Antimicrobial peptides from diverse families isolated from the skin of the Asian frog, Rana grahami

J. Michael Conlon, Nadia Al-Ghaferi, Bency Abraham, Hu Jiansheng, Pascal Cosette, Jérôme Leprince, Thierry Jouenne, Hubert Vaudry

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40 Citations (Scopus)


Seven peptides with antimicrobial activity were isolated in pure form from an extract of the skin of the Yunnanfu Kunming frog Rana grahami Boulenger, 1917. The peptides were identified as belonging to the nigrocin-2 (three peptides), brevinin-1 (one peptide), brevinin-2 (three peptides), and esculentin-1 (one peptide) families. Nigrocin-2GRb (GLFGKILGVGKKVLCGLSGMC) containing three lysine residues, represented the peptide with highest potency against microorganisms (MIC = 3 μM against Escherichia coli, 12.5 μM against Staphylococcus aureus and 50 μM against Candida albicans) and the greatest hemolytic activity against human erythrocytes (LD50 = 40 μM). In contrast, nigrocin-2GRa (GLLSGILGAGKHIVCGLSGLC) and nigrocin-2GRc (GLLSGILGAGKNIVCGLSGLC), with only a single lysine residue, showed weak antimicrobial and hemolytic activity. Phylogenetic relationships among Eurasian ranid frogs are less well understood than those of North American ranids but the primary structures of the R. grahami antimicrobial peptides suggest a close relationship of this species with the Japanese pond frogs R. nigromaculata and R. porosa brevipoda.

Original languageEnglish
Pages (from-to)2111-2117
Number of pages7
Issue number9
Publication statusPublished (in print/issue) - Sept 2006


  • Antimicrobial peptides
  • Brevinin
  • Esculentin
  • Frog skin
  • Nigrocin


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