ecdysteroid conjugate
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1987 ◽  
Vol 4 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Malcolm J. Thompson ◽  
Mark F. Feldlaufer ◽  
Ruben Lozano ◽  
Huw H. Rees ◽  
William R. Lusby ◽  
...  

1985 ◽  
Vol 2 (3) ◽  
pp. 227-236 ◽  
Author(s):  
Malcolm J. Thompson ◽  
Gunter F. Weirich ◽  
Huw H. Rees ◽  
James A. Svoboda ◽  
Mark F. Feldlaufer ◽  
...  

1984 ◽  
Vol 217 (3) ◽  
pp. 783-789 ◽  
Author(s):  
D R Greenwood ◽  
L N Dinan ◽  
H H Rees

The stereochemistry of hydroxylation at C-2 during the biosynthesis of ecdysone in the ovaries of Schistocerca gregaria was investigated by incorporation of [1 alpha,2 alpha-3H(n)]cholesterol in admixture with [4-14C]cholesterol into oöcyte 2-deoxyecdysone and ecdysone conjugates in maturing adult female S. gregaria. Extraction of the eggs followed by enzymic hydrolysis of the ecdysteroid conjugate fraction yielded free ecdysteroids, from which 2-deoxyecdysone and ecdysone were purified. The 3H/14C ratios in the 2-deoxyecdysone and ecdysone were similar, suggesting that the 2 alpha hydrogen of cholesterol was retained during hydroxylation at C-2. This was corroborated by oxidation at C-2 of the 3,22-diacetate derivative of the ecdysone, yielding the corresponding 2-oxo compound with removal of essentially all the 3H originally present at the 2 alpha position of cholesterol. The results indicate that the 2 beta hydrogen of cholesterol has been eliminated during the hydroxylation at C-2. Thus, during ecdysone biosynthesis, hydroxylation at C-2 is direct and occurs with retention of configuration.


1984 ◽  
Vol 217 (1) ◽  
pp. 239-243 ◽  
Author(s):  
R E Isaac ◽  
H P Desmond ◽  
H H Rees

A major ecdysteroid conjugate, which accumulates in the eggs of the desert locust, Schistocerca gregaria, during the later stages of embryogenesis, has been isolated by reversed-phase and anion-exchange high-performance liquid chromatography. Hydrolysis of the conjugate with a crude arylsulphatase preparation from Helix pomatia liberates mainly ecdysone 3-acetate. The compound was identified as 3-acetylecdysone 2-phosphate by phosphate analysis of an acid-hydrolysed sample, fast atom bombardment, electron impact and chemical ionization mass spectrometry and 1H and 13Cn.m.r. spectroscopy. The instability of 3-acetylecdysone 2-phosphate on storage results in the formation of ecdysone 2-phosphate, which was identified by physicochemical techniques. 3-Acetylecdysone 2-phosphate and ecdysone 2-phosphate are less susceptible than ecdysone 22-phosphate to hydrolysis in vitro by an enzyme preparation from S. gregaria embryos. The possible role of 3-acetylecdysone 2-phosphate as an inactive end product of ecdysteroid metabolism is discussed.


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