Chitosan, a cationic polysaccharide derived from one of the most abundant natural polymers, chitin, has been investigated extensively for its antimicrobial properties. However, it suffers from the inherent drawbacks of natural products such as batch-to-batch variability, limited supply, contamination, and potential adverse reaction. Additionally, its solubility depends on the degree of deacetylation and pH, as it is only soluble under acidic conditions. As an alternative to chitosan, we synthesized the protected cationic glycomimetic monomer methyl N-Fmoc-6-acryloyl-β-d-glucosaminoside from glucosamine. This monomer retains structural features critical to recapitulating the properties of the chitosan repeat unit, namely, the pKa of the protonated amine. We optimized the free radical polymerization of methyl N-Fmoc-6-acryloyl-β-d-glucosaminoside and fractionated the resultant poly(methyl N-Fmoc-6-acryloyl-β-d-glucosaminoside) to obtain a range of molecular weights. Following Fmoc deprotection, the cationic glycopolymers retained 95% of their expected amine content by mass and exhibited a pKa of 6.61. Poly(methyl 6-acryloyl-β-d-glucosaminoside) mimicked the molecular weight-dependent bacterial inhibitory property of chitosan in acidic solutions. Importantly, poly(methyl 6-acryloyl-β-d-glucosaminoside) remained soluble at elevated pH (conditions under which chitosan is insoluble) and maintained its antibacterial activity. Mammalian cell viability in the presence of poly(methyl 6-acryloyl-β-d-glucosaminoside) at acidic pH is good, although somewhat lower than viability in the presence of chitosan. No cytotoxic effect was observed at neutral pH. These results demonstrate that poly(methyl 6-acryloyl-β-d-glucosaminoside) is not only a suitable biomimetic for chitosan, but that it can be utilized as an antibacterial agent in a broader range of biologically relevant pHs.
壳聚糖是一种从几丁质(最丰富的天然
多糖之一)中提取的阳离子
多糖,因其抗菌特性而受到广泛研究。然而,它存在天然产品的固有缺陷,如批次间差异、供应有限、污染以及潜在的不良反应。此外,其溶解性依赖于脱乙酰度和pH值,只有在酸性条件下才能溶解。作为
壳聚糖的替代品,我们合成了受保护的阳离子
糖类模拟单体甲基N-Fmoc-6-
丙烯酰基-β-
D-葡萄糖胺苷酸。该单体保留了重现
壳聚糖重复单元特性的关键结构特征,即质子化胺的pKa值。我们优化了甲基N-Fmoc-6-
丙烯酰基-β-
D-葡萄糖胺苷酸的自由基聚合反应,并将所得聚合物进行了分子量分级。在Fmoc脱保护后,这些阳离子
糖类聚合物保留了其预期胺含量95%的质量,并展现出6.61的pKa值。聚甲基6-
丙烯酰基-β-
D-葡萄糖胺苷酸在酸性溶液中模拟了
壳聚糖与分子量相关的细菌抑制特性。重要的是,在升高的pH值条件下(
壳聚糖不溶于此条件),聚甲基6-
丙烯酰基-β-
D-葡萄糖胺苷酸仍然保持溶解性并维持其抗菌活性。在使用酸性pH值的聚甲基6-
丙烯酰基-β-
D-葡萄糖胺苷酸时,哺乳动物细胞的存活率良好,尽管略低于使用
壳聚糖时的存活率。在中性pH下未观察到细胞毒性效应。这些结果表明,聚甲基6-
丙烯酰基-β-
D-葡萄糖胺苷酸不仅是一个合适的
壳聚糖生物模拟物,而且可以在更广泛的与
生物相关的pH范围内作为抗菌剂使用。