ABSTRACT

To improve the therapeutic potential of β-cyclodextrin (β-CD)-threaded acid-degradable polyrotaxanes (β-CD PRXs) in cholesterol-related metabolic disorders, we investigated the effect of carboxylation of β-CD PRXs on intracellular uptake. In this study, we established a synthetic method for the modification of carboxylalkyl carbamates on β-CD PRXs without degradation and synthesized three series of carboxyalkyl carbamate group-modified β-CD PRXs with different alkyl spacer lengths. The modification of carboxymethyl carbamate (CMC), carboxyethyl carbamate (CEC), and carboxypropyl carbamate (CPC) on the β-CD PRXs slightly reduced the interaction of the PRXs with the lipid layer model compared with the modification of 2-(2-hydroxyethoxy)ethyl carbamate (HEE-PRX), which was used in our previous studies. However, all the carboxylated β-CD PRXs showed a significantly stronger interaction with a protein model compared with HEE-PRX. The carboxylated β-CD PRXs showed significantly high intracellular uptake, through macrophage scavenger receptor A (MSR-A)-mediated endocytosis, in MSR-A-positive RAW 264.7 cells compared with HEE-PRX. Interestingly, the carboxylated β-CD PRXs also showed significantly higher intracellular uptake even in MSR-A-negative cells compared with HEE-PRX. Carboxylated β-CD PRXs are considered to strongly interact with other membrane proteins, resulting in high intracellular uptake. The length of the alkyl spacer affected the intracellular uptake levels of carboxylated PRXs, however, this relationship was varied for different cell types. Furthermore, none of the carboxylated β-CD PRXs exhibited cytotoxicity in the RAW 264.7 and NIH/3T3 cells. Altogether, carboxylation of β-CD PRXs is a promising chemical modification approach for their therapeutic application because carboxylated β-CD PRXs exhibit high cellular internalization efficiency in MSR-A-negative cells and negligible toxicity.

 抽象的

为了提高β-环糊精（β-CD）线状酸可降解聚轮烷（β-CD PRX）在胆固醇相关代谢性疾病中的治疗潜力，我们研究了β-CD PRX的羧化对细胞内摄取的影响。在本研究中，我们建立了一种在不降解的情况下对β-CD PRX进行羧基烷基氨基甲酸酯修饰的合成方法，并合成了三个系列的具有不同烷基间隔长度的羧烷基氨基甲酸酯基团修饰的β-CD PRX。与2-(2-羟基乙氧基)的修饰相比，β-CD PRX上的羧甲基氨基甲酸酯(CMC)、羧乙基氨基甲酸酯(CEC)和羧丙基氨基甲酸酯(CPC)的修饰略微降低了PRX与脂质层模型的相互作用）氨基甲酸乙酯（HEE-PRX），在我们之前的研究中使用过。然而，与 HEE-PRX 相比，所有羧化 β-CD PRX 与蛋白质模型的相互作用明显更强。与 HEE-PRX 相比，在 MSR-A 阳性 RAW 264.7 细胞中，通过巨噬细胞清道夫受体 A (MSR-A) 介导的内吞作用，羧化 β-CD PRX 显示出显着较高的细胞内摄取。有趣的是，与 HEE-PRX 相比，即使在 MSR-A 阴性细胞中，羧化 β-CD PRX 也表现出显着更高的细胞内摄取。羧化 β-CD PRX 被认为与其他膜蛋白强烈相互作用，导致细胞内高摄取。烷基间隔基的长度影响羧化 PRX 的细胞内摄取水平，然而，这种关系对于不同的细胞类型是不同的。此外，羧化β-CD PRX 在 RAW 264.7 和 NIH/3T3 细胞中均未表现出细胞毒性。 总而言之，β-CD PRX 的羧化对于其治疗应用来说是一种有前途的化学修饰方法，因为羧化的 β-CD PRX 在 MSR-A 阴性细胞中表现出高细胞内化效率和可忽略不计的毒性。