Evaluation of the Anti-biofilm Efficacy of Kyotorphin Derivatives and Biosafety Assessment: In Vitro and In Vivo Investigations Targeting Bacterial and Fungal Pathogens

Kyotorphin (KTP) dipeptide (l-Tyrosine-l-Arginine) and their derivatives possess a multitude of functions, qualifying them as "multifunctional peptides." Considering the escalating bacterial resistance to antibiotics, antimicrobial peptides offer a promising road, forming the central focus of this current investigation. The effectiveness of KTP derivatives, GABA-KTP-NH₂ and Indol-KTP-NH₂, were assessed for biofilm inhibition in bacterial and fungal strains. The viability of these derivatives was tested in fibroblasts and B16-F10-Nex2 cells. In vivo toxicity was evaluated using the model organisms Galleria mellonella and Danio rerio. Notably, both GABA-KTP-NH₂ and Indol-KTP-NH₂ derivatives effectively hindered biofilm formation in E. coli, S. pneumoniae, and C. krusei. In the G. mellonella model, the derivatives exhibited significant larval survival rates in toxicity tests, while in infection tests, they demonstrated efficient treatment against the evaluated microorganisms. Conversely, zebrafish assays revealed that Indol-KTP-NH₂ induced substantial mortality rates in embryos after 72 and 96 h of exposure. Similarly, the GABA-KTP-NH₂ derivative exhibited heightened lethality, noticeable at the 100 μM concentration after the same exposure periods. Importantly, toxicity assessments unveiled a relatively lower toxicity profile, coupled with a reduced potential for inducing abnormalities. These results highlight the necessity of employing a comprehensive approach that integrates diverse techniques to thoroughly assess toxicity implications.