Activity of the antimicrobial peptide probrelin from traditional Chinese medicine grub against Candida albicans

Abstract:

[Objective] To investigate the activity of the peptide probrelin from traditional Chinese medicine grub against Candida albicans. [Methods] The broth microdilution method was used to determine the MIC of probrelin against normal and clinical resistant strains of C. albicans, and the MFC were determined by plate count method. Time-kill curves were drawn by plate counting after treatment with different concentrations of probrelin. The influences of probrelin on the integrity of the cell membrane and morphology of C. albicans were evaluated by PI absorption experiment and scanning electron microscope, respectively. The binding effect between probrelin and nucleic acid was evaluated by DNA gel retardation assay. Crystal violet staining method was used to evaluate the influences of probrelin on the formation of biofilm and mature biofilm of C. albicans. And the influences of probrelin on the hyphae formation of C. albicans were also tested. Checkerboard method was used to determine the interaction between probrelin and antifungal drugs. And a mouse subcutaneous infection model was used to tested the activity of probrelin against C. albicans under physiological conditions. [Results] The MICs of probrelin against normal and clinical resistant strains of C. albicans were 100 μg/mL, and the MFCs were 100-200 μg/mL. Probrelin showed time-and concentration-dependent antifungal activity against C. albicans, as well as on the integrity of the cell membrane, and could destroy the cell wall, but did not bind with nucleic acids. Probrelin not only inhibited the formation of the biofilm of C. albicans, but also disrupted the mature biofilm, and could also inhibit the hyphae formation. Furthermore, probrelin showed synergistic effect with the antifungal drug Clotrimazole, and could effectively clear C. albicans cells in the mouse subcutaneous infection model. [Conclusion] Probrelin showed good activity against C. albicans, and had the potential for the development of anti-C. albicans drugs.

Key words:traditional Chinese medicine;antimicrobial peptides;Candida albicans;biofilm;synergistic effect