title: 8-O-acetylharpagide is not an ecdysteroid agonist.
abstract: We have reinvestigated the activity of 8-O-acetylharpagide, an iridoid glucoside, as an ecdysteroid agonist. Elbrecht et al. (Insect Biochem. Mol. Biol. 26 (1996) 519) isolated a preparation of this compound from Ajuga reptans L. and ascribed ecdysteroid agonist activity on the basis of the induction of an ecdysteroid-like response in Drosophila melanogaster KcO cells, the displacement of [3H]ponasterone A from the Drosophila receptor and the activation of an ecdysteroid-regulated gene in a transactivation assay. We provide evidence that the agonist activity derives from contaminating ecdysteroids; A. reptans is a species rich in ecdysteroids. Purified 8-O-acetylharpagide is not active in the D. melanogaster B(II) cell bioassay, neither as an agonist nor as an antagonist, nor does it displace [3H]ponasterone A from dipteran or lepidopteran ecdysteroid receptor complexes.
authors.affiliation: Department of Biological Sciences, University of Exeter, Hatherly Laboratories, Prince of Wales Road, EX4 4PS, Exeter, UK. l.n.dinan@exeter.ac.uk
authors.forename: L
authors.initials: L
authors.lastname: Dinan
authors.forename: P
authors.initials: P
authors.lastname: Whiting
authors.forename: P
authors.initials: P
authors.lastname: Bourne
authors.forename: J
authors.initials: J
authors.lastname: Coll
mesh_terms: D000818:Animals; D001681:Biological Assay; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004331:Drosophila melanogaster; D026461:Ecdysteroids / Q000819:agonists*; D015394:Molecular Structure; D011714:Pyrans / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011863:Radioimmunoassay; D013056:Spectrophotometry, Ultraviolet
chemical_list: D026461:Ecdysteroids; D011714:Pyrans; C077626:8-O-acetylharpagide