First bioprospecting study of skin host: Defense peptides in Odontophrynus americanus

Abstract

The amphibians adaptation to diverse environments is closely related to the characteristics of their skin. The complex glandular system of frogs skin plays a pivotal role in enabling these animals to thrive in both aquatic and terrestrial habitats, and comprise crucial functions such as respiration, water balance, as well as serving as a defensive barrier due to the secretion of bioactive compounds. We herein report the first investigation on the skin secretion of O. americanus, as a potential source of bioactive peptides and also as an indicator of its evolutionary adaptations to changing environments. Americanin-1 was isolated and identified as a neutral peptide exhibiting moderate antibacterial activity against E. coli. Its amphipathic sequence including 19 amino acids and showing a propensity for alpha-helix structure, is discussed. Comparisons of the histomorphology of the skin of O. americanus with other previously documented species within the same genus revealed distinctive features in the Patagonian specimen, differing from conspecifics from other Argentine provinces. The presence of the Eberth-Katschenko layer, a prevalence of iridophores, and the existence of glycoconjugates in its serous glands, suggest that the integument is adapted to retain skin moisture. This adaptation is in line with the prevailing aridity of its native habitat.