Antimicrobial peptides (AMPs) are interesting compounds owing to their ability to kill several pathogens. In order to identify new AMPs, c-PLAI analogues were synthesized and evaluated together with their linear precursors for their antimicrobial properties against two Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus), two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae), and two fungal strains (Candida albicans and Trichophyton mentagrophytes). The new c-PLAI analogues were prepared through a combination of solid- and solution-phase syntheses, as previously employed for the synthesis of c-PLAI. The antimicrobial activity tests showed that the synthetic parent peptide c-PLAI was inactive or weakly active towards the bioindicators employed in the assay. The tests also indicated that cyclic c-PLAI analogues possessed enhanced antimicrobial properties against most of the bacteria and fungi tested. Furthermore, this study revealed that analogues containing cationic lysine residues displayed the highest activity towards most bioindicators. A combination of lysine and aromatic residues yielded analogues with broad-spectrum antimicrobial properties.

抗菌肽（AMPs）由于具有杀死多种病原体的能力而成为令人感兴趣的化合物。为了鉴定新的AMP，合成了c-PLAI类似物并与它们的线性前体一起评估了它们对两种革兰氏阳性细菌（金黄色葡萄球菌和蜡状芽孢杆菌），两种革兰氏阴性细菌（大肠杆菌和肺炎克雷伯菌）的抗菌性能。和两个真菌菌株（白色念珠菌和毛癣菌）。新的c-PLAI类似物是通过固相和溶液相合成的组合制备的，就像以前用于c-PLAI的合成一样。抗菌活性测试表明，合成的母体肽c-PLAI对测定中使用的生物指示剂没有活性或具有弱活性。测试还表明，环状c-PLAI类似物具有增强的对大多数细菌和真菌的抗菌性能。此外，这项研究表明，含有阳离子赖氨酸残基的类似物对大多数生物指示剂显示出最高的活性。赖氨酸和芳香族残基的组合产生具有广谱抗微生物特性的类似物。