Betulin and its derivatives – precursors of new drugs
White birch bark extract, used in traditional medicine, has many medical properties. Its main components are betulin and betulinic acid – lupane type pentacyclic triterpenes. The discovery of the anti-tumor and anti-viral properties of betulinic acid has become an impulse to modify the structures of these compounds in order to obtain better activity. Over twenty years of research, several derivatives have been selected that have significantly better anti-tumor or antiviral properties than their precursors. This paper presents all new derivatives of betulin and betulinic acid, which have been tested in phase I, II or III of clinical trials.