Frog skin constitutes a rich source of
peptides with a wide range of biological properties. These include
host-defense peptides with cytotoxic activities against bacteria, fungi, protozoa, viruses, and mammalian cells. Several hundred such
peptides from diverse species have been described. Although attention has been focused mainly on antimicrobial activity, the therapeutic potential of frog skin
peptides as
anti-infective agents remains to be realized and no compound based upon their structures has yet been adopted in clinical practice. Consequently, alternative applications are being explored. Certain naturally occurring frog skin
peptides, and analogs with improved therapeutic properties, show selective cytotoxicity against
tumor cells and viruses and so have potential for development into anti-
cancer and anti-viral agents. Some
peptides display complex
cytokine-mediated immunomodulatory properties. Effects on the production of both pro-inflammatory and anti-inflammatory
cytokines by peritoneal macrophages and peripheral blood mononuclear cells have been observed so that clinical applications as anti-inflammatory, immunosuppressive, and immunostimulatory agents are possible. Several frog skin
peptides, first identified on the basis of antimicrobial activity, have been shown to stimulate
insulin release both in vitro and in vivo and so show potential as
incretin-based
therapies for treatment of patients with
Type 2 diabetes mellitus. This review assesses the therapeutic possibilities of
peptides from frogs belonging to the Ascaphidae, Alytidae, Pipidae, Dicroglossidae, Leptodactylidae, Hylidae, and Ranidae families that
complement their potential role as anti-infectives for use against multidrug-resistant microorganisms.