Ecdysteroids

Subsequent hydroxylation of a-ecdysone yields )8-ecdysone (Fig. 19), the most oxidized ecdysone normally encountered in plants. 

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Insects, crustaceans, platehelminthes, nematodes and annelids use homoses-quiterpenoid epoxides (juvenile hormones) and ecdysteroids (ecdysone, 20-... 

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)... 

Sehnal F, Bryant P J 1993 Delayed pupariation in Drosophila imaginal disc overgrowth mutants is associated with reduced ecdysteroid titer. J Insect Physiol 39 1051-1059... 

Chitwood, D.J. and Feldlaufer, M.F. (1990) Ecdysteroids in axenically propagated Caenorhabditis ekgans and culture-medium. Journal ofNematology 22, 598-607. 

Barker, G., Chitwood, D. and Rees, H. (1990) Ecdysteroids in helminths and annelids. Invertebrate Reproduction and Development 18, 1—11. 

From these studies, some patterns of effect potentially mediated by the endocrine system have been observed. These include the accumulation of vitellogenin in ticks [50-52] and accelerated ovarian development in beetles and ticks [51, 53]. Different researchers have attributed these effects to a range of different mechanisms, including induced excitation of neurosecretory cells releasing juvenile hormone [50], and ecdysteroid disruption either by blocking the neuropeptide itself or at the epidermal site of synthesis [51]. Other researchers have not corroborated these results and have even found contradictory effects, e.g., suppressed ovarian development [52], Therefore at present for SPs, there is no clear evidence for adverse population-relevant effects with an underlying endocrine mode of action. 

Another aspect of the sex pheromone communication system concerns the endogenous signals that control pheromone production and release from the emitting insect. A number of hormones have been found to be involved in the control of pheromone production in various insect species (18). Juvenile hormone was found to induce vitellogenesis and sex pheromone production in some cockroach and beetle species. However, ecdysteroids were found to be involved in regulating reproductive processes, including vitellogenin synthesis, in dipteran species. 

LC-NMR can be used to identify natural products in crnde plant extracts that usually consist of complex mixtnres. The crnde natural product extracts normally contain a great nnmber of closely related and difficult-to-separate compounds. The classical separation approach may become very tedious and time-consuming. The directly conpled HPLC-NMR presents an efficient separation techniqne together with a powerfnl spectroscopic method to speed up the identification process. LC-NMR has been nsed extensively for characterization of natnral prodncts. More recently, the combination of LC-NMR and LC-MS has been further developed in this field. Eor example, Wilson et al. have nsed combined on-flow NMR and electrospray ionization MS to characterize ecdysteroids in extracts of silene otites. After reversed-phase HPLC nsing D2O in acetonitrile-dj and UV detection, the LC flow was split 95 5 for the simnl-taneous detection by NMR and MS. The peaks of interest were analyzed by stop-flow NMR to give better quality spectra for structural assignment. 

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... 

Thuy, T.T. et al., Chalcones and ecdysteroids from Vitex leptobotrys. Phytochemistry, 49, 2603,... 

Ecdysteroids. Ecdysteroids can be isolated from many species of the annual kingdom that belong to the phyla Protomia, e.g., insects, worms, and arthropods, as well as a variety of different plant species. Ecdysteroids include the molting hormones, however, nnl all the over 60 ecdysteroids that have been isolated are active hormones. Ecdysteroids from animals... 

It is not only fatty acids that are modified (see section on Lipids ) in parasitic flatworms, but also cholesterol obtained from the host is not only used directly as a component of membranes in F. hepatica and 5. mansoni, but it is also used as a substrate for the synthesis of other compounds such as ecdysteroids (Foster etal., 1992). 

Apparently, parasitic flatworms have discarded some pathways of de novo lipid synthesis, but have selectively retained several biosynthetic pathways that modify host lipids. Although lipids like fatty acids and cholesterol are obtained from the host, less abundant lipids that are more difficult to acquire because of their low concentration in the host (e.g. specific unsaturated fatty acids, eicosanoids, ecdysteroids and quinones) are synthesized de novo by the parasite, usually by the modification of more abundant substrates. In this way, lipid metabolism of parasitic flatworms is adapted to an opportunistic way of life, just like their energy metabolism. 

Foster, J.M., Mercer, J.C. and Rees, H.H. (1 992) Analysis of ecdysteroids in the trematodes, Schistosoma man-soni and Fasciola hepatica. Tropical Medicine and Parasitology 43, 239-244. 

The first application of LC-NMR-MS to natural products analysis was presented in 1999 [37]. The additional mass spectroscopic information allowed the identification of a further ecdysteroid in an extract of Silene otides which could not be identified by LC-NMR alone [24], Further applications of this double hyphenation dealt with the identification of napthodianthrones [38] and flavone glycosides [38,39] in natural products extracts. Taking the hyphenated technique one step further, the suitability of an integrated LC-UV-IR-NMR-MS system for natural products analysis has been assessed [40] - again using ecdysteroids as an example. Such systems still suffer from different requirements of the individual detectors (mainly in terms of sensitivity). However, the results obtained are promising. 

Tomaschko, K.H., Ecdysteroids from Pycnogonum litorale (Arthropoda, Pantopoda) act as a chemical defense against Carcinus maenas (Crustacea, Decapoda), J. Chem. Ecol., 20, 1445, 1994. 

Unlike in dipterans, there is no ecdysteroid to complicate JH III action in adult bark beetles indeed, JH III appears to act alone in elevating HMG-R transcription in males. Furthermore, the clear, vigorous response by the mevalonate pathway in bark beetle midgut cells presents a simple metabolic focus, in contrast to the complicated developmental contexts studied in moths and flies. 

Biosynthesis and ecdysteroid regulation of housefly sex pheromone production... 

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