RESUMO
Two new azafluoranthene alkaloids (1 and 2), and a new phytoecdysone (3), were isolated from the stems of Cyclea barbata Miers, together with six known compounds (4-9). Their structures were elucidated by spectroscopic data analysis and comparison with published data. This is the first report of azafluoranthene alkaloids (1 and 2) and phytoecdysones (3, 8, and 9) from Cyclea genus. In in vitro bioassay, four isolates (3, 5, 6, and 9) showed moderate hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced toxicity in HepG2 cells.
Assuntos
Alcaloides/química , Antineoplásicos Fitogênicos/química , Cyclea/química , Ecdisona/química , Fitosteróis/química , Alcaloides/isolamento & purificação , Alcaloides/farmacologia , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Ecdisona/farmacologia , Células Hep G2 , Humanos , Modelos Moleculares , Estrutura Molecular , Fitosteróis/farmacologiaRESUMO
Although tissue regeneration has been studied in a variety of organisms, from Hydra to humans, many of the genes that regulate the ability of each animal to regenerate remain unknown. The larval imaginal discs of the genetically tractable model organism Drosophila melanogaster have complex patterning, well-characterized development and a high regenerative capacity, and are thus an excellent model system for studying mechanisms that regulate regeneration. To identify genes that are important for wound healing and tissue repair, we have carried out a genetic screen for mutations that impair regeneration in the wing imaginal disc. Through this screen we identified the chromatin-modification gene trithorax as a key regeneration gene. Here we show that animals heterozygous for trithorax are unable to maintain activation of a developmental checkpoint that allows regeneration to occur. This defect is likely to be caused by abnormally high expression of puckered, a negative regulator of Jun N-terminal kinase (JNK) signaling, at the wound site. Insufficient JNK signaling leads to insufficient expression of an insulin-like peptide, dILP8, which is required for the developmental checkpoint. Thus, trithorax regulates regeneration signaling and capacity.
Assuntos
Proteínas Cromossômicas não Histona/fisiologia , Proteínas de Drosophila/fisiologia , Drosophila melanogaster/crescimento & desenvolvimento , Regulação da Expressão Gênica , Discos Imaginais/fisiologia , Regeneração , Asas de Animais/fisiologia , Animais , Padronização Corporal , Ecdisona/química , Epigênese Genética , Feminino , Heterozigoto , Histonas/química , Peptídeos e Proteínas de Sinalização Intercelular/fisiologia , Masculino , Mutação , Fosfoproteínas Fosfatases/fisiologia , Estrutura Terciária de Proteína , Transdução de SinaisRESUMO
The steroid hormone ecdysone, which controls insect molting and metamorphosis, is synthesized in the prothoracic gland (PG), and several steroidogenic enzymes that are expressed specifically in the PG are involved in ecdysteroidogenesis. In this study, we identified new regulators that are involved in the transcriptional control of the silkworm steroidogenic enzyme genes. In silico analysis predicted several potential cis-regulatory elements (CREs) for the homeodomain transcription factors Antennapedia (Antp) and POU-M2 in the proximal promoters of steroidogenic enzyme genes. Antp and POU-M2 are expressed dynamically in the PG during larval development, and their overexpression in silkworm embryo-derived (BmE) cells induced the expression of steroidogenic enzyme genes. Importantly, luciferase reporter analyses, electrophoretic mobility shift assays, and chromatin immunoprecipitation assays revealed that Antp and POU-M2 promote the transcription of the silkworm steroidogenic enzyme gene Phantom (Phm) by binding directly to specific motifs within overlapping CREs in the Phm promoter. Mutations of these CREs in the Phm promoter suppressed the transcriptional activities of both Antp and POU-M2 in BmE cells and decreased the activities of mutated Phm promoters in the silkworm PG. In addition, pulldown and co-immunoprecipitation assays demonstrated that Antp can interact with POU-M2. Moreover, RNA interference-mediated down-regulation of either Antp or POU-M2 during silkworm wandering not only decreased the ecdysone titer but also led to the failure of metamorphosis. In summary, our results suggest that Antp and POU-M2 coordinate the transcription of the silkworm Phm gene directly, indicating new roles for homeodomain proteins in regulating insect ecdysteroidogenesis.
