Abstract
Ethanolic extracts from stem bark of Tetrapleura tetraptera exerted an inhibitory effect on the luteinizing hormone (LH) released by cultured
rat pituitary cells. These extracts contained triterpenic saponins, tannins, and flavonoids
as estimated through phytochemical screening. Saponins were extracted. They apparently
inhibited the luteinizing hormone-releasing hormone (LHRH)-induced LH release, the
inhibition level being dose-dependent. Yet, the intracellular LH content remained
constant whatever the saponin concentration, which demonstrated a lack of effect on
the true release process. Accordingly, an interaction between saponins and LH released
into the medium was demonstrated, which led to a decrease in the amount of immunoassayable
hormone. This decrease was both time- and dose-dependent. It occurred even in the
presence of serum in the medium, which suggests that the inactivation process may
occur in vivo. Taken together, these results could explain the anti-gonadotrope properties of T. tetraptera extracts that are used as natural contraceptives in Ivory Coast pharmacopoeia.
Key words
Tetrapleura tetraptera
- saponins - pituitary - LH release - cell culture
