RESUMO
The present study was designed to examine the effects of a sesquiterpene lactone isolated from Artemisia douglasiana Besser (dehydroleucodine), a xanthanolide sesquiterpene isolated from Xanthium cavanillesii Schouw (xanthatin) and a semisynthetic butenolide (3-benzyloxymethyl-5H-furan-2-one) on mast cell degranulation induced by compound 48/80. Peritoneal mast cells from male adult Sprague-Dawley rats were purified in Percoll, preincubated in the presence of test lactones (dehydroleucodine, xanthatin or 3-benzyloxymethyl-5H-furan-2-one) and then challenged with the mast cell activator compound 48/80 (10 microg/ml). Concentration-response and kinetic studies of mast cell serotonin release evoked by compound 48/80, evaluation of mast cell viability and morphology by light and electron microscopy, and comparative studies using ketotifen and sodium chromoglycate were carried out. Serotonin release studies, carried out together with morphological studies, showed the effectiveness of the above lactones to stabilize mast cells. The comparative study with ketotifen and sodium chromoglycate, well known mast cell stabilizers, showed the following order of potency dehydroleucodine=xanthatin>3-benzyloxymethyl-5H-furan-2-one> or =ketotifen/sodium chromoglycate to inhibit mast cell serotonin release induced by compound 48/80. The present study provides the first strong evidence in favour of the hypothesis that dehydroleucodine, xanthatin and 3-benzyloxymethyl-5H-furan-2-one inhibit compound 48/80-induced serotonin release from peritoneal mast cells, acting thus as mast cell stabilizers. Our findings may provide an insight into the design of novel pharmacological agents which may be used to regulate the mast cell response.
Assuntos
Antiulcerosos/farmacologia , Degranulação Celular/efeitos dos fármacos , Lactonas/farmacologia , Mastócitos/efeitos dos fármacos , p-Metoxi-N-metilfenetilamina/farmacologia , Animais , Antiulcerosos/química , Corantes/metabolismo , Relação Dose-Resposta a Droga , Processamento de Imagem Assistida por Computador , Lactonas/química , Masculino , Mastócitos/ultraestrutura , Estrutura Molecular , Peritônio/citologia , Ratos , Ratos Sprague-Dawley , Serotonina/metabolismo , Cloreto de Tolônio/metabolismoRESUMO
In this paper, the effects of 3 natural sesquiterpene lactones, i.e., helenalin (Hln), mexicanin (Mxc), and dehydroleucodine (DhL), were evaluated using cultured Leishmania mexicana promastigotes. It was observed that the compounds inhibited the in vitro growth of the parasites at relatively low concentrations. The effect was rapid and irreversible with an estimated IC50 of 2-4 microM, while all the lactones were more effective than ketoconazole. Moreover, these compounds exhibited low cytotoxicity for mammalian cells. Hln induced strong vacuolization of the parasite cytoplasm, although pericellular microtubules were preserved. The 3 lactones induced DNA fragmentation as judged by the high labeling with the fluorescent TUNEL method, which was confirmed by electrophoresis on agarose gels. The ability of the parasites to invade Vero cells was also decreased by exposure to low concentrations of the compounds. We conclude that these compounds can affect the parasite's life cycle, possibly through multiple mechanisms. Identification of the molecular targets of these natural products and their effects on amastigotes should be determined to evaluate the possible therapeutic use of the compounds against leishmaniasis.
Assuntos
Antiprotozoários/farmacologia , Lactonas/farmacologia , Leishmania mexicana/efeitos dos fármacos , Sesquiterpenos/farmacologia , Animais , Artemisia/química , Asteraceae/química , Chlorocebus aethiops , Fragmentação do DNA , DNA de Protozoário/efeitos dos fármacos , Marcação In Situ das Extremidades Cortadas , Leishmania mexicana/genética , Leishmania mexicana/crescimento & desenvolvimento , Leishmania mexicana/ultraestrutura , Microscopia Eletrônica de Transmissão , Sesquiterpenos de Guaiano , Células VeroRESUMO
Linear diterpenes isolated from aerial parts of Baccharis thymifolia ( 1- 3) were tested for insect growth inhibitory activity against Tenebrio molitor larvae. Compounds 4- 16 were prepared by various chemical transformations. The diterpenes 6,10-( E,E)-thymifodioic acid ( 1), the butenolide 3, and the derivatives 4, 11, and 14 produced developmental deficiencies in assays using topical application on fifth instar larvae of T. molitor. Compound 3 is a new natural product.