Assuntos
Proteína do Homeodomínio de Antennapedia/metabolismo , Proteínas de Helminto/metabolismo , Proteínas de Homeodomínio/metabolismo , Proteínas de Insetos/metabolismo , Metamorfose Biológica , Oxigenases de Função Mista/metabolismo , Fatores do Domínio POU/metabolismo , Fatores de Transcrição/metabolismo , Transcrição Gênica , Animais , Proteína do Homeodomínio de Antennapedia/genética , Bombyx , Biologia Computacional , Ecdisona/química , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Helminto/genética , Proteínas de Homeodomínio/genética , Proteínas de Insetos/genética , Oxigenases de Função Mista/genética , Muda , Mutação , Nucleopoliedrovírus/genética , Fatores do Domínio POU/genética , Regiões Promotoras Genéticas , Ligação Proteica , Mapeamento de Interação de Proteínas , Estrutura Terciária de Proteína , Interferência de RNA , Fatores de Transcrição/genéticaRESUMO
Bioassay-guided fractionation of an ethanolic extract of Zoanthus spp. collected in Taiwan has resulted in the isolation of one new ecdysone, zoanthone A (1), along with thirteen known compounds (2-14). The structures of these compounds were determined by spectroscopic methods, especially 2D NMR analyses. The in vitro antiviral activities of all isolated ecdysones (1-14) against dengue virus type 2 (DENV-2) were evaluated using DENV infectious system. New compound (1) exhibited potent antiviral activity (EC50=19.61 ± 2.46 µM) with a selectivity index (CC50/EC50) value of 36.7. The structure-activity relationships of isolated ecdysones against DENV-2 were concluded. Molecular docking information of 3 and NS5 polymerase was performed either.
Assuntos
Antozoários/química , Antivirais/farmacologia , Vírus da Dengue/efeitos dos fármacos , Ecdisona/farmacologia , Animais , Antivirais/química , Ecdisona/química , Relação Estrutura-AtividadeRESUMO
Juvenile hormone (JH) has an ability to repress the precocious metamorphosis of insects during their larval development. Krüppel homolog 1 (Kr-h1) is an early JH-inducible gene that mediates this action of JH; however, the fine hormonal regulation of Kr-h1 and the molecular mechanism underlying its antimetamorphic effect are little understood. In this study, we attempted to elucidate the hormonal regulation and developmental role of Kr-h1. We found that the expression of Kr-h1 in the epidermis of penultimate-instar larvae of the silkworm Bombyx mori was induced by JH secreted by the corpora allata (CA), whereas the CA were not involved in the transient induction of Kr-h1 at the prepupal stage. Tissue culture experiments suggested that the transient peak of Kr-h1 at the prepupal stage is likely to be induced cooperatively by JH derived from gland(s) other than the CA and the prepupal surge of ecdysteroid, although involvement of unknown factor(s) could not be ruled out. To elucidate the developmental role of Kr-h1, we generated transgenic silkworms overexpressing Kr-h1. The transgenic silkworms grew normally until the spinning stage, but their development was arrested at the prepupal stage. The transgenic silkworms from which the CA were removed in the penultimate instar did not undergo precocious pupation or larval-larval molt but fell into prepupal arrest. This result demonstrated that Kr-h1 is indeed involved in the repression of metamorphosis but that Kr-h1 alone is incapable of implementing normal larval molt. Moreover, the expression profiles and hormonal responses of early ecdysone-inducible genes (E74, E75, and Broad) in transgenic silkworms suggested that Kr-h1 is not involved in the JH-dependent modulation of these genes, which is associated with the control of metamorphosis.
