Antioxidation, proanthocyanidins

Knowledge of the identity of phenolic compounds in food facilitates the analysis and discussion of potential antioxidant effects. Thus studies of phenolic compounds as antioxidants in food should usually by accompanied by the identification and quantification of the phenols. Reversed-phase HPLC combined with UV-VIS or electrochemical detection is the most common method for quantification of individual flavonoids and phenolic acids in foods (Merken and Beecher, 2000 Mattila and Kumpulainen, 2002), whereas HPLC combined with mass spectrometry has been used for identification of phenolic compounds (Justesen et al, 1998). Normal-phase HPLC combined with mass spectrometry has been used to identify monomeric and dimeric proanthocyanidins (Lazarus et al, 1999). Flavonoids are usually quantified as aglycones by HPLC, and samples containing flavonoid glycosides are therefore hydrolysed before analysis (Nuutila et al, 2002). 

Recent scientific investigations of natural polyphenols have demonstrated their powerful antioxidant property (Niki et al, 1995). Several classes of polyphenols have been chemically identified. Some of these are grape polyphenols, tea polyphenols, soy polyphenols, oligomeric proanthocyanidines (OPA) and other natural polyphenols of the flavone class. Rice bran polyphenols are different from the above in that they are p-hydroxy cinnamic acid derivatives such as p-coumaric acid, ferulic acid and p-sinapic acid. Tricin, a flavone derivative, has also been isolated from rice bran. 

Wu, X. et al.. Characterization of anthocyanins and proanthocyanidins in some cul-tivars of Rihes, Aronia and Samhucus and their antioxidant capacity, J. Agric. Food Chem., 52, 7846, 2004. 

Hatano, T. et al., Proanthocyanidin glucosides and related polyphenols from cacao liquor and their antioxidant effects. Phytochemistry, 59, 749, 2002. 

Greul, A.K. et al., Photoprotection of UV-irradiated human skin an antioxidative combination of vitamins E and C, carotenoids, selenium and proanthocyanidins, Skin Pharmacol. Appl. Skin Physiol., 15, 307, 2002. 

Free radicals might be involved in the incidences of various diseases such as arthritis, hemorrhagic shock, atherosclerosis, advancing age, ischemia and reperfusion injury of many organs, Alzheimer and Parkinson s disease, gastrointestinal dysfunctions, tumor promotion and carcinogenesis, AIDS, and other human health problems [85]. The oxidative proanthocyanidins as antioxidants could quench the free radicals and might help to enhance the action of other antioxidants such as vitamin C. 

Oligomeric proanthocyanidin Widespread (fruit, vegetables, nuts, COX, LOX [Al, antioxidant]... 

Proanthocyanidins (PAs) are oligomeric and polymeric flavan-3-ols, better known as condensed tannins. They are ubiquitous and one of the most abundant groups of natural phenols (Porter, 1988). PAs affect the texture, color, and taste of many common foods including cereals, fruits, vegetables, and wines. PAs in foods are also of interest in nutrition and medicine because of their potent antioxidant capacities and beneficial effects on human health in reducing the risk of chronic diseases, such as cardiovascular diseases and cancers (Santos-Buelga and Scalbert, 2000 Prior and Gu, 2005). 

Antioxidant and disease prevention capacities of proanthocyanidins from cocoa, grape seed, cranberries, and Pycnogenols (French pine... 

Deprez, S. Mila, I. Huneau, J.F. Tome, D. Scalbert, A. 2001. Transport of proanthocyanidin dimer, trimer, and polymer across monolayers of human intestinal epithelial Caco-2 cells. Antioxid. Redox. Signal 3 957-967. 

Maldonado, P.D. Rivero-Cruz, L Mata, R. Pedraza-Chaverri, J. 2005. Antioxidant activity of A-type proanthocyanidins from Geranium niveum (Geraniaceae). J. Agric. Food Chem. 53 1996-2001. 

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