Antimicrobial, antifungal and antioxidant activity from the mucus cocoon of the Parrotfish (Genus Scarus : Laboridei: Scaridae)

Abstract

The ocean harbors one of the largest sources of important bioactive molecules due to the complex, dynamic nature of the various ecosystems and biodiversity interactions. The complexity and inaccessibility of certain species or component of a species make it difficult to collect and preserve samples for testing. In this study, the cocoon produced by Parrotfishes (genus Scarus) at night was collected using scuba diving techniques and tested for antimicrobial, antifungal, and antioxidant properties. Five extracts (crude, acidic, aqueous 1, aqueous 2, and organic) were obtained from the mucus and antimicrobial tests were carried out using well diffusion and minimal inhibitory concentration (MIC) against the following bacteria: Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, Klebsiella pneumoniae ATCC 700603, Salmonella enterica ATCC 13076, Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa ATCC 27853 and four fungi: Fusarium equiseti ATCC 200472, Alternaria spp. (environmental isolate), Guignardia citricarpa (environmental isolate) and Candida albicans ATCC 10231. The 1-diphenyl-2-picrylhydrazyl (DPPH) assay was used to measure the scavenging activity of the extracts. The acidic extract showed the highest (11.56 mm) zone of inhibition (ZOI) against E. coli and the MIC (0.406 mg/ml). In terms of ZOI, the least effective extracts were the crude (2.67 mm) followed by the aqueous 1 (3.33 mm) while for the MIC the least effective extract was the aqueous 2 (13 mg/ml). Significant inhibition was observed on the gram-negative bacteria compared to gram-positive bacteria in both methods. Regarding the antifungal assay, the organic extract was most effective against C. albicans (9.03 mm), and only the acidic extract showed inhibition zone (14.0 mm) against Guignardia citricarpa. The aqueous 2 extract exhibited the highest inhibition (71.96 %), while the crude extract showed the lowest inhibition (34.11 %). The present findings indicate that Parrotfish mucus can further be explored in terms of its pharmacological properties.