聚乙二醇修饰埃坡霉素B偶联物的合成及其体外抗肿瘤作用

目的 埃坡霉素B（EPOB）在治疗恶性肿瘤方面处于临床研究状态。为改善其水溶性,本文合成了聚乙二醇（PEG）修饰的EPOB偶联物PEG5000-EPOB和PEG20 000-EPOB。方法 采用N,N-二环己基碳二亚胺作为缩合剂，4-二甲氨基吡啶作为催化剂的酯化方法，将相对分子质量分别为5000和20 000的PEG-COOH与EPOB偶联。通过1H NMR 和MALDI-TOF-MS对合成产物进行结构表征。用UPLC测定产物在水中的溶解度。MTT法评价偶联物对人乳腺癌细胞MCF-7的细胞毒性。结果 结构鉴定表明，EPOB与PEG按照1∶1发生偶联且偶联位点是EPOB的7-OH。 PEG5000-EPOB和PEG20 000-EPOB的溶解度分别为4.93×10-2和1.58×10-2 ml/L，与EPOB的溶解度1.4×10-3mol/L相比分别提高了35倍和11倍。EPOB、PEG5000-EPOB和PEG20 000-EPOB对人乳腺癌细胞系的IC50值分别为6.0×10-4、5.7×10-4和8.4×10-3μmol/L。结论 PEG修饰EPOB后溶解度提高，且修饰后的化合物具有体外细胞毒性，为进一步的研究奠定了基础。

Synthesis and in vitro cytotoxicity of polyethylene glycol-epothilone B conjugates

Objective Natural epothilone B （EPOB） is currently used in clinical trials for the treatment of advanced cancers. To improve its water solubility, two polyethylene glycol（PEG）-EPOB conjugates, PEG5000-EPOB and PEG20 000-EPOB, were synthesized. Methods The products were synthesized using carbodiimide chemistry and confirmed by 1H NMR and MALDI-TOF-MS. The solubility of PEG5000-EPOB and PEG20 000-EPOB were determined by UPLC. Moreover, the cytotoxicity of conjugates was evaluated on human breast cancer MCF-7 cells using a MTT based assay. Results Structural identification indicated that one PEG molecule conjugated exactly one EPOB molecule and PEGylation only took place at the site of 7-OH of EPOB. The solubility of PEG5000-EPOB and PEG20 000-EPOB was 4.93×10-2 and 1.58×10-2 mol/L, which had improved 35 times and 11 times over free EPOB, 1.4×10-3 mol/L, respectively. Moreover, the IC50 values of EPOB, PEG5000-EPOB and PEG20 000-EPOB on human breast cancer MCF-7 cells were 6.0×10-4, 5.7×10-4 and 8.4×10-3 μmol/L, respectively. Conclusion PEGylation can improve the water solubility of EPOB and keep its cytotoxicity to human breast cancer MCF-7 cells.