Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 26
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Med Food ; 2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31770044

RESUMO

Polysaccharide from Ma-chi-xian (Portulacae oleracea L., POLP) was prepared and the therapeutic effect on dextran sodium sulfate-induced colitis mice was investigated in this study. The results of clinical activity score and H&E staining confirmed the therapeutic effect of POLP. POLP could diminished the symptoms of colitis and improve colon histopathological structure of the colitis mice. The expression levels of four cytokines were determined. The concentrations of PGE2 and IL-6 were downregulated by POLP treatment. The COX-2 protein expression levels and the STAT3 phosphorylation levels were detected. The results showed that these two protein levels were all increased in colitis and decreased after POLP treatment, indicating that these two proteins were closely related with the protective effect of POLP. Because the synthesis of PGE2 is catalyzed by COX-2 and phosphorylation of STAT3 can induce the expression of COX-2, it was concluded that STAT3 was a key protein related to the POLP exerting its activity in colitis.

2.
Molecules ; 24(22)2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31726738

RESUMO

Indigo naturalis (IN) is a traditional Chinese medicine, named Qing-Dai, which is extracted from indigo plants and has been used to treat patients with inflammatory bowel disease (IBD) in China and Japan. Though there are notable effects of IN on colitis, the mechanisms remain elusive. Regarding the significance of alterations of intestinal flora related to IBD and the poor water solubility of the blue IN powder, we predicted that the protective action of IN on colitis may occur through modifying gut microbiota. To investigate the relationships of IN, colitis, and gut microbiomes, a dextran sulfate sodium (DSS)-induced mice colitis model was tested to explore the protective effects of IN on macroscopic colitis symptoms, the histopathological structure, inflammation cytokines, and gut microbiota, and their potential functions. Sulfasalazine (SASP) was used as the positive control. Firstly, because it was a mixture, the main chemical compositions of indigo and indirubin in IN were detected by ultra-performance liquid chromatography (UPLC). The clinical activity score (CAS), hematoxylin and eosin (H&E) staining results, and enzyme-linked immunosorbent assay (ELISA) results in this study showed that IN greatly improved the health conditions of the tested colitis mice, ameliorated the histopathological structure of the colon tissue, down-regulated pro-inflammatory cytokines, and up-regulated anti-inflammatory cytokines. The results of 16S rDNA sequences analysis with the Illumina MiSeq platform showed that IN could modulate the balance of gut microbiota, especially by down-regulating the relative quantity of Turicibacter and up-regulating the relative quantity of Peptococcus. The therapeutic effect of IN may be closely related to the anaerobic gram-positive bacteria of Turicibacter and Peptococcus. The inferred metagenomes from 16S data using PICRUSt demonstrated that decreased metabolic genes, such as through biosynthesis of siderophore group nonribosomal peptides, non-homologous end-joining, and glycosphingolipid biosynthesis of lacto and neolacto series, may maintain microbiota homeostasis during inflammation from IN treatment in DSS-induced colitis.

3.
Nat Prod Res ; : 1-9, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31596143

RESUMO

Two new highly-oxygenated neo-clerodane diterpenoids, 3S-acetoxyl-mollotucin D dilactone ester (1) and 6S-crotoeurin C (2), and a new lupane-type triterpene, 16ß-hydroxyl-3ß-O-trans-coumaroyl-betulin (6), as well as three known analogues (3-5) were obtained from the leaves of Croton laui. The structures of the new compounds were determined by extensive spectroscopic methods, and their absolute configurations were determined by combination of single-crystal X-ray diffraction analysis, electronic circular dichroism (ECD) spectra, and literature data. Compounds 2 and 3 exhibited inhibitory activities of lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages with IC50 values of 1.2 and 1.6 µM, respectively. Additionally, compound 6 exhibited activity against Col205 and HepG2 cell lines with IC50 values of 12.9 and 17.7 µM, respectively.

