The elucidation of the multimodal action of the investigational anti- Candida lipopeptide (AF 4 ) lead from Bacillus subtilis

• Published in: Frontiers in molecular biosciences 2023-12, Vol.10, p.1248444-1248444
• Main Authors: Ramesh, Swetha, Roy, Utpal, Roy, Subhashis
• Format: Article
• Language: English
• Subjects: apoptosis; Candida albicans; drug-resistance silica gel-based chromatography; lipopeptide; membrane disruption; Molecular Biosciences; oxidative damage
• ISSN: 2296-889X; 2296-889X
• DOI: 10.3389/fmolb.2023.1248444

species are the main etiological agents for candidiasis, and are the most common infectious species. species' growing resistance to conventional therapies necessitates more research into novel antifungal agents. Antifungal peptides isolated from microorganisms have potential applications as novel therapeutics. AF a -derived lipopeptide demonstrating broad-spectrum antifungal activity has been investigated for its ability to cause cell death in species via membrane damage and oxidative stress. Using biophysical techniques, the secondary structure of the AF lipopeptide was identified. Scanning electron microscopy and confocal microscopy with fluorescent dyes were performed to visualise the effect of the lipopeptide. The membrane disruption and permeabilization were assessed using the 1,6-diphenyl hexatriene (DPH) fluorescence assay and flow cytometric (FC) assessment of propidium iodide (PI) uptake, respectively. The reactive oxygen species levels were estimated using the FC assessment. The induction of apoptosis and DNA damage were studied using Annexin V-FITC/PI and DAPI. -derived antifungal variant AF was found to have structural features typical of lipopeptides. Microscopy imaging revealed that AF damages the surface of treated cells and results in membrane permeabilization, facilitating the uptake of the fluorescent dyes. A loss of membrane integrity was observed in cells treated with AF due to a decrease in DPH fluorescence and a dose-dependent increase in PI uptake. Cell damage was also determined from the log reduction of viable cells treated with AF . AF treatment also caused elevated ROS levels, induced phosphatidylserine externalisation, late-stage apoptosis, and alterations to nuclear morphology revealed by DAPI fluorescence. Collectively, the mode of action studies revealed that AF acts primarily on the cell membrane of and has the potential to act as an antifungal drug candidate.