多酚抗氧化剂

多酚抗氧化剂是一种抗氧化剂，特征是拥有多种苯酚的功效。超过4000种不同的多酚抗氧化剂可以抵抗导致神经退化性疾病及一些心血管疾病的氧化应激。

多酚抗氧化剂的主要来源是可供摄取的，多在植物营养素食物中可以找到。例如大部分的荚果、果实如苹果、黑莓、香瓜、樱桃、蔓越莓、葡萄、梨、布冧、覆盆子及草莓、及蔬菜如绿色花椰菜、卷心菜、芹菜、洋葱及香芹等都有丰富的多酚抗氧化剂。红酒、巧克力、绿茶、橄榄油、蜂花粉及多种谷物都是其他的来源。摄取多酚抗氧化剂的主要好处是等同于摄取了多种不同的植物营养素。

生物化学调节

调节化学包含多酚抗氧化剂排除自由基及调节上升金属螯合物反应的能力。不同活性氧必须不断从细胞中被移除，以维持健康的代谢功能。某些特定的自由基影响活性氧的单线态氧、过氧亚硝基及过氧化氢。降低活性氧浓度可以有多种好处。由于活性氧与离子运输系统有关连，它们有着氧化传讯的角色。尤其是血小板涉及在复修伤口，而血液内环境稳态可以释放活性氧吸引血小板到受伤的位点。这亦与免疫系统拉上关系，因需要补充白血球。当多酚抗氧化剂降低活性氧的形成时，它们的抗炎性能力可改善内皮健康。

生物效果

丰富的多酚抗氧化剂在高等动物品种中可以有多种有益的效用：

降低炎症的影响，如冠心病^[1]^[2]，包括透过下调氧化低密度脂蛋白来促进内皮健康。^[3]

一般来说，茶多酚抗氧化剂的表没食子儿茶素没食子酸脂是可以减低体内活性氧水平。^[4]活性氧是炎症的重要生物标志。

一些多酚抗氧化剂，如逆转醇，阻碍哺乳动物肿瘤的出现及生成。^[5]

其他有益的效用都可在食用丰富多酚抗氧化剂的食物中获得。这些有益效用有抗衰老效果如减慢皮肤皱纹过程。^[6]就其他副好处，如防止周围动脉疾病等，都需要作出详细的研究，以证明多酚抗氧化剂的角色。^[7]^[8]

分析效用的难处

多酚抗氧化剂的医学疗效是很难去评估，因为在单一种食物中就可能已经有大量的物质。举例来说，在红酒中就已经有超过60种不同的黄酮类。多个研究都希望去达至一个一致的指数来表示食物的抗氧化功能。由于已证实摄取含有抗氧化剂的物质是在医疗上重要的，不同化学的、生物学的及电气化学的方法都被建议来评估如多酚等物质的抗氧化能力。虽然酒并非必要食物，但它有着高含量的多酚，如从传统浸软方法提炼的红酒约有2-3g/L的多酚。而酒的多酚含量多以Folin-Ciocalteu试剂来评估，这种试剂可以提供合适酒厂要求的反应。利用统计学的最小二乘法分析可以显示这种试剂与交替性化学及生物检测抗氧化潜能的过程有关联。^[9]所以相信可以发展一种合适的方法来量化评估多酚抗氧化强度。

其他更详细的研究亦有进行以阐述分隔多酚抗氧化剂的困难。在不同种类的茶中有着大量不同的多酚含量^[10]可以解释过往在流行病学研究上，特定绿茶中的多酚抗氧化剂的健康效用的矛盾。氧自由基吸收能力测试是一种可行的标准来量度食物及膳食补充剂的抗氧化能力。

食用的实际问题

现正就多酚抗氧化剂的身体总吸收量作出讨论。部分研究指某些特定的多酚才能提供健康效用，而在体内不同化合物之间的相互作用仍有待更多的研究。有证据显示一些食物的组合可以阻碍肠有效运送多酚抗氧化剂。精制糖证实会在某些情况下阻止吸收。^[11]再者食用膳食补充剂代替食物种类时需要特别小心，因为某些产品内有益物质的质素及浓度都成疑问。

总体应用

有数据显示活性氧促进老龄化的过程。皮肤作为身体最外层的保障，经常暴露于外在的氧化应激来源，特别是紫外光。一般相信紫外光就是令皮肤产生外在的老龄化，这称为光老化。所以提高保护性低分子量抗氧化剂的水平可以在皮肤产生抗衰老的效果。少量的低分子量抗氧化剂，尤其是维生素C(即抗坏血酸)及维生素E及生育酚，与及硫辛酸都可以提供保护效用对抗氧化应激。但是现时缺乏长期就低分子量抗氧化剂在防止及保护皮肤衰老上的对照研究。^[12]不单止食用丰富植物营养素，直接在皮肤涂上低分子量抗氧化剂亦可以提升保护水平。^{[来源请求]}

