Antimicrobial properties of bioactive compounds isolated from epidermal mucus in two Ray species (Dasyatis marmorata and Gymnura altavela)

Purpose: To investigate the occurrence and antimicrobial effects of certain biochemical compounds in the epidermal mucus secretions of fish and to demonstrate their potential for biomedical applications. Methods: Crude, aqueous, and acidic epidermal mucus samples were collected from live ray specimens. Gas chromatography and gas chromatography-mass spectrometry (GC/MS) analyses were performed to identify the biochemical compounds present in the mucus. The spectrophotometric broth microdllution method was used to determine the antibacterial and antifungal properties of the mucus extracts. The bacterial strains, Bacillus subtilis, Escherichia coli, Enterococcus faecalis, and Klebsiella pneumonia, were used for the tests, as well as the fungal strains, Candida parapsilosis and Candida albicans. Results: GC/MS analysis revealed the presence of several hydrocarbon-derived compounds in the epidermal mucus of the two ray species. The acidic extract of G. altavela epidermal mucus produced a high MIC value, indicating the highest inhibitory effect of 8.64 mu L against E. coli, while the crude extract of G. altavela epidermal mucus (41.13 mu L against B. subtilis) was the least effective. Conclusion: Epidermal mucus extracts, especially when acid-based, displays strong antimicrobial properties against all the tested pathogens. These findings suggest the plants possess some potential for the development of novel antimicrobial components for applications in medicine.