In order to highlight the potential of photodynamic antimicrobial chemotherapy in case of infections by antibiotic resistant-strains, a new antimicrobial peptide conjugate has been synthesized, consisting of a derivative of polymyxin B and a cationic porphyrin covalently attached together to a spacer. A polymyxin-derived moiety was subjected to a primary structural modification in the replacement of four diaminobutyrate residues with lysine ones. This modification was done in order to strongly reduce bactericidal activity, with the aim to eliminate the potential rise of polymyxin-resistant strains. Despite this modification, this new conjugate displayed a strong photobactericidal activity against Gram-positive as well as Gram-negative bacteria. It was further shown that this conjugate was able to strongly stick to the cell walls of either kind of strain, thus helping to inactivate bacteria through the production of reactive oxygen species under light irradiation.

中文翻译：

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多粘菌素B的赖氨酸类似物是光动力抗菌化学疗法的重要机会。

为了突出在抗生素抗性菌株感染的情况下光动力抗菌化学疗法的潜力，已经合成了一种新的抗菌肽缀合物，其由多粘菌素B的衍生物和共价连接到间隔子上的阳离子卟啉组成。在用赖氨酸取代四个二氨基丁酸酯残基的过程中，对多粘菌素衍生的部分进行了主要的结构修饰。进行这种修饰是为了强烈降低杀菌活性，目的是消除多粘菌素抗性菌株的潜在上升。尽管进行了这种修饰，但是这种新的结合物对革兰氏阳性细菌和革兰氏阴性细菌仍显示出强大的光杀菌活性。