title: Procyanidin dimers are metabolized by human microbiota with 2-(3,4-dihydroxyphenyl)acetic acid and 5-(3,4-dihydroxyphenyl)-gamma-valerolactone as the major metabolites.
abstract: Procyanidins (PCs) are highly abundant phenolic compounds in the human diet and might be responsible for the health effects of chocolate and wine. Due to low absorption of intact PCs, microbial metabolism might play an important role. So far, only a few studies, with crude extracts rich in PCs but also containing a multitude of other phenolic compounds, have been performed to reveal human microbial PC metabolites. Therefore, the origin of the metabolites remains questionable. This study included in vitro fermentation of purified PC dimers with human microbiota. The main metabolites identified were 2-(3,4-dihydroxyphenyl)acetic acid and 5-(3,4-dihydroxyphenyl)-gamma-valerolactone. Other metabolites detected were 3-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid, 3-hydroxyphenylpropionic acid, phenylvaleric acids, monohydroxylated phenylvalerolactone, and 1-(3',4'-dihydroxyphenyl)-3-(2'',4'',6''-trihydroxyphenyl)propan-2-ol. Metabolites that could be quantified accounted for at least 12 mol % of the dimers, assuming 1 mol of dimers is converted into 2 mol of metabolite. A degradation pathway, partly different from that of monomeric flavan-3-ols, is proposed.
authors.affiliation: Laboratory of Food Chemistry, Wageningen University, Wageningen, The Netherlands.
authors.forename: Maaike M
authors.initials: MM
authors.lastname: Appeldoorn
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Vincken
authors.forename: Anna-Marja
authors.initials: AM
authors.lastname: Aura
authors.forename: Peter C H
authors.initials: PC
authors.lastname: Hollman
authors.forename: Harry
authors.initials: H
authors.lastname: Gruppen
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D005243:Feces / Q000382:microbiology; D005285:Fermentation; D005707:Gallic Acid / Q000302:isolation & purification; D056604:Grape Seed Extract; D006801:Humans; D007783:Lactones / Q000032:analysis / Q000378:metabolism*; D013058:Mass Spectrometry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D044945:Proanthocyanidins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: C406785:(-)-5-(3',4'-dihydroxyphenyl)-valerolactone; D056604:Grape Seed Extract; C511402:Grape Seed Proanthocyanidins; D007783:Lactones; D010936:Plant Extracts; D044945:Proanthocyanidins; D015102:3,4-Dihydroxyphenylacetic Acid; D005707:Gallic Acid