石蓮之50%乙醇萃出物之效果雖低於乙酸乙酯萃出物，也達顯著水準(p < 0.05)；在tert-butyl hydroperoxide (tBHP)誘發氧化壓力下，石蓮乙酸乙酯(GEA, 0.1-0.5 mg/ml)與山藥乙酸乙酯(DEA, 0.02-0.5 mg/ml)萃出物處理組細胞GSH含量不但較對照組細胞高(p < 0.05)，且增加程度相較前述未加入tBHP誘發氧化壓力之細胞還顯著(0.5 mg/ml GEA: 45.6% vs. 79.5%；0.5 mg/ml DEA: 46.0% vs. 77.0%)。在調解GSH相關抗氧化酵素與超氧歧化酶(superoxide dismutase)活性上，除0.5 mg/ml DE50增加GSH reductase (GSH Rd)與GSH S- transferase (GST)酵素活性(p < 0.05)或2.5 mg/ml GW與0.5 mg/ml GEA降低GSH Rd與GST酵素活性(p < 0.05)外，其餘各萃出物對抗氧化酵素均無影響。石蓮各萃出物隨著劑量增加，都可降低大鼠初代肝細胞內生性thiobarbituric acid-reactive substances (TBARS)的生成，山藥萃出物中則僅50%乙醇和乙酸乙酯萃出物有抑制效果，也以石蓮之效果優於山藥(p<0.05)；除抑制內生性TBARS的生成外，石蓮與山藥萃出物也可有效抑制0.5 mM tBHP誘發脂質過氧化作用。綜合上述結果，石蓮與山藥各萃出物在影響大鼠初代肝細胞內GSH含量並降低TBARS生成之效果上，以乙酸乙酯萃出物的保護效果最佳，似乎顯示此活性成分屬低極性化合物，且石蓮保護效果優於山藥。

關鍵字

石蓮 ； 山藥 ； 不同極性萃出物 ； 麩胱甘肽脂質過氧化 ； 抗氧化

並列摘要

Evidence supports the emergence of many degenerative diseases is closely related to the state of oxidative stress in the body. Phytochemicals including polyphenols and flavonoids display excellent anti-oxidant activity. This may explain the consumption of vegetables and fruits are reversely related to the incidence of many degenerative diseases. In this study, we intend to examine the anti-oxidation activity of Graptopetalum paraguayense E. Walther and Discorea alata L. in rat primary hepatocytes. Graptopetalum paraguayense E. Walther and Discorea alata L. were extracted sequentially by water (GW, DW), 50% ethanol (GE50, DE50), and ethyl acetate (GEA, DEA), and also by boiling water (GWH, DWH), respectively. Results show the 50% ethanol extracts of both vegetables had the highest total phenolic contents (GE: 530.9 ± 2.5 mg/g；DE: 26.0 ± 0.5 gallic acid equivalent mg/g) as compared to other solvent extracts. Ethyl acetate extract of Graptopetalum paraguayense E. Walther (GEA) and Discorea alata L. (DEA) and 50% ethanol extract of the Graptopetalum paraguayense E. Walther (GE50) dose-dependently increased glutathione (GSH) content and suppressed thiobarbituric acid-reactive substances (TBARS) (p<0.05) in the absence or presence of tert-butyl hydroperoxide (tBHP). As compared, the effect of Graptopetalum paraguayense E. Walther on GSH contents and TBARS production was greater than that of the Discorea alata L. We also noted the increase of hepatic GSH content by GEA, DEA, and GE50 was even higher under oxidative stress induced with tBHP. An increase of 46.6 and 46.0% GSH content was noted in cells treated with GEA and DEA alone, respectively. However, the increase turned to 79.5% and 77.0% as the cells were co-treated with tBHP. The activity of superoxide dismutase and three GSH-related antioxidant enzymes including GSH peroxidase, GSH reductase, and GSH S-transferase, however, was only minor changed by either Graptopetalum paraguayense E. Walther or Discorea alata L. extracts. These results suggest that, among various extracts, ethyl acetate extract of both Graptopetalum paraguayense E. Walther and Discorea alata L. display the greatest antioxidation activity in rat primary hepatocytes. And, the protection of the Graptopetalum paraguayense E. Walther is better than that of Discorea alata L..

並列關鍵字

Graptopetalum paraguayense E. Walther ； Discorea alata L. ； organic solvent-extracts ； glutathione ； thiobarbituric acid-reactive substances ； antioxidation

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