title: First identification of dimethoxycinnamic acids in human plasma after coffee intake by liquid chromatography-mass spectrometry.
abstract: There is a substantial amount of published literature on the bioavailability of various coffee components including the most abundant metabolites, caffeic and ferulic acids. Surprisingly, to date, the appearance of dimethoxycinnamic acid derivatives in humans has not been reported despite the fact that methylated form of catechol-type polyphenols could help maintain, modify or even improve their biological activities. This study reports an LC-MS method for the detection of dimethoxycinnamic acid in human plasma after treatment with an esterase. Liquid chromatography, including the combination of methanol and acetonitrile as organic eluent, was optimized to resolve all interferences and enable reliable detection and identification of 3,4-dimethoxycinnamic and 3,4-dimethoxy-dihydrocinnamic acids. In addition to the good mass accuracy achieved (better than 5 ppm), tandem mass spectrometric and co-chromatography experiments further confirmed the identity of the compounds. The optimized method was applied to analyze samples obtained immediately, 1 and 10 h after coffee ingestion. The results show that in particular 3,4-dimethoxycinnamic acid appears in high abundance (∼380 nM at 60 min) in plasma upon coffee intake, indicating that it is important to consider these derivatives in future bioavailability and bioefficacy studies.
authors.affiliation: Metabonomics & Biomarkers Group-BioAnalytical Science Department, Nestlé Research Center, Nestec Ltd., Lausanne, Switzerland. kornel.nagy@rdls.nestle.com
authors.forename: Kornél
authors.initials: K
authors.lastname: Nagy
authors.forename: Karine
authors.initials: K
authors.lastname: Redeuil
authors.forename: Gary
authors.initials: G
authors.lastname: Williamson
authors.forename: Serge
authors.initials: S
authors.lastname: Rezzi
authors.forename: Fabiola
authors.initials: F
authors.lastname: Dionisi
authors.forename: Karin
authors.initials: K
authors.lastname: Longet
authors.forename: Frédéric
authors.initials: F
authors.lastname: Destaillats
authors.forename: Mathieu
authors.initials: M
authors.lastname: Renouf
mesh_terms: D000328:Adult; D002853:Chromatography, Liquid / Q000379:methods*; D002934:Cinnamates / Q000097:blood* / Q000737:chemistry; D003069:Coffee / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008745:Methylation; D008875:Middle Aged; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D002934:Cinnamates; D003069:Coffee