From the rhizomes of Dioscorea cayenensis Lam.-Holl (Dioscoreaceae), the new 26-O-β-D-glucopyranosyl-22-methoxy-3β,26-dihydroxy-25(R)-furost-5-en-3-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (1) was isolated together with the known dioscin (2) and diosgenin 3-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (3). Their structures were established on the basis of spectral data. Compound 2 exhibited antifungal activity against the human pathogenic yeasts Candida albicans, C. glabrata and C. tropicalis (MICs of 12.5, 12.5 and 25 µg/mL, respectively) whereas 3 showed weak activity and 1 was inactive.

The aim of this review is to update current knownledge on the betulinic, ursolic and echinocystic acids and their natural and semisynthetic analogs, focussing on their cytotoxic and anti-HIV activities. Then, the last results of the authors team on unusual semisynthetic derivatives of these triterpenoids will be presented in order to establish structure / activity relationships.