Peptidomic analysis of norepinephrine-stimulated skin secretions from Italian stream frog Rana italica led to the purification and characterization of two host-defense peptides differing by a single amino acid residue belonging to the brevinin-1 family (brevinin-1ITa and -1ITb), a peptide belonging to the temporin family (temporin-ITa) and a component identified as prokineticin Bv8. The secretions contained relatively high concentrations of the methionine-sulphoxide forms of brevinin-1ITa and -1ITb suggesting that these peptides may have a role as antioxidants in the skin of this montane frog. Brevinin-1ITa (IVPFLLGMVPKLVCLITKKC) displayed potent cytotoxicity against non-small cell lung adenocarcinoma A549 cells (LC50 = 18 μM), breast adenocarcinoma MDA-MB-231 cells (LC50 = 8 μM) and colorectal adenocarcinoma HT-29 cells (LC50 = 18 μM), but the peptide was also strongly hemolytic against mouse erythrocytes (LC50 = 7 μM). Temporin-ITa (VFLGAIAQALTSLLGKL.NH2) was between three and fivefold less potent against these cells. Brevinin-1ITa inhibited growth of both Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli as well as a strain of the opportunist yeast pathogen Candida parapsilosis, whereas temporin-ITa was active only against S. epidermidis and C. parapsilosis. Both peptides stimulated the release of insulin from BRIN-BD11 clonal β-cells at concentrations ≥1 nM, but brevinin-1ITa was cytotoxic to the cells at concentrations ≥3 μM.
- Frog skin
- Antimicrobial peptide
- Insulin release
Conlon, JM., Musale, V., Attoub, S., Mangoni, ML., Leprince, J., Coquet, L., Jouenne, T., Abdel-Wahab, YHA., Flatt, P., & Rinaldi, AC. (2017). Cytotoxic peptides with insulin-releasing activities from skin secretions of the Italian stream frog Rana italica (Ranidae). Journal of Peptide Science, 23(10), 769-776. https://doi.org/10.1002/psc.3025