Ecdysteroids 20-hydroxyecdysone

Meng Y, Whiting P, Sik V, Rees HH, Dinan L (2001) Limnantheoside C (20-hydroxyecdysone 3-0-beta-D-glucopyranosyl-[1 3]-beta-D-xylopyranoside), a phytoecdysteroid from seeds of Limnanthes alba (Limnanthaceae). Zeitschrift fur Naturforschung 56 988-994 Sarker SD, Girault JP, Lafont R, Dinan L (1997) Ecdysteroid xylosides from Limnanthes douglasii. Phytochemistry 44 513-521... 

Fig. 4.4. HPLC fractionation of the free ecdysteroid fraction from Moniezia expansa (a) sample 1, 3.3% portion (bj sample 2, 10% portion on a chromatographic system with collection of fractions every minute for the radioimmunoassay (RIA) (ICT-1 antiserum). The positions of authentic ecdysteroids are shown IV, 20, 26-dihydroxyecdysone II, 20-hydroxyecdysone I, ecdysone. (After Mendis et al., 1984.)...

Lin et al. [149] have recently reported the synthesis of 2-(4,5-dimethoxy-2-nitrobenzyl)-20-hydroxyecdysone (6-6), which itself has a very low affinity for ecdysteroid receptors expressed in mammalian 293T cells, but can be photolysed at 348 nm to release 20E, which then activates the receptor-regulated reporter gene. With this system, it will be possible not only to control the temporal activation of transfected genes, but also their spatial activation. The authors recognise that the effectiveness of this system can be considerably improved in future by derivatising an ecdysteroid (poA or muA) which is more active in ecdysteroid-responsive mammalian cells. 

Table 7 Relative potencies of known ecdysteroid antagonists in the Drosophila melanogaster Bn bioassay. EC50 values were determined in the presence of 5 x 10 8M 20-hydroxyecdysone. Only compounds for which it was possible to determine distinct EC50 values are included.

Scheme 3). A clone of cells from the midge Cbironomus tentans was found to be resistant to the effects of ecdysteroids because they metabolized 20-hydroxyecdysone rapidly. The initial oxidation product was 20,26-dihydroxyecdysone, but this was oxidized further to 20-hydroxy-26-oxo-ecdysone (21). This aldehyde (21) then formed a tautomeric equilibrium mixture of two cyclic hemiacetals (22) and (23), which were separable, isolated, and their structures determined (Scheme 3) with the use of acetonides (Section 4.03.3.6).32 These are the first examples of ecdysteroids with side-chain hemiacetals. Although 20,26-dihydroxyecdysterone still... 

The plant-insect chemical interactions concerning the stilbenoids have just been reviewed [509] (-i-)-Ampelopsin B (806) and ct-viniferin (635) antagonized the action of 20-hydroxyecdysone [510] cw-miyabenol A (735), kobophenol B and cw-miyabenol C (663) showed competitive binding to ecdysteroid receptors [337] resveratrol (1) and oligomers (suffruticosols A-C, 589-591) also exhibited ecdysteroid antagonistic activity [297]. 

The biosynthesis of ecdysteroids in filarial worms has been studied [75]. It has been shown that D. immitis and Brugia pahangi can not synthesize ecdysteroids from cholesterol. Further, no evidence was available to support the conversion of ecdysone (14) to 20-hydroxyecdysone (15). Not withstanding the fact that the basic studies regarding endocrinology of female worms are still not elaborate, interference of ecdysteroid biosynthesis and function in female helminths may provide... 

Ecdysteroids All ecdysteroids used in this work were a kind gift of Prof. Dr. Jan Koolmann, University of Marburg. They were ecdysone, 20-hydroxyecdysone, makisterone and muristerone for the growth experiments, as well as radiolabeled ponasterone A for the binding assay. Preparation of stock solutions, sterilization and addition to media was exactly the same as for brassinosteroids. 

Molecular modelling of ecdysteroids (7) and brassinosteroids is still in its infancy. A comparison of the three dimensional (3D-) structures of the two biologically most active representatives of brassinosteroids and ecdysteroids, i.e. of brassinolide and 20-hydroxyecdysone, suggests that functional groups relevant for bioactivity are found at similar positions in both molecules in spite of the structural differences mentioned above. More detailed comparative studies of the 3D-structures of ecdysteroids and brassinosteroids are eagerly awaited. 

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