title: Polyunsaturated monoglycerides and a pregnadiene in defensive glands of the water beetle Agabus affinis.
abstract: In addition to the C21 steroid 15alpha-hydroxypregna-4,6-dien-3,20-dione, four 1- or 2-acylated polyunsaturated monoglycerides, 1- or 2-(cis-5,8,11,14-eicosatetraenoyl)-glycerol and 1- or 2-(cis-5,8,11,14,17-eicosapentaenoyl)glycerol were identified as constituents of the prothoracic defensive gland secretion of the dytiscid beetle Agabus affinis by gas chromatography-mass spectrometry of trimethylsilylated gland extracts. In a feeding assay with minnows, synthetic samples of the two 2-acylated monoglycerides showed only a weak activity as a feeding deterrent. For that reason, other possible functions of the monoglycerides are discussed, such as roles as emulsifiers of cannabimimetics.
authors.affiliation: University of Bayreuth, Department of Animal Ecology II, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Schaaf
authors.forename: K
authors.initials: K
authors.lastname: Dettner
mesh_terms: D000818:Animals; D001681:Biological Assay; D001517:Coleoptera / Q000737:chemistry*; D003530:Cyprinidae; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005989:Glycerides / Q000737:chemistry*; D008297:Male; D013256:Steroids / Q000737:chemistry; D013696:Temperature; D013909:Thorax / Q000378:metabolism*
chemical_list: D005989:Glycerides; D013256:Steroids