RESUMO
Eight alkaloids (1â»8) were isolated from Ruta graveolens, and their herbicide activities were evaluated through in vitro, semivivo, and in vivo assays. The most relevant results were observed for Compounds 5 and 6â»8 at 150 µM, which decreased dry biomass by 20% and 23%, respectively. These are significant results since they presented similar values with the positive control, commercial herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Based on the performed assays, Compound 5 (graveoline) is classified as an electron-transport inhibitor during the light phase of photosynthesis, as well as a plant-growth regulator. On the other hand, Compounds 6â»8 inhibited electron and energy transfers, and are also plant-growth inhibitors. These phytotoxic behaviors based on acridone and quinolone alkaloids may serve as a valuable tool in the further development of a new class of herbicides since natural products represent an interesting alternative to replace commercial herbicides, potentially due their low toxicity.
Assuntos
Alcaloides/isolamento & purificação , Metoxaleno/análogos & derivados , Fotossíntese/efeitos dos fármacos , Ruta/química , Alcaloides/química , Alcaloides/farmacologia , Biomassa , Diurona/farmacologia , Transporte de Elétrons , Herbicidas/farmacologia , Metoxaleno/química , Metoxaleno/isolamento & purificação , Metoxaleno/farmacologiaRESUMO
A high performance liquid chromatography (HPLC) method was developed for the simultaneous isolation, on a semi-preparative scale, of chavibetol and methyleugenol from the crude essential oil of P. pseudocaryophyllus leaves. The purity of the isolated compounds and their quantifications were developed using GC/FID. Chavibetol was isolated with high purity (98.7%) and mass recovery (94.6%). The mass recovery (86.4%) and purity (85.3%) of methyleugenol were lower than those of chavibetol. Both compounds were identified on the basis of spectral analysis. The results suggest that the method can provide chavibetol with high purity, mass recovery, and productivity from crude essential, which will be used in bioassays against stored insect pests.
Assuntos
Eugenol/análogos & derivados , Pimenta/química , Cromatografia Líquida de Alta Pressão , Eugenol/isolamento & purificação , Óleos Voláteis/química , Folhas de Planta/química , Óleos de Plantas/químicaRESUMO
Antidesmone, isolated from Waltheria brachypetala Turcz., owns special structural features as two α,ß-unsaturated carbonyl groups and a side alkyl chain that can compete with the quinones involved in the pool of plastoquinones at photosystem II (PSII). In this work, we showed that the alkaloid is an inhibitor of Hill reaction and its target was located at the acceptor side of PSII. Studies of chlorophyll (Chl) a fluorescence showed a J-band that indicates direct action of antidesmone in accumulation of QA- (reduced plastoquinone A) due to the electron transport blocked at the QB (plastoquinone B) level similar to DCMU. In vivo assays indicated that antidesmone is a selective post-emergent herbicide probe at 300µM by reducing the biomass production of Physalis ixacarpa plants. Furthermore, antidesmone also behaves as pre-emergent herbicide due to inhibit Physalis ixacarpa plant growth about 60%. Antidesmone, a natural product containing a 4(1H)-pyridones scaffold, will serve as a valuable tool in further development of a new class of herbicides.
Assuntos
Alcaloides/toxicidade , Compostos Aza/toxicidade , Herbicidas/toxicidade , Lolium/efeitos dos fármacos , Physalis/efeitos dos fármacos , Alcaloides/isolamento & purificação , Compostos Aza/isolamento & purificação , Clorofila/metabolismo , Clorofila A , Cloroplastos/efeitos dos fármacos , Cloroplastos/metabolismo , Herbicidas/isolamento & purificação , Lolium/crescimento & desenvolvimento , Lolium/metabolismo , Malvaceae/química , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Physalis/crescimento & desenvolvimento , Physalis/metabolismo , Folhas de Planta/química , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Caules de Planta/química , Caules de Planta/efeitos dos fármacos , Caules de Planta/crescimento & desenvolvimentoRESUMO
NS2B-NS3 is a serine protease of the Dengue virus considered a key target in the search for new antiviral drugs. In this study flavonoids were found to be inhibitors of NS2B-NS3 proteases of the Dengue virus serotypes 2 and 3 with IC50 values ranging from 15 to 44 µM. Agathisflavone (1) and myricetin (4) turned out to be noncompetitive inhibitors of dengue virus serotype 2 NS2B-NS3 protease with Ki values of 11 and 4.7 µM, respectively. Docking studies propose a binding mode of the flavonoids in a specific allosteric binding site of the enzyme. Analysis of biomolecular interactions of quercetin (5) with NT647-NHS-labeled Dengue virus serotype 3 NS2B-NS3 protease by microscale thermophoresis experiments, yielded a dissociation constant KD of 20 µM. Our results help to understand the mechanism of inhibition of the Dengue virus serine protease by flavonoids, which is essential for the development of improved inhibitors.
