Bioorg Med Chem. 2005 May 16;13(10):3447-54.
Kvasnica M , Sarek J , Klinotova E , Dzubak P , Hajduch M .
Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University in Prague , Hlavova 8, 128 43 Prague 2, Czech Republic .
Synthesis of 3beta-O-phthalic esters from betulinic acid and its esters and synthesis of phthalic esters from betulin and its monoacetates using classical acylation procedure with phthalic anhydride. The evaluation of cytotoxicity of the prepared compounds was using numbers of tumor cell lines in MTT test. It was discovered that hemiphthalic esters had better cytotoxicity than starting compounds as betulinic acid or quite inactive betulin.