RESUMO
A new strategy for preparing amphibious ZnO quantum dots (QDs) with blue fluorescence within hyper-branched poly(ethylenimine)s (HPEI) was proposed in this paper. By changing [Zn2+]/[OH-] molar ratio and heating time, ZnO QDs with a quantum yields (QY) of 30% in ethanol were obtained. Benefiting from the amphibious property of HPEI, the ZnO/HPEI nanocomposites in ethanol could be dissolved in chloroform and water, acquiring a QY of 53%, chloroform and 11% in water. By this strategy, the ZnO/HPEI nano-composites could be applied in not only in optoelectronics, but also biomedical fields (such as bio-imaging and gene transfection). The bio-imaging application of water-soluble ZnO/HPEI nanocomposites was investigated and it was found that they could easily be endocytosed by the COS-7 cells, without transfection reagent, and they exhibited excellent biological imaging behavior.
RESUMO
Three new labdane diterpenoids, leojaponicone A (1), isoleojaponicone A (2) and methylisoleojaponicone A (3), were isolated from the herb of Leonurus japonicus. The chemical structures of these secondary metabolites were elucidated on the basis of 1D and 2D NMR, including HMQC, and HMBC spectroscopic techniques. All the new compounds were tested in vitro for their acetylcholinesterase and α-glucosidase inhibitory activity. Compounds 1-3 exhibited low inhibitory effects on α-glucosidase with respect to acarbose and exhibited high inhibitory effects on acetylcholinesterase with respect to huperzine A.
Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Diterpenos/farmacologia , Leonurus/química , Extratos Vegetais/farmacologia , Inibidores da Colinesterase/química , Inibidores da Colinesterase/isolamento & purificação , Diterpenos/química , Diterpenos/isolamento & purificação , Inibidores de Glicosídeo Hidrolases/química , Inibidores de Glicosídeo Hidrolases/isolamento & purificação , Inibidores de Glicosídeo Hidrolases/farmacologia , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Extratos Vegetais/químicaRESUMO
The present study aimed at isolation and purification of the bioactive terpenoids from the herb of Leonurus japonicus by chromatographic separations such as silica gel, sephadex LH-20 and C18 reversed phase silica gel, as well as preparative HPLC. As a result, leojaponic acids A (1, C17H24O4) and B (2, C18H26O4), two homologous terpenoids, together with (-)-loliolide (3), 1-(3-ethylphenyl) ethane-1, 2-diol (4) and dibutyl phthalate (5), were isolated from the EtOH extract of L. japonicus. All the chemical structures of the isolates were elucidated on the basis of 1D and 2D NMR analyses. Compounds 1 and 2 were new terpenoids, and Compounds 3 and 4 were isolated and identified for the first time from this plant. In addition, the α-glucosidase and tyrosinase inhibitory activity of the new compounds were evaluated.
Assuntos
Leonurus/química , Extratos Vegetais/química , Terpenos/química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Frutas/química , Glucosidases/análise , Glucosidases/antagonistas & inibidores , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Extratos Vegetais/isolamento & purificação , Terpenos/isolamento & purificaçãoRESUMO
Metal-free methylation of a pyridine N-oxide C-H bond was developed using peroxide as a methyl reagent under neat conditions. Pyridine N-oxide derivatives with various groups (e.g., Cl, NO2, and OCH3) were all suitable substrates, and the desired products were obtained in moderate to excellent yields under standard conditions. Moreover, the methylation can be performed with a good yield on the gram-scale experiment. Tentative mechanistic studies show that the methylation is a classical radical process.
RESUMO
Copper acetate-catalyzed C-H bond functionalization amination of quinoline N-oxides was achieved using O-benzoyl hydroxylamine as an electrophilic amination reagent, thereby affording the desired products in moderate to excellent yields. Electrophilic amination can also be performed in good yield on a gram scale.
Assuntos
Cobre/química , Hidroxilamina/química , Compostos Organometálicos/química , Óxidos/química , Quinolinas/química , Aminação , Catálise , Estrutura MolecularRESUMO
Leojaponin (2), a labdane diterpene, was isolated from the EtOH extract of the herb of Leonurus japonicus together with a new halimane diterpene named isoleojaponin (1). Isoleojaponin has a new diterpene skeleton with a unique cross-conjugated α,ß-unsaturated ketone system, Their structures were elucidated by physical and spectroscopic analysis, and the relative configuration of the chiral C-9 carbon was determined by a computational method, and analysis of its possible biogenesis pathways.
Assuntos
Diterpenos/isolamento & purificação , Leonurus/química , Cromatografia Líquida de Alta Pressão , Diterpenos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria UltravioletaRESUMO
Phytochemical investigation of the leaves of Cecropia schreberiana Miq. (Urticaceae) led to the isolation of four triterpenoids (1-4), three flavone C-glycosides (5-7), two flavan-3-ols (8, 9), two flavanolignans (10, 11), and two proanthocyanidins (12, 13). All compounds were isolated from C. schreberiana for the first time. This is the first report demonstrating the presence of arjunolic acid (4), cinchonain Ia (10), and cinchonain Ib (11) in the Urticaceae family. The occurrence of flavanolignans within the family Urticaceae supports the likelihood that such compounds are more common within the class Magnoliopsida than previously thought.
