Skin secretions of Leptodactylidae (Anura) and their potential applications

Abstract

The skin of anuran species is a protective barrier against predators and pathogens, showing also chemical defense by substances that represent a potential source for bioactive substances. This review describes the current chemical and biological knowledge from the skin secretions of Leptodactylidae species, one of the most diverse neotropical frog families. These skin secretions reveal a variety of substances such as amines (12), neuropeptides (16), and antimicrobial peptides (72). The amines include histamine and its methylated derivatives, tryptamine derivatives and quaternary amines. The peptides of Leptodactylidae species show molecular weight up to 3364 Da and ocellatins are the most reported. The peptides exhibit commonly glycine (G) or glycine-valine (GV) as C-terminal amino acids, and the most common N-terminal amino acids are glutamic acid (E), lysine (K), and valine (V). The substances from Leptodactylidae species have been evaluated against pathogenic microorganisms, particularly Escherichia coli and Staphylococcus aureus , and the most active peptides showed MIC of 1-15 µM. Furthermore, some compounds showed also pharmacological properties such as immunomodulation, treatment of degenerative diseases, anticancer, and antioxidant. Currently, only 9% of the species in this family have been properly studied, highlighting a large number of unstudied species such as an entire subfamily (Paratelmatobiinae). The ecological context, functions, and evolution of peptides and amines in this family are poorly understood and represent a large field for further exploration.

First Report of Ocellatin-VT from the Skin Secretion of Leptodactylus vastus Lutz (Amphibia: Leptodactylidae)

“…There are more than forty ocellatins described in the literature, and these peptides are the most abundant peptides found in the skin secretions of Leptodactylidae [10,12]. Glycine is a recurrent amino acid in multiple positions of these peptides [10], which can be observed in the ocellatin-VT from L. vastus.…”

“…There are more than forty ocellatins described in the literature, and these peptides are the most abundant peptides found in the skin secretions of Leptodactylidae [10,12]. Glycine is a recurrent amino acid in multiple positions of these peptides [10], which can be observed in the ocellatin-VT from L. vastus. Carrillo et al [10] also observed that leucine and lysine are often present, which also occurs in ocellatin-VT: leucine appears in five positions while there are four lysine residues.…”

“…Glycine is a recurrent amino acid in multiple positions of these peptides [10], which can be observed in the ocellatin-VT from L. vastus. Carrillo et al [10] also observed that leucine and lysine are often present, which also occurs in ocellatin-VT: leucine appears in five positions while there are four lysine residues.…”

“…and viruses [7][8][9]. Ocellatins are AMPs found in the secretion of leptodactylid a [10]. More than forty ocellatins and their variations have been described in the lit One example is ocellatin-P1, found for the first time in Leptodactylus pentadactyl Ocellatin-P1 showed antibacterial activity against Escherichia coli, Enterobacter Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Staphy epidermidis, and Enterococcus faecalis [12], as well as antitumor activity against the melanoma lineage [13].…”

“…The secretion released through the integument of anurans, mainly by the granular glands, is rich in bioactive peptides and has been the subject of different studies, especially on antimicrobial peptides (AMPs), which act on different targets such as fungi, bacteria, and viruses [7][8][9]. Ocellatins are AMPs found in the secretion of leptodactylid anurans [10]. More than forty ocellatins and their variations have been described in the literature.…”