Ecdysonoic Acid Research Articles

Distribution and metabolism of exogenous ecdysteroids in the egyptian cotton leafwormSpodoptera littoralis (lepidoptera: noctuidae)

After ingestion of various amounts of either [3H]ecdysone or [3H]20-hydroxyecdysone (0.8 ng to 10 μg) by sixth instar larvae of the Egyptian cotton leafworm Spodoptera littoralis, apolar metabolites are rapidly detected in the gut and frass. Hydrolysis of the apolar products with Helix hydrolases releases solely [3H]ecdysone or [3H]20-hydroxyecdysone, respectively. This, coupled with the formation of chemical derivatives (acetonide and acetate) which cochromatograph with authentic reference compounds on hptlc and hplc demonstrates that these apolar metabolites consist of ecdysone or 20-hydroxyecdysone esterified at C-22 with common long-chain fatty acids. The major fatty acids have been identified by RP-hplc and their contribution to the mixture determined. In contrast, [3H]ecdysone injected into the haemolymph of S. littoralis is metabolized to yield 20-hydroxyecdysone, ecdysonoic acid, and 20-hydroxyecdysonoic acid. Thus, two different pathways exist for the metabolism of ecdysteroids in this species. In addition to an essentially polar pathway operating on injected and endogenous ecdysteroids, exogenous ecdysteroids entering the gut of S. littoralis are detoxified, yielding apolar ecdysteroid 22-fatty acyl esters which are rapidly excreted. The significance of these results in relation to the effects of ingested ecdysteroids on S. littoralis is discussed. Arch. Insect Biochem. Physiol. 34:329–346, 1997. © 1997 Wiley-Liss, Inc.

Induction of an inactivation pathway for ecdysteroids in larvae of the cotton leafworm, Spodoptera littoralis

Treatment of the last-instar larvae of the cotton leafworm (Spodoptera littoralis) with ecdysteroids (moulting hormones) results in the induction of an ecdysteroid-inactivation pathway. Administration of ecdysone, 20-hydroxyecdysone or an ecdysteroid agonist, RH 5849, leads to induction of an ecdysteroid 26-hydroxylase activity. This induction occurred in both early sixth-instar larvae and in older larvae which had been head-ligated to prevent the normal developmental increase in ecdysone 20-mono-oxygenase activity. The induction of 26-hydroxylase activity requires both RNA and protein synthesis, as demonstrated by experiments involving actinomycin D and cycloheximide. The 26-aldehyde derivative of ecdysone and ecdyson-26-oic acid were also formed from ecdysone in the RH 5849-induced systems. Formation of the aldehyde and the corresponding 26-oic acid (ecdysonoic acid) from 26-hydroxyecdysone was directly demonstrated in a cell-free system, thus establishing the following inactivation pathway: Ecdysteroid-->26-hydroxyecdysteroid-->ecdysteroid 26-aldehyde-->ecdysteroid 26-oic acid.

Metabolism of ecdysone and 20-hydroxyecdysone in adult drosophila melanogaster

The metabolism of [3H]ecdysone injected into adult female and male Drosophila melanogaster was investigated. The metabolites present in flies and faeces were analysed separately after incubation times of 1, 2 or 4 h. In female flies ecdysone-22-fatty acid acyl esters were the major metabolites followed by 3-dehydroecdysone, 26-hydroxyecdysone, ecdysonoic acid, 20-hydroxyecdysone and a negatively charged conjugate of ecdysone. In male flies the same compounds were formed, but their relative concentrations were somewhat different from those in female flies. All metabolites formed can be excreted. [3H]20-hydroxyecdysone was metabolized in much the same way: 20-hydroxyecdysone-22-acyl esters, 3-dehydro-20-hydroxyecdysone, 20-hydroxy-ecdysonoic acid and a negatively charged conjugate of 20-hydroxyecdysone were formed. However, 20,26-dihydroxyecdysone could not be detected after injection of [3H]20-hydroxyecdysone.

