Polyphenol antioxidant 5538293 218849072 2008-06-12T12:54:51Z BeardWand 7283361 add a few internal links {{Mergeto|Polyphenol|date=December 2007}} [[Image:Apigenin.png|thumb|right|200px|Molecular structure of [[apigenin]], a '''polyphenol antioxidant''']] A '''polyphenol antioxidant''' is a type of [[antioxidant]] containing a [[polyphenol]]ic substructure. In [[human health]] these compounds, numbering over 4000 distinct species, are thought to be instrumental in combating [[oxidative stress]], a syndrome causative of some [[neurodegenerative disease]]s and some [[cardiovascular disease]]s. The main source of polyphenol antioxidants is nutritional, since they are found in a wide array of [[phytonutrient]]-bearing foods. For example, most [[legume]]s; fruits such as [[apple]]s, [[blackberry|blackberries]], [[blueberry|blueberries]], [[cantaloupe]], [[cherry|cherries]], [[cranberry|cranberries]], [[grape]]s, [[pear]]s, [[plum]]s, [[raspberry|raspberries]], and [[strawberry|strawberries]]; and [[vegetable]]s such as [[broccoli]], [[cabbage]], [[celery]], [[onion]] and [[parsley]] are rich in polyphenol antioxidants. [[Red wine]], [[chocolate]], [[green tea]], [[olive oil]], [[bee pollen]] and many [[grain]]s are alternative sources. The principal benefit of ingestion of antioxidants seems to stem from the consumption of a wide array of phytonutrients; correspondingly, the role of dietary supplements as a method of realizing these health benefits is the subject of considerable discussion. [[Image:Blackberry fruits10.jpg|thumb|200px|[[Blackberry|Blackberries]] are a source of polyphenol antioxidants]] ==Biochemical regulation== The regulation chemistry consists of a polyphenol antioxidant’s ability to scavenge [[free radical]]s and up-regulate certain metal [[chelation]] reactions. That is to say various [[reactive oxygen species]] must be continually removed from cells to maintain healthy metabolic function. Some specific free radicals affected are the reactive oxygen species [[singlet oxygen]], [[peroxynitrite]] and [[hydrogen peroxide]]. Diminishing the concentrations of reactive oxygen species can have several benefits. Since reactive oxygen species are linked to mobilization of ion transport systems, they are known to have roles in [[redox signaling]]. In particular, [[platelets]] involved in [[wound]] repair and [[blood]] [[homeostasis]] can release reactive oxygen species to recruit platelets to sites of [[injury]]. These also provide a link to the adaptive [[immune system]] via the recruitment of [[leukocytes]]. When polyphenols down-regulate reactive oxygen species formation, they also contribute to improved [[endothelial]] health through [[anti-inflammatory]] action. ==Biological consequences== [[Image:Macrophage.jpg|thumb|right|250px|A [[macrophage]] stretching its arms to engulf two particles. Reactive oxygen species promote oxidized [[LDL]] and polyphenol antioxidants combat this [[inflammatory response]].]] Occurrence of an abundance of polyphenol antioxidants is associated with several salutary effects in higher animal species: * Reduction in [[inflammatory]] effects such as [[coronary artery disease]]<ref>M.F. Muldoon and S.B. Kritchevsky, ''Flavonoids and heart disease''. Brit Med J 312:458-459 (1996)</ref><ref>John P. Cooke, The Cardiovascular Cure, Random House Inc., New York (2002) ISBN 0-7679-0881-3</ref> including specific medical research into the pathways of improved [[endothelial]] health via downregulation of oxidative [[LDL]].<ref>Serafini M, Laranjinha JA, Almeida LM, Maiani G, ''Inhibition of human LDL lipid peroxidation by phenol-rich beverages and their impact on [[blood plasma|plasma]] total [[antioxidant]] capacity in humans'', J Nutr Biochem 2000 Nov;11(11-12):585-590</ref> *More generally the [[tea]] polyphenol (medically known as TP) antioxidant [[epigallocatechin gallate]], has been shown to reduce reactive oxygen species levels ''in vivo''.<ref>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, Vol: 4 | Issue: 4 | April 2005 | pgs: 468-473</ref> Reactive oxygen species are important [[biomarker (medicine)|markers]] for inflammatory diseases. * Some polyphenol antioxidants, such as [[resveratrol]], inhibit occurrence and/or growth of mammalian [[tumor]]s.<ref>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 275:218-220 (1997)</ref> *A variety of other beneficial health effects have been attributed to consumption of foods rich in polyphenolic antioxidants. Among these salutary effects discussed are anti-aging consequences such as slowing the process of skin wrinkling.<ref>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 Feb; 123(3): 565-73</ref> For some of the side-benefits (such as prevention of [[peripheral artery disease]]), further research is continuing to clarify the role polyphenol antioxidants may have.