华萝藦C21甾体成分及其逆转肿瘤细胞多药耐药的作用

摘要

The aim of this study was to screen active constituents that reverse multidrug resistance (MDR) in P-glycoprotein (Pgp) overexpressing cancer cells from plant Metaplexis hemsleyana Oliv.(Asclepiadaceae).The aerial parts of M.hemsleyana were extracted with hot ethanol.After removal of ethanol,the concentrated ethanol extract was successively extracted with petrol ether(PE),ethyl acetate(EtOAc) and n-butanol(BuOH) to yield PE,EtOAc and BuOH fractions.Chemical constituents from the BuOH fraction were isolated through silica gel and ODS chromatographic columns.The chemical structures of isolated compounds were identified by comprehensive spectroscopic analysis on their NMR and MS data.Activity of the four compounds in reversing resistance of MDR cancer cells to vinblastine,doxorubicin and paclitaxel was evaluated in Pgp-overexpressing human epidermoid carcinoma cell KB V1,leukemia cell K562/Dox,hepatoma cell HepG2/Dox and cervical carcinoma cell HeLa/Tax.Four compounds were obtained from the BuOH fraction and their structures were identified as tenacissoside H (1),marsdenoside B (2),tenacissoside A (3) and marsdenoside H (4).Compounds 1 and 2 at 5 μM,a non-cytotoxic concentration,significantly reversed the resistance to vinblastine,doxorubicin and paclitaxel in all four MDR cells.At the same concentration,compounds 3 and 4 had no or only weak reversal effect on drug resistance.This is the first report that tenacigenin B derivatives were found from M.hemsleyana and tenacissoside H and marsdenoside B showed activity in reversing MDR in Pgp overexpressing human cancer cells.%华萝藦化学成分的分离鉴定及其逆转P-糖蛋白(P-glycoprotein,Pgp)过表达肿瘤细胞多药耐药(multidrug resistance,MDR)的活性筛选.华萝藦地上部分粗粉经乙醇回流提取并制成石油醚、乙酸乙酯和正丁醇可溶部位,取正丁醇部位经正相、反相硅胶柱层析分离化学成分,采用NMR和MS等波谱学技术鉴定化合物结构,运用Pgp过表达的人宫颈癌细胞HeLa/Tax、肝癌细胞株HepG2/Dox、白血病细胞株K562/Dox和口腔上皮癌细胞株KB V1为模型,评价其逆转细胞对Pgp转运底物类抗肿瘤药物长春碱、多柔比星和紫杉醇耐药的作用.结果显示,华萝藦正丁醇部位中首次鉴定出具有通光散苷元乙母核结构类型的4个酯类化合物Tenacissoside H(1)、Marsdenoside B(2)、Tenacissoside A(3)和Marsdenoside H(4);化合物1和2在5μM的无细胞毒浓度下能显著逆转MDR细胞对长春碱、多柔比星和紫杉醇的耐药,化合物3和4在相同浓度下无此作用或作用较弱.本文首次报道了华萝藦中的C21甾体酯类化合物具有逆转Pgp过表达肿瘤细胞MDR的作用.