Ovarian and Hemolymph Ecdysteroid Titers during Vitellogenesis in Macrobrachium rosenbergii

Changes in ovarian and hemolymph ecdysteroid concentration and composition during vitellogenesis have been investigated in the freshwater prawn Macrobrachium rosenbergii. Free ecdysteroids (20-hydroxyecdysone and ecdysone) in hemolymph increased in concentration during vitellogenesis from zero at stage 0 to 1.5 ng/ml at stage I to 7.3 ng/ml in mature, stage IV animals. 20-Hydroxyecdysonoic acid (1.2 ng/ml) was detected in the stage IV hemolymph. Ovarian-free ecdysteroid concentration, expressed as nanograms per gram of tissue, fell during vitellogenesis from 83.2 ng/g at stage 0, non-pigmented tissue to 14.2 ng/g at stage IV tissue, being minimal at stage I (6.3 ng/g). However, expression of ovarian free ecdysteroid content as nanograms per ovary revealed a rise from 7.7 ng/ovary at stage 0, nonpigmented tissue to 28.3 ng/ovary at stage IV, again being minimal at stage I (2.0 ng/ovary). 20-Hydroxyecdysonoic acid and ecdysonoic acid were identified at ovarian stages II-III and stage IV.

Profile of embryonic ecdysteroids in the decapod crustacean,Macrobrachium rosenbergii

Summary The ecdysteroid composition of embryos of M. rosenbergii at various stages of embryogenesis has been studied by means of radioimmunoassay (RIA), high-performance liquid chromatography—RIA (HPLC-RIA) and gas chromatography/mass spectrometry (selected ion monitoring; GC/MS(SIM). In newly-laid eggs, only free ecdysteroids (ecdysone and 20-hydroxyecdysone) were detected, whereas eggs at an early stage of embryogenesis contained ecdysone and also low levels of apolar ecdysteroid conjugates. Mid stage embryonating eggs contained comparatively high levels of both free ecdysteroid (ecdysone, 18.3 ng/g) and apolar conjugates (29.9ng/g). Late embryos contained by far the highest overall level of ecdysteroid, indicating the ability of the developing embryo to synthesize ecdysteroid. In contrast to the other stages, late embryos contained 26-hydroxyecdysone, ecdysonoic acid and 20-hydroxyecdysonoic acid at relatively low levels and 2, 3-diacetylecdysone 22-phosphate at a comparatively high level (324.0 ng/g)....

Metabolism and fate of ecdysteroids in the nematodes Ascaris suum and Parascaris equorum

When injected with [3H]ecdysone and maintained in vitro, the parasitic nematodes, Ascaris suum and Parascaris equorum each produced a series of polar and relatively apolar metabolites. A. suum metabolised the compound into ecdysonoic acid ([3H]EOIC), ecdysone 25-glucoside ([3H]E25gluc), putative ecdysone 22-phosphate ([3H]E22P) and a series of at least six relatively apolar metabolites. All of these, except ecdysonoic acid, were hydrolysed by a crude enzyme preparation from Helix pomatia, releasing ecdysone. In a similar study, P. equorum produced ecdysone 25-glucoside, putative ecdysone 22-phosphate and a series of relatively apolar compounds all of which were hydrolysed by H. pomatia enzymes, releasing ecdysone. [3H]Ecdysone 25-glucoside was the most abundant single metabolite in both species, and in P. equorum, at least, was released into the culture medium in relatively large amounts. Apolar metabolites were present in worm samples and were the major, if not the only radiolabelled compounds detected in eggs of both species. Data indicated a metabolic relationship between some of the apolar conjugates found in both nematode species and ecdysone 25-glucoside.

