To study the effect of the sugar chains in glycoalkaloids against cancer cells, 6-O-sulfated solamargine and acid-catalyzed hydrolytic products of α-solamargine and α-solasonine were prepared. The sulfation at O-6 of solamargine was proceeded in five steps. The 6-OH group was first selectively protected with DMT-Cl, and then the secondary hydroxyl groups on the sugar ring were acetylated. After the protective group DMTr was removed, the free 6-OH group was sulfated. Finally, the acetyl groups were removed to give 6-O-sulfated solamargine in a good yield. The hydrolyses of solamargine and solasonine were performed in diluted hydrogen chlorede. Three and two hydrolyzed products were obtained from solamargine and solasonine, respectively. The antiproliferative activities against HCT-8 tumor cells of two glycoalkaloids and their derivaties were examined via a MTT assay. The results show that α-solamargine and α-solasonine exhibit strong cytotoxic activities with an IC50 of 10.63 and 11.97 μmol/L, respectively, wheras their derivaties seem to be less activities.