Assuntos
Vírus da Dengue/enzimologia , Flavonoides/farmacologia , Serina Endopeptidases/química , Inibidores de Serina Proteinase/química , Inibidores de Serina Proteinase/farmacologia , Antivirais/química , Antivirais/farmacologia , Vírus da Dengue/efeitos dos fármacos , Flavonoides/química , Cinética , Modelos Moleculares , Simulação de Acoplamento Molecular , Serina Endopeptidases/metabolismo , Relação Estrutura-AtividadeRESUMO
Byrsonima coccolobifolia leaf and stem extracts were studied in the search for possible leishmanicidal compounds using arginase (ARG) from Leishmania amazonensis as a molecular target. Flavonoids 1b, 1e-1g, 2a, 2b, and 2d-2f showed significant inhibitory activity, with IC50 values ranging from 0.9 to 4.8 µM. The kinetics of the most active compounds were determined. Flavonoids 1e, 1f, 2a, 2b, and 2e were characterized as noncompetitive inhibitors of ARG with dissociation constants (Ki) ranging from 0.24 to 3.8 µM, demonstrating strong affinity. Structure-activity relationship studies revealed some similarities in the structural features of flavonoids related to ARG activity.
Assuntos
Arginase/antagonistas & inibidores , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Leishmania/efeitos dos fármacos , Malpighiaceae/química , Brasil , Flavonoides/química , Concentração Inibidora 50 , Estrutura Molecular , Folhas de Planta/química , Caules de Planta/química , Relação Estrutura-AtividadeRESUMO
The aim of the study was to evaluate the effects of the seeds, exocarp and aril extracts from Trichilia catigua A. Juss. (Meliaceae) against Spodoptera frugiperda and present the phytochemical study carried out with the aril extract of T. catigua. Limonoids were isolated from the aril of T. catigua through chromatographic techniques and their structures were proposed by spectroscopic analysis and comparison with literature data. The effects of the seeds, exocarp and aril extracts from T. catigua against S. frugiperda were evaluated considering as parameters the duration and mortality of the larval phase, in addition to the pupal weight. Phytochemical investigation of the aril extracts of T. catigua has led to the identification of the limonoids 6α-O-acetyl-7-deacetyl-14,15-dihydro-15-oxo-nimocinol (1), cedrelone (2) and 6α-O-acetyl-7-deacetylnimocinol (3). The hexane and CH2Cl2 extracts of the aril showed a high rate of larval mortality (100 and 90%, respectively). In addition, a prolongation of larval phase and a reduction in the pupal weight were observed for insects treated with hexane, CH2Cl2 and methanol extracts of seeds and with CH2Cl2 extract of exocarp of T. catigua.
Assuntos
Inseticidas , Limoninas , Meliaceae , Animais , Inseticidas/farmacologia , Spodoptera , Limoninas/farmacologia , Hexanos , Extratos Vegetais/farmacologia , Meliaceae/química , LarvaRESUMO
Objective. To evaluate the effect of an experimental gel containing Euclea natalensis extract on dentin permeability. Methods. Thirty-six dentin discs, 1-mm-thick. The discs were prepared from the coronal dentin of extracted human third molars that were divided into 3 groups (n = 10). The dentin discs in each group were treated with the groups following experimental materials: (FG): 1.23% fluoride gel, pH 4.1; (EG): Euclea natalensis extract gel, pH 4.1; (CG): control gel, pH 4.1. The gels were applied to the occlusal slide of the dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. The hydraulic conductance (HC) of each condition was determined four times using a fluid flow apparatus (Flodec). The data were analyzed using Two-way ANOVA and Tukey's test (P < 0.05). Results. The greatest mean reduction in HC was produced in group EG dentin discs (61.2%; P < 0.05). Even after acid challenge with 6% citric acid the great reduction occurred in group EG (66.0%; P < 0.05) than other groups (CG-77.1%, FG-90.8%). Conclusion. E. natalensis gel not only reduced dentin permeability, but also resisted posttreatment citric acid challenge without changing its permeability. Further research has to confirm this promising result in the clinical situation.