Assuntos
Bombyx/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Insetos/metabolismo , Fatores de Transcrição Kruppel-Like/metabolismo , Metamorfose Biológica , Animais , Animais Geneticamente Modificados , Bombyx/genética , Bombyx/metabolismo , Ecdisona/química , Ecdisteroides/química , Feminino , Perfilação da Expressão Gênica , Proteínas de Insetos/química , Proteínas de Insetos/genética , Fatores de Transcrição Kruppel-Like/genética , Larva/genética , Larva/metabolismo , Masculino , Fases de Leitura Aberta , Transdução de SinaisRESUMO
(+)-proto-Quercitol (1) and (-)-vibo-quercitol (2), both of which could be readily prepared by the bioconversion of myo-inositol, were successfully converted into the corresponding 4-methylenecyclohex-5-ene-1,2,3-triol derivatives. These compounds were demonstrated to be suitable precursors, preserving their configurations, for bioactive carba-aminosugars such as the potent chemical chaperone drug candidates, N-octyl-4-epi-ß-valienamine (NOEV, 3) and N-octyl-ß-valienamine (NOV, 4).
Assuntos
Cicloexanos/química , Hexosaminas/química , Inositol/análogos & derivados , Cloreto de Metileno/química , Compostos de Anilina/química , Animais , Sequência de Carboidratos , Bovinos , Ecdisona/análogos & derivados , Ecdisona/química , Inibidores Enzimáticos/química , Concentração Inibidora 50 , Inositol/síntese química , Inositol/química , Fígado/enzimologia , Dados de Sequência Molecular , Relação Estrutura-AtividadeRESUMO
A novel, water-soluble 20-hydroxylecdysono-20,22-phosphoric acid 2 and its sodium salt 3 were designed and synthesized from 20-hydroxylecdysone 1 in six steps and with 67% overall yield. The synthesized phosphoric acid 2 exhibited hypoglycemic activity >40-fold more potent than that of 20-hydroxylecdysone 1 at concentrations between 2 × 10â»7 and 2 × 10â»8 mol/l in a glucose consumption test in HepG2 cells. At a concentration of 2 × 10â»9 mol/l, phosphoric acid 2 was still active, causing a maximum increase in glucose consumption of more than 500%, while 20-hydroxylecdysone 1 was inactive.
Assuntos
Ecdisona/análogos & derivados , Ecdisona/síntese química , Hipoglicemiantes/síntese química , Hipoglicemiantes/farmacologia , Ecdisona/química , Ecdisona/farmacologia , Células Hep G2 , Humanos , Hipoglicemiantes/química , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Solubilidade , Água/químicaRESUMO
OBJECTIVE: Study the chemical constituents of the rhizomes of Paris bashanensis to search after the alternative resourc for the Chinese medicinal material Rhizoma Paridis. METHODS: The n-BuOH extracts of P. bashanensis was applied to silica gel column and eluted with EtOAc-EtOH,then the gained fractions were further purified by chromatography on Sephadex LH-20 column and PreRP-HPLC to give pure compounds whose structures were elucidated mainly on the basis of analyzing the spectral data of MS,1H-NMR, 13C-NMR,2D-NMR. RESULTS: Five compounds were isolated and identified as P-ecdysone (1), pinnatasterone(2), pennogenin-3-0-alpha-L-rhamnopyranosyl (1-->2)-[alpha-L-arabinofuranosyl ( 1- -4) ] -pf-D-glycopyranoside (3), diosgenin-3-O-alpha-L-rhamnopyranosyl (1-->2) - [ a-L-arabinofuranosyl (1-->4)]-beta-D-glycopyranoside(4), pennogenin-3-O-alpha-L-rhamnopyranosyl (1-->4) -a-L-rhamnopyranosyl (1-4)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D-glycopyranoside (5). CONCLUSION: Compound 1-5 are obtained from this plant for the first time.
