Abstract：
Ultrashort cationic lipopeptides (USCLs) are promising antimicrobial agents that may be used to combat pathogens such as bacteria and fungi. USCLs consist of a few basic amino acid residues and at least one lipid moiety, usually a fatty acid chain. Generally, USCLs are potent antimicrobials but their major shortcoming is a relatively high cytotoxicity and hemolytic activity. Glycopeptide antibiotics (e.g. vancomycin) are essential in combating bacterial infections and are popular in medicinal practice. However, literature concerning the effect of glycosylation of peptides on their antimicrobial activity is rather scarce. For the first time, this study highlights the effect of USCLs glycosylation on in vitro biological activity. The aim of this study was to evaluate the impact of glycosylation of a series of USCLs on antimicrobial activity, cytotoxicity and hemolytic activity. Straight-chain fatty acids (C14, C16, C18) were attached to the N-terminal amino group of tripeptides-SRR-NH2, RSR-NH2 and RRS-NH2. Two groups of the lipopeptides were synthetized, the first with unmodified L-serine (USCLs) and the other with L-serine O-glycosylated by N-acetyl-β-d-glucosamine to produce new class of glycosylated ultrashort cationic lipopeptide (gUSCLs). Both USCLs and gUSCLs were tested against planktonic and biofilm cultures of ESKAPE strains (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) and Candida glabrata, and hemolytic activity on human erythrocytes and cytotoxicity against the HaCaT cell line was examined. Generally, USCLs and gUSCLs proved to be active against all the tested strains. The highest activity displayed was by lipopeptides containing the C18 fatty acid. Antimicrobial, hemolytic and cytotoxic activities were mainly correlated with amino acid sequence (position of serine/glycosylated serine) and hydrophobicity of molecule and were found to be highly strain-dependent. In general, glycosylation did not guarantee an increased antimicrobial activity or a decreased hemolytic and cytotoxic activities. However, in some cases, gUSCLs proved to be superior to their USCLs analogs. The most pronounced differences were found for peptides with C18 fatty acid and serine at the first and second position against both planktonic cells and biofilm of C. glabrata, as well as the second and third position against S. aureus. It is noteworthy that gUSCLs were also more active against biofilm than were USCLs.
摘要：
超短阳离子脂肽（USCL）是有前途的抗微生物剂，可用于对抗病原体，例如细菌和真菌。USCL由几个碱性氨基酸残基和至少一个脂质部分组成。通常是脂肪酸链。一般来说,USCL是有效的抗微生物剂,但它们的主要缺点是相对高的细胞毒性和溶血活性。糖肽抗生素(例如万古霉素)在对抗细菌感染中是必需的,并且在医学实践中很受欢迎。然而,有关肽的糖基化对其抗微生物活性的影响的文献相当少。第一次,本研究强调了USCLs糖基化对体外生物活性的影响。这项研究的目的是评估一系列USCL的糖基化对抗菌活性的影响，细胞毒性和溶血活性。将直链脂肪酸（C14，C16，C18）连接到三肽-SRR-NH2，RSR-NH2和RRS-NH2的N末端氨基上。合成两组脂肽，第一种是未修饰的L-丝氨酸（USCL），另一种是由N-乙酰基-β-d-葡糖胺糖基化的L-丝氨酸O-，以产生新型的糖基化超短阳离子脂肽（gUSCL）。USCL和gUSCL均针对ESKAPE菌株的浮游和生物膜培养物进行了测试（屎肠球菌，金黄色葡萄球菌,肺炎克雷伯菌,鲍曼不动杆菌,铜绿假单胞菌,肠杆菌属。)和光滑念珠菌，并检查了对人红细胞的溶血活性和对HaCaT细胞系的细胞毒性。一般来说,USCL和gUSCL证明对所有测试菌株都有活性。显示的最高活性是含有C18脂肪酸的脂肽。抗菌药物,溶血和细胞毒活性主要与氨基酸序列（丝氨酸/糖基化丝氨酸的位置）和分子的疏水性相关，并且发现高度依赖于菌株。总的来说,糖基化不能保证抗菌活性增加或溶血和细胞毒性活性降低。然而,在某些情况下,gUSCL被证明优于其USCL类似物。对于在第一和第二位置具有C18脂肪酸和丝氨酸的肽，针对浮游细胞和光滑梭菌的生物膜，发现了最明显的差异。以及针对金黄色葡萄球菌的第二和第三位置。值得注意的是,gUSCL对生物膜也比USCL更具活性。
