Polyphenolic Compounds: Interactions with the Gut and Implications for Human Health

Abstract

Polyphenolic compounds are abundant throughout the plant kingdom and are found in a wide variety of human foods. The flavonoids, which are the best defined group of polyphenols in the human diet, themselves comprise a large and complex group, all of which contain a three-ring structure with two aromatic centres and a central oxygenated heterocycle. Recent evidence suggests that significant quantities of quercetin and possibly myricetin and kaempferol are absorbed in the gut. A larger fraction probably remains in the lumen, and thus a substantial proportion of the gastrointestinal mucosa is exposed to biologically significant concentrations of these compounds. A substantial body of experimental work has established that flavonoids can suppress carcinogenesis in animal models and there is considerable interest in the biological effects of these compounds at the cellular level. Flavonoids interact with cellular signal pathways controlling the cell cycle, differentiation and apoptosis. Their potentially antineoplastic effects include antioxidant activity, induction of Phase II enzyme activity, inhibition of protein kinases and interactions with Type II estrogen binding sites. Naturally occurring polyphenolic compounds may play a role in the protective effects of fruits and vegetables against cancers in general, and they appear to have considerable potential for pharmaceutical uses as chemopreventive agents against neoplastic changes in the alimentary tract. Future research should therefore focus on the biological effects of flavonoids in the human body, using biomarkers to define their effects at each stage in the onset of neoplasia.

Extraction, separation, and detection methods for phenolic acids and flavonoids

“…Flavonoid glycosides are poorly absorbed until they have undergone hydrolysis by bacterial enzymes in the intestine, whereupon their aglycones can be absorbed. However, recent studies suggest that a fair degree of absorption of flavonol glycosides can also occur in the small intestine [38,39].…”

Further Pharmacological Evidence Supporting the Development of an Antiulcerogenic Drug Based on Rhizophora mangle L. Aqueous Extract. HPLC Method Proposed for Determinating a Chemical Marker

“…It was expected that the aglycones only could pass freely into the bloodstream from the gut wall, because no enzymes are secreted in the gut that could cleave the glycosidic bonds. Recent studies, however, have demonstrated that he bioavailability of specific flavonoids is much higher than previously believed [39] [40].…”

Dietary Fiber and Availability of Nutrients: A Case Study on Yoghurt as a Food Model

“…Several phenolic compounds, having antioxidative properties, are present especially in cereal fiber sources. They are released from their bound states by bacterial enzymatic action in the colon, and can act in the intestine locally as anticarcinogens both in preventing cancer initiation and progression [115][116][117].…”