Assuntos
Ecdisona/isolamento & purificação , Glicosídeos/isolamento & purificação , Liliaceae/química , Saponinas/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Ecdisona/química , Glicosídeos/química , Estrutura Molecular , Plantas Medicinais/química , Rizoma/química , Saponinas/químicaRESUMO
Although N-glycosylation has been known to increase the stability of glycoproteins, it is difficult to assess the structural importance of glycans in the stabilization of glycoproteins. APA (Antheraea pernyi arylphorin) is an insect hexamerin that has two N-glycosylations at Asn196 and Asn344 respectively. The glycosylation of Asn344 is critical for the folding process; however, glycosylation of Asn196 is not. Interestingly, the N196-glycan (glycosylation of Asn196) remains in an immature form (Glc1Man9GlcNAc2). The mutation of Asn196 to glutamine does not change the ecdysone-binding activity relative to that of the wild-type. In the present study, we determined the crystal structure of APA, and all sugar moieties of the N196-glycan were clearly observed in the electron-density map. Although the sugar moieties of the glycan generally have high structural flexibility, most sugar moieties of the N196-glycan were well organized in the deep cleft of the subunit interface and mediated many inter- and intrasubunit hydrogen bonds. Analytical ultracentrifugation and GdmCl (guanidinium chloride) unfolding experiments revealed that the presence of the N196-glycan was important for stabilizing the hexameric state and overall stability of APA respectively. Our results could provide a structural basis for studying not only other glycoproteins that carry an immature N-glycan, but also the structural role of N-glycans that are located in the deep cleft of a protein.
Assuntos
Proteínas de Insetos/química , Polissacarídeos/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Linhagem Celular , Ecdisona/química , Ecdisona/metabolismo , Glicosilação , Humanos , Proteínas de Insetos/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Polissacarídeos/química , Ligação Proteica , Conformação Proteica , Dobramento de ProteínaRESUMO
Using pure phytoecdysteroids isolated from Ajuga iva (L.) Schreber (Lamiales: Lamiaceae) and Silene nutans L. (Caryophyllales: Caryophyllaceae), plants known for their high ecdysteroid content, a study was carried out on the effects of ingestion of four different phytoecdysteroids (20-hydroxyecdysone, polypodine B, ponasterone A and makisterone A) on the growth and development of the Indian meal moth, Plodia interpunctella Hübner (Lepidoptera: Pyralidae) larvae when added at a concentration of 200 ppm in their diet. The experiments clearly showed the susceptibility of P. interpunctella to phytoecdysteroid ingestion. The toxicity of phytoecdysteroids manifested itself by a decrease in larval weight, induction of cannibalism and an increase of mortality, together with disruption of development. The severity of the phytoecdysteroid effect on P. interpunctella depended on the structure of the molecule. The results demonstrate that the minimal structural differences existing between these four phytoecdysteroids significantly affected their toxicity toward P. interpunctella. Makisterone A was the most toxic of the four compounds towards P. interpunctella larvae. In conclusion, phytoecdysteroids ingestion evokes disruptive growth effects on P. interpunctella. This work supports a role for phytoecdysteroids in plant defence against phytophagous insects.
Assuntos
Ajuga/química , Ecdisona/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/fisiologia , Fitosteróis/farmacologia , Silene/química , Animais , Peso Corporal , Canibalismo , Ecdisona/química , Privação de Alimentos , Larva/efeitos dos fármacos , Larva/fisiologia , Estrutura Molecular , Controle Biológico de Vetores , Fitosteróis/química , PupaRESUMO
The process of molting, known alternatively as ecdysis, is a feature integral in the life cycles of species across the arthropod phylum. Regulation occurs as a function of the interaction of ecdysteroid hormones with the arthropod nuclear ecdysone receptor-a process preceding the triggering of a series of downstream events constituting an endocrine signaling pathway highly conserved throughout environmentally prevalent insect, crustacean, and myriapod organisms. Inappropriate ecdysone receptor binding and activation forms the essential molecular initiating event within possible adverse outcome pathways relating abnormal molting to mortality in arthropods. Definition of the characteristics of chemicals liable to stimulate such activity has the