Assuntos
Baccharis/química , Diterpenos/isolamento & purificação , Diterpenos/farmacologia , Inseticidas/isolamento & purificação , Inseticidas/farmacologia , Plantas Medicinais/química , Animais , Argentina , Diterpenos/química , Inseticidas/química , Larva/efeitos dos fármacos , Estrutura Molecular , Tenebrio/efeitos dos fármacosRESUMO
5,6-Epoxycholestan-3beta-ol derivatives were hydrolyzed in a diastereoconvergent manner by growing and resting cells of several strains of Aspergillus niger, particularly A. niger ATCC 11394. These strains displayed opposite regioselectivity toward each isomer in an alpha and beta epoxide mixture, thus, the nucleophilic attack took place at the less substituted and the most substituted carbon atom on each diasteromer, respectively. These biocatalysts opened trisubstituted oxiranes but were unable to hydrolyze the disubstituted oxiranes in the tested sterol derivatives. These findings suggest that A. niger strains possess another hydrolytic ability different from the commercial A. niger epoxide hydrolase (EH) that did not accept this kind of steroidal oxiranes as substrates.
Assuntos
Aspergillus niger/metabolismo , Epóxido Hidrolases/metabolismo , Compostos de Epóxi/química , Óxido de Etileno/química , Biotransformação , Óxido de Etileno/metabolismo , Hidrólise , Cinética , Modelos Moleculares , Estrutura Molecular , EstereoisomerismoRESUMO
Modulation of vascular smooth muscle cell (VSMC) proliferation has critical therapeutic implications for vascular disease. Recently, we demonstrated that the sesquiterpene lactone dehydroleucodine (DhL) inhibited the proliferation of VSMCs in G2 phase. It is known that the alpha,beta-unsaturated carbonyl group of the sesquiterpene lactone has a nonspecific alkylating activity that inhibits a large number of enzymes or factors involved in key biological processes. We analyzed whether the DhL alpha-methylene-gamma-lactone function is directly involved in cell proliferation arrest in G2 and in cell toxicity. To this end, the effects of both DhL and 11,13-dihydro-dehydroleucodine (2H-DhL), a derivative of DhL with inactivated alpha-methylenelactone function, on cultured VSMC viability and proliferation were assessed. We found that both DhL and 2H-DhL inhibited the proliferation of VSMCs in a dose-dependent manner, inducing a transient arrest in G2 phase. DhL, but not 2H-DhL, had a cytotoxic effect at concentrations up to 12 microM, indicating that cell proliferation arrest and cytotoxicity are mediated by different cellular targets. From these results we infer that only 2H-DhL is able to arrest cell proliferation in G2 without affecting cell viability at any concentration.
Assuntos
Proliferação de Células/efeitos dos fármacos , Fase G2 , Lactonas/farmacologia , Músculo Liso/citologia , Miócitos de Músculo Liso/efeitos dos fármacos , Sesquiterpenos/farmacologia , Animais , Aorta Torácica/citologia , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Replicação do DNA/efeitos dos fármacos , Masculino , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Miócitos de Músculo Liso/fisiologia , Ratos , Ratos Endogâmicos WKYRESUMO
In order to establish structure-activity relationships, nine neo-clerodane diterpenes isolated from the acetone extract of aerial parts of Baccharis flabellata Hook & Arn var. fabellata were assayed for antifeedant activity against Tribolium castaneum (Coleoptera: Tenebrionidae). Compounds exhibiting maximal antifeedant activities showed an alpha,beta-unsaturated carbonyl group on the decalin portion and a furan ring at the side chain. Stereoelectronic studies indicate that the distance between the furan heteroatom and the more electrophilic carbon of the decaline moiety, as well as the electrostatic charge on that atom, were important features for antifeedant activity. Compounds possesing an alpha,beta,gamma,delta-unsaturated carbonyl group or an acetoxyl group at C-2, were inactive. Theoretical calculations were performed in order to find some structure-activity relationships.
Assuntos
Baccharis/química , Diterpenos Clerodânicos/química , Diterpenos Clerodânicos/farmacologia , Tribolium/efeitos dos fármacos , Animais , Diterpenos Clerodânicos/isolamento & purificação , Comportamento Alimentar/efeitos dos fármacos , Conformação Molecular , Ressonância Magnética Nuclear Biomolecular , Rotação Ocular , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Relação Estrutura-Atividade , Tribolium/fisiologiaRESUMO
Grindelia pulchella callus and cell suspension cultures were established from seedling leaves. When several phytoregulator supplementations were assayed in solid Murashige and Skoog medium containing 3 percent (w/v) of sucrose (MS medium), combinations of indole-3-butyric acid (IBA) and N6-benzylaminopurine (BA) resulted the most appropriate conditions to generate fast growing friable calli with detectable levels of grindelic acid. Moreover, the same basal media supplemented with 20.0 µM IBA/4.4 µM BA was found to be optimal for cell growth in submerged cultures (µmax = 0.26 days-1) while the addition of 20.0 µM IBA/18.0 µM BA resulted in a relative higher metabolite production (4.55 mg/gDW) when the inocula was 5 percent (v/v). Furthermore, three different stress factors and combinations of them were used to elicit cell suspensions. These experiments demonstrated that the combination of CuSO4 and dimethylsulfoxide (DMSO) increase the grindelic acid production to 2.63 mg/gDW in the elicited essay versus 0.756 mg/gDW in the control, at expense of cell growth. In contrast, the addition of jasmonic acid (JA) alone and combined with DMSO neither affected cell growth nor grindelic acid accumulation.
