Abstract
Structural transformation of arctiin and tracheloside, major components of seeds of
Arctium lappa and Carthamus tinctorius, were investigated using rat gastric juice (pH 1.2-1.5) and rat large intestinal
flora in vitro. Quantitative analysis of lignans and their metabolites was carried out by high performance
liquid chromatography. Both lignans were stable in rat gastric juice and arctiin was
rapidly transformed to arctigenin in rat large intestinal flora, followed by conversion
to the major metabolite, 2-(3″,4″-dihydroxybenzyl)-3-(3′,4′-dimethoxybenzyl)-butyrolactone.
On the other hand, tracheloside also decreased dependently with time and was converted
to trachelogenin and its major metabolite, 2-(3″,4″-dihydroxybenzyl)-3-(3′ ,4′-dimethoxybenzyl)-2-hydroxybutyrolactone.
These experiments suggest that in the course of metabolism of lignans, firstly a cleavage
of the glycosidic bond occurred and then demethylation of the phenolic methoxy group
in the alimentary tract followed.
Key words
Arctiin - tracheloside - structural transformation - gastric juice - intestinal flora
