Prospection of bioactive peptides from South America anuran species

Abstract

The secretion of multiple antimicrobial peptides (AMPs) from the skin allows amphibians to occupy moist environments with a high density of microorganisms. Although there are some limitations to their pharmacological applicability, AMPs are suitable candidates for developing new antibiotics, either directly or as templates. The main focus of our BIAPEP research group is the prospecting of peptides of technological interest through the exploration of anurans of Argentine biodiversity. Our current objective is the functional and structural evaluation of antimicrobial peptides present in the skin of amphibians together with the design of improved-performance analogs. To this end, we combined HPLC-MS/MS, molecular biology, and microbiology for peptide identification. We described more than 70 mature host defense peptides from twelve anuran species (Pleurodema thaul, P. bufoninum, P. somuncurence, Odonthophrynus occidentalis, Boana pulchella, B. punctata, B. prasina, Leptodactylus latrans, L. chaquensis, L. pustulatus, Physalaemus albonotatus, Pseudopaludicola boliviana). Identified peptides had between 4 and 69 residues, molecular weights ranged from 892 to 6,022 Da, and net charges from -8 to +4. In silico and structural studies of several peptides were performed. A selected set of these peptides was chemically synthesized, characterized, and tested for their bioactivity. We observed antimicrobial (MIC ≥14µM) and antiparasitic (IC50 ≥10µM) peptides. Additionally, some peptides showed an ability to scavenge radicals in vitro in different systems showing potential antioxidant capacity. The compilation, comparison, and analysis of all identified sequences demonstrate the hypervariability of peptide sequences in the studied species and the relevance of prospection of unexplored biodiversity.