- Naturally occurring 20, 26-dihydroxyecdysone exists as two C-25 epimers which exhibit different degrees of moulting hormone activity
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20,26-Dihydroxyecdysone (20,26-ECD) isolated from Vitex canescens, V. glabrata and V. pinnata has been shown to exist as two C-25 epimers. Synthesis and separation of the two epimers were accomplished and they exhibited different degree of moulting hormone activity in the Musca assay.
- Suksamrarn, Apichart,Yingyongnarongkul, Boon-Ek,Promrangsan, Nart
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- Dimeric ecdysteroid analogues and their interaction with the Drosophila ecdysteroid receptor
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Three structurally related specific ecdysteroid derivatives, 7,7′-dimers of 14-deoxy-8(14)-ene transformed 20-hydroxyecdysone, ponasterone A and ajugasterone C, were obtained by photochemical transformation. The structures of the dimeric ecdysteroids were identified mainly by NMR spectroscopy supported by MS and IR spectroscopy. Yields of the dimerisation products were dependent on the reactant concentrations and photoreaction conditions. Inert gas atmosphere supported high yields, whereas oxygen atmosphere fully prevented the dimer formation. All the three dimers retained a rather high agonistic activity at the ecdysteroid receptor in the Drosophila BII bioassay when compared with the relevant original ecdysteroids.
- Harmatha, Juraj,Budesinsky, Milos,Vokac, Karel,Dinan, Laurence,Lafont, Rene
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p. 1229 - 1238
(2008/03/28)
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- Asymmetric dihydroxylation of stachysterone C: Stereoselective synthesis of 24-epi-abuasterone
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Stachysterone C was synthesized from 20-hydroxyecdysone (20-ECD). Sharpless asymmetric dihydroxylation of this rare ecdysteroid using osmium tetroxide and a chiral ligand afforded 24-epi-abutasterone, another rare ecdysteroid, and its C-24 epimer, abutasterone. High diastereomeric excess of the former ecdysteroid was obtained when the chiral ligands dihydroquinidine 1,4-phthalazinediyl diether and dihydroquinidine 2,5-diphenyl-4,6-pyrimidinediyl diether were employed. The two C-24 epimeric ecdysteroids exhibited similar moulting hormone activity in the Musca bioassay. However, they were significantly less active than 20-ECD.
- Yingyongnarongkul, Boon-Ek,Suksamrarn, Apichart
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p. 2795 - 2800
(2007/10/03)
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