Vancomycin, a glycopeptide antibiotic, has long been a drug of choice for life-threatening Gram-positive bacterial infections. Vancomycin confers its antibacterial activity by inhibiting bacterial cell wall biosynthesis. However, over the time, vancomycin has also been rendered ineffective by vancomycin-resistant bacteria (VRB). These bacteria developed resistance to it by alteration of cell wall precursor from D-Ala-D-Ala to D-Ala-D-Lac (vancomycin-resistant Enterococci, VRE), which leads to manifold reduction in the binding constant and results in the loss of antibacterial activity. Herein, we report various vancomycinâsugar analogs, based on a simple design rationale, which exhibit increased binding affinity to VRB, thereby resensitizing VRB to vancomycin. Optimized vancomycinâsugar conjugate exhibited 150-fold increase in affinity for N,Nâ²-diacetyl-Lys-D-Ala-D-Lac compared with vancomycin. This improved binding affinity was also reflected in its antibacterial activity, wherein the MIC value was brought down from 750 to 36âμM against VRE (VanA phenotype). To further sensitize against VRE, we appended lipophilic alkyl chain to optimized vancomycinâsugar conjugate. This lipophilicâvancomycinâsugar conjugate was >1000-fold (MIC=0.7âμM) and 250-fold (MIC=1âμM) more effective against VanA and VanB strains of VRE, respectively, compared with vancomycin. Therefore, this synthetically simple approach could lead to the development of new generation of glycopeptide antibiotics, which can be clinically used to tackle VRB infections.
万古霉素是一种糖肽抗生素,长期以来一直是治疗危及生命的革兰氏阳性细菌感染的首选药物。
万古霉素通过抑制细菌细胞壁的
生物合成来发挥其抗菌活性。然而,随着时间的推移,
万古霉素也被
万古霉素抗性细菌(VRB)所抵消。这些细菌通过将细胞壁前体从D-Ala-D-Ala改变为D-Ala-D-Lac(
万古霉素抗性肠球菌,VRE)而对其产生了抗性,这导致结合常数大幅降低,进而造成抗菌活性的丧失。在此,我们报告了多种
万古霉素–
糖类类似物,基于简单的设计原理,这些类似物对VRB表现出更强的结合亲和力,从而使VRB对
万古霉素重新敏感。优化后的
万古霉素–
糖类结合物对N,N′-
二乙酰-Lys-D-Ala-D-Lac的亲和力比
万古霉素提高了150倍。这种亲和力的提升也反映在其抗菌活性上,MIC值从750降低到36μM(针对VRE,VanA表型)。为了进一步增强对VRE的敏感性,我们在优化的
万古霉素–
糖类结合物上附加了脂溶性烷基链。该脂溶性–
万古霉素–
糖类结合物对VanA和VanB型VRE表现出分别>1000倍(MIC=0.7μM)和250倍(MIC=1μM)的效力,相比于
万古霉素。因此,这种合成简单的方法可能导致新一代糖肽抗生素的开发,可以在临床上用于应对VRB感染。