Investigation of the effects of TOAP2 derivative (LI-15) designed with database filtering technology against pathogeneic microorganisms

Antimicrobial peptides (AMPs) are important components of the innate immune system and are small molecules with a broad antimicrobial spectrum synthesized by bacteria, fungi, plants, and animals. The emergence of antibiotic resistance as a serious global health threat has increased the need for novel and effective antimicrobial agents, positioning AMPs as promising alternative biological molecules. However, certain limitations of natural AMPs, such as toxicity and stability, have increased interest in synthetically designed peptides. Recent advances in bioinformatics have enabled the rational design of AMPs with target specificity, low toxicity, and high efficacy. In this study, an AMP was designed using "database filtering technology," and the antibiofilm peptide ToAP2 was analyzed to design a novel derivative, LI-15. The antimicrobial, antibiofilm, and cytotoxic properties of LI-15 were evaluated in vitro, and its secondary structure was characterized using FTIR and CD spectroscopy. Antimicrobial activity was tested via microdilution and time-kill kinetics assays, while antibiofilm activity was assessed using crystal violet staining and SEM analysis. Cytotoxicity was evaluated using MTT and LDH assays with human fibroblast (HDFa) cells. Additionally, the effect of LI-15 on biofilm-related virulence genes was analyzed by qRT-PCR. The results demonstrated that LI-15, designed for the first time through a bioinformatic approach, exhibited antimicrobial and antibiofilm activity under in vitro conditions and had a low cytotoxicity profile. These findings suggest that LI-15 is a promising candidate as a novel antibiofilm peptide.