Tseng T H, Kao E S, Chu C Y, Chou F P, Lin Wu H W, Wang C J
Institute of Biochemistry, Chung Shan Medical and Dental College, Taiwan, ROC.
Food Chem Toxicol. 1997 Dec;35(12):1159-64. doi: 10.1016/s0278-6915(97)85468-3.
Dried flower extracts of Hibiscus sabdariffa L., a local soft drink material and medical herb, was found to possess antioxidant activity in the present study. In the preliminary studies, antioxidant potential of three fractions of the ethanol crude extract (HS-C: chloroform-soluble fraction; HS-E: ethyl acetate soluble fraction; HS-R: residual fraction) obtained from the dried flowers of Hibiscus sabdariffa L. were evaluated by their capacity of quenching 1,1 -diphenyl-2-picrylhydrazyl (DPPH) free radical and inhibiting xanthine oxidase (XO) activity. HS-E showed the greatest capacity of scavenging free radical (EC50=0.017mg/ml), and HS-C showed the strongest inhibitory effect on XO activity (EC5o=0.742 mg/ml). Furthermore, antioxidant bioactivities of these crude extracts were investigated using a model of tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in rat primary hepatocytes. All fractions were found to inhibit significantly the unscheduled DNA synthesis (UDS) induced by t-BHP at a concentration of 0.20 mg/ml. HS-C and HS-E also decreased the leakage of lactate dehydrogenase (LDH) and the formation of malondialdehyde (MDA) induced by t-BHP (1.5 mM) considerably at a concentration of 0.10 and 0.20 mg/ml in the rat primary hepatocyte cultures. These results indicated that the dried flower extracts (HS-C and HS-E) of H. sabdariffa L. protect rat hepatocytes from t-BHP-induced cytotoxicity and genotoxicity by different mechanisms.
本研究发现，当地软饮料原料及药草玫瑰茄（Hibiscus sabdariffa L.）的干花提取物具有抗氧化活性。在初步研究中，通过测定玫瑰茄干花乙醇粗提物的三个组分（HS-C：氯仿可溶组分；HS-E：乙酸乙酯可溶组分；HS-R：残留组分）清除1,1-二苯基-2-苦基肼（DPPH）自由基的能力以及抑制黄嘌呤氧化酶（XO）活性，对其抗氧化潜力进行了评估。HS-E表现出最强的自由基清除能力（EC50 = 0.017mg/ml），而HS-C对XO活性的抑制作用最强（EC50 = 0.742mg/ml）。此外，利用叔丁基过氧化氢（t-BHP）诱导大鼠原代肝细胞氧化损伤的模型，对这些粗提物的抗氧化生物活性进行了研究。结果发现，所有组分在浓度为0.20mg/ml时均能显著抑制t-BHP诱导的DNA非程序性合成（UDS）。在大鼠原代肝细胞培养物中，HS-C和HS-E在浓度为0.10和0.20mg/ml时，也能显著降低t-BHP（1.5mM）诱导的乳酸脱氢酶（LDH）泄漏和丙二醛（MDA）生成。这些结果表明，玫瑰茄的干花提取物（HS-C和HS-E）通过不同机制保护大鼠肝细胞免受t-BHP诱导的细胞毒性和基因毒性。
