Malvidin-3-O-β glucoside, major grape anthocyanin, inhibits human macrophage-derived inflammatory mediators and decreases clinical scores in arthritic rats

Polyphenolic anthocyanins are major colorful compounds in red fruits, known to prevent cardiovascular and other diseases. Grape polyphenols are a mixture of various molecules and their exact contribution to above bioactivities remains to be clarified. In the present study, we first analyzed the effect of purified grape-derived compounds on human peripheral blood mononuclear cell (PBMC) survival, proliferation, as well as for their ability to inhibit the activation of human normal macrophages. Data indicated that malvidin-3-O-β glucoside (Malβg), the major grape anthocyanin, is bioactive with no toxicity on human PBMC. Malβg decreased the transcription of genes encoding inflammatory mediators, confirmed by the inhibition of TNFα, IL1, IL-6 and iNOS-derived nitric oxide (NO) secretion from activated macrophages. As Malβg also inhibited inflammatory response of rat macrophages, we investigated the anti-inflammatory potential of Malβg in chronic rat adjuvant-induced arthritis (AIA). Malβg significantly diminished inflammatory cachexia and arthritic paw scores in AIA rats at both therapeutic and preventive levels. In vivo effects of Malβg correlated with down-regulation of NO generation from AIA rats' peritoneal macrophages ex vivo. These data indicate that Malβg, major grape anthocyanin, is a potent anti-inflammatory agent in vitro and in vivo, without detectable toxic effect.

Production of highly 13C-labeled polyphenols in Vitis vinifera cell bioreactor cultures

The use of Vitis vinifera cells grown in a 2 l-stirred tank bioreactor for producing isotopically 13C-labeled phenolic substances is presented. Several culture parameters were optimized to achieve characteristics of growth and polyphenol metabolism similar to that recorded in shake flasks. Administration of [1-13C]L-phenylalanine (3 mM) to grape cell suspension cultures led to the production of 13C-labeled stilbenes (trans- and cis-piceids), catechins (catechin and epicatechin) and anthocyanins (delphinidin-, cyanidin-, petunidin-, peonidin- and malvidin-3-O-beta-glucosides). Incorporation of [1-13C]L-phenylalanine into polyphenols was measured by means of 13C satellites in the proton NMR spectrum and EA-IRMS. The enrichment of labeling obtained for all the compounds (between 40 and 65%) is sufficient to investigate their absorption and metabolism in humans.

Regioselective and stereospecific glucuronidation of trans- and cis-resveratrol in human

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenol present in wine, which has been reported to have anti-inflammatory, anti-platelet, and anti-carcinogenic effects. The glucuronidation of this compound and that of the cis-isomer also naturally present, has been investigated in human liver microsomes. Both isomers were actively glucuronidated. The reaction led to the formation of two glucuronides (3-O- and 4'-O-glucuronides), whose structure was characterized by LC-MS and proton NMR. Glucuronidation was regio- and stereoselective. It occurred at a faster rate with the cis-isomer and preferred the 3-position on both isomers. In addition, the glucuronidation of resveratrol was tested using several recombinant UDP-glucuronosyltransferase (UGT) isoforms. The reaction was catalyzed by UGT of the family 1A (UGT1A1, 1A6, 1A7, 1A9, 1A10). The bilirubin conjugating UGT1A1 was mainly involved in the 3-O-glucuronidation of trans-resveratrol, whereas the phenol conjugating UGT1A6 activity was restricted to cis-resveratrol. The UGT1A9 and 1A10 were active toward both isomers. The activity supported by UGT2B7 and UGT2B15 was very low and restricted to cis-resveratrol. UGT1A3, 1A4, 2B4, and 2B11 were unable to form resveratrol glucuronides.