Effects of ferrocene position isomerization on the self-assembly behavior and antibacterial effect of coupled cationic peptides / 中国药房

ABSTRACT

OBJECTIVE To design the two isomers of ferrocene （Fc）-coupled cationic peptides （hereinafter referred to as “peptides”） [Fc-K（C8）FFHK and C8-K（Fc） FFHK] and the control peptide [C8-K（C8）FFHK]， and to explore the effects of Fc position isomerization on the self-assembly behavior and antibacterial effect of peptides. METHODS All isomerized peptides were prepared by standard solid-phase synthesis and purified by reversed-phase high-performance liquid chromatography. The stability of the peptide was analyzed by using UV spectrophotometry to detect UV absorption spectra， and Zeta potential analyzer to determine Zeta potential. The secondary structure was characterized by circular dichroism spectrum （CD）， Fourier transform infrared spectrometer （FTIR）， thioflavin T （ThT） fluorescence spectrum and transmission electron microscopy （TEM）. The differences in antibacterial activity and biocompatibility of the 2 kinds of isomerized peptides were evaluated by in vitro reactive oxygen species （ROS） generation test， growth curve determination test， plate method， cytotoxicity assay and hemolysis test. RESULTS Three peptides with purity higher than 95% were synthesized. The stability test results showed that the UV absorption spectra of Fc-K（C8）FFHK and C8-K（Fc）FFHK remained almost unchanged when placed at room temperature for 24 and 96 hours， and their Zeta potential were decreased by 0.3 mV and 0.5 mV， respectively. Secondary structure characterization results showed that Fc-K（C8）FFHK and C8-K（Fc）FFHK were self-assembled to form twisted nanoribbons and short nanofibers， respectively； C8-K（C8）FFHK was assembled into cylindrical nanofibers. The optical spectrum results showed that there were certain differences in the content of structures such as β-sheet and α-helix. The in vitro ROS generation test results showed that ROS generation efficiency of Fc-K（C8）FFHK at pH 6.0 was higher than C8-K（Fc）FFHK. The results of in vitro antibacterial activity showed that for methicillin-resistant Staphylococcus aureus， both the isomeric peptides had similar minimum inhibitory concentration （MIC） values of 50 μg/mL which were far lower than the control peptide （400 μg/mL）. To Escherichia coli， Fc-K（C8）FFHK had better antibacterial activity than C8-K（Fc）FFHK. Finally， cytotoxicity assay and hemolysis test results showed that both isomeric peptides had good biocompatibility. CONCLUSIONS By wangjingwen8021@163.com coupling Fc， the antibacterial activity of cationic self-assembled peptides can be improved. Regulating the position of Fc in the peptide sequence could regulate the self-assembly behavior and antibacterial effect of the self-assembled peptides.