Abstract

Betulinic acid, a natural product with a lupane-type pentacyclic triterpenoid skeleton, is widely distributed in nature and has been described in more than 200 different plant species as a secondary metabolite. It has been primarily isolated from the genera Betula, Platanus, and Eucalyptus. This compound incorporates a privileged scaffold for pharmacological development, due to its broad variety of promising biological activities that justify its consideration as one of the natural products most deserving of research. In this chapter, its occurrence in relatively high-yielding natural sources, its classical and novel methods of extraction, and its main physical-chemical characteristics, as well as methods of characterization, detection, and quantification are described, together with a historical revision of semisynthetic preparations starting from the more abundant betulin, and chemical approaches to the preparation of related terpenoids. Finally, the principal biological activities of betulinic acid, which include antiinflammatory, antineoplastic and anti-HIV effects, are listed, and its mechanisms of action on biological targets, its pharmacokinetics, and its significance for drug design and discovery are highlighted.