Absorption of N-phenylpropenoyl-L-amino acids in healthy humans by oral administration of cocoa (Theobroma cacao).
Besides flavan-3-ols, a family of N-phenylpropenoyl-L-amino acids (NPAs) has been recently identified as polyphenol/amino acid conjugates in the seeds of Theobroma cacao as well as in a variety of herbal drugs. Stimulated by reports on their biological activity, the purpose of this study was to investigate if these amides are absorbed by healthy volunteers after administration of a cocoa drink. For the first time, 12 NPAs were quantified in human urine by means of a stable isotope dilution analysis with LC-MS/MS (MRM) detection. A maximum amount was found in the urine taken 2 h after the cocoa consumption. The highest absolute amount of NPAs excreted with the urine was found for N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid (5), but the highest recovery rate (57.3 and 22.8%), that means the percentage amount of ingested amides excreted with the urine, were determined for N-[4'-hydroxy-(E)-cinnamoyl]-L-glutamic acid (6) and N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tyrosine (13). In order to gain first insights into the NPA metabolism in vivo, urine samples were analyzed by LC-MS/MS before and after beta-glucuronidase/sulfatase treatment. As independent of the enzyme treatment the same NPA amounts were found in urine, there is strong evidence that these amides are metabolized neither via their O-glucuronides nor their O-sulfates. In order to screen for caffeic acid O-glucuronides as potential NPA metabolites, urine samples were screened by means of LC-MS/MS for caffeic acid 3-O-beta-D-glucuronide and 4-O-beta-D-glucuronide. But not even trace amounts of one of these glucuronides were detectable, thus excluding them as major NPA metabolites and underlining the importance of future investigations on a potential O-methylation or reduction of the N-phenylpropenoyl moiety in NPAs.
Stark
Timo
T
Lehrstuhl für Lebensmittelchemie und Molekulare Sensorik, Technische Universität München, Freising, Germany.
Lang
Roman
R
Keller
Daniela
D
Hensel
Andreas
A
Hofmann
Thomas
T
D000042:Absorption; D000328:Adult; D000596:Amino Acids / Q000378:metabolism / Q000652:urine*; D001628:Beverages; D002099:Cacao / Q000737:chemistry*; D002109:Caffeic Acids / Q000378:metabolism / Q000652:urine; D005260:Female; D005419:Flavonoids / Q000378:metabolism / Q000652:urine*; D020719:Glucuronides / Q000378:metabolism / Q000652:urine; D006801:Humans; D008297:Male; D010636:Phenols / Q000378:metabolism / Q000652:urine*; D059808:Polyphenols
D000596:Amino Acids; D002109:Caffeic Acids; D005419:Flavonoids; D020719:Glucuronides; D010636:Phenols; D059808:Polyphenols