Synthesis and Biological Evaluation of Some Pentacyclic Lupane Triterpenoid Esters

This paper presents the biological activity of betulin and betulinic acid derivatives with a fatty acid chain tailing, compared with that of native compounds. Their activity as tumor cell inhibiting agents was tested on two tumor cell lines, A431 (skin epidermoid carcinoma) and A375 (human melanoma). The aim of the chemical acylation was to obtain highly hydrophobic compounds with an improved biological activity and lower side effects. Betulin and betulinic acid derivatives were synthesized following the path of chemical esterification in solvent medium, in the presence of triethylamine and fatty acid chloride. Betulin esterification was focused on both hydroxyl groups, C-3 and C-28, while for betulinic acid only the C-3 position was taken into account, due to previous reports that showed a high biological activity conferred by the C-28 carboxylic acid, and C-30 allylic positions.