RESUMO
Soybean crop is regulated by abiotic and biotic stresses with great potential in reducing grain yield and quality. The selection of resistant cultivars is a promising approach for mitigating these damages. We evaluated the chemical profile of Glycine max leaves from different cultivars in order to explore their defense mechanisms against Spodoptera cosmioides caterpillars. We optimized solid-liquid extraction techniques using ultrasound bath and static headspace extraction. Additionally, we developed an approach based on liquid and gas chromatography for analyzing the chemical profile of G. max cultivars. The principal component analysis allowed the classification of transgenic cultivars, which are classified as susceptible to S. cosmioides, from those obtained by genetic improvement and resistant to the insect. Differences were observed in the abundance of phenolic glycosides, lipids, aldehydes, and alcohols. More specifically, S. cosmioides resistant cultivars presented molecules related to the jasmonic and salicylic acid pathways. Such data can contribute to a molecular understanding of phenotypic diversity in soybean cultivars, from plant quality to resistance mechanisms and adaptation, to environmental stress and herbivory.
RESUMO
In this work, we describe the insecticidal activity against Spodoptera frugiperda of flavanone derivatives (naringin, naringenin and hesperidin) complexed to copper (II). For the assays, the compounds were incorporated into an artificial diet and offered to S. frugiperda during its larval period. The duration of larval and pupal phases, the weight of pupae and the percentage of dead insects at the end of the larval phase were evaluated. Among the tested compounds, the free flavanones 1 and 3 and the complexes 4 and 6 showed a shortening of the larval phase when compared to the control. Complex 9 showed the highest toxicity, with 96.66% larval mortality. This is the first report on the insecticidal activity of the Cu2+ complexes of the flavanones naringin, naringenin and hesperidin.[Formula: see text].
Assuntos
Flavanonas , Inseticidas , Animais , Cobre/farmacologia , Flavanonas/farmacologia , Inseticidas/farmacologia , Larva , SpodopteraRESUMO
Glyphosate excessive use is reported in Brazilian citrus orchards, whereas there is speculation about its consequences and the published studies are contradictory and inconclusive. This study aimed to describe the possible harmful effects by simulating glyphosate drift directly to the leaves of â¼4-yr-old citrus plants. As major results, glyphosate doses >360 g ae ha-1 increased the shikimate accumulation in leaves (up to 2.3-times above control), which was increased after a second glyphosate application (up to 3.5-times above control), even after a 240-d interval. Interestingly, shikimate accumulation was occasionally related to a dose-response of the herbicide at specific times; however, the doses had their accumulation peak on determined dates. These accumulations were directly correlated to reduced net photosynthesis even months after the glyphosate sprays. Quantum productivity based on electron transport through the photosystem II and apparent electron transport reductions up to 17% were also observed during the entire experiment course. Similarly, quantum productivity based on CO2 assimilation of glyphosate sprayed leaves decreased up to four times compared to the control after the second application. Glyphosate doses >360 g ae ha-1 increased stomatal conductance and transpiration as the carboxylation efficiency decreased, evidencing a carbon drainage in the Calvin-Benson cycle. These metabolic and physiological disturbances suggest possible photooxidative damage and an increase in photorespiration, which may be a mitigation strategy by the citrus plants to glyphosate effects, by the cost of reducing the citrus fruit yield (up to 57%). It is concluded that glyphosate phytotoxicity damages citrus plants over time due to chronic disturbances in the shikimate pathway and photosynthesis, even when there are no symptoms. This study is the first report to demonstrate how glyphosate damages citrus trees beyond the shikimate pathway.
