Isolation and structure of cytostatic steroidal saponins from the African medicinal plant Balanites aegyptica

Bioactivity-guided separation of a CH2Cl2/MeOH extract of Balanites aegyptica afforded four new cytostatic saponins, named balanitins 4 [1], 5 [2], 6 [3], and 7 [4]. On the basis of enzymatic hydrolyses and glycosidation nmr chemical shifts employing the peracetates, structures 1-4 were established as yamogenin 3 beta-O-beta-D-glucopyranosyl-(1----3)-beta-D-glucopyranosyl-(1----4)-[al pha- L-rhamnopyranosyl-(1----2)]-beta-D-glucopyranoside [1], yamogenin 3 beta-O-alpha-L-rhamnopyranosyl-(1----3)-beta-D-glucopyranosyl-(1----4)- [alpha-L-rhamnopyranosyl-(1----2)]-beta-D-glucopyranoside [2], yamogenin 3 beta-O-beta-D-glucopyranosyl-(1----4)-[alpha-L- rhamnopyranosyl-(1----2)]-beta-D-glucopyranoside [3], and diosgenin 3 beta-O-beta-D-xylopyranosyl-(1----3)-beta-D-glucopyranosyl-(1----4)-[alp ha- L-rhamnopyranosyl-(1----2)]-beta-D-glucopyranoside [4].