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J Nat Prod. 2016 Sep 23;79(9):2350-6. doi: 10.1021/acs.jnatprod.6b00494. Epub 2016 Aug 25.

Purification, Conformational Analysis, and Properties of a Family of Tigerinin Peptides from Skin Secretions of the Crowned Bullfrog Hoplobatrachus occipitalis.

Author information

1
SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster , Coleraine, U.K.
2
Department of Chemical and Geological Sciences and Department of Biomedical Sciences, Biochemistry Unit, University of Cagliari , Cagliari, Italy.
3
CNRS UMR 6270, PISSARO, University of Rouen, Institute for Research and Innovation in Biomedicine (IRIB) , Mont-Saint-Aignan, France.
4
Rare Species Conservatory Foundation , St. Louis, Missouri, United States.
5
Instituto Pasteur-Fondazione Cenci Bolognetti, Department of Biochemical Sciences, Sapienza University of Rome , Rome, Italy.
6
Center for Molecular Medicine, Faculty of Medicine, University of Kragujevac , Kragujevac, Serbia.

Abstract

Four host-defense peptides belonging to the tigerinin family (tigerinin-1O: RICTPIPFPMCY; tigerinin-2O: RTCIPIPLVMC; tigerinin-3O: RICTAIPLPMCL; and tigerinin-4O: RTCIPIPPVCF) were isolated from skin secretions of the African crowned bullfrog Hoplobatrachus occipitalis. In aqueous solution at pH 4.8, the cyclic domain of tigerinin-2O adopts a rigid amphipathic conformation that incorporates a flexible N-terminal tail. The tigerinins lacked antimicrobial (MIC > 100 μM) and hemolytic (LC50 > 500 μM) activities but, at a concentration of 20 μg/mL, significantly (P < 0.05) inhibited production of interferon-γ (IFN-γ) by peritoneal cells from C57BL/6 mice without affecting production of IL-10 and IL-17. Tigerinin-2O and -4O inhibited IFN-γ production at concentrations as low as 1 μg/mL. The tigerinins significantly (P ≤ 0.05) stimulated the rate of insulin release from BRIN-BD11 clonal β-cells without compromising the integrity of the plasma membrane. Tigerinin-1O was the most potent (threshold concentration 1 nM) and the most effective (395% increase over basal rate at a concentration of 1 μM). Tigerinin-4O was the most potent and effective peptide in stimulating the rate of glucagon-like peptide-1 release from GLUTag enteroendocrine cells (threshold concentration 10 nM; 289% increase over basal rate at 1 μM). Tigerinin peptides have potential for development into agents for the treatment of patients with type 2 diabetes.

PMID:
27560386
DOI:
10.1021/acs.jnatprod.6b00494
[Indexed for MEDLINE]

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