Enzymatic synthesis and chromatographic purification of lignan glucuronides.

Enterolactone, enterodiol and secoisolariciresinol were conjugated with glucuronic acid by solubilized rabbit liver microsomal UDP-glucuronyltrasnferase. The monoglucuronide conjugate of all three substrates was formed and its identity confirmed by nuclear magnetic resonance (NMR) spectroscopy. Analytical high pressure liquid chromatography (HPLC) and NMR spectroscopy indicated conjugation with glucuronic acid to occur at several positions in the molecule. The enzymatic conjugation was monitored by analytical capillary isotachophoresis (ITP). The Km-values for enterlactone, enterodiol, and secoisolariciresinol were calculated to be 0.30, 0.23, and 0.22 mmol/l respectively.