Assuntos
Citrus , Herbicidas , Carbono/farmacologia , Dióxido de Carbono/metabolismo , Glicina/análogos & derivados , Herbicidas/toxicidade , Fotossíntese , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Ácido Chiquímico/metabolismo , Árvores/metabolismo , GlifosatoRESUMO
The fungus Beauveria bassiana is widely used for pest control; however, biostability and dispersion for broth pulverization are limiting factors for its application in the field. In this context, formulation techniques such as microencapsulation are viable alternatives. The aim of this work is to optimize B. bassiana formulations by spray dryer and evaluate its stability and biological activity against Spodoptera cosmioides compared to ionic gelatinization formulations. The fungus was biocompatible with all evaluated biopolymers (lignin, cellulose, starch, humic substances, and alginate). The encapsulation by spray drying was optimized by factorial design in an inlet and outlet air temperature of 120°C and 68°C, respectively; aspirator rate of 35 m3·h-1, feed flow rate of 12 mL·min-1; and drying gas flow at 35 L·h-1. The ionic gelation capsules were obtained using a 0.5% quantity of conidia in a 1% sodium alginate solution dropped into a 0.5 mol·L-1 CaCl2 solution using a peristaltic pump. Spray drying provided smaller microcapsules than those by ionic gelation. Both techniques produced more stable conidia when exposed to temperature and UV-radiation than non-formulated B. bassiana. The formulations prepared by spray drying showed gains at aqueous dispersion. Biological assays against Spodoptera cosmioides showed a mortality rate of up to 90%. These results demonstrate the suitability of encapsulating B. bassiana conidia stably in aqueous dispersion without loss of viability and virulence.
RESUMO
Although many copper-based antimicrobial compounds have been developed to control pathogenic bacteria and fungi in plants and applied for crop protection, there is evidence that several plant pathogens have developed resistance to copper-based antimicrobial compounds, including some Xanthomonas species. Xylella is a bacterial genus belonging to the Xanthomonas family; and X. fastidiosa, which is responsible for citrus variegated chlorosis (CVC) in sweet orange, may develop resistance to one or more copper-based antimicrobials. Because of the time required for the development and approval of new antimicrobials for commercial use, the discovery of novel bactericidal compounds is essential before the development of resistance to the antimicrobials currently in use becomes widespread. Here, we explored the antimicrobial potential of two newly synthesized antimicrobials complexes and one natural compound against X. fastidiosa. Several nuclear magnetic resonance (NMR) assays with high resolution and sensitivity were developed to identify new diastereoisomers in the context of octahedral ruthenium - [Ru(narin)(phen)2]PF6-and magnesium naringenin 5-alkoxide - [Mg(narin)(phen)2]OAc - complexes, obtained in the present work. The NMR assays proved to be powerful tools for the identification of isomers in metal complexes. Moreover, a protocol for the in-vivo determination of the effects of these complexes against X. fastidiosa was developed. The main trunks of X. fastidiosa infected plants were injected with the two complexes as well as with the limonoid azadirachtin using a syringe; the number of bacterial cells in the plants following treatment was estimated via real-time quantitative PCR (qPCR). Importantly, the administration of both complexes and of azadirachtin drastically reduced the number of X. fastidiosa cells in vivo.
Assuntos
Anti-Infecciosos , Citrus , Rutênio , Xylella , Antibacterianos/farmacologia , Flavanonas , Magnésio , Espectroscopia de Ressonância Magnética , Doenças das PlantasRESUMO
Fruit processing waste, such as kernels (endocarp + seed) of avocado [Persea americana Mill. (Lauraceae)], could be used as raw material in the preparation of botanical insecticides. In light of this potential, this study assessed the insecticidal action of extracts and fractions from kernels of two avocado cultivars (Breda and Margarida) on Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B, an important pest species in tropical conditions. Ethanolic and aqueous extracts prepared from kernels of P. americana, regardless of the plant cultivar used, caused promising insecticidal activity to whitefly nymphs. Based on yield in crude extracts [10.32 and 9.85% (w/w), respectively, for cultivars Breda and Margarida], on the bioassay results with crude extracts and on the chemical profiles, the ethanolic extract of kernels of P. americana cv. Breda was chose for the continuation of the study. Thus, the ethanolic extract of kernels of cv. Breda (LC50 = 197.84 ppm and LC90 = 567.19 ppm) was selected and subjected to fractionation by the liquid-liquid partition technique. The hexane and dichloromethane fractions of this extract caused significant mortality of nymphs. The analysis using the ultraviolet (UV) and hydrogen nuclear magnetic resonance (1H NMR) showed the presence of long-chain aliphatic compounds (alkanols or acetogenins of Lauraceae), alkylfurans (or avocadofurans), and unsaturated fatty acids in these fractions, which are possibly related to bioactivity observed in B. tabaci, besides saccharides. The results show that kernels of P. americana are promising sources of compounds with insecticidal action for the control of B. tabaci biotype B, a great opportunity to transform environmental problems into eco-friendly solutions to agriculture.
