The effect of halogenation on the antimicrobial activity, antibiofilm activity, cytotoxicity and proteolytic stability of the antimicrobial peptide Jelleine-I

Antimicrobial peptides (AMPs) are believed to be a promising class of antimicrobial agents against bacteria and fungi. To promote the clinical use of AMPs, their antimicrobial activity and susceptibility to protease degradation should be further improved. The antimicrobial peptide Jelleine-I was originally isolated from the royal jelly of honeybees (Apis mellifera) with a short sequence of PFKLSLHL-NH₂ (953.24 Da). Here, a series of halogenated derivatives of the antimicrobial peptide Jelleine-I were designed and synthesized. The results showed that the in vitro antimicrobial activity, antibiofilm activity and in vivo antimicrobial efficacy were enhanced 1-8-fold after halogenation. Additionally, the proteolytic stability of Jelleine-I was improved 10-100-fold by halogenation. Meanwhile, the halogenated derivatives retained negligible hemolytic activity and cytotoxicity. Among these derivatives, the antimicrobial activity and antibiofilm activity of chlorine-Jelleine-I (Cl-J-I), bromine-Jelleine-I (Br-J-I), and iodine-Jelleine-I (I-J-I) were better than those of fluorine-Jelleine-I (F-J-I). The stabilities of Br-J-I and I-J-I against the degradation of enzymes and the serum were better than those of F-J-I and Cl-J-I. In conclusion, this study may offer a useful strategy to enhance antimicrobial efficacy and proteolytic stability by halogenation. The halogenated derivatives Cl-J-I, Br-J-I and I-J-I may be considered as potential antimicrobial agents against microbial infection.