potential to be of great utility in mitigation of hazards posed toward vulnerable species. Thus the aim of the present study was to develop a series of rule-sets, derived from the key structural and physicochemical features associated with identified ecdysone receptor ligands, enabling construction of Konstanz Information Miner (KNIME) workflows permitting the flagging of compounds predisposed to binding at the site. Data describing the activities of 555 distinct chemicals were recovered from a variety of assays across 10 insect species, allowing for formulation of KNIME screens for potential binding activity at the molecular initiating event and adverse outcome level of biological organization. Environ Toxicol Chem 2020;39:1438-1450. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Assuntos
Simulação por Computador , Receptores de Esteroides/metabolismo , Rotas de Resultados Adversos , Aminopirina/química , Aminopirina/metabolismo , Animais , Cloranfenicol/metabolismo , Ecdisona/química , Ecdisona/metabolismo , Ecdisterona/química , Ecdisterona/metabolismo , Ecotoxicologia , Ligantes , Ftalazinas/química , Ftalazinas/metabolismo , Ligação Proteica , Piridinas/química , Piridinas/metabolismo , Reprodutibilidade dos Testes , Especificidade da EspécieRESUMO
INTRODUCTION: The genus Asparagus is known to contain phytoecdysteroids that have been shown to exhibit many beneficial pharmacological properties such as improving lipid metabolism, modulating immunological responses, etc. Currently, knowledge about the contents of phytoecdysteroids in the roots of Asparagus species is limited and HPLC methods for their analyses are unsatisfactory. OBJECTIVE: To develop an HPLC method for the simultaneous determination of three phytoecdysteroids, 20-hydroxyecdysone, ecdysone and ajugasterone C, in the roots of four Asparagus species. METHODOLOGY: Reference standards of phytoecdysteroids were isolated from the roots of Asparagus filicinus by open column chromatography. HPLC analysis was performed on an Alltima C(18) column with gradient elution using aqueous 0.2% formic acid solution containing 0.2% isopropanol and acetonitrile. RESULTS: All calibration curves showed good linear correlation coefficients (r(2) > 0.9994) within the tested ranges. Limits of detection (S/N = 3) and quantification (S/N = 10) for the three analytes were less than 2.7 and 9.9 ng, respectively. Intra- and inter-day RSDs of retention times and peak areas were less than 2.61%. The recoveries were between 93.2 and 107.5%, and the RSDs were less than 3.83% for the root samples of A. filicinus. CONCLUSION: The HPLC method established is appropriate for the efficient quantitative and qualitative analyses of important phytoecdysteroids in Asparagus species. This study showed that A. filicinus is rich in phytoecdysteroids, especially 20-hydroxyecdysone. However the three studied phytoecdysteroids were not detected in A. cochinchinensis, A. officinalis and A. setaceus.
Assuntos
Asparagus/química , Ecdisteroides/química , Calibragem , Cromatografia Líquida de Alta Pressão , Ecdisona/química , Ecdisona/isolamento & purificação , Ecdisterona/análogos & derivados , Ecdisterona/química , Ecdisterona/isolamento & purificação , Raízes de Plantas/química , Plantas Medicinais/química , Padrões de Referência , Reprodutibilidade dos Testes , Solventes , Especificidade da Espécie , Espectrofotometria UltravioletaRESUMO
Ecdysteroids (arthropod molting hormones) play an important role in the development and sexual maturation of arthropods, and they have been shown to have anabolic and "energizing" effect in higher vertebrates. The aim of this study was to assess ecdysteroid diversity, levels according to bird species and months, as well as to observe the molting status of hard ticks (Acari: Ixodidae) infesting the birds. Therefore, blood samples and ticks were collected from 245 birds (244 songbirds and a quail). Mass spectrometric analyses showed that 15 ecdysteroids were regularly present in the blood samples. Molting hormones biologically most active in insects (including 20-hydroxyecdysone [20E], 2deoxy-20E, ajugasterone C and dacryhainansterone) reached different levels of concentration according to bird species and season. Similarly to ecdysteroids, the seasonal presence of affected, apolytic ticks peaked in July and August. In conclusion, this study demonstrates the presence of a broad range and high concentrations of ecdysteroids in the blood stream of wild-living passerine birds. These biologically active, anabolic compounds might possibly contribute to the known high metabolic rate of songbirds.
