The polyhydroxylated derivatives of 6-keto,7-dehydrocholesterol (ecdysone, ecdysteroids, Ecd) are natural compounds widely distributed in plants. They exhibit strong anabolic, vitamin D-like, pharmacological effects in vertebrate animals and in the human body. In the larval stages of insects, injections of pure Ecd cause serious pathophysiological, "hyperecdysonic" syndromes associated with neuromuscular paralysis, premature cuticular apolysis and complete inhibition of ecdysis. Ecds do not penetrate insect cuticle. For this reason, all previous attempts to induce ecdysone responses by topical applications of Ecd failed. In this work, we tried to induce the topical effects of Ecd by preparation of more lipophilic complexes, with 2 or 4 molecules of 20-hydroxyecdysone (E20) attached to a relatively large nucleus of the porphyrin. The resulting porphyrin-E20 complexes (ecdysogens) have been subjected to standardised assays for ecdysone activity in the ligatured larvae ("dauerlarvae") of the greater waxmoth (Galleria mellonella). Similarly like the free E20 alone, porphyrin-E20 complexes had no effect when applied on the body surface or administered in the larval diet. When injected, however, they exhibited delayed effects, but the adverse ("hyperecdysonic") pathophysiological syndromes were reduced or abolished. It is concluded, therefore, that the replacement of pathophysiological, precocious or "hyperecdysonic" moults by the larval-pupal transformation, was due to successive metabolic liberation of the biologically active, free E20 from the porphyrin-E20 complex. The biological status of Ecd does not agree with their definition as the prothoracic gland (PG) hormone of insects, nor with the assumptions about a growth hormone of plants. A possibility that the most important status of Ecd may depend on the pharmacological properties of a sterolic D6 vitamin has been discussed.
- Klíčová slova
- 20-hydroxyecdysone (E20), Ecdysone, Ecdysone bioassays, Ecdysteroids (Ecds), Galleria mellonella, Hyperecdysonic syndromes, Neuromuscular paralysis by Ecd,
- MeSH
- aplikace lokální MeSH
- aplikace orální MeSH
- biologická proměna účinky léků MeSH
- ekdysteron aplikace a dávkování chemie farmakologie fyziologie MeSH
- kukla účinky léků MeSH
- larva účinky léků MeSH
- Lepidoptera účinky léků fyziologie MeSH
- porfyriny chemie farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ekdysteron MeSH
- porfyriny MeSH
The aim of the work was to examine the effect of brassinosteroid (24-epibrassinolide; 24E) and ecdysteroid (20-hydroxyecdysone; 20E) on various parts of primary photosynthetic processes in maize and spinach. Additionally, the effect of steroids on gaseous exchange, pigment content and biomass accumulation was studied. The efficiency of the photosynthetic whole electron-transport chain responded negatively to the 24E or 20E treatment in both species, but there were interspecific differences regarding Photosystem (PS) II response. A positive effect on its oxygen-evolving complex and a slightly better energetical connectivity between PSII units were observed in maize whereas the opposite was true for spinach. The size of the pool of the PSI end electron acceptors was usually diminished due to 24E or 20E treatment. The treatment of plants with 24E or 20E applied individually positively influenced the content of photosynthetic pigments in maize (not in spinach). On the other hand, it did not affect gaseous exchange in maize but resulted in its reduction in spinach. Plants treated with combination of both steroids mostly did not significantly differ from the control plants. We have demonstrated for the first time that 20E applied in low (10nM) concentration can affect various parts of photosynthetic processes similarly to 24E and that brassinosteroids regulate not only PSII but also other parts of the photosynthetic electron transport chain - but not necessarily in the same way.
- Klíčová slova
- Brassinosteroids, Chlorophyll, Ecdysteroids, Gas exchange, OJIP analysis, Photosynthetic electron transport,
- MeSH
- brassinosteroidy aplikace a dávkování MeSH
- ekdysteron aplikace a dávkování MeSH
- fotosyntéza účinky léků genetika MeSH
- fotosystém II - proteinový komplex účinky léků genetika MeSH
- kukuřice setá účinky léků růst a vývoj MeSH
- listy rostlin účinky léků metabolismus MeSH
- oxidace-redukce MeSH
- rostlinné proteiny biosyntéza MeSH
- Spinacia oleracea účinky léků růst a vývoj MeSH
- steroidy heterocyklické aplikace a dávkování MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- brassinolide MeSH Prohlížeč
- brassinosteroidy MeSH
- ekdysteron MeSH
- fotosystém II - proteinový komplex MeSH
- rostlinné proteiny MeSH
- steroidy heterocyklické MeSH
Ecdysteroids are hormones controlling cell proliferation, growth and the developmental cycles of insects and other invertebrates. They are occasionally present in various unrelated plants for no apparent reason; no phytohormonal function has yet been identified. In certain cases, ecdysteroids are accumulated to high levels in leaves, roots or seeds. Some ecdysteroid-containing plants have been known as medicinal plants for centuries. One of them, Leuzea carthamoides Iljin (Asteraceae), growing in Central Asia, contains 0.4% ecdysteroid in dry roots and 2% in seeds. A pharmacological preparation from this plant, "Ecdisten', is already available as a commercial preparation for its anabolic, tonic and other effects, for medical use (review). It remained problematic, however, whether ecdysteroids were truly responsible for these effects, because Leuzea contains a number of other biologically active compounds in addition to ecdysteroids. We extracted and purified ecdysteroids from the seeds of Leuzea. With 6 g of 96% 20-hydroxyecdysone (20E), we made a large-scale feeding assay with Japanese quail to find out whether ecdysteroid alone could duplicate the anabolic effects of the seeds. We found that the 96% ecdysteroid increased the mass of the developing quails in a dose-dependent manner, with the rate of increase proportional to the ecdysteroid content in the seeds; there was a 115% increase in living mass with 100 mg kg-1 of pure 20E compared with 109.5% increase with 100-180 mg kg-1 20E equivalents in the seeds. We conclude that the plethora of growth-promoting, vitamin-like effects induced in vertebrates by Leuzea is mediated by ecdysteroids.
- MeSH
- Coturnix krev růst a vývoj MeSH
- dieta MeSH
- ekdysteron aplikace a dávkování krev farmakologie MeSH
- pohlavní dospělost MeSH
- rostliny chemie MeSH
- semena rostlinná chemie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- ekdysteron MeSH
