Antidermatophytic activity of synthetic peptides: Action mechanisms and clinical application as adjuvants to enhance the activity and decrease the toxicity of Griseofulvin

• Published in: Mycoses Vol. 63; no. 9; pp. 979 - 992
• Main Authors: Souza, Pedro F. N., Lima, Patrícia G., Freitas, Cleverson D. T., Sousa, Daniele O. B., Neto, Nilton A. S., Dias, Lucas P., Vasconcelos, Ilka M., Freitas, Larissa B. N., Silva, Rafael G. G., Sousa, Jeanlex S., Silva, Ayrles F. B., Oliveira, Jose T. A.
• Format: Journal Article
• Language: English
• Published: Berlin Wiley Subscription Services, Inc 01.09.2020
• Subjects: action mechanisms; Adjuvants; antifungal activity; Atomic force microscopy; Cell walls; clinical application; Dermatomycosis; dermatophytosis; Erythrocytes; Fluorescence microscopy; Fungi; Griseofulvin; Hydrophobicity; Microscopy; Peptides; Reactive oxygen species; Scanning electron microscopy; synergism; Synthetic peptides; Toxicity; Trichophyton
• ISSN: 0933-7407; 1439-0507
• DOI: 10.1111/myc.13138

Background Dermatophytes belonging to the Trichophyton genus are important human pathogens, but they have developed resistance to griseofulvin, the most common antifungal drug used to treat dermatophytosis. Objective This study was aimed to evaluate the antidermatophytic activity of synthetic peptides, as well as mechanisms of action and synergistic effect with griseofulvin. Methods Scanning electron microscopy (SEM), atomic force microscopy (AFM) and fluorescence microscopy (FM) were employed to understand the activity and the mechanism of action of peptides. Results Here we report that synthetic peptides at 50 μg/mL, a concentration 20‐fold lower than griseofulvin, reduced the microconidia viability of T. mentagrophytes and T. rubrum by 100%, whereas griseofulvin decreased their viability by only 50% and 0%, respectively. The action mechanism of peptides involved cell wall damage, membrane pore formation and loss of cytoplasmic content. Peptides also induced overproduction of reactive oxygen species (ROS) and enhanced the activity of griseofulvin 10‐fold against both fungi, suggesting synergistic effects, and eliminated the toxicity of this drug to human erythrocytes. Docking analysis revealed ionic and hydrophobic interactions between peptides and griseofulvin, which may explain the decline of griseofulvin toxicity when mixed with peptides. Conclusion Therefore, our results strongly suggest six peptides with high potential to be employed alone as new drugs or as adjuvants to enhance the activity and decrease the toxicity of griseofulvin.