Assuntos
Animais Selvagens/sangue , Ecdisona/sangue , Ecdisteroides/sangue , Aves Canoras/sangue , Animais , Animais Selvagens/parasitologia , Artrópodes/crescimento & desenvolvimento , Artrópodes/metabolismo , Ecdisona/química , Ecdisteroides/química , Ecdisterona/análogos & derivados , Ecdisterona/sangue , Ecdisterona/química , Ecdisterona/metabolismo , Interações Hospedeiro-Parasita , Ixodidae/crescimento & desenvolvimento , Ixodidae/fisiologia , Estrutura Molecular , Muda , Estações do Ano , Aves Canoras/classificação , Aves Canoras/parasitologia , Especificidade da EspécieRESUMO
Phytoecdysteroids are structural analogs of the insect molting hormone ecdysone. Plants comprise rich sources of ecdysteroids in high concentration and with broad structural diversity. Ecdysteroids have a number of proven beneficial effects on mammals but the hormonal effects of ecdysteroids have been proven only in arthropods. Their structures are somewhat similar to those of the vertebrate steroid hormones but there are several structural differences between the two steroid groups. Despite of these essential structural differences, ecdysteroids exert numerous effects in vertebrates that are similar to those of vertebrate hormonal steroids, and they may serve as effective anabolic, hepatoprotective, immunoprotective, antioxidant and hypoglycemic agents. Ecdysteroids do not bind to the cytosolic steroid receptors, instead, they are likely to influence signal transduction pathways, like the anabolic steroids, possibly via membrane bound receptors. The application of phytoecdysteroids is a promising alternative to the use of anabolic-androgenic steroids because of the apparent lack of adverse effects. The prospective use of phytoecdysteroids may extend to treatments of pathological conditions where anabolic steroids are routinely applied. One of the most cited aspects of phytoecdysteroid application (on the Internet) is the increase of muscle size. However in this field too stringent research is needed as an adequate cytological explanation is not yet available for the anabolic. This paper reports on the most important structural differences between androgenic hormones, their synthetic analogs and ecdysteroids. The anabolic/hormonal effects and the possible mechanisms of action of these compounds are also discussed as concerns the skeletal muscle.
Assuntos
Anabolizantes/farmacologia , Androgênios/farmacologia , Ecdisona/farmacologia , Fitosteróis/farmacologia , Anabolizantes/química , Anabolizantes/uso terapêutico , Androgênios/química , Animais , Ecdisona/química , Ecdisona/uso terapêutico , Humanos , Estrutura Molecular , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Fitosteróis/química , Fitosteróis/uso terapêutico , Biossíntese de Proteínas/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
Three new phytoecdysteroids have been isolated from the seeds of Chenopodium quinoa and structurally identified as 20,26-dihydroxy, 28-methyl ecdysone, 20,26-dihydroxy, 24(28)-dehydro ecdysone, and 20-hydroxyecdysone 22-glycolate using serial chromatographic and spectroscopic methods. Both previously reported compounds and newly identified phytoecdysteroids were evaluated for their inhibitory effect on calf skin collagenase, as this enzyme is involved in aging skin diseases. Their effectiveness on scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, as well as in chelating the iron metal ions was also investigated. All isolated compounds demonstrated a higher potency to inhibit this matrix metalloproteinase and to chelate the iron ion, both with respect to the number of carbonyl groups bearing their carbon skeleton, suggesting that their mechanism of action involves their ability to coordinate both ions (either the zinc ion of the catalytic domain of collagenase or the iron ion), acting as an electron donor. The DPPH-scavenging ability was hydroxyl dependent. Satisfactory results obtained from the enzyme in vitro experiment were further supported by the gel electrophoresis. These results indicate that ecdysteroids might be considered as potent chemical agents to prevent or delay both collagenase-related skin damages and oxidative stress.