<ref>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 Jun;36(10):1235-47</ref><ref> 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 Jun; 35(6): 633-8</ref> ==Difficulty in analyzing effects of specific chemicals== [[Image:Close up grapes.jpg|thumb|190px|left|[[Grape]]s contain certain polyphenol antioxidant compounds.]] It is difficult to evaluate the medical effects of specific polyphenolic antioxidants, since such a large number of individual compounds may occur even in a single food. For example, over sixty different chemically distinct flavonoids are known to occur in a given [[red wine]]. Numerous scientific studies have been conducted to attempt to arrive at one consistent index for food antioxidant power. Since it has been proved that the dietary intake of compounds having antioxidant activity is medically important, various chemical, biological, and electrochemical methods have been proposed to evaluate the antioxidant power of compounds such as polyphenols. Wine, although [[Essential nutrient|nonessential]], has a high polyphenol content up to two to three grams per liter in red wines obtained by traditional [[maceration (wine)|maceration]]. The polyphenol content of wines is usually evaluated by the [[Folin-Ciocalteu reagent]], which provides an appropriate response to the requirements of wine manufacturers. [[Statistical]] [[least squares]] analysis has been conducted to demonstrate the Folin method correlates well with alternative chemical and biological procedures for determining antioxidant potential.<ref>Oreste V. Brenna and Ella Pagliarini, Department of Food Science and Microbiology, University of Milan, Italy ''Multivariate Analysis of Antioxidant Power and [[Polyphenol]]ic Composition in Red Wines'', American Chemical Society, July 5, 2001</ref> Therefore, there is some reason to believe more universally accepted protocols may be forthcoming to permit quantitative evaluation of antioxidant strength of polyphenol antioxidant compounds. Other more detailed chemical research has been conducted elucidating the difficulty of isolating individual polyphenolic antioxidants. Fajardo-Lirai et al. have demonstrated that significant variation in polyphenol content among various brands of tea can explain<ref> 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, Session 46C, 2002 Annual meeting of Food Expo, Anaheim, Ca</ref> the inconsistency in previous epidemiological studies that have tried to correlate beneficial health effects of polyphenol antioxidants using specific [[green tea]] blends. The [[Oxygen Radical Absorbance Capacity]] (ORAC) test is a possible emerging standard by which science measures antioxidant power in foods and [[dietary supplement]]s ==Practical aspects of dietary polyphenol antioxidants== [[Image:Cacao-pod-k4636-14.jpg|thumb|[[Cocoa]] is the prime ingredient of [[chocolate]], a source of polyphenol antioxidants.]] There is debate regarding the total body absorption of dietary intake of polyphenolic compounds. While individual studies seem to demonstrate the favourable health effects of certain specific polyphenols, more research is needed to understand the interactions between a variety of these chemicals acting in concert within the human body. In particular there is evidence that some combinations of foods may inhibit efficient intestinal transfer of certain polyphenol antioxidants; refined sugars, for example, have been shown to impede this uptake under certain circumstances.<ref>Lotito SB, Frei B., Linus Pauling Institute, Oregon State University, Corvallis, Or, ''Relevance of apple polyphenols as antioxidants in human plasma: contrasting ''in vitro'' and ''in vivo'' effects'' Free Radic Biol Med. 2004 Jan 15;36(2):201-11</ref> Furthermore caution should be exercised in attempting diets depending largely on dietary supplements as opposed to a broad array of food sources, since the quality and concentrations of beneficial chemicals in some commercial products is subject to question, given lack of [[Food and Drug Administration]] (FDA) regulation. ==Topical application of polyphenol antioxidants== There is some data that reactive oxygen species play a role in the process of [[ageing|aging]]. The skin is exposed to various [[exogenous]] sources of [[oxidative stress]], including [[ultraviolet]] radiation. These spectral components are generally viewed as responsible for the [[extrinsic]] type of skin aging, sometimes termed photo-aging. It has been shown not only that increased levels of protective low molecular weight antioxidants through a diet rich in phytochemicals, but also by direct topical dermal application<ref>Clin Exp Dermatol. 2001 Oct;26(7):578-82 There is increasing evidence that reactive oxygen species play a pivotal role in the process of aging. The skin, as the outermost barrier of the body, is exposed to various exogenous sources of oxidative stress, in particular UV-irradiation. These are believed to be responsible for the extrinsic type of skin aging, termed photo-aging. It therefore seems possible to increase levels of protective low molecular may produce anti-aging effects on human skin. Indeed, various ''in vitro'' and animal studies</ref> have proved that a few low [[molecular weight]] antioxidants, notably [[vitamin C|vitamins C]] and [[vitamin E|E]], as well as [[lipoic acid]], exert protective effects against oxidative stress. However, controlled long-term studies on the efficacy of low molecular weight antioxidants in the prevention or treatment of [[skin]] aging in humans are lacking. == References== <div class="references-small"> <references /> </div> ==See also== * [[Asymmetric dimethylarginine]] * [[Coronary artery disease]] * [[Low density lipoprotein]] * [[Nitric oxide]] [[Category:Cardiovascular system]] [[Category:Chemopreventive agents]] [[Category:Flavonoids]] [[Category:Phenols]] [[zh:多酚抗氧化劑]]