title: The C-glycosyl flavonoid, aspalathin, is absorbed, methylated and glucuronidated intact in humans.
abstract: Human bioavailability of the flavonoid dihydrochalcones is little understood, and no evidence exists for C-glycosyl flavonoid absorption in humans. The present study uses catechol-O-methyltransferase to generate methylated metabolites of aspalathin (a C-glycosyl dihydrochalcone from rooibos tea). One of the methylated forms, both with and without glucuronidation, was detected using LC-MS/MS in the urine of human subjects (n = 6), demonstrating that deglycosylation is not a prerequisite for C-glycosyl flavonoid absorption. Methylation is catalysed by both intestine and liver cytosolic extracts. The results show that flavonoid C-glycosides are methylated and glucuronidated in vivo in an intact form in humans.
authors: School of Food Science and Nutrition, University of Leeds, Leeds, UK.
authors: Fraser L
authors: FL
authors: Courts
authors: Gary
authors: G
authors: Williamson
mesh_terms: D000042:Absorption; D000328:Adult; D002394:Catechol O-Methyltransferase / Q000502:physiology; D047188:Chalcones / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D020719:Glucuronides / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D008745:Methylation
chemical_list: D047188:Chalcones; D020719:Glucuronides; C517016:aspalathin; D002394:Catechol O-Methyltransferase