• Mattila, Ismo
• Bazzocco, Sarah
• Aura, Anna-Marja
• Miettinen, Jarkko
• Oresic, Matej
• Seppänen-Laakso, Tuulikki

Abstract

Dietary phenolic compounds are plant derived secondarymetabolites,which can be divided into flavonoids,phenolic acids, stilbenes, tannins andlignans. Catechinscan be found as monomers e.g. in tea or as condensedforms, proanthocyanidins (PA), in bilberries, apples,grapes and beveragesderived from those fruits. PAs areformed from (+)-catechin and(-)-epicatechin units.Phenolic compounds are ubiquitous metabolites that aremetabolised extensively during uptake. It is possiblethat a majorproportion of the metabolites are formed inthe colon by microbiota. Forexample lignans areconverted to enterodiol and enterolactone, flavonols areconverted to phenylacetic acids and flavanols andflavanones tophenylpropionic acid derivatives. Thesemetabolites, predominantly smallphenolic acids, havebeen identified in human plasma and urine. The residencetime of the colonic metabolites is longer than theoriginal structures fromplant foods. Epidemiologicalstudies have shown that high concentration ofenterolactone is associated to lowered risk of chronicdiseases like cancerand cardiovascular disease. Similarevidence for flavanoids and otherphenolic compounds islacking. Identification of diverse flavonoidmetabolitesis needed.This work aims to compare the in vitro microbialmetabolism of (+)-catechin and (-)-epicatechin unitsusing human faecalmicrobiota as an inoculum to identifytheir main degradation products. Pure(+)-catechin and(-)-epicatechin were fermented with pooled human faecalmicrobiota in strictly anaerobic conditions. The samplepreparation stepsinclude extraction with ethyl acetateand silylation with MSTFA. GCxGC-TOFanalytical methodwas developed for the analysis of the microbialmetabolites. We will describe the method including dataprocessing steps andthe preceding sample preparationsteps for the analysis of microbialmetabolites of(+)-catechin and (-)-epicatechin. The compounds includee.g.hydroxyphenyl propionic and acetic acid derivatives.Financial support of theproject STREP-FLAVO(Food-CT-2004-513960) is gratefully acknowledged.

Topics

• impedance spectroscopy
• compound
• extraction
• positron annihilation lifetime spectroscopy
• Photoacoustic spectroscopy