Uapaca genus (Euphorbiaceae), a good source of betulinic acid.

Betulinic acid, isolated in substantial amounts from stem barks of five distinct species of Uapaca could be considered as an important chemotaxomic marker of the Uapaca genus. It inhibited Trypanosoma brucei GAPDH with an IC(50) value of 240 microM and has been shown to be a competitive reversible inhibitor (Ki=200+/-10 microM) of this enzyme with respect to its cofactor NAD(+).