In vitro enzymic hydrolysis of chlorogenic acids in coffee.
METHODS
Coffee is rich in quinic acid esters of phenolic acids (chlorogenic acids) but also contains some free phenolic acids. A proportion of phenolic acids appear in the blood rapidly after coffee consumption due to absorption in the small intestine. We investigated in vitro whether this appearance could potentially be derived from free phenolic acids in instant coffee or from hydrolysis of chlorogenic acids by pancreatic or brush border enzymes.


RESULTS
We quantified six free phenolic acids in instant coffees using HPLC-DAD-mass spectrometry. The highest was caffeic acid, but all were present at low levels compared to the chlorogenic acids. Roasting and decaffeination significantly reduced free phenolic acid content. We estimated, using pharmacokinetic modelling with previously published data, that the contribution of these compounds to small intestinal absorption is minimal. Hydrolysis of certain chlorogenic acids was observed with human-differentiated Caco-2 cell monolayers and with porcine pancreatin, which showed maximal rates on 3- and 5-O-caffeoylquinic acids, respectively.


CONCLUSIONS
The amounts of certain free phenolic acids in coffee could only minimally account for small intestinal absorption based on modelling. The hydrolysis of caffeoylquinic, but not feruloylquinic acids, by enterocyte and pancreatic esterases is potentially a contributing mechanism to small intestinal absorption.
School of Food Science and Nutrition, University of Leeds, Leeds, United Kingdom.
Joana Amarante
JA
da Encarnação
Tracy L
TL
Farrell
Alexandra
A
Ryder
Nicolai U
NU
Kraut
Gary
G
Williamson
D000818:Animals; D001682:Biological Availability; D018938:Caco-2 Cells; D002109:Caffeic Acids / Q000032:analysis; D002726:Chlorogenic Acid / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry* / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D003069:Coffee / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D062385:Hydroxybenzoates / Q000032:analysis; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism; D013058:Mass Spectrometry; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism; D011801:Quinic Acid / Q000031:analogs & derivatives / Q000032:analysis; D013552:Swine
D002109:Caffeic Acids; D002726:Chlorogenic Acid; D003069:Coffee; D062385:Hydroxybenzoates; D011801:Quinic Acid; C017616:phenolic acid; C473200:5-caffeoylquinic acid; C040048:caffeic acid
Caco-2 cells; Human plasma; Instant coffee; Pancreatic digestion; Phenolic acids