Assuntos
Ciclopentanos/metabolismo , Dimetil Sulfóxido/metabolismo , Diterpenos/química , Sulfato de Cobre/metabolismo , Ácidos Graxos Insaturados/metabolismo , Células Cultivadas , Diterpenos/isolamento & purificaçãoRESUMO
A series of sesquiterpene compounds possessing both eudesmane and eremophilane skeletons were tested as gastric cytoprotective agents on male Wistar rats. The presence of an alpha,beta-unsaturated aldehyde on the C-7 side chain together with a hydroxyl group at C-4 is the requirement for the observed antiulcerogenic activity. In an attempt to establish new molecular structural requirements for this gastric cytoprotective activity, a structure-activity study was performed.
Assuntos
Antiulcerosos/farmacologia , Trato Gastrointestinal/efeitos dos fármacos , Sesquiterpenos/farmacologia , Animais , Antiulcerosos/química , Trato Gastrointestinal/citologia , Masculino , Ratos , Ratos Wistar , Sesquiterpenos/química , Úlcera Gástrica/tratamento farmacológico , Relação Estrutura-AtividadeRESUMO
The preventive effect of natural xanthanolides as well as a series of synthetic derivatives on ulcer formation induced by absolute ethanol in rats was examined. Among the compounds tested, xanthatin gave the strongest protective activity. The inhibitory action exerted by this molecule on the lesions induced by 0.6N HCl and 0.2N NaOH was highly significant, reducing ulceration in the range of 58-96% at a dose from 12.5 to 100mg/kg. These results appear to confirm that the presence of a non-hindered alpha,beta-unsaturated carbonyl group seems to be an essential structural requirement for the gastric cytoprotective activity of these compounds. In order to explore this possibility, a theoretical conformational analysis was performed. We suggest that the mechanism of protection would involve, at least in part, a nucleophylic attack of the sulfhydryl group from the biological molecules present in the gastric mucosa to electrophylic carbons accessible in suitable Michael acceptors.
Assuntos
Antiulcerosos/farmacologia , Sesquiterpenos/farmacologia , Xanthium/química , Animais , Antiulcerosos/química , Depressores do Sistema Nervoso Central , Fenômenos Químicos , Físico-Química , Etanol , Ácido Clorídrico , Espectroscopia de Ressonância Magnética , Masculino , Modelos Moleculares , Conformação Molecular , Método de Monte Carlo , Extratos Vegetais/química , Ratos , Ratos Wistar , Sesquiterpenos/química , Hidróxido de Sódio , Úlcera Gástrica/induzido quimicamente , Úlcera Gástrica/prevenção & controle , Relação Estrutura-AtividadeRESUMO
Sesquiterpene lactones constitute a large group of biologically active compounds obtained from plants. The lactones, mexicanin (MXN) and helenalin (HLN), were reported recently as active against the infective form of Trypanosoma cruzi. In this work, we studied the effects of these compounds on the growth and viability of the noninfective epimastigote, to compare the sensitivity of the 2 stages and to characterize their actions. Both compounds were cytotoxic to the parasites, with HLN (inhibitory concentration 50% [IC50] 1.9 +/- 0.08 microM) more potent than MXN (IC50 3.8 +/- 0.19 microM) and the typanocidal drug, benznidazole (IC50 8.6 +/- 2.5 microM). The results showed that epimastigotes are less sensitive than trypomastigotes to the compounds. The trypanocidal effect of these lactones, irreversible after 12-hr exposure, was not reversed by the reducing agents dithiotreitol or beta-mercaptoethanol. Ultrastructurally, we observed cytoplasmic vacuolization and nuclear disorganization. Although concentrations between 0.5 and 1.5 microM of the drugs were not lethal to the parasites, epimastigotes became thinner and their nuclei became more pycnotic after exposure. We conclude that MXN and HLN are deleterious for T. cruzi epimastigotes and that their mechanism of action is different than that of the related lactone, dehydroleucodine.