Ecdysteroids from developing eggs of Pieris brassicae

AbstractEcdysone metabolism in Pieris brassicae eggs was revealed after injection of [3H]ecdysone into eggs. Labeled ecdysteroids were analyzed by HPLC. The metabolic fate of [3H]ecdysone is similar to that observed during postembryonic development, i.e., the larval instars and pupal instar. The ecdysone molecule is affected by hydroxylations at C‐20 and at C‐26; 26‐hydroxyecdysteroids can be further oxidized into ecdysteroid acids. In an effort to identify egg ecdysteroids, we examined the metabolism of [3H]cholesterol injected into female pharate adults to achieve long‐term labeling. In eggs, [3H]cholesterol was converted to 20‐hydroxyecdysonoic acid, ecdysonoic acid, 20‐hydroxyecdysone, and ecdysone. The rates of [3H]cholesterol incorporation into ecdysteroids increase according to the age of the eggs (from 0.06% at laying to 0.12% at hatching), while the cholesterol level remains constant throughout embryogenesis, suggesting that the embryos of Pieris brassicae can produce ecdysteroids either from cholesterol or from apolar ecdysteroids not identified by the analytical method. Pieris eggs contain amounts of ecdysteroids which increase from 1.5 nmol/g at laying to 3.8 nmol/g at hatching.

The Fate of [3H]Ecdysone in Three Species of Annelids

Summary The metabolism of [3H]ecdysone was examined in 3 species of annelids: the bloodworm, Tubifex vulgaris (a freshwater oligochaete), the earthworm, Lumbricus terrestris (a terrestrial oligochaete) and the ragworm, Nereis divtrsicolor (a marine polychaete). One of these species, N. diversicolor, metabolised injected [3H]ecdysone into compounds which co-chromatographed on both reversed-phase and adsorption HPLC with authentic 20-hydroxyecdysone, 26-hydroxyecdysone and 20,26-dihydroxyecdysone, thus demonstrating the occurrence of 20-hydroxylation and 26-hydroxylation capability in the Annelida. Furthermore, [3H]ecdysonoic acid was also formed and excreted by N. diversicolor, suggesting that 26-oic acid formation is involved in ecdysteroid inactivation in this species. Other, as yet unidentified, radioactive metabolites were also excreted by N. diversicolor. Several metabolites of [3H]ecdysone were also detected in the other 2 species examined, T. vulgaris and L. terrestris.

Conversion of ecdysone and 20-hydroxyecdysone into 3-dehydroecdysteroids is a major pathway in third instar Drosophila melanogaster larvae

Ecdysone and 20-hydroxyecdysone metabolism was investigated in third instar Drosophila larvae both in vivo by injecting radiolabelled ecdysteroids and in vitro by incubating various tissues with labelled ecdysteroids. Ecdysone metabolism proceeds through different pathways: (1) C-20 hydroxylation; (2) C-26 hydroxylation and C-26 oxidation leading to the formation of 26-hydroxyecdysteroids (26-hydroxyecdysone and 20,26-dihydroxyecdysone) and acidic compounds (ecdysonoic acid and 20-hydroxyecdysonoic acid); C-3 oxidation and C-3 epimerization then conjugation leading to the formation of 3-dehydrocompounds (3-dehydroecdysone and 3-dehydro-20-hydroxyecdysone), 3-epimers (3-epiecdysone and 3-epi-20-hydroxyecdysone) and conjugates (only one conjugate was tentatively characterized as 3-epi-20-hydroxyecdysone-3-phosphate). 3-Dehydrocompounds are the major metabolites formed in third instar Drosophila larvae and C-3 oxidation occurs in various tissues. Experiments using tritiated cholesterol provided evidence that 3-dehydroecdysone and 3-dehydro-20-hydroxyecdysone are true endogenous ecdysteroids in Drosophila larvae.

Profile of free and conjugated ecdysteroids and ecdysteroid acids during embryonic development of Manduca sexta (L.) following maternal incorporation of [14C]cholesterol