4.
Nat Prod Res ; : 1-7, 2019 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-31081703

RESUMO

A pair of new neo-clerodane diterpenoid epimers, 3S-methoxyl-teucvin (1) and 3R-methoxyl-teucvin (2), were isolated from the Roots of Croton crassifolius. Their structures were completely established on the basis of spectroscopic methods, and the absolute configurations were determined by analysis of electronic circular dichroism (ECD) spectroscopy and X-ray diffraction analysis. Compounds 1 and 2 exhibited anti-inflammatory activities with IC50 values of 0.82 and 0.54 µM, respectively, while the IC50 value of dexamethasone as a positive control was found to be 0.14 µM.

5.
Fitoterapia ; 130: 265-271, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30243779

RESUMO

Gracilistones A (1) and B (2), two new eudesmane-type sesquiterpenoids with an unusual tetrahydrofuran-fused 6/6/5 tricyclic ring system, were obtained from Acanthopanax gracilistylus under the guidance of LC-MS investigation. Their structures and absolute configurations were assigned by extensive spectroscopic analyses and quantum calculation methods. Compounds 1 and 2 showed potent inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages, compared with the positive control L-NMMA. In addition, compounds 1 and 2 were also evaluated for their antioxidant (DPPH• and ABTS•+) and xanthine oxidase (XO) inhibitory activities, and they exhibited weak inhibitory effects at 100 µM.


Assuntos
Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Eleutherococcus/química , Sesquiterpenos de Eudesmano/farmacologia , Animais , Anti-Inflamatórios/isolamento & purificação , Antioxidantes/isolamento & purificação , China , Cromatografia Líquida , Furanos , Espectrometria de Massas , Camundongos , Estrutura Molecular , Óxido Nítrico/metabolismo , Compostos Fitoquímicos/isolamento & purificação , Compostos Fitoquímicos/farmacologia , Raízes de Plantas/química , Células RAW 264.7 , Sesquiterpenos de Eudesmano/isolamento & purificação
6.
Molecules ; 23(5)2018 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-29724065

RESUMO

Inflammatory bowel disease (IBD) is a notable health problem and may considerably affect the quality of human life. Previously, the protective roles of tryptanthrin (TRYP) against dextran sulfate sodium (DSS) induced colitis has been proved, but the concrete mechanism remained elusive. It has been suggested that TRYP could diminish the weight loss and improve the health conditions of mice with DSS induced colitis. Hematoxylin and eosin staining revealed that TRYP could improve the histopathological structure of the colon tissue. Two signaling pathways (TNF-α/NF-κBp65 and IL-6/STAT3) were investigated using immunochemistry and western blot. The detected concentrations of the two cytokines TNF-α and IL-6 showed that their levels decreased after TRYP treatment of the colitis. The protein expression level of NF-κBp65 in cytoplasm increased after TRYP treatment of the induced colitis. However, the protein level of NF-κBp65 in the nucleus decreased after administration of TRYP. The expression level of IκBα, the inhibitory protein of NF-κBp65, was tested and the results suggested that TRYP could inhibit the degradation of IκBα. The phosphorylation level of STAT3 was inhibited by TRYP and the expression level of STAT3 and p-STAT3 decreased after administration of TRYP. We conclude that TRYP improves the health condition of mice with DSS induced colitis by regulating the TNF-α/NF-κBp65 and IL-6/STAT3 signaling pathways via inhibiting the degradation of IκBα and the phosphorylation of STAT3.


Assuntos
Colite , Sulfato de Dextrana/toxicidade , Interleucina-6/metabolismo , NF-kappa B/metabolismo , Quinazolinas/farmacologia , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo , Animais , Colite/induzido quimicamente , Colite/tratamento farmacológico , Colite/metabolismo , Colite/patologia , Masculino , Camundongos
7.
J Ethnopharmacol ; 219: 32-49, 2018 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-29526703

