Antiviral saponins from Tieghemella heckelii.

Arganine C (1) and a new saponin, tieghemelin (2), were isolated from Tieghemella heckelii fruits. Arganine C (1) strongly inhibited HIV entry into cells in a cell fusion assay. The less potent tieghemelin (2) was converted into arganine C (1) by reduction of its ethyl ester with sodium borohydride.