scholarly journals Mosquito repellents in frog skin

2006 ◽  
Vol 2 (2) ◽  
pp. 242-245 ◽  
Author(s):  
C.R Williams ◽  
B.P.C Smith ◽  
S.M Best ◽  
M.J Tyler
Keyword(s):  
Frog Skin ◽  
Volatile Components ◽  
Insect Repellents ◽  
Host Seeking ◽  
Culex Annulirostris ◽  
Litoria Caerulea ◽  
Frog Species ◽  
Mosquito Repellents ◽  
Skin Secretions ◽  
Ectoparasite Infestation

The search for novel insect repellents has been driven by health concerns over established synthetic compounds such as diethyl- m -toluamide (DEET). Given the diversity of compounds known from frog skin and records of mosquito bite and ectoparasite infestation, the presence of mosquito repellents in frogs seemed plausible. We investigated frog skin secretions to confirm the existence of mosquito repellent properties. Litoria caerulea secretions were assessed for mosquito repellency by topical application on mice. The secretions provided protection against host-seeking Culex annulirostris mosquitoes. Olfactometer tests using aqueous washes of skin secretions from L. caerulea and four other frog species were conducted to determine whether volatile components were responsible for repellency. Volatiles from Litoria rubella and Uperoleia mjobergi secretions were repellent to C. annulirostris , albeit not as repellent as a DEET control. The demonstration of endogenous insect repellents in amphibians is novel, and demonstrates that many aspects of frog chemical ecology remain unexplored.

scholarly journals Skin secretions of Rana saharica frogs reveal antimicrobial peptides esculentins-1 and -1B and brevinins-1E and -2EC with novel insulin releasing activity

2006 ◽  
Vol 188 (1) ◽  
pp. 1-9 ◽  
Author(s):  
L Marenah ◽  
P R Flatt ◽  
D F Orr ◽  
C Shaw ◽  
Y H A Abdel-Wahab
Keyword(s):  
Antimicrobial Peptides ◽  
Insulin Release ◽  
Skin Surface ◽  
Bioactive Molecules ◽  
Peptide Family ◽  
Insulin Secretagogues ◽  
Frog Species ◽  
Molecular Masses ◽  
Skin Secretions ◽  
Toxic Peptides

Skin secretions of Rana saharica were evaluated for the isolation and characterisation of novel insulinotropic peptides. Crude secretions obtained from young adult frogs by mild electrical stimulation of the dorsal skin surface were purified by reverse phase HPLC yielding 80 fractions. In acute 20-min incubations with glucose responsive BRIN-BD11 cells, fractions 36–43, 46–54 and 57–63 significantly stimulated insulin release by 2- to 8-fold compared with 5.6 mM glucose alone. Pooled fractions in the latter two bands were rechromatographed to reveal 9 homogenous peaks, which elicited significant 1.3- to 3.5-fold increases in insulin release (P < 0.05). Structural analysis of the most potent non-toxic peptides was performed by mass spectrometry and automated Edman degradation. This revealed four major insulin-releasing peaks with molecular masses of 2676.9 Da, 3519.3 Da, 4920.4 Da and 4801.2 Da respectively. These peptides were found to be identical to brevinin-1E, brevinin-2EC, esculentin-1 and esculentin-1B, which belong to the group of antimicrobial peptides isolated from skin secretions of various Rana frog species. Preliminary studies on the mechanism underlying the insulinotropic actions of esculentins-1 and -1B suggested possible involvement of both cyclic AMP–protein kinase A and –C-dependent G-protein sensitive pathways. These data indicate that the skin secretions of Rana saharica frogs contain bioactive molecules with significant insulin-releasing activity. Relatives of the brevinin/esculentin peptide family merit further investigation as novel insulin secretagogues.

scholarly journals Discovery of Novel Caeridins from the Skin Secretion of the Australian White’s Tree Frog, Litoria caerulea

2018 ◽  
Vol 2018 ◽  
pp. 1-18
Author(s):  
Lei Li ◽  
Qing Wu ◽  
Xi Wang ◽  
Huimin Lu ◽  
Xinping Xi ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Drug Discovery ◽  
Frog Skin ◽  
Smooth Muscles ◽  
Biologically Active ◽  
Tree Frog ◽  
Skin Secretion ◽  
Bladder Smooth Muscle ◽  
Gram Positive Bacteria ◽  
Litoria Caerulea

Abundant biologically active peptides have been discovered from frog skin secretions, a rich natural source of bioactive compounds with great potential in drug discovery. In this study, three Caeridin peptides, namely, Caeridin-1, S5-Caeridin-1, and Caeridin-a1, were discovered from the skin secretion of the Australian White’s tree frog, Litoria caerulea, for the first time, by means of combining transcriptomic and peptidomic analyses. It also represents the first report on bioactive Caeridins since this family of peptides was initially studied 20 years ago. Chemically synthetic versions of each natural Caeridin demonstrated promising bioactivities either on rat smooth muscles or against microbial growth. Specifically, Caeridin-1 produced contraction of rat bladder smooth muscle, while S5-Caeridin-1 induced relaxation of rat ileum smooth muscle, both at nanomolar concentrations. Moreover, Caeridin-a1 was shown to potently inhibit the growth of the planktonic Gram-positive bacteria Staphylococcus aureus (S. aureus), methicillin-resistant S. aureus (MRSA), and Enterococcus faecalis (E. faecalis), the Gram-negative bacterium, Escherichia coli (E. coli), and the yeast, Candida albicans (C. albicans). The discovery of these Caeridins may induce further intensive and systematic studies of frog skin peptides to promote the discovery of natural templates as lead compounds for drug discovery and therapeutic application.

scholarly journals Antithrombotics from Frog Skin Secretions

2020 ◽  
Vol 120 (10) ◽  
pp. 1351-1351
Author(s):  
Heyu Ni
Keyword(s):  
Frog Skin ◽  
Skin Secretions

Antitumor and angiostatic peptides from frog skin secretions

Amino Acids ◽  
2010 ◽  
Vol 42 (1) ◽  
pp. 385-395 ◽  
Author(s):  
Hanneke van Zoggel ◽  
Yamina Hamma-Kourbali ◽  
Cécile Galanth ◽  
Ali Ladram ◽  
Pierre Nicolas ◽  
...  
Keyword(s):  
Frog Skin ◽  
Skin Secretions
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