Phytochemicals, polyphenols, and their derivatives including the flavonoids, tannins, and catechins discussed herein, are molecules derived from plants that have potential benefit for human health. One of the many proposed benefits of the polyphenols and their derivatives is their potential for antioxidant effects. Due to their structural similarities, the polyphenols act as antioxidants by donating electrons. In addition, like many of the other antioxidant compounds, polyphenols are associated with prevention of diseases such as atherosclerosis and cancer. Listed below are several compounds that contain polyphenolic derivatives. We are unaware of any published data examining the effects of any of the following compounds in exercise trained individuals or athletes. However, because of the positive results seen in recent research and their popularity as dietary supplements, we have addressed them here.
Milk Thistle
This herb, otherwise known as Silybum marianum, contains the active flavonolignans which include the compounds silybin, silydianin, and silychristine. These compounds are collectively known as silymarins. Silymarins are known primarily for their hepatoprotective effects including protection against toxins, including acetaminophen, ethanol, carbon tetrachloride, and D-galactosamine; and protection against ischemic injury, radiation, iron toxicity, and viral hepatitis. The hepatoprotective effects of silymarin are thought to include antioxidant action, prevention of lipid peroxidation, enhanced detoxification, and protection against glutathione depletion. The improved antioxidant status displayed by hepatic Kupffer cells (which detoxify the blood as it perfuses the liver) with milk thistle supplementation can actually result in improved clinical outcomes in liver disease.
Pine Bark (Pycnogenol)
The French maritime pine, Pinus maritima, has been examined for its principal extract, pycnogenol. This extract contains a variety of bioavailable phenolic derivatives (catechins and flavonoids) and investigations have shown that pycnogenol has strong free radical-scavenging activity against reactive oxygen and nitrogen species. In addition it also seems to interact with the cellular antioxidant systems by the regeneration of vitamin C, protecting endogenous vitamin E and glutathione from oxidative stress, and upregulating intracellular enzymatic and nonenzymatic oxidant scavenging systems. Pycnogenol has been shown to increase cellular glutathione content, SOD, and CAT activities in bovine artery endothelial cells (that line the inner lumen of the vessel), resulting in a concentration-dependent increase in oxygen and hydro-dioxide removal.
Grape Seed Extract
Grapes and wine have been receiving much attention lately due to their proposed health benefits, including the reduction of the incidence of mortality and morbidity from coronary heart disease. The polyphenols, which are found in grape seeds, skin, and stems, are thought to serve many favorable biological roles with respect to heart disease. Grape seeds contain the polyphenol, proanthocyanidin, which is thought to have protective properties against free radicals. In one study, grape seed proanthocyanidin was shown to be better than vitamins C and E in scavenging biochemically generated superoxide anions and hydroxyl radicals. In addition, decreases in lipid peroxidation and DNA fragmentation in liver and brain, as well as an inhibition of reactive oxygen species production in peritoneal macrophages has been shown. 141 In this study, grape seed extract was more effective than vitamin C, E, and beta-carotene at similar doses. In another study, grape seed proanthocyanidins were shown to possess a cardioprotective effect against ischemia reperfusion injury This property was attributed to its ability to directly scavenge peroxyl and hydroxyl radicals and to reduce oxidative stress developed during this state.
The plant Camellia sinensis has been the subject of many investigations on the positive health benefits of tea. In epidemiological research, it has been shown that the daily consumption of tea is involved in the prevention of coronary heart disease, artherosclerosis, and some types of cancer. The health benefits of tea are related to the antioxidant effects of its components, namely, its polyphenolic tannins and catechins that are present in highest con centra nons m green tea as oppose to types.
Although black tea contains a number of polyphenols as well (i.e., theaflavine gallate, digallate, etc.), the effects of these compounds are not as well researched. The polyphenols in tea appear to act in the prevention of lipid peroxidation and in cellular defense of the reactive oxygen species released during carcinogenesis.
Ginkgo Biloba
The leaves and fruit of this plant have been used as therapeutic agents in China for over 5000 years. More recently, ginkgo biloba extracts have been used in western medicine to treat peripheral artery disease and cerebral insufficiency It has been speculated that the beneficial actions of this extract are due to the antioxidant properties of its ingredients, especially its variety of polyphenols including flavonoids and terpenes. Ginkgo biloba may exert its antioxidant actions by scavenging the superoxide and hydroxyl radicals produced as a result of ischemiareperfusion injury and inflammation It has been shown in vivo that ginkgo biloba is active in the prevention of lipid peroxidation with age, and in the prevention of LDL oxidation.
Tags:antioxidant action, antioxidant compounds, antioxidant effects, antioxidant status, Antioxidant Supplementation, carbon tetrachloride, catechins, dietary supplements, french maritime pine, lipid peroxidation, liver disease, milk thistle, polyphenols silybum marianum
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