AbstractThe levels of both free and conjugated ecdysteroids, maternally labeled from [14C]cholesterol, of six different age groups of Manduca sexta eggs were quantitatively determined. Eggs 0–1‐h old contain about 2.5 and 35 μ/g of the 2‐ and 26‐phosphates of 26‐hydroxyecdysone, respectively, and 1 μg/g of 26‐hydroxyecdysone. During embryogenesis of 26‐hydroxyedcdysone 26‐phosphate is hydrolyzed to 26‐hydroxyecdysone, which reaches a peak titer in 1–18‐h‐old eggs; the level of 26‐hydroxyecdysone 2‐phosphate remains rather constant. Additionally, other metabolic modifications such as hydroxylation, conjugation, epimerization, and oxidation are occurring; and as the level of the 26‐hydroxyecdysone 26‐phosphate decreases there is a progression of other ecdysteroids. C‐20 hydroxylation first appears in 24–40‐h‐old eggs and reaches peak activity in 48–64‐h‐old eggs, where 20‐hydroxyecdysone and 20, 26‐dihydroxyecdysone are both present at peak titer but the latter is the major free ecdysteroid. Ecdysone is observed at measurable levels only in the three age groups of eggs between 1 and 64 h‐old. C‐3 epimerase activity also appears at 24–40 h and continually increases throughout embryogenesis to the point that 3‐epi‐26‐hydroxyecdysone and 3‐epi‐20, 26‐dihydroxyecdysone are the major free ecdysteroids in 96‐h‐old eggs. A new ecdysteroid conjugate, 26‐hydroxyecdysone 22‐glucoside, first appears at 24–40h and becomes the major conjugate in 72–80‐h‐old eggs; it represents an apparent end‐product as its peak titer is reached and maintained throughout the final embryonic stages. 20‐Hydroxyecdysonoic acid occurs in 48–64‐h‐old eggs, and along with 3‐epi‐20‐hydroxyecdysonoic and ecdysonoic acids in 72–88‐h‐old eggs. 20‐Hydroxyecdysonoic acid peaks during the latter time interval, and as its titer subsequently falls, there is a concurrent increase in the level of 3‐epi‐20‐hydroxyecdysonoic which was identified as the second major component of the ecdysteroid conjugate fraction of 0–1‐h‐old larvae. Our results indicate that there is little or no biosynthesis of ecdysteroids during embryogenesis; that the materal ecdysteroid conjugate 26‐hydroxyecdysone 26‐phosphate serves as source for 26‐hydroxyecdysone and the numerous metabolites; that 26‐hydroxyecdysone and 20,26‐dihydroxyecdysone may be the active hormones during embryonic development; and that glucosylation, epimerization, and formation of acids cosntitute inactivation processes. A scheme of the proposed pathways involved in the metabolism of 26–hydroxyecdysone 26‐phosphate in the developing eggs of m. sexta is presented.

Ecdysteroids in Carausius eggs during embryonic development

AbstractPeaks of ecdysteroids were observed during the different phases of embryonic development of intact Carausius eggs or eggs precociously deprived of their exochorion and cultivated under paraffin oil. Several groups of ecdysteroids were separated and analyzed by thin‐layer chromatography (TLC) and high performance liquid chromatography (HPLC) combined with radioimmunoassay. Ecdysteroids were similar in the two categories of eggs, including high‐polarity products (essentially conjugates hydrolyzable by Helix pomatia digestive juice, or alkaline phosphatase), possible ecdysonoic acids (unhydrolyzable polar substances), free hormones, and nonpolar ecdysteroids. Four ecdysteroids were identified by co‐elution during HPLC with reference compounds of 20,26‐dihydroxyecdysone, 20‐hydroxyecdysone, ecdysone, and 2‐deoxy‐20‐hydroxyecdysone. Concentrations of these substances (free and conjugated forms) were studied during the different stages of embryonic development: 20‐hydroxyecdysone and 2‐deoxy‐20‐hydroxyecdysone were the major free ecdysteroids. They showed parallel variations with large peaks at stages VI8 and VII6 whereas ecdysone titers were consistently low. Injected labelled ecdysone was converted efficiently into 20‐hydroxyecdysone, and both compounds underwent 26‐hydroxylation and/or conjugation to polar or apolar metabolites.

