Identification of a novel antimicrobial peptide, scolopendin 1, derived from centipede Scolopendra subspinipes mutilans and its antifungal mechanism

In this study, a novel antimicrobial peptide, scolopendin 1, was identified from adult centipedes, Scolopendra subspinipes mutilans using RNA sequencing. Scolopendin 1 exerted an antimicrobial activity without inducing haemolysis of human erythrocytes. In order to understand the antifungal mechanism, a reactive oxygen species (ROS) assay was performed, which indicated that scolopendin 1 induced ROS accumulation in Candida albicans. Evaluation of fungal viability using N-acetyl cysteine, a ROS scavenger, suggested that ROS are a major factor in scolopendin 1-induced fungal cell death. Co-staining of annexin V-fluorescein isothiocyanate (FITC) and propidium iodide, and TUNEL and 4′,6-diamidino-2-phenylindole (DAPI) assays confirmed that ROS-induced fungal cell death is associated with apoptosis. To further investigate the mechanism that facilitates the progression of apoptosis, changes in intracellular Ca²⁺ concentration and mitochondrial dysfunction were examined. Ca²⁺, a signalling molecule in the apoptotic pathway, was increased in the cytosol and mitochondria, and ROS accumulation triggered mitochondrial depolarization and the release of cytochrome c, a pro-apoptotic factor, from the mitochondria to the cytosol. Finally, the released cytochrome c activated intracellular caspase. The present study suggests that scolopendin 1 could emerge as a model molecule that targets the apoptotic pathway and provides a novel remedy.