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Updated: Aug 5, 2025
Isolation and Identification of Bacterial Strains from Skin of Terrestrial Amphibians
Published on: June 17, 2025
Purification and Biological Properties of Raniseptins-3 and -6, Two Antimicrobial Peptides from Boana raniceps (Cope,
Gabriel Gonçalves de Freitas1,2, João Martins Barbosa1,2, Carlos José Correia de Santana1,2
1Laboratory of Toxinology, Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia 70.910-900, DF, Brazil.
Abstract:
The number of multidrug-resistant pathogenic microorganisms has been growing in recent years, most of which is due to the inappropriate use of the commercial antibiotics that are currently available. The dissemination of antimicrobial resistance represents a serious global public health problem. Thus, it is necessary to search for and develop new drugs that can act as antimicrobial agents. Antimicrobial peptides are a promising alternative for the development of new therapeutic drugs. Anurans' skin glands are a rich source of broad-spectrum antimicrobial compounds and hylids, a large and diverse family of tree frogs, are known as an important source of antimicrobial peptides. In the present study, two novel antimicrobial peptides, named Raniseptins-3 and -6, were isolated from Boana raniceps skin secretion and their structural and biological properties were evaluated. Raniseptins-3 and -6 are cationic, rich in hydrophobic residues, and adopt an α-helix conformation in the presence of SDS (35 mM). Both peptides are active against Gram-negative bacteria and Gram-positive pathogens, with low hemolytic activity at therapeutic concentrations. No activity was observed for yeasts, but the peptides are highly cytotoxic against B16F10 murine melanoma cells and NIH3T3 mouse fibroblast cells. None of the tested compounds showed improvement trends in the MTT and LDH parameters of MHV-3 infected cells at the concentrations tested.
Insights
Two novel antimicrobial peptides, Raniseptins-3 and -6, were isolated from frog skin secretions. These peptides show broad-spectrum antimicrobial activity against bacteria but are cytotoxic to mammalian cells.
Area of Science:
- Biochemistry
- Pharmacology
- Microbiology
Background:
- Growing antimicrobial resistance necessitates novel therapeutic agents.
- Antimicrobial peptides (AMPs) from anuran skin offer a promising alternative to conventional antibiotics.
- Hylid frogs are a known source of diverse AMPs.
Purpose of the Study:
- To isolate and characterize two novel antimicrobial peptides, Raniseptins-3 and -6, from *Boana raniceps* skin secretion.
- To evaluate the structural and biological properties of these novel peptides.
Main Methods:
- Isolation of peptides from *Boana raniceps* skin secretion.
- Structural analysis, including conformational studies in SDS.
- Assessment of antimicrobial activity against various pathogens.
- Evaluation of hemolytic activity and cytotoxicity against mammalian cell lines.
Main Results:
- Raniseptins-3 and -6 are cationic, hydrophobic α-helical peptides.
- Both peptides exhibit activity against Gram-negative and Gram-positive bacteria.
- Low hemolytic activity was observed at therapeutic concentrations.
- No activity against yeasts, but high cytotoxicity against B16F10 melanoma and NIH3T3 fibroblast cells.
- No observed improvement in MHV-3 infected cells.
Conclusions:
- Raniseptins-3 and -6 represent novel antimicrobial peptides with potential therapeutic applications against bacterial infections.
- Their cytotoxic effects on mammalian cells warrant further investigation for targeted drug delivery or specific applications.
- These findings contribute to the exploration of anuran-derived compounds for antimicrobial drug discovery.
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