Ecdysone isolation

Members of the family Amaranthaceae are known to produce ecdysteroids such as 8-ecdysone (19) and inocosterone (20). From petroleum ether extracts of Amaranthus splnosus Linn. Behari and Andhiwal (21) obtained 8-sitosterol (4), stigmasterol (3), campesterol and cholesterol. From the roots of the same species, Banerji (22) isolated two new saponins, a diglucoside and a triglucoside of o-spinasterol. More recently, Roy et al. (23)... 

As reviewed by Williams (43), ecdysone has been isolated from more than 10 species of conifers, 20 ferns, and 30 flowering plants (out of 1000 species surveyed). A total of 28 different plant ecdysones are known, the most ubiquitous being /3-ecdysone. The ecological significance of /3-ecdysone in plants is unclear. It is not toxic when orally ingested (as feeding larvae would obtain it from a food plant), but there is some evidence that it could be a feeding deterrent in concentrations as low as 1 ppb. Perhaps it serves as a steroid base for other compounds once it is in an insect s metabolic system. 

Another developmental hormone is the juvenile hormone, which predominates early in larval life later ecdysone predominates. It is a methyl ester of the epoxide of a fatty acid derivative, and there is some evidence that its structure differs in different groups of insects. By a series of coincidences, it was discovered that certain paper toweling prevented the European bug, Pyrrhocoris apterus, from developing into sexually mature adults. Instead, an extra one or two larval molts ensued, and all eventually died without being able to complete metamorphosis. The juvenility factor was traced to particular conifers used in American paper pulp, mainly Abies balsamea, Tsuga canadensis, Taxus brevifolia, and Larix laricina. The active principle was isolated and characterized. It... 

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 cDNAs for the glucocorticoid and the oestrogen receptors were isolated more than 15 years ago. They were among the first genes, coding for transcriptional gene activators, to be identified. The family of nuclear receptors is the largest family of transcription factors. Until now, more than 150 different members of the superfamily of nuclear receptors, from worms to insects to humans, have been described. The discovery of an insect receptor for a steroid hormone, ecdysone, indicated that this kind of receptor must have evolved prior to the separation of vertebrates and invertebrates. 

Ecdysone is a steroid that is formed and secreted by the prothoracic glands of immature insects but also by the ovaries of adult female insects. It was first isolated from the silk worm, Bombix mori. Bedstone is the prohormone of the moulting hormone eedysterone, but the prohormone has also effects on its own at other stages of insect development. 

Where functional groups are present which are more readily oxidized than the ether group, multiple reactions can occur. For example, in their total synthesis of (-i-)-tutin and (-i-)-asteromurin A, Yamada et al. observed concomitant oxidation of a secondary alcohol function in the oxidation of the ether (30) with ruthenium tetroxide (equation 24). The same group successfully achieved the simultaneous oxidation of both ether functions of the intermediate (31) in their related stereocontrolled syntheses of (-)-picrotox-inin and (-i-)-coriomyrtin (equation 25). Treatment of karahana ether (32) with excess ruthenium tetroxide resulted in the formation of the ketonic lactone (33) via oxidation of both the methylene group adjacent to the ether function and the exocyclic alkenic group (equation 26). In contrast, ruthenium tetroxide oxidation of the steroidal tetral drofuran (34) gave as a major product the lactone (35) in which the alkenic bond had been epoxidized. A small amount of the 5,6-deoxylactone (17%) was also isolated (equation 27). This transformation formed the basis of a facile introduction of the ecdysone side chain into C-20 keto steroids. 

A detailed survey of the isolation and chemistry of the ecdysones has appeared. The isolation of deoxycrustecdysone (402a), deoxyecdysone (402b), and a-ecdysone (402c) has been reported. The structures of stachysterone A... 

Sterols. A considerable amount of work was devoted to the study of backbone rearrangements. - While partial syntheses of an insect moulting hormone, ecdysone, were announced by several groups, evidence is accumulating on the widespread occurrence in natxire of its hydroxylated derivatives. This year saw the isolation of 20-hydroxy-ecdysone - - from silkworm (ecdysterone), crayfish - (crustecdysone), oak-silk moth, tobacco hornworm, and from plants such as Podocarpus nakaii, Podocarpus elatus, and Achyranthis. The ready isolation of insect-moulting hormones from plants in contrast to -the extremely poor... 

The biosynthesis and metabolism of the insect moulting hormone, ecdysone have been the subject of recent reviews [184-186]. Ecdysone (107) was first isolated in a crystalline form from the silkworm, Bombyx mori, by Butenandt and Karlson in 1954, and the structure was determined in 1965. Soon after, the second moulting hormone was isolated and the structure was elucidated as 20-hydroxyecdysone (108). Ibe same hormone was also isolated from the sea-water crayfish, Jasus lalandei by Horn in 1966. Many ecdysone analogues were isolated from arthropods and certain... 

Since the elucidation of the structure of ecdysone, a number of synthetic cholesterol derivatives have been demonstrated as possible intermediates in the conversion of cholesterol into ecdysone. However, few attempts have been made to isolate the intermediates of ecdysone synthesis in the PG. Only 3j8-hydroxy-5a-cholestan-6-one (111) was isolated from the organ culture medium of the silkworm PG as a possible intermediate [193]. The PG possesses a comparatively large percentage of 7-dehydro-cholesterol (110) in several insects. Thus, 7-dehydrocholesterol may also be a possible early intermediate in the transformation of cholesterol into ecdysone [194]. 

Many endogenous ecdysteroids which can be considered as the intermediates of ecdysone biosynthesis were isolated from the ovaries of L. migratoria by Hoffmann and Horn [204]. From the results of the bioconversion of labelled precursors, the following sequence in the biosynthetic pathway of ecdysteroids in vitellogenic ovaries of the insect was proposed conversion of cholesterol to 3)3-hydroxy-5)8-cholest-7-en-6-one followed by 14a-hydroxylation to 3/S,14-dihydroxy-5/6-cholest-7-en-6-one (112) hydroxylation at C-25 and C-22 (in this order) to 2-deoxyecdysone (114) hydroxylation at C-2 to ecdysone (107). 

Butenandt and Karlson (1954) isolated the moulting hormone and called it a-ecdysone (80). The elucidation of its structure is associated with the name of Karlson et al. (Karlson et al., 1963 Huber and Hoppe, 1965 Hoppe and Huber, 1965). 

Horn, D. H. S., Wilkie, J. S. and Thompson, J. A. (1974) Isolation of /3-ecdysone (20-hydroxyecdysone) from the parasitic nematode Ascaris lumbricoides. Experientia 30 110 ... 

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