title: Absorption of dimethoxycinnamic acid derivatives in vitro and pharmacokinetic profile in human plasma following coffee consumption.
abstract: METHODS
  This study reports the 24 h human plasma pharmacokinetics of 3,4-dimethoxycinnamic acid (dimethoxycinnamic acid) after consumption of coffee, and the membrane transport characteristics of certain dimethoxycinnamic acid derivatives, as present in coffee.
  
  
  RESULTS
  Eight healthy human volunteers consumed a low-polyphenol diet for 24 h before drinking 400 mL of commercially available coffee. Plasma samples were collected over 24 h and analyzed by HPLC-MS(2) . Investigation of the mechanism of absorption and metabolism was performed using an intestinal Caco-2 cell model. For the first time, we show that dimethoxycinnamic acid appears in plasma as the free aglycone. The time to reach the C(max)  value of approximately 0.5 μM was rapid, T(max)  = 30 min, and showed an additional peak at 2-4 h for several subjects. In contrast, smaller amounts of dimethoxy-dihydrocinnamic acid (C(max)  ∼ 0.1 μM) peaked between 8 and 12 h after coffee intake. In the cell model, dimethoxycinnamic acid was preferentially transported in the free form by passive diffusion, and a small amount of dimethoxycinnamoylquinic acid hydrolysis was observed.
  
  
  CONCLUSIONS
  These findings show that dimethoxycinnamic acid, previously identified in plasma after coffee consumption, was rapidly absorbed in the free form most likely by passive diffusion in the upper gastrointestinal tract.
authors.affiliation: School of Food Science and Nutrition, University of Leeds, Leeds, UK.
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Farrell
authors.forename: Miren
authors.initials: M
authors.lastname: Gomez-Juaristi
authors.forename: Laure
authors.initials: L
authors.lastname: Poquet
authors.forename: Karine
authors.initials: K
authors.lastname: Redeuil
authors.forename: Kornél
authors.initials: K
authors.lastname: Nagy
authors.forename: Mathieu
authors.initials: M
authors.lastname: Renouf
authors.forename: Gary
authors.initials: G
authors.lastname: Williamson
mesh_terms: D000042:Absorption; D000328:Adult; D018938:Caco-2 Cells; D002851:Chromatography, High Pressure Liquid; D002934:Cinnamates / Q000097:blood* / Q000493:pharmacokinetics*; D003069:Coffee; D004032:Diet; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D059808:Polyphenols / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D002934:Cinnamates; D003069:Coffee; D059808:Polyphenols; C065784:3-(3,4-dimethoxyphenyl)propenoic acid