Assuntos
Ecdisona/farmacologia , Ecdisteroides/farmacologia , Inibidores Enzimáticos/farmacologia , Inibidores de Metaloproteinases de Matriz , Estresse Oxidativo/efeitos dos fármacos , Fitosteróis/farmacologia , Pele/efeitos dos fármacos , Pele/enzimologia , Animais , Antioxidantes/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Bovinos , Chenopodium quinoa/química , Ecdisona/química , Ecdisona/isolamento & purificação , Ecdisteroides/química , Ecdisteroides/isolamento & purificação , Técnicas In Vitro , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Fitosteróis/química , Fitosteróis/isolamento & purificaçãoRESUMO
The nonsteroidal ecdysone mimic 1,2-dibenzoyl-1-tert-butylhydrazine (RH-5849), a novel insect growth regulator, is mainly registered for use in rice fields. So far, its toxicity and ecological risks towards aquatic cladoceran invertebrates remain unclear. In this study, RH-5849 was evaluated for its acute and 21-day chronic toxicity towards Daphnia magna. The viability, morphology, growth, and reproduction of D. magna were observed to establish a concentration-toxicity relationship associated with the RH-5849 exposure. In addition, the relationship between the changes of physiological and biochemical indices and the chronic indices was analyzed in order to find potential early warning indicators in D. magna to the chronic risk of RH-5849 exposure. The results showed that the 48-h EC50 of acute immobilization and EC50 of 21-day survival of RH-5849 on D. magna were 45.3 and 1.34 mg/L, respectively. Chronic exposure to RH-5849 mainly affected the reproductive parameters of D. magna and the no observed effect concentration (NOEC) and the EC50 were 0.050 and 0.5423 mg/L, respectively. The number of offspring per female reduced significantly after 21-day exposure to 0.10 mg/L of RH-5849. The morphological changes, manifested in head width and body length, the length of the helmet or apical spine, and the curvature and transparency of the body, were observed in RH-5849-treated groups. Moreover, it was found that the alkaline phosphatase activity in D. magna after 5-7-day exposure was positively correlated with the number of offspring per female after 21 days. These results indicate the potential risk of RH-5849 towards aquatic crustaceans should be taken into consideration when applied to rice fields.
Assuntos
Daphnia/efeitos dos fármacos , Ecdisona/química , Hidrazinas/química , Oryza/química , Reprodução/efeitos dos fármacos , Animais , Daphnia/química , FemininoRESUMO
A series of our SAR and QSAR studies of synthetic moulting hormone agonists, dibenzoylhydrazines (DBH), exhibiting insecticidal/larvicidal activity are reviewed in this article. We prepared a number of analogues where various substituents are introduced into the two benzene rings of DBH and measured their biological activity using various biological systems. Larvicidal activity was against larvae of the rice stem borer Chilo suppressalis and the moulting hormone activity was in terms of the stimulation of N-acetylglucosamine incorporation in a cultured integument system of the same insect species. Binding affinity to the ecdysone receptor was assayed with intact Sf-9 cell lines in which the ADME processes are negligible as well as using receptor proteins obtained by in vitro translation of the responsible cDNA cloned from cell-free preparation of integumentary tissue of C. suppressalis. Variations in the biological activity indices were either correlated between two types of activity or correlated using physicochemical molecular and substituent parameters in terms of the classical QSAR. Comparisons among correlations and with recently revealed X-ray crystallographic findings clearly indicate the physicochemical meaning of parameters significant in the correlation equations to help understanding molecular mechanism of the moulting hormonal action.
Assuntos
Hidrazinas/química , Inseticidas/química , Relação Quantitativa Estrutura-Atividade , Receptores de Esteroides/agonistas , Acetilglucosamina/química , Animais , Benzoatos/química , Benzoatos/farmacologia , Benzopiranos/química , Benzopiranos/farmacologia , Ecdisona/química , Ecdisona/farmacologia , Hidrazinas/farmacologia , Inseticidas/farmacologia , Hormônios Juvenis/química , Hormônios Juvenis/farmacologia , Larva/efeitos dos fármacos , Mariposas/efeitos dos fármacos , Receptores de Esteroides/químicaRESUMO
Ecdysone receptor (EcR) is a significant target in the identification of new environmentally friendly pesticides. There are two types of ecdysone agonists: steroidal ecdysone agonists and dibenzoylhydrazines (DBHs). In this study, various modeling methods (homology modeling, molecular docking, MD simulation, binding free energy calculation, and per-residue binding free energy decomposition) were utilized to study the different binding mechanisms of two types of ecdysone agonists. Our theoretical results indicated that the relative binding potencies of DBHs can be ranked sufficiently accurately using the MOE docking method. However, MM/PBSA calculations more accurately predicted the binding affinities between steroidal ecdysone agonists and EcR-LBD. To identify the key residues involved in ecdysone agonist binding, the binding free energy (ΔG Bind) was decomposed into the energy contributions of individual residues. The results revealed that nine residues-Ile339, Thr343, Met380, Met381, Tyr403, Tyr408, Asp419, Gln503, and Asn504-determined the binding affinities of the DBHs. Glu309, Met342, Arg383, Arg387, and Leu396 were important influences on the binding affinities of the steroidal ecdysone agonists. Graphical abstract The ecdysone receptor (EcR) is related to insect growth and has been shown to be a useful target for insecticides.