Metabolism and biosynthesis of ecdysteroids in the Drosophila development mutant ecd1

Abstract The biosynthesis and metabolism of ecdysteroids were compared in Drosophila larvae of the wild strain Canton-S and the thermosensitive mutant ecd1 at normal (22°C) and restrictive temperatures (29°C). At 22°C, ecdysteroid metabolism proceeds through a limited number of reactions: C-20 hydroxylation, C-26 hydroxylation followed by oxidation to ecdysonoic acids, C-3 oxidation, C-3 epimerization and conjugation. Epimerization and conjugation appeared to be minor pathways. The major processes of ecdysone conversion in Drosophila larvae were thus C-20 hydroxylation, a reaction that occurred in all types of larvae, and C-3 oxidation leading to the formation of 3-dehydroecdysone and 3-dehydro-20-hydroxyecdysone, a reaction particularly efficient in Dipteran larvae. Biosynthesis of ecdysteroids was investigated by [ 3 H]chloresterol labelling. Active conversion into 20-hydroxyecdysone and 3-dehydro-20-hydroxyecdysone was observed. At restrictive temperature (29°C), while the wild strain Canton-S developed and normally pupated, the mutant ecd1 grew to full size but failed to pupate. The rate of ecdysteroid metabolism slowed down in the mutant, especially the conversion into 3-dehydrocompounds. Ecdysone biosynthesis fell dramatically in the mutant larvae but a basal level persisted and the conversion of chloresterol into 20-hydroxyecdysone and 3-dehydro-20-hydroxyecdysone was always observed.

Ecdysone metabolism in Pieris brassicae during the feeding last larval instar

AbstractEcdysone metabolism in Pieris brassicae during the feeding last larval stage was investigated by using 3H‐labeled ecdysteroid injections followed by high‐performance liquid chromatographic (HPLCAbbreviations: 3DE = 3‐dehydroecdysone; 3D20E = 3‐dehydro‐20‐hydroxyecdysone; 2026E = 20,26‐dihydroxyecdysone; E = ecdysone; Eoic = ecdysonoic acid; 2026E′ = 3‐epi‐20,26‐dihydroxyecdysone; E′ = 3‐epiecdysone; E′oic = 3‐epiecdysonoic acid; E′8P = 3‐epiecdysone 3‐phosphate; 20E′ = 3‐epi‐20‐hydroxyecdysone; 20E′3P = 3‐epi‐20‐hydroxyecdysone 3‐phosphate; FT = Fourier transform; HPLC = high‐performance liquid chromatography; 20E = 20‐hydroxyecdysone; 20Eoic = 20‐hydroxyecdysonoic acid; NMR = nuclear magnetic resonance; NP‐HPLC = normal phase HPLC; RP‐HPLC = reverse phase HPLC; TFA = trifluoroacetic acid; Tris = tris(hydroxymethyl)‐aminomethane. ) analysis of metabolites. Metabolites were generally identified by comigration with available references in different HPLC systems. Analysis of compounds for which no reference was available required a large‐scale preparation and purification for their identification by 1H nuclear magnetic resonance spectrometry.The metabolic reactions affect the ecdysone molecule at C‐3, C‐20, and C‐26, leading to molecules which are modified at one, two, or three of these positions. At C‐20, hydroxylation leads to 20‐hydroxyecdysteroids. At C‐26, hydroxylation leads to 26‐hydroxyecdysteroids which can be further converted into 26‐oic derivatives (ecdysonoic acids) by oxidation. At C‐3, there are several possibilities: there may be oxidation into 3‐dehydroecdysteroids, or epimerization possibly followed by phosphate conjugation.Thus, injected 20‐hydroxyecdysone was converted principally into 20‐hydroxyecdysonoic acid, 3‐dehydro‐20‐hydroxyecdysone, and 3‐epi‐20‐hydroxyecdysone 3‐phosphate. Labelled ecdysone mainly gave the same metabolites doubled by a homologous series lacking the 20‐hydroxyl group.

Ecdysteroid metabolism in the terrestrial snailCepaea nemoralis(L.)

Summary Garden snails (Cepaea nemoralis) contain both ecdysone and ecdysterone. Attempts to determine whether they originate from their food or are endogenously synthesized did not allow a definite conclusion. The metabolism of ecdysone and 20-hydroxyecdysone in Cepaea nemoralis has been investigated by using tritiated hormone injections followed by HPLC analysis of labelled compounds. It was observed that snails convert ecdysone into 20-hy-hroxyecdysone and the latter into two new ecdysteroids. These metabolites were isolated and identified by mass spectrometry and two-dimensional PMR. They correspond to 20-hydroxyecdysone 22-acetate and 16β,20-dihydroxyecdysone. We propose the name of ‘malacosterone’ for the second compound. Snails do not form ecdysonoic acids nor polar conjugates. These pathways are common to other gastropod species tested and they are discussed by comparison with those already described in Arthropods.