Assuntos
Hemípteros , Inseticidas , Persea , Animais , Dose Letal Mediana , NinfaRESUMO
Tahiti lemon juice (Citrus latifolia) (TLJ), as a natural source of flavonoids, has been used as an alternative to anti-inflammatory drugs for the treatment of dysmenorrhea and menstrual excessive bleeding, often associated with an imbalance of the prostaglandins (PG) levels. However, despite the positive effects, the mechanisms that rule menstruation control are still unknown. Therefore, the objectives were to characterize the TLJ and analyze its effect on the production of PGF2α, PGE2 and pro-inflammatory cytokines involved inmenstruation. Flavonoids from TLJ were discriminated by UPLC-DAD-MS/MS (Qq-TOF) and the effects of TLJ were studied in vitro by quantification of the contraction of myoblasts in culture and PGF2α and PGE2 productions. Further, the systemic and menstrual fluid levels of PGF2α, PGE2, IL-1ß, TNF-α, IL-6, AK1B1 and AK1C3 enzymes produced by women during the menstrual period were compared after exposition or not to TLJ or meloxicam. The results showed that TLJ induces an increase in the contraction of myoblasts and the PGF2α supernatant level. Regarding in vivo analysis, a higher concentration of PGF2α and an unaltered PGE2 level was also found in the menstrual blood of women treated with TLJ, in contrast with a lower level of PGE2 and PGF2α observed in the meloxicam group. Concerning cytokines, only menstrual TNF-α levels decrease after treatment with TLJ or meloxicam. In conclusion, TLJ may favor the control of menstruation events via a PGF2α mediated muscle contractile response.
Assuntos
Citrus/química , Citocinas/metabolismo , Menstruação/efeitos dos fármacos , Menstruação/metabolismo , Extratos Vegetais/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Cromatografia Líquida de Alta Pressão , Dinoprosta/metabolismo , Dinoprostona/metabolismo , Feminino , Humanos , Inflamação/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Espectrometria de Massas , Camundongos , Mioblastos/efeitos dos fármacos , Mioblastos/metabolismo , Extratos Vegetais/química , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Extracts from Hortia oreadica afforded four dihydrocinnamic acid derivatives, isolated from the n-hexane extract, as well as limonoid guyanin and the furoquinoline alkaloid dictamnine, both isolated from the dichloromethane extract. The extracts and the isolated compounds were tested against some oral pathogens, so as to investigate their antibacterial activity. The results showed that the n-hexane extract and the compound dictamnine are the most active against the selected microorganisms.
RESUMO
In the title compound, C(18)H(16)O(6), the benzopyran group is essentially planar, with the O atoms of the substituent groups lying close to its mean plane. The mol-ecular conformation is governed by intra-molecular inter-actions. The crystal packing is mainly determined by one classical inter-molecular hydrogen bond which gives rise to the formation of an infinite chain along the a axis.
RESUMO
The treatment of diseases using enzymes as targets has called for the development of new and reliable methods for screening. The protease cathepsin D is one such target involved in several diseases such as tumors, degenerative processes, and vital processes of parasites causing schistosomiasis. Herein, we describe the preparation of a fused silica capillary, cathepsin D (CatD)-immobilized enzyme reactor (IMER) using in a multidimensional High Performance Liquid Chromatography-based method (2D-HPLC) and zonal affinity chromatography as an alternative in the search for new ligands. The activity and kinetic parameters of CatD-IMER were evaluated by monitoring the product MOCAc-Gly-Lys-Pro-Ile-Leu-Phe (P-MOCAc) (KMâ¯=â¯81.9⯱â¯7.49⯵mol/L) generated by cleavage of the fluorogenic substrate MOCAc-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Leu-Lys(DNP)-d-Arg-NH2 (S-MOCAc). Stability studies have indicated that CatD-IMER retained 20% of activity after 5 months, a relevant result, because proteases are susceptible to autoproteolysis in solution assays with free enzyme. In the search for inhibitors, 12 crude natural product extracts were analyzed using CatD-IMER as the target, resulting in the isolation of different classes of natural products. In addition, 26 compounds obtained from different species of plants were also screened, demonstrating the efficiency and reproducibility of the herein reported assay even in the case of complex matrices such as plant crude extracts.