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Ligularia przewalskii (Maxim.) Diels (LP) (called zhangyetuowu in Chinese), is generally found in moist forest areas in the western regions of China. The root, leaves and flower of LP are utilized as a common traditional medicine in China. It has been utilized conventionally in herbal remedies for the remedy of haemoptysis, asthma, pulmonary phthisis, jaundice hepatitis, food poisoning, bronchitis, cough, fever, wound healing, measles, carbuncle, swelling and phlegm diseases. AIM OF THE STUDY: The review aims to provide a systematic summary of LP and to reveal the correlation between the traditional uses and pharmacological activities in order to provide updated, comprehensive and categorized information and identify the therapeutic potential for its use as a new medicine. MATERIALS AND METHODS: The relevant data were searched by using the keywords "Ligularia przewalskii" "phytochemistry", "pharmacology", "Traditional uses", and "Toxicity" in "Scopus", "Scifinder", "Springer", "Pubmed", "Wiley", "Web of Science", "China Knowledge Resource Integrated databases (CNKI)", "Ph.D." and "M.Sc. dissertations", and a hand-search was done to acquire peer-reviewed articles and reports about LP. The plant taxonomy was validated by the databases "The Plant List", "Flora Reipublicae Popularis Sinicae", "A Collection of Qinghai Economic Plants", "Inner Mongolia plant medicine Chi", Zhonghua-bencao and the Standard of Chinese herbal medicine in Gansu. RESULTS: Based on the traditional uses, the chemical nature and biological effects of LP have been the focus of research. In modern research, approximately seventy-six secondary metabolites, including thirty-eight terpenoids, nine benzofuran derivatives, seven flavonoids, ten sterols and others, were isolated from this plant. They exhibit anti-inflammatory, antioxidative, anti-bacterial and anti-tumour effects, and so on. Currently, there is no report on the toxicity of LP, but hepatotoxic pyrrolizidine alkaloids (HPA) were first detected with LC/MSn in LP, and they have potential hepatotoxicity. CONCLUSIONS: The lung-moistening, cough-relieving and phlegm-resolving actions of the root of LP are attributed to the anti-inflammatory properties of flavonoids and terpenoids. The heat-clearing, dampness-removing and gallbladder-normalizing (to cure jaundice) actions of the flowers of LP are based on the anti-inflammatory, antioxidant and hepatoprotective activity properties of terpenoids, flavonoids and sterols. The Traditional Chinese Medicine (TCM) characteristics of LP (bitter flavour) corroborate its potent anti-inflammatory effects. In addition, the remarkable anti-inflammatory and antioxidant capacities of LP contribute to its anti-tumour and antitussive activities. Many conventional uses of LP have now been validated by modernized pharmacological research. For future research, further phytochemical and biological studies need to be conducted on LP, In particular, the safety, mechanism of action and efficacy of LP could be of future research interest before beginning clinical trials. More in vivo experiments and clinical studies are encouraged to further clarify the relation between traditional uses and modern applications. Regarding the roots, leaves and flowers of LP, their chemical compositions and clinical effects should be compared. The information on LP will be helpful in providing and identifying its therapeutic potential and economic value for its use as a new medicine in the future.


Assuntos
Asteraceae , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/farmacologia , Medicina Tradicional Chinesa/métodos , Animais , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Antineoplásicos Fitogênicos/uso terapêutico , Antioxidantes/química , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Medicamentos de Ervas Chinesas/uso terapêutico , Humanos , Medicina Tradicional Chinesa/tendências , Neoplasias/tratamento farmacológico , Fitoterapia/métodos , Fitoterapia/tendências , Transtornos Respiratórios/tratamento farmacológico
8.
Sci Rep ; 7(1): 5417, 2017 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-28710371

RESUMO

We investigate lattice thermal conductivity κ of MgSiO3 perovskite (pv) by ab initio lattice dynamics calculations combined with exact solution of linearized phonon Boltzmann equation. At room temperature, κ of pristine MgSiO3 pv is found to be 10.7 W/(m · K) at 0 GPa. It increases linearly with pressure and reaches 59.2 W/(m · K) at 100 GPa. These values are close to multi-anvil press measurements whereas about twice as large as those from diamond anvil cell experiments. The increase of k with pressure is attributed to the squeeze of weighted phase-spaces phonons get emitted or absorbed. Moreover, we find κ exhibits noticeable anisotropy, with κ zz being the largest component and [Formula: see text] being about 25%. Such extent of anisotropy is comparable to those of upper mantle minerals such as olivine and enstatite. By analyzing phonon mean free paths and lifetimes, we further show that the weak temperature dependence of κ observed in experiments should not be caused by phonons reaching 'minimum' mean free paths. These results clarify the microscopic mechanism of thermal transport in MgSiO3 pv, and provide reference data for understanding heat conduction in the Earth's deep interior.

