新型顺铂给药系统的制备及其生物活性评价

Novel Delivery System of Cisplatin: Preparation and Evaluation of its Antitumor Activity

以生物发酵法获得的γ-聚谷氨酸经酸降解后得到小分子γ-聚谷氨酸(γ-PGA),柠檬酸(CA)通过酯化反应修饰其侧链羧基制备γ-聚谷氨酸-柠檬酸(γ-PGA-CA),再将顺铂(CDDP)与γ-PGA-CA上的羧基相结合制备得载药复合物γ-PGA-CA-CDDP,凝胶色谱法测定分子量,OPDA法测定载药量及有效结合率,透析法结合HPLC研究其对顺铂的缓释效果,MTT法检测复合物的体外抗肿瘤活性,采用新鲜兔血检测载体材料及复合物的溶血性。实验结果表明:成功获得γ-PGA-CA及γ-PGA-CA-CDDP,该复合物相对分子质量约为66k,有效结合率达65%,载药率达16%～20%,48 h时顺铂的累计释放率达到50%,MTT检测显示该复合物对肿瘤细胞具有良好的抑制效果,相对于游离顺铂具有较低的毒性,且无溶血性。因此,γ-PGA-CA可作为药物载体,γ-PGA-CA-CDDP具有潜在的临床应用价值。

γ-Glutamyl citrate （γ-PGA-CA） conjugate, a new water soluble polymer as drug carrier was synthesized by conjugation of γ-PGA with citric acid. It was then conjugated with CDDP to yield γ-PGA-CA-CDDP. The average molecular weight was determined by gel permeation chromatography （GPC）. The sustained release profile was investigated using dialysis method and the amount of cisplatin released determined using HPLC. MTT assay was used to investigate the in-vitro antitumor activity of the conjugate. Assay for hemolysis was performed on freshly collected rabbit blood. The results showed that the average molecular weight of γ-PGA-CA-CDDP was 66k. The conjugated yield （cisplatinum/γ-PGA-CA-CDDP） was 20% with conjugation efficiency of approximately 65%. The conjugate delivery system sustained the release of CDDP in PBS at 37 ℃with an initial burst release during the first 8 h and 50% cumulative release in 48 h. The MTT assay showed thatγ-PGA-CA-CDDP could well inhibit the tumor cells,less toxic effects than uneonjugated CDDP, and produce no hemolysis. Therefore, γ-PGA-CA can be used as a drug carrier and γ-PGA-CA-CDDP may have the potential clinical application.