Assuntos
Catepsina D/antagonistas & inibidores , Inibidores Enzimáticos/análise , Enzimas Imobilizadas/antagonistas & inibidores , Extratos Vegetais/análise , Catepsina D/química , Catepsina D/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Avaliação Pré-Clínica de Medicamentos/instrumentação , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Estabilidade Enzimática , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Ligantes , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Reprodutibilidade dos Testes , Dióxido de Silício/química , Especificidade por SubstratoRESUMO
Sclerotinia sclerotiorum is responsible for the white mold of soybeans, and the difficulty to control the disease in Brazil is causing million-dollar damages. Stachybotrys levispora has shown activity against S. sclerotiorum. In our present investigation, we analyzed the chemical basis of this inhibition. Eight compounds were isolated, and using spectroscopic methods, we identified their structures as the known substances 7-dechlorogriseofulvin, 7-dechlorodehydrogriseofulvin, griseofulvin, dehydrogriseofulvin, 3,13-dihydroxy-5,9,11-trimethoxy-1-methylbenzophenone, griseophenone A, 13-hydroxy-3,5,9,11-tetramethoxy-1-methylbenzophenone, and 12-chloro-13-hydroxy-3,5,9,11-tetramethoxy-1-methylbenzophenone. Griseofulvin inhibited the mycelial growth of S. sclerotiorum at 2 µg mL-1. Thus, the antagonistic effect of S. levispora to S. sclerotiorum may well be due to the presence of griseofulvins. Our results stimulate new work on the biosynthesis of griseofulvins, to locate genes that encode key enzymes in these routes and use them to increase the production of these compounds and thus potentiate the fungicide effect of this fungus. S. levispora represents an agent for biocontrol, and griseofulvin represents a fungicide to S. sclerotiorum.
Assuntos
Ascomicetos/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Griseofulvina/farmacologia , Doenças das Plantas/prevenção & controle , Stachybotrys/química , Ascomicetos/fisiologia , Brasil , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fungicidas Industriais/química , Fungicidas Industriais/metabolismo , Griseofulvina/química , Griseofulvina/metabolismo , Doenças das Plantas/microbiologia , Glycine max/microbiologia , Stachybotrys/genética , Stachybotrys/metabolismoRESUMO
20-Hydroxyecdysone (20E) is effective in stimulating protein synthesis, therefore, it has been largely used as anabolic agent in several commercial formulas. Phytochemical study of methanolic extract of twigs from Vitex polygama, used in traditional Brazilian medicine as emenagogue, yielded a large quantity of 20E. This finding led us to developing and validating a simple and reliable method to determine 20E in the surveyed extract. Chromatographic separation of 20E was achieved on a phenyl-hexyl-based column using reversed elution mode. Extract was cleaned-up by solid phase extraction employing C(18) cartridge, and an absolute recovery of 97% was acquired. External standard and standard addition calibration graphs were obtained and good linearity was accomplished (r>0.999 for both curves). The limit of quantification and detection were determined. The results for accuracy fell within the -5 to +7% range.
Assuntos
Ecdisterona/análise , Metanol/química , Extratos Vegetais/química , Vitex/química , Cromatografia Líquida de Alta Pressão/métodos , Espectroscopia de Ressonância Magnética , Padrões de Referência , Espectrofotometria UltravioletaRESUMO
Metal chelates strongly influence the nature and magnitude of pharmacological activities in flavonoids. In recent years, studies have shown that a promising class of flavanone-metal ion complexes can act as selective cholinesterase inhibitors (ChEIs), which has led our group to synthesize a new series of flavanone derivatives (hesperidin, hesperetin, naringin, and naringenin) complexed to either copper (II) or zinc (II) and to evaluate their potential use as selective ChEIs. Most of the synthesized complexes exhibited greater inhibitory activity against acetylcholinesterase (AChE) than against butyrylcholinesterase (BChE). Nine of these complexes constituted potent, reversible, and selective ChEIs with inhibitory potency (IC50) and inhibitory constant (Ki) ranging from 0.02 to 4.5µM. Copper complexes with flavanone-bipyridine derivatives afforded the best inhibitory activity against AChE and BChE. The complex Cu(naringin)(2,2'-bipyridine) (11) gave IC50 and Ki values of 0.012±0.002 and 0.07±0.01µM for huAChE, respectively, which were lower than the inhibitory values obtained for standard galanthamine (IC50=206±30.0 and Ki=126±18.0µM). Evaluation of the inhibitory activity of this complex against butyrylcholinesterase from human serum (huBChE) gave IC50 and Ki values of 8.0±1.4 and 2.0±0.1µM, respectively. A Liquid Chromatography-Immobilized Capillary Enzyme Reactor by UV detection (LC-ICER-UV) assay allowed us to determine the IC50 and Ki values and the type of mechanism for the best inhibitors.