Assuntos
Ecdisona/química , Proteínas de Insetos/química , Praguicidas/química , Receptores de Esteroides/química , Sequência de Aminoácidos/genética , Animais , Sítios de Ligação , Ecdisona/agonistas , Hidrazinas/química , Proteínas de Insetos/genética , Inseticidas/química , Modelos Moleculares , Simulação de Acoplamento Molecular , Ligação ProteicaRESUMO
The steroidal moulting hormones (ecdysteroids) mediate developmental transitions in insects, and their regulation is mainly controlled by the production and inactivation of these steroid hormones at the appropriate developmental times. One route of metabolism of ecdysteroids in insects involves EO (ecdysone oxidase)-catalysed conversion into 3-dehydroecdysteroid, which undergoes reduction to the corresponding 3-epiecdysteroid. By a twin-stranded bioinformatics approach, employing both phylogenomics and model structure-based analysis, we first predicted that DmEO (the EO of Drosophila melanogaster) corresponds to the protein product of gene CG9504. When CG9504 was expressed in COS7 cells, significant conversion of ecdysone into 3-dehydroecdysone was observed. Quantitative PCR and enzyme assay showed that DmEO was mainly expressed in the midgut during the late instars at a time corresponding to a hormone titre peak. DmEO shares only 27% amino acid sequence identity with Spodoptera littoralis (Lepidoptera) EO, yet key substrate-binding residues are well conserved. A model of DmEO is consistent with an inability to catalyse reaction of cholesterol derivatives. The significance of DmEO in ligand activation is discussed in relation to new evidence suggesting that 3-dehydro- and 3-epiecdysteroids may be functionally active as ligands in a novel, atypical ecdysteroid signalling pathway involving the Drosophila orphan nuclear receptor, DHR38, rather than being merely hormone inactivation products.
Assuntos
3-Hidroxiesteroide Desidrogenases/química , 3-Hidroxiesteroide Desidrogenases/metabolismo , Drosophila melanogaster/enzimologia , Drosophila melanogaster/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , 3-Hidroxiesteroide Desidrogenases/genética , Sequência de Aminoácidos , Animais , Benzoatos/farmacologia , Sítios de Ligação , Ecdisona/análogos & derivados , Ecdisona/antagonistas & inibidores , Ecdisona/química , Ecdisona/metabolismo , Regulação Enzimológica da Expressão Gênica , Hidrazinas/farmacologia , Larva/efeitos dos fármacos , Larva/enzimologia , Larva/genética , Larva/metabolismo , Dados de Sequência Molecular , Filogenia , Ligação Proteica , Pupa/enzimologia , Pupa/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Transdução de Sinais , Distribuição TecidualRESUMO
Ecdysteroids are known insect moulting hormones, regulating the insects' metamorphosis. At the same time, ecdysteroids reveal beneficial effects on humans and animals alike. Medicinal plants have been subjected to an intensive research, addressing the presence of ecdysteroids. The possible utilization of medicinal plant deals with their use as raw materials for health preparations and also for the isolation of new phytoecdysteroids. Research on the plant ecdysteroids involves two basic lines. Isolation of major compounds and scout their physiological effects; and isolation of minor ecdysteroids to find new compounds. This review summarizes the recent efforts in the ecdysteroid research including their indication as health improvement preparations, chromatography of ecdysteroids and certain methods for identification of new ecdysteroids.