Cheng Jianjun, Khin Kay T, Jensen Gregory S, Liu Aijie, Davis Mark E
Insert Therapeutics, Inc, 2585 Nina Street, Pasadena, California 91107, USA.
Bioconjug Chem. 2003 Sep-Oct;14(5):1007-17. doi: 10.1021/bc0340924.
6(A),6(D)-Bis-(2-amino-2-carboxylethylthio)-6(A),6(D)-dideoxy-beta-cyclodextrin 1, a diamino acid derivative of beta-cyclodextrin, is synthesized and condensed with difunctionalized PEG comonomers to give linear, high molecular weight (M(w) over 50 kDa) beta-cyclodextrin-based polymers (2-4) with pendant functionality (carboxylate). 2-4 are all highly soluble in aqueous solutions (over 200 mg/mL). 20-O-trifluoroglycinylcamptothecin, 5a, and 20-O-trifluoroglycinylglycinylglycinylcamptothecin, 5b, are synthesized and conjugated to 2 to give polymer-camptothecin (CPT) prodrugs. The solubility of CPT is increased by more than three orders of magnitude when it is conjugated to 2. The rates of CPT release from the conjugates HGGG6 (high molecular weight polymer (M(w) 97 kDa), glyglygly linker and 6 wt % CPT loading) and HG6 (high MW polymer (M(w) 97 kDa), gly linker and 6 wt % CPT loading) in either mouse or human plasma are dramatically accelerated over the rates of pure hydrolysis at pH = 7.4, indicating the presence of enzymatic cleavage as a rate-determining step at this pH in the release of the CPT. The pH of aqueous solution has a large effect on hydrolysis rate of CPT from HGGG6 and HG6; the lower the pH, the slower the rate in the range at 4.1 <or= pH <or= 13.1. The IC(50)'s of polymer 2e, CPT, and the CPT conjugates HG6 and HGGG6 are found to be cell-line dependent with LS174T, HT29, A2780, and PC3 cells using in vitro MTT assays. The parent polymer 2e has very low toxicity to all cultured cells tested.
6(A),6(D)-双-(2-氨基-2-羧基乙硫基)-6(A),6(D)-二脱氧-β-环糊精1，一种β-环糊精的二氨基酸衍生物，被合成并与双官能化聚乙二醇共聚单体缩合，得到具有侧链官能团（羧酸盐）的线性、高分子量（Mw超过50 kDa）的基于β-环糊精的聚合物（2 - 4）。2 - 4在水溶液中均具有高溶解性（超过200 mg/mL）。合成了20 - O - 三氟甘氨酰喜树碱（5a）和20 - O - 三氟甘氨酰甘氨酰甘氨酰喜树碱（5b），并将它们与2偶联，得到聚合物 - 喜树碱（CPT）前药。当CPT与2偶联时，其溶解度增加了三个多数量级。在小鼠或人血浆中，共轭物HGGG6（高分子量聚合物（Mw 97 kDa），甘氨酰甘氨酰甘氨酸连接子和6 wt% CPT负载量）和HG6（高分子量聚合物（Mw 97 kDa），甘氨酸连接子和6 wt% CPT负载量）中CPT的释放速率比在pH = 7.4时纯水解的速率显著加快，表明在该pH下，酶促裂解是CPT释放的速率决定步骤。水溶液的pH对CPT从HGGG6和HG6的水解速率有很大影响；在4.1≤pH≤13.1范围内，pH越低，速率越慢。使用体外MTT试验发现，聚合物2e、CPT以及CPT共轭物HG6和HGGG6的IC50值取决于细胞系，所使用的细胞系为LS174T、HT29、A2780和PC3细胞。母体聚合物2e对所有测试的培养细胞毒性非常低。
