Synthesis of betulin derivatives and their protective effects against the cytotoxicity of cadmium.

The protecting effect of betulin against cadmium toxicity was investigated using 11 kinds of analogues. It was elucidated by analyzing the analogue activities that both hydroxyl groups on C-3 and C-28 and the isopropenyl group on C-19 played important roles for expressing efficient activities. In addition, the cytotoxicity of betulin was also reduced by being functionalized using the above functional group.