Related Experiment Video
Updated: Jun 21, 2026

Structural Biology and Analytical Chemistry Approaches for Characterizing C-Glycoside Metabolic Enzymes in Human Gut Microbiota
Published on: May 23, 2025
The C-glycosyl flavonoid, aspalathin, is absorbed, methylated and glucuronidated intact in humans
Fraser L Courts1, Gary Williamson
1School of Food Science and Nutrition, University of Leeds, Leeds, UK.
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.
Related Concept Videos
Drug Metabolism: Phase II Reactions
Phase II Reactions: Glucuronidation
Phase I Reactions: Oxidation of Aliphatic and Aromatic Carbon-Containing Systems
Oxidation reactions are fundamental in aromatic carbon-containing systems. An example is the hydroxylation of phenobarbital, a process that transforms it into...
Factors Influencing Drug Absorption: Presystemic Elimination
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Oral Hypoglycemic Agents: α-Glucosidase Inhibitors
Acarbose and miglitol are typically...