9.
Org Lett ; 19(15): 3998-4001, 2017 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-28718654

RESUMO

Two unusual normonoterpenoid indole alkaloids rauvomine A (1) and rauvomine B (2), together with two known compounds peraksine (3) and alstoyunine A (4), were isolated from the aerial parts of Rauvolfia vomitoria. The structures with absolute configurations of 1 and 2 were elucidated by spectroscopic analysis, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations. Compound 2 is a novel C18 normonoterpenoid indole alkaloid with a substituted cyclopropane ring that forms an unusual 6/5/6/6/3/5 hexcyclic rearranged ring system. The plausible biogenetic pathways of 1 and 2 were proposed. Compound 2 exhibited significant anti-inflammatory activity.


Assuntos
Anti-Inflamatórios/isolamento & purificação , Anti-Inflamatórios/farmacologia , Rauwolfia/química , Alcaloides de Triptamina e Secologanina/isolamento & purificação , Alcaloides de Triptamina e Secologanina/farmacologia , Descoberta de Drogas , Humanos , Estrutura Molecular , Relação Estrutura-Atividade
10.
Tumour Biol ; 39(6): 1010428317699798, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28618943

RESUMO

Gastric cancer remains the third leading cause of cancer-related mortality worldwide, and proliferation of gastric cancer represents the major reason for its poor prognosis. Recent evidence indicates that long non-coding RNAs play crucial roles in development and progression of gastric cancer. Long non-coding RNA differentiation antagonizing non-protein coding RNA is upregulated in hepatic cell carcinoma, but the role of lncRNA differentiation antagonizing non-protein coding RNA in gastric cancer has not been explored. In this article, we found that differentiation antagonizing non-protein coding RNA is also upregulated in gastric cancer. Experiments revealed that silencing differentiation antagonizing non-protein coding RNA significantly inhibited gastric cancer cell proliferation in vitro and in vivo. Overexpression of differentiation antagonizing non-protein coding RNA notably increases gastric cancer cell proliferation. From RNA-seq and gene ontology annotations, we found that differentiation antagonizing non-protein coding RNA influences the gene expression programs in cell metabolic and cycle process. Taken together, our findings suggest that the long non-coding RNA differentiation antagonizing non-protein coding RNA promotes the proliferation of gastric cancer and is a potential prognostic biomarker and therapeutic target in gastric cancer.


Assuntos
Biomarcadores Tumorais/biossíntese , Proliferação de Células/genética , RNA Longo não Codificante/biossíntese , Neoplasias Gástricas/genética , Adulto , Idoso , Biomarcadores Tumorais/genética , Ciclo Celular/genética , Linhagem Celular Tumoral , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Prognóstico , RNA Longo não Codificante/genética , Neoplasias Gástricas/patologia
11.
J Phys Condens Matter ; 29(17): 175701, 2017 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-28247850

RESUMO

The temperature and Sn isotope effects on SnTe are investigated using the hybrid scheme that combines ab initio molecular dynamics and lattice dynamics (AIMD + LD). The unstable softening of TA phonon mode at 0 K in cubic phase SnTe disappears and the TO mode is stiffened by considering the temperature effect, in agreement with the inelastic neutron scattering (INS) observations. A linear dependence on isotope mass of phonon frequency, lifetime, and mean free path for isolate phonon mode is observed with the possibility of positive, negative, and nearly zero shifts. The lattice thermal conductivity ([Formula: see text]) shows saturation characteristic as Sn isotope mass increases to 120SnTe, with an increase rate of ∼2.1% from 112SnTe to 124SnTe. Considering the effects of partial isotope doping, we obtain a reduced [Formula: see text] with respect to the undoped case. The [Formula: see text] is reduced by ∼14.6% at 600 K when considering the volumetric expansion.