INTRODUCTION: TEN YEARS OF ECDYSONE WORKSHOPS: RETROSPECT AND PERSPECTIVES

Publisher Summary This chapter provides an overview of ecdysone workshops. The methods for the separation and analysis of ecdysteroids have undergone spectacular improvements, largely because of the introduction of high-performance liquid chromatography (HPLC) and the use of combined gas chromatography–mass spectrometry (GC–MS) of 1 H-NMR and 13 C-NMR. Ecdysone and/or 20-hydroxyecdysone are inactivated primarily by the esterification or epimerization of the C-3 hydroxyl group or, to a lesser extent, by the esterification of the C-2 hydroxyl group on the A nucleus. A relatively wide-spread inactivation pathway is the hydroxylation of the C-26 methyl group followed by oxidation to an ecdysonoic acid. In higher insect orders, like the dipterans, ovarian ecdysteroids play a role in the control of vitellogenin synthesis, whereas in other orders, they play a role in the early events of embryogenesis. Vitellogenic ovaries synthesize ecdysteroids at a given stage of their development; in some species, this synthesis occurs only towards the end of vitellogenin uptake; in others, it occurs at almost the same time as concomitantly the onset of vitellogenin synthesis.

Comparative studies on ecdysone metabolism between mature larvae and pharate pupae in the fleshfly, Sarcophaga peregrina

AbstractMetabolites of radioactive ecdysone or 20‐hydroxyecdysone in larvae and pharate pupae of Sarcophaga peregrina were separated and identified by using thin‐layer chromatography, high‐performance liquid chromatography, and chemical methods. At the larval stage ecdysone was metabolized to biologically less active ecdysteroids predominantly through 20‐hydroxyecydsone, at the pharate pupal stage, to other ecdysteroids which were tentatively identified as 26‐hydroxyecdysone, 3‐epi‐26‐hydroxyecdysone, and 3‐epi‐20,26‐dihydroxyecdysone. Ecdysteroid acids were found in the polar metabolites during pharate pupal‐pupal transformation, but scarcely detected in the larval metabolites. These acids were presumed to be ecdysonoic acid, 20‐hydroxyecdysonoic acid, and their epimers. The conjugates of ecdysteroid that released the free ecdysteroids by enzymatic hydrolysis were produced more in larvae than in pupae, whereas the very polar ecdysteroids that were not affected by the enzyme were found more in pupae. Therefore, there are different metabolic pathways of ecdysone between these two successive developmental stages, and the alteration of the metabolic pathway may serve as one of the important factors in a regulatory mechanism of molting hormone activity which is responsible for normal development of this insect.

Metabolism of maternal ecdysteroid-22-phosphates in developing embryos of the desert locust, Schistocerca gregaria

The ecdysteroid composition of Schistocerca gregaria eggs at different stages of development was determined by analysis of ecdysteroids labelled maternally from [4- 14 C]cholesterol. At all stages studied, highly polar ecdysteroid derivatives predominated, but changes in their composition occurred between day 10 of development and hatching (day 17). During this period, polar conjugates of ecdysone-3-acetate and 3-epi-2-deoxyecdysone appeared together with ecdysteroid acids. At day 17, the polar conjugate of [ 14 C]ecdysone-3-acetate represented 36% of the total conjugated steroids. Separate in vivo studies on the metabolism of [ 14 C]ecdysteroid conjugates isolated from newly-laid eggs and consisting primarily of the 22-phosphates of ecdysone, 2-deoxyecdysone and 20-hydroxyecdysone showed that ecdysteroid phosphates could be hydrolysed to give primarily free ecdysone during embryogenesis. Developing eggs can metabolize [ 3 H]ecdysone to ecdysonoic acid, 3-acetylecdysone-2-phosphate and to a lesser extent ecdysone-22-phosphate and 20-hydroxyecdysonoic acid. A polar conjugate of 20-hydroxyecdysone-3-acetate, possibly the 2-phosphate derivative, was detected as a minor metabolite of ecdysone. A scheme of the proposed pathways involved in the metabolism of ecdysteroid-22-phosphates in the developing eggs of S. gregaria is presented.

