Identification of higenamine and its metabolites in rat by gas chromatography/mass spectrometry

(±)-Higenamine is known as a cardiotonic principle of aconite root (root ofAconitum spp., Ranunculaceae). A simple and sensitive detection method for higenamine was developed by using gas chromatography-mass spectrometry (GC/MS). The recovery of higenamine after extraction and concentration with XAD-2 resin column was around 95% from rat biological fluids such as bile, plasma and urine. The limits of detection of higenamine in these biological fluids were approximately 0.1 ng/ml each. It has well been suggested that tetrahydroisoquinolines possessing catechol moiety such as higenamine should be subjected to the catechol-O-methyl transferase (COMT) activityin vivo. We detected two major peaks of presumed metabolites of higenamine in the total ion chromatogram obtained from the rat urine sample after the oral administration of (±)-higenamine. The scan mass spectrum of one of the metabolites coincided with those obtained from coclaurine (C₆-O-methyl higenamine) and those of the other metabolite are suggestive of isococlaurine (C₇-O-methyl higenamine).