Thaulin-1: The first antimicrobial peptide isolated from the skin of a Patagonian frog Pleurodema thaul (Anura: Leptodactylidae: Leiuperinae) with activity against Escherichia coli

Abstract

Patagonia's biodiversity has been explored from many points of view, however, skin secretions of native amphibians have not been evaluated for antimicrobial peptide research until now. In this sense, Pleurodema thaul is the first amphibian specie to be studied from this large region of South America. Analysis of cDNA-encoding peptide in skin samples allowed identification of four new antimicrobial peptides. The predicted mature peptides were synthesized and all of them showed weak or null antimicrobial activity against Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli with the exception of thaulin-1, a cationic 26-residue linear, amphipathic, Gly- and Leu-rich peptide with moderate antimicrobial activity against E. coli (MIC of 24.7μM). AFM and SPR studies suggested a preferential interaction between these peptides and bacterial membranes. Cytotoxicity assays showed that thaulin peptides had minimal effects at MIC concentrations towards human and animal cells. These are the first peptides described for amphibians of the Pleurodema genus. These findings highlight the potential of the Patagonian region's unexplored biodiversity as a source for new molecule discovery.

The Antioxidant Peptide Salamandrin-I: First Bioactive Peptide Identified from Skin Secretion of Salamandra Genus (Salamandra salamandra)

“…The peptide sequence was compared with antimicrobial peptides deposited at the antimicrobial peptide database [17]. Physical and chemical parameters (MW, theoretical pI, instability index, aliphatic index, and grand average of hydropathicity, GRAVY) were calculated using the ProtParam website, while hydrophobic moments (µH) and helix wheel projections were determined using the HeliQuest program [18]. Peptide concentration was measured by using the following equation: [peptide concentration] mg/mL = (A 280 × DF × Mw)/ε, where A 280 is the absorbance of the peptide solution at 280 nm in a 1 cm cell, DF is the dilution factor, Mw is the molecular weight of the peptide, and ε is the molar extinction coefficient of tryptophan or tyrosine at 280 nm [19].…”

Identification of Eschweilenol C in derivative of Terminalia fagifolia Mart. and green synthesis of bioactive and biocompatible silver nanoparticles

“…For the biocompatibility study, the haemolytic activity assay was performed using human erythrocytes, collected in tubes containing EDTA (1.8 mg/mL) by spectrophotometric measurement of haemoglobin release after exposure to various concentrations of AgNPs in vitro, according to Marani et al (2016). The red blood cell (RBC) suspension (2%) was mixed with the AgNP solution and AgNO 3 in the concentrations of 0.84-27 μgAg/mL, the mixtures were incubated for 30 min at 35 ± 2°C and then centrifuged at 10,000g for 1 min.…”

An Atlas of Anionic Antimicrobial Peptides from Amphibians

“…He- A number of AAMPs have been reported from South America, including those with the highest levels of negative charge: for example, almost a decade ago, he-1 with a net charge of -8 was identified in the Mountain tree frog, Hyla eximia, which is endemic to Mexico [35]. Most recently, thaulin-4, which also has a net charge -8, was isolated from the Chilean four-eyed frog, Pleurodema thaul, which is widely distributed in Argentina and Chile [36]. In contrast, the Manaus slender-legged tree frog, Osteocephalus taurinus, native to many parts of South America and was found to produce octacidin (net charge -2) in its skin secretions.…”