Bioavailability and metabolism of artichoke caffeoylquinic acids in man

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Year of publication 2002
Type Article in Proceedings
Conference Zborník XVIII. Biochemický zjazd
MU Faculty or unit

Faculty of Medicine

Field Endocrinology, diabetology, metabolism, nutrition
Keywords bioavailability; artichoke; metabolism; caffeoylquinic acids; chlorogenic acid; caffeic acid; dihydrocaffeic acid; electrochemical detection; HPLC; antioxidants; Cynara; dicaffeoylquinic acid
Description Caffeoylquinic acids belong to the most frequently encountered phenolic acids in plants. They are present in many fruits (e.g. apples and pears) and vegetables (e.g. artichoke), chlorogenic acid (5-caffeoylquinic acid) occurs at very high level in coffee (CLIFFORD 2000). Caffeoylquinic acids display the strong antioxidant activity in respect of the presence of catechol moiety (PAULOVÁ et al., 2000). However, very little is known about their bioavailability and metabolism in humans. Analysis of urinary metabolites of artichoke caffeoylquinic acids using reversed-phase high-performance liquid chromatography is described. The HPLC system consisted of an LiChrospher 100 RP-18 column (5 um, 125 x 4 mm) and a mobile phase with 35% methanol in 50 mM phosphate buffer (pH 2.5). High selectivity and low detection limits of caffeic acid derivatives were achieved by using electrochemical detection (Coulochem II, ESA) at a low potential (channel 1: 0 mV, channel 2: 150 mV). The method was applied to the identification of caffeoylquinic acids metabolites in human urine after a single dose of an extract from the leaves of Cynara cardunculus taken orally. Conjugates were hydrolyzed enzymatically (glucuronidase/ sulfatase type HP-2, Sigma). In our study, caffeic acid and dihydrocaffeic acid were found in human urine after oral administration of Cynara extracts rich on chlorogenic acid (32 mg) and 1,5-dicaffeoylquinic acid (31 mg). Concentrations of caffeic acid and dihydrocaffeic acid in human urine increased after intake of the extract in the least 35 times and 14 times, respectively. Both phenolic acids were present in urine mostly as glucuronide and/or sulfate conjugates (approx. 95 %). However, 1,5-dicaffeoylquinic acid was not detected in urine and confirmation of presence of chlorogenic acid in urine involves next study.
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