8-O-acetylharpagide is not an ecdysteroid agonist.
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.
Dinan
L
L
Department of Biological Sciences, University of Exeter, Hatherly Laboratories, Prince of Wales Road, EX4 4PS, Exeter, UK. l.n.dinan@exeter.ac.uk
Whiting
P
P
Bourne
P
P
Coll
J
J
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
D026461:Ecdysteroids; D011714:Pyrans; C077626:8-O-acetylharpagide