一种天然三萜皂苷的化学合成和抗肿瘤活性研究

目的 合成具有抗炎活性的天然三萜皂苷oleanolic acid 3-O-β-D-glucopyranosyl(1→3)-α-L-rhamnopyranosyl(1→2)-α-L-arabinopyranoside(1)。方法 以齐墩果酸为起始原料，采用逐步糖苷化策略，应用苄基、异丙亚甲基、乙酰氧基、过原酸酯等保护基方法，合成目标产物。以三萜皂苷β-hederin为阳性对照,采用MTT法测试目标物对肿瘤细胞的抑制活性。结果与结论 经13步反应，合成目标化合物，总收率23.7%，目标化合物结构经MS和1H-NMR确证。初步的体外药理实验结果表明，合成的皂苷产物仍然具有较强的肿瘤细胞毒活性。

Chemical synthesis and antitumor activities of a nature triterpenoid saponin

As one class of pentacyclic triterpenoid saponins,oleanane type saponin often presented excellent inhibitory activity against many tumor cells.For example,both α-hederin and β-hederin were reported owning prominent tumor cytotoxities and their unique disaccharides,α-L-rhamnopyranosyl-（1→2）-α-L-arabinopyranoside,was regarded as a determinant moiety,which played an impotant role in the antitumor activity of this type of saponins.Oleanolic acid 3-O-β-D-glucopyranosyl（1→3）-α-L-rhamnopyranosyl（1→2）-α-L-arabinopyranoside（1）,purified from edible plant Aralia elata,also bear this unique disaccharide.Based on our previous work,compound 1 was synthesized via a stepwise glycosylation strategy,and proper protective groups manipulations were applied to ensure the specific glycosylation motifs.Therefore,the first chemical synthesis of the target saponin compound was accomplished in 13 steps with 23.7% overall yield.The structure of the final product was confirmed by MS and 1H-NMR.The result of the preliminary pharmacological study showed that this saponin also displayed moderate tumor cytotoxity.