RESUMO
Three known (leoleorins A-C) and eight hitherto unknown (leoleorins D-J and 16-epi-leoleorin F) labdane diterpenoids, were isolated from leaves of Leonotis leonurus. The absolute configurations of leoleorins A and D were established by X-ray crystallographic analyses. In a competitive binding assay, all isolated compounds showed inhibition in excess of 50% at various CNS receptors. Leoleorin C showed moderate binding affinity (Ki=2.9 µM) for the Sigma 1 receptor.
Assuntos
Diterpenos/farmacologia , Lamiaceae/química , Cristalografia por Raios X , Diterpenos/química , Diterpenos/isolamento & purificação , Relação Dose-Resposta a Droga , Modelos Moleculares , Conformação Molecular , Folhas de Planta/química , Receptores Colinérgicos/metabolismo , Receptores de Dopamina D1/antagonistas & inibidores , Receptores Histamínicos H1/metabolismo , Receptores de Serotonina/metabolismo , Receptores sigma/antagonistas & inibidores , Relação Estrutura-AtividadeRESUMO
Six new labdane diterpenoids, preleosibirone A (1), 13-epi-preleosibirone A (2), isopreleosibirone A (3), leosibirone A (4), leosibirone B (5), and 15-epi-leosibirone B (6), were isolated from the leaves of Leonurus sibiricus. The absolute configurations of 1, 2, 5, and 6 were established by X-ray crystallographic analyses, and leosibirone A (4) was shown to be an artifact of the isolation process.
Assuntos
Diterpenos/química , Diterpenos/isolamento & purificação , Leonurus/química , Cristalografia por Raios X , Conformação Molecular , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Folhas de Planta/químicaRESUMO
Phytochemical study of the leaves and stems of Calea zacatechichi Schl. (Asteraceae) led to the isolation of a series of six germacranolides (1-6) with significant antileishmanial activity. The structure of a new compound named by us as calealactone D (1) was determined by NMR and MS, and its absolute configuration by X-ray crystallography. In addition, calealactone E (5) was discovered as a new naturally occurring compound, and the absolute configuration of calealactone C (2) was also determined by X-ray crystallography. All compounds were biologically evaluated in antimicrobial and antiprotozoal assays.
Assuntos
Asteraceae/química , Sesquiterpenos de Germacrano/isolamento & purificação , Sesquiterpenos de Germacrano/farmacologia , Antibacterianos/farmacologia , Antifúngicos/farmacologia , Antiprotozoários/química , Antiprotozoários/isolamento & purificação , Antiprotozoários/farmacologia , Cromatografia Líquida de Alta Pressão , Cristalografia por Raios X , Humanos , Lactonas/química , Lactonas/isolamento & purificação , Lactonas/farmacologia , Testes de Sensibilidade Microbiana , Componentes Aéreos da Planta/química , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Sesquiterpenos de Germacrano/químicaRESUMO
Although the medicinal plant Artemisia rupestris L. has been widely researched for several decades, its alkaloids have never been isolated before. To our surprise, the alkaloids in the plant were not detected in the stems but detected in the flowers. Herein, a novel and strange guaipyridine sesquiterpene alkaloid with a carboxyl group named rupestine was purified successfully from the total alkaloids extracted from the flowers by high-speed counter-current chromatography (HSCCC). The two-phase solvent system used was composed of ethyl acetate-methanol-water (8:1:7, v/v/v). Fifty six milligrams of rupestine was obtained at over 97% purity and 95% recovery from 200 mg of the total alkaloids in one-step separation. Its structure was elucidated by spectroscopic methods including high resolution ESI-MS, (1)H NMR, (13)C NMR, Heteronuclear Multiple Bond Correlation (HMBC), Heteronuclear Single Quantum Coherence (HSQC), and Nuclear Overhauser Enhancement Spectroscopy (NOESY).
Assuntos
Alcaloides/isolamento & purificação , Artemisia/química , Distribuição Contracorrente/métodos , Sesquiterpenos/isolamento & purificação , Alcaloides/química , Cromatografia Líquida de Alta Pressão/métodos , Flores/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Sesquiterpenos/química , Solventes , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Preparative separation of elatine in Delphinium shawurense was achieved for the first time using high-speed countercurrent chromatography (HSCCC). The separation was performed with a solvent system composed of ethyl acetate-chloroform-methanol-water (3:0.1:2:3, v/v) using the lower organic phase as a mobile phase under a revolution speed of 800 rpm. This yielded 72 mg of elatine at over 97% purity with an approximately 95% recovery. The chemical structure was identified by MS and NMR.
RESUMO
Because of the skeletal complexity and similarity of the polarity, little research was reported on the isolation of sesquiterpene lactones by high-speed counter-current chromatography (HSCCC). Herein, three sesquiterpene lactones were successfully purified from the ethyl acetate extract of the roots of the traditional Uyghur medicinal plant Cichorium glandulosum Boiss. et Huet. by HSCCC. The separation was performed in two steps with two solvent systems: n-hexane-ethyl acetate-methanol-water (1.5:5:2.75:5, v/v/v/v) and ethyl acetate-methanol-water (20:1:20, v/v/v). From 166 mg of the ethyl acetate extract, 19 mg of lactucopicrin was isolated with the first solvent system and 10 mg of 11beta,13-dihydrolactucin and 16 mg of lactucin were obtained with the second solvent system. All purified compounds were over 94% purity as determined by HPLC analysis, and these chemical structures were confirmed by (1)H NMR and (13)C NMR.