Abstract: To study the biotransformation of deoxyaconitine in intestine, aconitine was incubated with human intestinal bacteria in vitro. The metabolites of deoxyaconitine were investigated by ion trap and Fourier transform ion cyclotron resonance electrospray ionization tandem mass spectrometry directly. Aconitine and its metabolites formed the protonated molecular ion [M+H]⁺ in the positive ion mode. According to the m/z of [M+H]⁺, the molecular weight of the metabolite was determined and the structure was characterized by using MSn and the data in literature. The results show that deoxyaconitine could be transformed by human intestinal bacteria. Deoxyaconitine was converted into more than ten kinds of new metabolites such as mono-ester aconitum alkaloids, diester aconitines and lipo-alkaloids by deacetylation, debenzoylation, dehydroxylation, demethylation and esterification. Diester deoxyaconitine is very toxic. When deoxyaconitine was transformed into mono-ester aconitum alkaloids and lipo-alkaloids by human intestinal bacteria, the toxicity decreased.

Key words: Deoxyaconitine, Human intestinal bacteria, Biotransformation, Electrospray ionization tandem mass spectrometry