Glycoalkaloids（GAS） have important biological and pharmaceutical activities, in order to study the relationship between the structures and the activities of carbohydrate chains, two natural glycoalkaloids, chaconine （compound 1 ） and solanine（ compound 2） , were isolated from potato stems and leaves（ Solanum tuberosum L. ）. The selective sulfation to the 6-hydroxy groups of chaeonine and solanine was carried out in a strategy by the use of protective groups. The 6-hydroxyl groups of the sugar chains in chaconine and solanine were protected with 4,4＇-dimethoxytrityl（DMT） while the other hydroxyl groups were acetylated. The protective group DMT was removed by using 0. 5% TFA in dichloromethane, The free 6-hydroxyl groups were sulfated by chlorosulfonic acid pyridine to give 6-O-sulfated products. After the acetyl groups were removed, the final products obtained were sulfated chaconine and sulfated solanine.^ 13C NMR spectra confirmed that chaconine and solanine were sulfated at O6 of the carbohydrate moiety.
To study the effect of the sugar chains in glycoalkaloids against cancer cells, 6-0-sulfated solamargine and acidcatalyzed hydrolytic products of α-solamargine and α-solasonine were prepared. The sulfation at 0-6 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 6-0-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.
LI Sheng-yu HE Da-jun ZHANG Xu NI Wei-hua ZHOU Yi-fa ZHANG Li-ping
