A comparison of the in vitro biotransformation of (-)-epicatechin and procyanidin B2 by human faecal microbiota.
The catabolism by human faecal microbiota of (-)-epicatechin (1) (2, 3-cis stereochemistry) and its dimer pure procyanidin B2 (2), has been compared using a static in vitro culture model. The catabolites were characterised by LC-MS(n), UV absorption and relative retention time, and quantified relative to standards. No more than approximately 10% of procyanidin B2 (2) was converted to epicatechin (1) by scission of the interflavan bond. Five phenolic acid catabolites (M(r)<290) were unique to 2, and ten phenolic acid catabolites (M(r)<290) were common to both substrates. The dominant catabolites (> or =24 h incubation) were 5-(3'-hydroxy phenyl) valeric acid (9), 3-(3'-hydroxyphenyl) propionic acid (10) and phenyl acetic acid (12) (maximum yields 27.4+/-4.2, 38.2+/-4.2, 22.7+/-2.9%, respectively, from 1 and 9.4+/-1.2, 52.8+/-2.1, 28.8+/-1.6%, respectively, from 2). Substrate 2 was degraded twice as rapidly as 1. Evidence is presented for the production of previously unreported catabolites of 2 that retain the flavanol A-ring and the C4-->C8 interflavan bond. It was confirmed that catabolism favoured removal of the 4'-hydroxyl rather than the 3'-hydroxyl group and that both beta-oxidation and alpha-oxidation occurred.
Stoupi
Stavroula
S
Division of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK.
Williamson
Gary
G
Drynan
J Warren
JW
Barron
Denis
D
Clifford
Michael N
MN
D001419:Bacteria / Q000378:metabolism*; D044946:Biflavonoids / Q000378:metabolism*; D001711:Biotransformation; D002392:Catechin / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005243:Feces / Q000382:microbiology*; D006801:Humans; D008970:Molecular Weight; D044945:Proanthocyanidins / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization
D044946:Biflavonoids; D044945:Proanthocyanidins; C479580:procyanidin B2; D002392:Catechin