A Review of Natural and Modified Betulinic, Ursolic and Echinocystic Acid Derivatives as Potential Antitumor and Anti-HIV Agents

The aim of this review is to update current knowledge 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.