Host Defense Peptides from Asian Frogs as Potential Clinical Therapies

Abstract

Host defense peptides (HDPs) are currently major focal points of medical research as infectious microbes are gaining resistance to existing drugs. They are effective against multi-drug resistant pathogens due to their unique primary target, biological membranes, and their peculiar mode of action. Even though HDPs from 60 Asian frog species belonging to 15 genera have been characterized, research into these peptides is at a very early stage. The purpose of this review is to showcase the status of peptide research in Asia. Here we provide a summary of HDPs from Asian frogs.

pH Dependent Antimicrobial Peptides and Proteins, Their Mechanisms of Action and Potential as Therapeutic Agents

“…Similar PE mediated mechanisms have been proposed to mediate the resistance of microbes to other AMPs [104,105], supporting the growing view that receptors could play a variety of roles in the biological activities of these peptides [23,98,106,107,108]. Esculentin-2EM (E2EM, previously gaegurin 4) is an α-helical peptide isolated from the frog, Glandirana emeljanovi (formerly Rana rugosa ) [109,110], that is able to kill protozoa, fungi, Gram-positive bacteria and Gram-negative bacteria [110,111,112]. E2EM possesses a C-terminal cyclic region stabilized by a disulphide bond (Rana box) that is conserved across many ranid AMPs and helps stabilize pore formation by the peptide thereby promoting its antimicrobial action (Figure 1) [109,110,112,113,114,115].…”

An Atlas of Anionic Antimicrobial Peptides from Amphibians

“…Many of these peptides are pleiotropic. For example, some antimicrobial peptides (AMPs) exhibit antibacterial, antifungal, antiviral and anticancer action [7][8]. Amphibian skin is a particularly rich repository of AMPs [5][6] and was the source of one of the first of these peptides to be discovered, namely magainin from Xenopus laevis in the early 1980s [9].…”

First report of Lividin and Spinulosain peptides from the skin secretion of an Indian frog

“…Low antimicrobial activity of some skin derived peptides are hypothesized to be due to the presence of symbiotic bacteria on the skin surface of amphibians that play defensive roles, which can survive only in less toxic environment [2] or they may have antioxidant or synergistic action with other peptides [3]. However, the biological roles of such peptides, enhanced by post-translational modification or synthetic analogues could not be ruled out in a therapeutic context [6]. The name Lividin was first proposed for peptides isolated from Odorrana livida [8].…”

“…nos: KR995268, KR995269). Both the peptides are cationic with +6 and +2 charges (which is the primary factor responsible for the interaction between biological membrane and peptide [6]), respectively and are hydrophilic (Table 1A). They exhibit weak antimicrobial activity against both Gram-positive and Gramnegative bacteria (Table 1B) and showed no haemolytic activity against human red blood cells even at a higher concentration of 175 µM.…”

“…Development of Host Defense peptide (HDP) libraries from the skin secretion of amphibians is currently gaining momentum not only because of their characteristic feature to disrupt biological membranes [6] but also their proposed therapeutic potentials. HDPs are a cocktail of compounds, especially peptides, having broad spectrum biological activities which act as a first line of defense and secreted upon stress or injury [2].…”