Absorption and metabolism of milk thistle flavanolignans in humans.
This study evaluated the absorption and metabolism of milk thistle flavonolignans silychristin, silydianin, silybin and isosilybin isomers (all together known as silymarin) in humans. Fourteen volunteers consumed an extract of milk thistle and urine was collected up to 48 h after consumption. Thirty-one metabolites were identified in urine by means of HPLC-MS/MS, monoglucuronides being the most common excreted form, followed by sulphate-glucuronides and diglucuronides, respectively. The excretion of monoglucuronides peaked 2 h after consumption, whereas sulphate-glucuronide and diglucuronide excretion peaked at 8 h. The bioavailability of milk thistle flavanolignans was 0.45±0.28% (mean±SD). In conclusion, milk thistle flavonolignans are extensively modified after ingestion and recovered in urine as sulpho- and glucuronyl-conjugates, indicating a strong affinity for hepatic phase II enzymes. All future studies (in vitro and in vivo) dealing with the effects of milk thistle should start by considering the modification of its flavonolignans after ingestion by humans.
The Laboratory of Phytochemicals in Physiology, Department of Food Science, University of Parma, Italy.
Luca
L
Calani
Furio
F
Brighenti
Renato
R
Bruni
Daniele
D
Del Rio
D000328:Adult; D001682:Biological Availability; D005260:Female; D020719:Glucuronides / Q000652:urine*; D006801:Humans; D007408:Intestinal Absorption; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D020944:Silybum marianum / Q000737:chemistry*; D010936:Plant Extracts / Q000493:pharmacokinetics* / Q000652:urine; D012838:Silymarin / Q000031:analogs & derivatives / Q000493:pharmacokinetics* / Q000652:urine; D055815:Young Adult
D020719:Glucuronides; D010936:Plant Extracts; D012838:Silymarin