Flavonoids and Polyphenols

Although they can undergo redox cycling, they can also act as radicaltrapping antioxidants. 

They reduce the activation of many procarcinogens to the active proximate carcinogen by lowering the activity of microsomal cytochrome P450 enzymes. 

They increase the metaholic clearance of potential carcinogens and their metabolites by inducing the enzymes involved in conjugation for excretion. 

Some of the flavonoids also have estrogenic and antiestrogenic actions (Section 14.7.4). 

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Milhury, P.E. Analysis of complex mixtures of flavonoids and polyphenols hy high-performance hquid chromatography electrochemical detection methods. Methods Enzy-mol. 2001, 335, 15-26. 

Grapes and berry fruits are rich sources of flavonoids and polyphenolics. Labor-intensive investigations over the years, initially from botanists and later from chemists and food scientists, provide a vast amount of knowledge about chemical structure, occurrence and stability of these compounds. As a consequence, food products, extracts, tinctures and dry powders are available with documented levels of flavonoids and other phenolics. 

Epidemiological studies in the Mediterranean region evidenced that a diet rich in grain, legumes, fruits and vegetables, wine and olive oil has beneficial effects on human health. In fact, these foods are rich in antioxidant vitamins, flavonoids and polyphenols that play an important role in prevention against cancer and coronary heart disease. 

Hu, M., Commentary Bioavailability of flavonoids and polyphenols Call to arms. Molecular Pharmaceutics (2007) 4, 803-806. 

A developing area of analytical development in HPLC is the determination of several groups of minor food components, like flavonoids and polyphenols in general, xanthophylls, and other carotenoids. Most of them have important bioactivities and have stimulated much interest in food and nutrition studies. 

Huck, C.W. Bonn, G.K. Evaluation of detection methods for the reversed-phase HPLC determination of 3, 4, 5 -tri-methoxyflavone in different phytopharmaceutical products and in human serum. Phytochem. Anal. 2001,12,104—109. Huck, C.W. Huber, C.G. Ongania, K.H. Bonn, G.K. Isolation and characterization of methoxylated flavones in the flowers of Primula veris hy Uquid chromatography and mass spectrometry. J. Chromatogr. A, 2000, 870,453-462. Milhury, P.E. Analysis of complex mixtures of flavonoids and polyphenols hy high-performance hquid chromatography electrochemical detection methods. Methods Enzymol. 2001, 335, 15-26. 

Bors, W., Heller, W., Michel, C., and Stettmaier, K. 1996. Flavonoids and polyphenols Chemistry and biology. Handb. Antioxid. 26 409-466. 

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