Isolation and identification of ecdysteroid phosphates and acetylecdysteroid phosphates from developing eggs of the locust, Schistocerca gregaria.

Maturing eggs of the desert locust, Schistocerca gregaria, contain a variety of ecdysteroid (insect moulting hormone) conjugates and metabolites, four of which have been previously isolated from polar extracts and identified as ecdysonoic acid, 20-hydroxyecdysonoic acid, 3-acetylecdysone 2-phosphate and ecdysone 2-phosphate. In the present study we have isolated eight additional ecdysteroids from similar late-stage eggs by high-performance liquid chromatography. The 22-phosphate esters of ecdysone, 2-deoxyecdysone, 20-hydroxyecdysone and 2-deoxy-20-hydroxyecdysone, all of which were first identified as ecdysteroid components of newly-laid eggs of S. gregaria, were identified by co-chromatography with authentic compounds and by physicochemical techniques. The remaining compounds were identified as 3-acetyl-20-hydroxyecdysone 2-phosphate, 3-epi-2-deoxyecdysone 3-phosphate, 3-acetylecdysone 22-phosphate and 2-acetylecdysone 22-phosphate by fast atom bombardment mass spectrometry, p.m.r. spectroscopy and analysis of the steroid moieties after enzymic hydrolysis. The latter two compounds, after isolation, are susceptible to nonenzymic acetyl migration and deacetylation to give mixtures of ecdysone 22-phosphate and its 2- and 3-acetate derivatives. The possible role and significance of these ecdysteroid conjugates with respect to the control of hormone titres in insect eggs is discussed.

Ecdysone metabolism inLocusta migratorialarvae and adults

Summary The metabolism of ecdysone and 20-hydroxyecdysone has been investigated in fifth instar larvae and male adults of Locusta migratoria (Insecta, Orthoptera). The major pathways have been elucidated by labelling experiments, followed by the isolation and the characterization of the different metabolites. These ecdysteroids are converted by locusts through three major reactions: (1) C-26 hydroxylation followed by conversion to ecdysonoic acids, (2) C-3 acetylation, and (3) C-2 phosphate ester formation. The combination of (2) and (3) gives rise to acetylphosphate derivatives, which represent the major conjugates in insect faeces. Minor metabolites are also formed, corresponding to 3-dehydroecdysteroids and phosphate conjugates of various metabolites which have not yet been fully characterized. The reactions are identical in larvae and adults and are similar to those described for embryos of the same species and the related Schistocerca gregaria. In vitro organ incubations have allowed us to determine ...

Ecdysteroid metabolism in a crab : Carcinus maenas l.

Ponasterone A (25-deoxy-20-hydroxyecdysone) and 20-hydroxyecdysone were the major ecdysteroids detected in crab hemolymph, although some ecdysone was also present. The metabolism of ponasterone A was examined in intermolt and premolt crabs either by injecting the radiolabeled hormone or by incubating tissues in its presence. Metabolites were extracted from the surrounding seawater and from tissues and separated by high-performance liquid chromatography. Ponasterone A metabolism proceeds through (1) C-25 and C-26 hydroxylation, followed by formation of inactivation products via oxidation of the terminal alcoholic group to a carboxylic residue, (2) conjugation, (3) "binding" to very polar compounds and (4) side-chain scission. The conversion of ponasterone A into 20-hydroxyecdysone, inokosterone (25-deoxy-20, 26-dihydroxyecdysone), 20, 26-dihydroxyecdysone and ecdysonoic acids, as well as the formation of conjugates and of very polar compounds, occurs in various tissues. These metabolites were excreted by both intermolt and premolt crabs.