Sustainable bioprospecting and circular economy approach: fractionation and identification of bioactive peptides from lusitanian toadfish (halobatrachus didactylus) mucus

Bioactive molecules from marine organisms, especially the Halobatrachus didactylus, also known as the Lusitanian toadfish, native to the Portuguese coast, remains largely unexplored. It is important to use sustainable bioprospecting practices to protect both the species and its ecosystem (1). Therefore, by adopting a circular economy approach, we can maximize the sustainable use of marine resources by sampling fish in a non-harmful way (e.g. mucus collection) and returning them to their natural habitat, thus allowing these organisms to thrive in their ecosystems. Fish mucus acts as a natural barrier from the surrounding environment, acting as a first line of defense, for instance, against pathogens (2,3). In this study, we carefully collected H. didactylus mucus using a synthetic sponge to ensure no physical harm to the fish and to minimize stress by reducing handling time. We evaluated the potential bioactivities of the body mucus and characterized its peptide fraction composition. The body mucus of H. didactylus exhibited promising antioxidant, antihypertensive, and antimicrobial activities (4). The body mucus peptide profile was obtained using size exclusion chromatography, revealing a prominent peak ca. 800 Da. Using LC-MS/MS, we identified several peptide sequences from the mucus peptide fraction and selected five of them based on their predicted bioactivities in silico. We then validated the bioactivities through in vitro assays. Peptides with the amino acid sequences EDNSELGQETPTLR (HdKTLR), DPPNPKNL (HdKNL), PAPPPPPP (HdPPP) and VYPFPGPLPN (HdVLPN) showed antibiofilm potential against P. aeruginosa. HdVLPN and PFPGPLPN (HdLPN) exhibit significant antioxidant activity, while HdPPP demonstrates antihypertensive and antidiabetic activities. In conclusion, this study not only underscores the therapeutic potential of H. didactylus peptides but also serves as a model for sustainable bioprospecting practices that align with circular economy principles.