Bioavailability and in vivo metabolism of intact glucosinolates

• Progoitrin, gluconapin and sinalbin are absorbed to the blood and excreted in urine in pigs.
• Sinalbin is partly glucuronated by liver phase II enzymes and excreted as such to the urine.
• Nitriles were detected but not quantified in digesta from the small intestine.

Health benefits associated with consumption of cruciferous vegetables have received considerable attention with a hitherto focus on the role and bioactivity of glucosinolate degradation products. We investigated the in vivo metabolism of intact glucosinolates by following their fate in digesta and in the endogenous metabolism in pigs. This is the first study to show an intact glucosinolate, sinalbin, being absorbed and transformed to a sinalbin metabolite in the liver by glucuronidation expectedly performed by liver phase II enzymes with subsequent excretion to the urine. From LC–MS/MS data we propose a structure of the sinalbin metabolite as containing two 4-oxybenzyl groups. Sinalbin and the metabolite were detected in plasma from the hepatic vein with a ratio of metabolite to sinalbin of approximately 12:1 after 2–4 hours. Induction of liver phase II enzymes by intact glucosinolates indicates that these also themselves are bioactive compounds with potential health risks or beneficial effects.