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Technical Briefs |
1 Institute for Preventive Medicine, Nutrition and Cancer, Folkhälsan Research Center and Division of Clinical Chemistry, University of Helsinki, Helsinki, Finland;
2 Department of Medicine, University of Helsinki, Helsinki, Finland;
3 Department of Food Science, Swedish University of Agricultural Science (SLU), Uppsala, Sweden;
aAddress correspondence to this author at: Institute for Preventive Medicine, Nutrition and Cancer, Folkhälsan Research Center and Division of Clinical Chemistry, PO Box 63, FIN-00014 University of Helsinki, Finland; fax 358-9-19125452, e-mail anna.linko{at}helsinki.fi
Abstract
Background: Whole-grain rye and wheat cereals contain high amounts of alkylresorcinols (ARs), phenolic lipids. ARs can be quantified in plasma. Two recently identified urinary AR metabolites, 3,5-dihydroxyphenylbenzoic acid (DHBA) and 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA), may be useful as biomarkers of intake of whole-grain rye and wheat.
Methods: We evaluated 4 pretreatment protocols for quantifying urinary DHBA and DHPPA using HPLC coupled with a coulometric electrode array detector. Syringic acid was used as the internal calibrator.
Results: Measured urinary concentrations of DHBA and DHPPA were 0.8115 µmol/L. The mean recoveries of all added concentrations were 85%104% for DHBA and 86%99% for DHPPA, depending on the degree of the purification. The protocol versions with less purification correlated well with the protocol including highest purification. The correlation coefficients (r2) were 0.96990.8153 for DHBA and 0.98540.8371 for DHPPA.
Conclusion: Although the protocol with the most purification steps was most specific, all protocols were suitable for measuring DHBA and DHPPA in urine. The rapid protocol with simple hydrolysis could be used in large-scale clinical studies. Additional investigation is needed to clarify whether these metabolites are useful biomarkers of whole-grain intake and helpful in the exploration of its association with human diseases.
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