Human metabolic pathways of dietary flavonoids and cinnamates

Abstract

Flavonoids and cinnamates are widespread phenolic secondary metabolites synthesized by plants for defensive purposes. Many foods and beverages contain high levels of phenolic compounds. Certain phenolics in the diet are particularly bioactive and have pronounced effects on mammalian cells. These effects, together with epidemiological studies and animal models, have led to the hypothesis that dietary phenolics contribute to the health benefits of a diet rich in fruit and vegetables. This paper examines the biochemistry of the uptake and metabolic route of two groups of plant phenolics, the flavonols and hydroxycinnamates.

Berries and anthocyanins: promising functional food ingredients with postprandial glycaemia-lowering effects

“…Nevertheless, the majority of absorption and transformation occurs in the small intestine (51,52) , although mechanisms are not entirely clear. Many flavonoid glycosides undergo hydrolysis of the sugar moiety by the membrane-bound enzyme, lactase phlorizin hydrolase with subsequent passive diffusion of the aglycone into the enterocyte.…”

Antioxidants: An Overview on the Natural and Synthetic Types

“…126 Besides the direct addition to food items, the antioxidants can be used to preserve food by preventing the degradation of food packaging during processing and storage. Thus, antioxidants can be added to packaging materials like paper, polyethylene, plastic and paperboard preventing the oxidation of the material itself, or allowing the added antioxidants to migrate into the packaged food inside and prevent oxidation there.…”

Regioselectivity of human UDP-glucuronosyl-transferase 1A1 in the synthesis of flavonoid glucuronides determined by metal complexation and tandem mass spectrometry

“…Early reports of unmodified flavonoid glycosides circulating in the bloodstream [9 -11] were likely mistaken identifications of flavonoid glucuronides, which have similar chromatographic and ultraviolet (UV) spectroscopic characteristics [7,12]. Flavonoids that fail to be absorbed in the small intestine may be broken down by microflora in the large intestine [1][2][3]. This process may release the free aglycons, which can then be absorbed and metabolized, but mostly results in the release of small phenolic acids, which are expelled in the urine [1][2][3].…”

“…Flavonoids lacking a 3= hydroxyl group were glucuronidated only at position 7, while those containing this functionality also formed 3=-O-glucuronides and sometimes 4=-O-glucuronides, thus supporting the conclusion that the presence or absence of the 3=-OH group is the major determinant of the regioselectivity of glucuronidation. Moreover, the specific distribution of multiple glucuronide products ( The currently accepted paradigm involves the consumption of flavonoid glycosides in plant-based food products, deglucosylation in the small intestine by ␤-glucosidase or lactose phloridzin hydrolase, and rapid metabolism by Phase I and (especially) Phase II enzymes [1][2][3]. Glucuronidation and sulfation are important metabolic routes for most flavonoids, while methylation or hydroxylation may also occur depending on the structure of the molecule in question [2,3].…”

“…The currently accepted paradigm involves the consumption of flavonoid glycosides in plant-based food products, deglucosylation in the small intestine by ␤-glucosidase or lactose phloridzin hydrolase, and rapid metabolism by Phase I and (especially) Phase II enzymes [1][2][3]. Glucuronidation and sulfation are important metabolic routes for most flavonoids, while methylation or hydroxylation may also occur depending on the structure of the molecule in question [2,3]. There has also been a report of glutathionerelated metabolites in human urine [4].…”