Due to the rise of antibiotic-resistant bacteria around the world, AMPs (antimicrobial peptides), depending on non-specific membrane mechanism and low tendency to develop bacterial resistance, attract widespread attentions as novel antimicrobial alternatives for treating bacterial infections. In this study, a series of new β-Ala modified-antimicrobial peptide analogues of anoplin were designed and synthesized, and their biological activities were described. Most of the new peptides showed perfect antimicrobial activities against two antibiotic-sensitive Pseudomonas aeruginosa strains and three clinical isolates of multidrug-resistant P. aeruginosa strains without significant hemolysis or cytotoxicity. More significantly, Ano-1β and Ano-8β (substituting positions 1 and 8 of anoplin with β-Ala, respectively) exhibited the best antimicrobial potency. Additionally, the two new peptides were stable under physiological conditions and displayed preferable in vivo antimicrobial activity with less acute toxicity. Notably, Ano-1β and Ano-8β hardly generated resistance in contrast to conventional antibiotics rifampicin and gentamicin, and they exhibited better anti-biofilm activity and synergistic or additive effects in combination with conventional antibiotics. What’s more, Ano-1β and Ano-8β had strong membrane disruption as evidenced by outer membrane permeabilization and cytoplasmic membrane depolarization assays. Confocal laser scanning microscopy and scanning electron microscopy further demonstrated that the two new peptides could destroy the bacterial membrane integrity. Collectively, the incorporation of β-Ala was a reasonable approach for new antimicrobial peptides design, and the new peptides Ano-1β and Ano-8β might be promising antimicrobial candidates in combating the increasing antibiotic-resistant bacteria.

由于全球耐药菌的兴起，AMPs（抗菌肽），视非特异性膜机制和低耐药性趋势而定，作为治疗细菌感染的新型抗菌替代品引起了广泛的关注。在这项研究中，设计和合成了一系列新的β-丙氨酸修饰的氨苄青霉素抗菌肽类似物，并描述了它们的生物学活性。大多数新肽对两种对抗生素敏感的铜绿假单胞菌菌株和对多药耐药的铜绿假单胞菌的三种临床分离株均表现出完美的抗菌活性。无明显溶血或细胞毒性的菌株。更重要的是，Ano-1β和Ano-8β（分别用β-Ala取代anoplin的1和8位）表现出最佳的抗菌效力。另外，这两种新肽在生理条件下是稳定的，并且在体内显示出较好的抗菌活性，急性毒性较小。值得注意的是，与常规抗生素利福平和庆大霉素相比，Ano-1β和Ano-8β几乎不产生抗药性，并且与常规抗生素结合使用时，它们表现出更好的抗生物膜活性以及协同或累加作用。此外，Ano-1β和Ano-8β具有很强的膜破坏能力，如外膜通透性和细胞质膜去极化分析所证明。共聚焦激光扫描显微镜和扫描电子显微镜进一步证明了这两种新肽可能破坏细菌膜的完​​整性。总的来说，掺入β-丙氨酸是设计新的抗菌肽的合理方法，