参考

[1]
M.F. Muldoon and S.B. Kritchevsky. Flavonoids and heart disease. Brit Med J. 1996, 312: 458–459.
[2]
John P. Cooke. The Cardiovascular Cure. New York: Random House Inc. 2002. ISBN 978-0-7679-0881-8.
[3]
Serafini M, Laranjinha JA, Almeida LM, Maiani G. Inhibition of human LDL lipid peroxidation by phenol-rich beverages and their impact on plasma total antioxidant capacity in humans. J Nutr Biochem. 2000, 11 (11-12): 585–590.
[4]
Yuying Mei, Dongzhi We and Jianwen Liu. Reversal of Multidrug Resistance in KB Cells with Tea Polyphenol Antioxidant Capacity. Journal of Cancer Biology and Therapy. 2005, 4 (4): 468–473.
[5]
M. Jang, L. Cai, G.O. Dean, K.V. Slowing, C.F. Thomas, C.W.W. Beecher , H.H.S. Fong, N.R, Farnsworth, A.D. Kinghorn, R.G. Mehta, R.C. Moon and J.M. Pezzuto. Cancer chemopreventive activity of reseveratrol, a natural product derived from grapes. Science. 1997, 275: 218–220.
[6]
Vieira O, Escargueil-Blanc I, Meilhac O, Basile JP, Laranjinha J, Almeida L, Salvayre R, Negre-Salvayre. A Effect of dietary phenolic compounds on apoptosis of human cultured endothelial cells induced by oxidized LDL. Br J Pharmacol. 1998, 123 (3): 565–73.
[7]
Owen RW, Giacosa A, Hull WE, Haubner R, Spiegelhalder B, Barstch H. The antioxidant/anticancer potential of phenolic compounds isolated from olive oil. Eur J Cancer. 2000, 36 (10): 1235–47.
[8]
Fito M, Covas MI, Lamuela-Raventos RM, Vila J, Torrents L, de la Torre C, Marrugat. Protective effect of olive oil and its phenolic compounds against low density lipoprotein oxidation. J Lipids. 2000, 35 (6): 633–8.
[9]
Oreste V. Brenna and Ella Pagliarini, Department of Food Science and Microbiology, University of Milan. Multivariate Analysis of Antioxidant Power and Polyphenolic Composition in Red Wines. Italy: American Chemical Society. 2001.
[10]
C. Fajardo-Lirai, S. M. Henning, H. W. Lee, V. L. W. Go, and D. Heber,. Department Family Environmental Sciences/Nutrition, Dietetics & Food Science, California State University, Northridge and, UCLA Center for Human Nutrition. 2002 Annual meeting of Food Expo, Anaheim, Ca. 2002: Session 46C.
[11]
Lotito SB, Frei B. Relevance of apple polyphenols as antioxidants in human plasma: contrasting in vitro and in vivo effects. Free Radic Biol Med. 2004, 36 (2): 201–11.
[12]
M. Podda and M. Grundmann-Kollmann. Low molecular weight antioxidants and their role in skin ageing. Clin Exp Dermatol. 2001, 26 (7): 578–82.

内部链接

[1] [1]
M.F. Muldoon and S.B. Kritchevsky. Flavonoids and heart disease. Brit Med J. 1996, 312: 458–459.

[2] [2]
John P. Cooke. The Cardiovascular Cure. New York: Random House Inc. 2002. ISBN 978-0-7679-0881-8.

[3] [3]
Serafini M, Laranjinha JA, Almeida LM, Maiani G. Inhibition of human LDL lipid peroxidation by phenol-rich beverages and their impact on plasma total antioxidant capacity in humans. J Nutr Biochem. 2000, 11 (11-12): 585–590.

[4] [4]
Yuying Mei, Dongzhi We and Jianwen Liu. Reversal of Multidrug Resistance in KB Cells with Tea Polyphenol Antioxidant Capacity. Journal of Cancer Biology and Therapy. 2005, 4 (4): 468–473.

[5] [5]
M. Jang, L. Cai, G.O. Dean, K.V. Slowing, C.F. Thomas, C.W.W. Beecher , H.H.S. Fong, N.R, Farnsworth, A.D. Kinghorn, R.G. Mehta, R.C. Moon and J.M. Pezzuto. Cancer chemopreventive activity of reseveratrol, a natural product derived from grapes. Science. 1997, 275: 218–220.

[6] [6]
Vieira O, Escargueil-Blanc I, Meilhac O, Basile JP, Laranjinha J, Almeida L, Salvayre R, Negre-Salvayre. A Effect of dietary phenolic compounds on apoptosis of human cultured endothelial cells induced by oxidized LDL. Br J Pharmacol. 1998, 123 (3): 565–73.

[7] [7]
Owen RW, Giacosa A, Hull WE, Haubner R, Spiegelhalder B, Barstch H. The antioxidant/anticancer potential of phenolic compounds isolated from olive oil. Eur J Cancer. 2000, 36 (10): 1235–47.

[8] [8]
Fito M, Covas MI, Lamuela-Raventos RM, Vila J, Torrents L, de la Torre C, Marrugat. Protective effect of olive oil and its phenolic compounds against low density lipoprotein oxidation. J Lipids. 2000, 35 (6): 633–8.

[9] [9]
Oreste V. Brenna and Ella Pagliarini, Department of Food Science and Microbiology, University of Milan. Multivariate Analysis of Antioxidant Power and Polyphenolic Composition in Red Wines. Italy: American Chemical Society. 2001.

[10] [10]
C. Fajardo-Lirai, S. M. Henning, H. W. Lee, V. L. W. Go, and D. Heber,. Department Family Environmental Sciences/Nutrition, Dietetics & Food Science, California State University, Northridge and, UCLA Center for Human Nutrition. 2002 Annual meeting of Food Expo, Anaheim, Ca. 2002: Session 46C.

[11] [11]
Lotito SB, Frei B. Relevance of apple polyphenols as antioxidants in human plasma: contrasting in vitro and in vivo effects. Free Radic Biol Med. 2004, 36 (2): 201–11.

[12] [12]
M. Podda and M. Grundmann-Kollmann. Low molecular weight antioxidants and their role in skin ageing. Clin Exp Dermatol. 2001, 26 (7): 578–82.

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