Chemical studies on the antifeedants in the skin secretion of the ranid frog Grandilana rugosa against predatory snakes

2017 Fiscal Year Final Research Report

• Project/Area Number: 26660096
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Bioorganic chemistry
• Research Institution: Toyama Prefectural University
• Principal Investigator: Oku Naoya 富山県立大学, 工学部, 講師 (90525388)
• Co-Investigator(Renkei-kenkyūsha): KUWAHARA Shigefumi 東北大学, 大学院農学研究科・生物産業創成科学専攻 (30170145)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: ツチガエル / 苦味 / ヘビ忌避 / 悪臭 / ペプチド / 呈味性

Outline of Final Research Achievements

Many reptiles and amphibians secrete odor and/or toxins from their skins. These secretions have been believed to repel predators, although no experimental verification has been made.
A ranid Glandirana rugosa is known to emit nuisance odor and bitter sweat when threatened. Moreover, the skin secretion evoked regurgitaion in predator snakes when applied to the surface of prey frogs. To give a chemical verification to the odor and taste of skin secretion, responsible substances were pursued. A non-lethal procedure to collect skin secretion, as well as an efficient volatile-capturing technique named "dry headspace sampling", was established for the conservation of this endangered species. The collected skin secretion was fractionated by a sequence of chromatography guided by tasting, which resulted in the isolation of a 24-residue peptide named rugosamarin A. A GC-MS analysis of the skin volatiles identified three odorants, which partly reproduced the characteristic odor of this animal.

Free Research Field

天然物化学