Flavonoids chemical transformations

Some of the potential uses of the fats and oils found in plants have been reviewed and some uses of carbohydrate-based polymers briefly discussed. Plants contain a whole variety of other chemicals including amino acids, terpenes, flavonoids, alkaloids, etc. When the potential for these naturally occurring materials are combined with the secondary products that can be obtained by fermentation or other microbial processes or by traditional chemical transformations, the array of chemicals that can readily be created from renewable resources is huge. In this section a few of the more interesting examples are considered. 

Since polyphenols are retained until they, or their metabolic products, are excreted by the urine or faeces, they undergo a number of complex microbial and chemical transformations that may include chemical conjugation, hydrolysis and biliary excretion [12], The few existing studies in humans show that the quantities of polyphenols found intact in urine vary from one phenolic compound to another. Among flavonoids, recovery is low for some flavonols, such as quercetin and rutin (0.3-14%), but high for other flavonoids, such as catechins, anthocyanins, flavanones and soy isoflavones (3-27%) [13],... 

The occurrence of heat- and chemical-induced transformations of tryptophan and the nutritional and toxicologic consequences suggest a need for additional research to define possible approaches to prevent or minimize the formation of antinutritional and toxic tryptophan condensation and oxidation products in foods. The possible beneficial effects of antioxidants such as vitamins C and E, carotenes, flavonoids, indole derivatives, selenium compounds, and sulfur amino acids in enhancing the stability of tryptophan in foods need to be investigated. 

---