Zhu Qin Yan, Holt Roberta R, Lazarus Sheryl A, Orozco Timothy J, Keen Carl L
Department of Nutrition, University of California-Davis, One Shields Avenue, Davis, CA 95616-8669, USA.
Exp Biol Med (Maywood). 2002 May;227(5):321-9. doi: 10.1177/153537020222700504.
Excessive peroxidation of biomembranes is thought to contribute to the initiation and progression of numerous degenerative diseases. The present study examined the inhibitory effects of a cocoa extract, individual cocoa flavanols (-)-epicatechin and (+)-catechin, and procyanidin oligomers (dimer to decamer) isolated from cocoa on rat erythrocyte hemolysis. In vitro, the flavanols and the procyanidin oligomers exhibited dose-dependent protection against 2,2'-azo-bis (2-amidinopropane) dihydrochloride (AAPH)-induced erythrocyte hemolysis between concentrations of 2.5 and 40 microM. Dimer, trimer, and tetramer showed the strongest inhibitory effects at 10 microM, 59.4%, 66.2%, 70.9%; 20 microM, 84.1%, 87.6%, 81.0%; and 40 microM, 90.2%, 88.9%, 78.6%, respectively. In a subsequent experiment, male Sprague-Dawley rats (approximately 200 g; n = 5-6) were given a 100-mg intragastric dose of a cocoa extract. Blood was collected over a 4-hr time period. Epicatechin and catechin, and the dimers (-)-epicatechin-(4beta>8)-epicatechin (Dimer B2) and (-)-epicatechin-(4beta>6)-epicatechin (Dimer B5) were detected in the plasma with concentrations of 6.4 microM, and 217.6, 248.2, and 55.4 nM, respectively. Plasma antioxidant capacity (as measured by the total antioxidant potential [TRAP] assay) was elevated (P < 0.05) between 30 and 240 min following the cocoa extract feeding. Erythrocytes obtained from the cocoa extract-fed animals showed an enhanced resistance to hemolysis (P < 0.05). This enhanced resistance was also observed when erythrocytes from animals fed the cocoa extract were mixed with plasma obtained from animals given water only. Conversely, plasma obtained from rats given the cocoa extract improved the resistance of erythrocytes obtained from rats given water only. These results show cocoa flavanols and procyanidins can provide membrane protective effects.
生物膜的过度过氧化被认为与多种退行性疾病的发生和发展有关。本研究检测了可可提取物、可可中的单体黄烷醇（-）-表儿茶素和（+）-儿茶素以及从可可中分离出的原花青素低聚物（二聚体至十聚体）对大鼠红细胞溶血的抑制作用。在体外，黄烷醇和原花青素低聚物在2.5至40微摩尔浓度范围内，对2,2'-偶氮双（2-脒基丙烷）二盐酸盐（AAPH）诱导的红细胞溶血表现出剂量依赖性保护作用。二聚体、三聚体和四聚体在10微摩尔时表现出最强的抑制作用，分别为59.4%、66.2%、70.9%；20微摩尔时，分别为84.1%、87.6%、81.0%；40微摩尔时，分别为90.2%、88.9%、78.6%。在随后的实验中，给雄性Sprague-Dawley大鼠（约200克；n = 5 - 6）灌胃100毫克可可提取物。在4小时内采集血液。在血浆中检测到表儿茶素和儿茶素，以及二聚体（-）-表儿茶素-（4β>8）-表儿茶素（二聚体B2）和（-）-表儿茶素-（4β>6）-表儿茶素（二聚体B5），其浓度分别为6.4微摩尔，以及217.6、248.2和55.4纳摩尔。在喂食可可提取物后30至240分钟内，血浆抗氧化能力（通过总抗氧化能力[TRAP]测定）升高（P < 0.05）。从喂食可可提取物的动物获得的红细胞对溶血的抵抗力增强（P < 0.05）。当将喂食可可提取物的动物的红细胞与仅给予水的动物的血浆混合时，也观察到这种增强的抵抗力。相反，从给予可可提取物的大鼠获得的血浆提高了仅给予水的大鼠获得的红细胞的抵抗力。这些结果表明可可黄烷醇和原花青素可以提供膜保护作用。
