Biotransformation of betulinic and betulonic acids by fungi

The biotransformation of betulinic (R = OH) and betulonic acid (R = O) by Arthrobotrys sp., Colletotrichum sp., Chaetophoma sp. and Dematium sp. oxidized the molecules at C-3, C-7, C-15, C-25 and C-30, respectively.