Browsing by Author "Christina Ritter"

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    Chiral separation of (+)/(−)-catechin from sulfated and glucuronidated metabolites in human plasma after cocoa consumption
    (2010) Christina Ritter; Benno F. Zimmermann; Rudolf Galensa
    Cocoa is well-known to be rich in flavan-3-ols. Previous analyses have established that alkaline treatment of cocoa beans results in epimerization of (−)-epicatechin to (−)-catechin and (+)-catechin to (+)-epicatechin. Now, the question is whether both epimers can be absorbed by the human organism. This paper describes sample preparation and an HPLC method for chiral determination of (+)/(−)- catechin from sulfated and glucuronidated metabolites in human plasma. The sample preparation includes enzymatic hydrolysis of the catechin metabolites, and solid-phase extraction (SPE). A PM-γ-cyclodextrin column is used with a coulometric electrode-array detection (CEAD) system. The recovery of catechin ranges from 89.9 to 96.8%. The limit of detection is 5.9 ng mL−1 for (−)-catechin and 6.8 ng mL−1 for (+)-catechin, and the limit of quantification is 12.8 ng mL−1 for (−)-catechin and 16.9 ng mL−1 for (+)- catechin. The relative standard deviation of the method ranges from 0.9 to 1.5%. This method was successfully applied to human plasma after consumption of a cocoa drink. In one human self-experiment, (+)-catechin and (−)- catechin were found in human plasma, but metabolism of the two enantiomers differed.