12.
Minerva Med ; 108(4): 317-323, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28248065

RESUMO

BACKGROUND: Numerous studies have demonstrated that long non-coding RNAs (lncRNAs) have many biological functions and play crucial roles in various human cancers, including cancer development, metastasis and prognosis of cancer patients. CCAT2, a novel long non-coding RNA, has been identified as correlating with several different types of cancers. However, the role of lncRNA CCAT2 in gastric cancer (GC) patients is unknown. The purpose of our research was to investigate the function and prognostic significance of lncRNA CCAT2 expression in GC patients. METHODS: Expression of lncRNA CCAT2 was examined in 208 paired normal and cancerous gastric tissues. Molecular and cellular techniques were used to explore the biological function of lncRNA CCAT2 in GC cells. Kaplan-Meier method and Cox proportional hazards model were used to analyze the prognostic significance of lncRNA CCAT2 expression. RESULTS: The results showed that lncRNA CCAT2 was upregulated in GC tissues (P=0.000), and positively correlated with TNM stage (P=0.029), lymphatic invasion (P=0.042) and nervous invasion (P=0.024) in GC patients. Furthermore, we also found that high expression of lncRNA CCAT2 was an unfavorable prognostic factor in GC patients. Silencing of lncRNA CCAT2 inhibits gastric cancer cell proliferation and invasion. CONCLUSIONS: lncRNA CCAT2 may serve as a tumor promoter and a new predictive prognostic factor for human gastric cancer.


Assuntos
Biomarcadores Tumorais/genética , Polimorfismo de Nucleotídeo Único/genética , RNA Longo não Codificante/genética , Neoplasias Gástricas/genética , Proliferação de Células/genética , Feminino , Seguimentos , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Estadiamento de Neoplasias , Valor Preditivo dos Testes , Prognóstico , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Neoplasias Gástricas/mortalidade , Neoplasias Gástricas/patologia
13.
Br J Educ Psychol ; 87(1): 57-74, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27858999

RESUMO

BACKGROUND: In spite of considerable advancements in our understanding of the different factors involved in achieving vocabulary-learning success, the overall pattern and interrelationships of critical factors involved in L2 vocabulary learning - particularly, the mechanisms through which learners regulate their motivation and learning strategies - remain unclear. AIMS: This study examined L2 vocabulary learning, focusing on the joint influence of different motivational factors and learning strategies on the vocabulary breadth of adolescent learners of English as a foreign language (EFL) in China. SAMPLE: The participants were 107 tenth graders (68 females, 39 males) in China. METHODS: The data were collected via two questionnaires, one assessing students' motivation towards English-vocabulary learning and the other their English vocabulary-learning strategies, along with a test measuring vocabulary breadth. RESULTS: Structural equation modelling (SEM) indicated that learning strategy partially mediated the relationship between motivation (i.e., a composite score of intrinsic and extrinsic motivation) and vocabulary learning. Separate SEM analyses for intrinsic (IM) and extrinsic motivation (EM) revealed that there were significant and positive direct and indirect effects of IM on vocabulary knowledge; and while EM's direct effect over and above that of learning strategies did not achieve significance, its indirect effect was significant and positive. CONCLUSIONS: The findings suggest that vocabulary-learning strategies mediate the relationship between motivation and vocabulary knowledge. In addition, IM may have a greater influence on vocabulary learning in foreign-language contexts.


Assuntos
Aprendizagem , Modelos Estatísticos , Motivação , Multilinguismo , Psicolinguística , Vocabulário , Adolescente , Feminino , Humanos , Masculino
14.
Planta Med ; 82(8): 712-6, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27002397

RESUMO

Ten indole alkaloids (1-10) were obtained from an antifungal extract of Winchia calophylla, of which two (2 and 4) were new. N(4)-Methyl-10-hydroxyl-desacetylakuammilin (2) was an akuammiline-type indole alkaloid. N(1)-Methyl-echitaminic acid (4) was an unusual zwitterion with a basic vincorine-type skeleton. This is the first report of 10 in W. calophylla. The structures of all of the compounds were determined based on spectroscopic data, and their bioactivities were assessed. Compound 1 showed potent activity against the plant pathogenic fungi of Penicillium italicum and Fusarium oxysporum f.sp cubens with IC50 s of 10.4 and 11.5 µM, respectively, and 3 inhibited Rhizoctonia solani with an IC50 of 11.7 µM. Compounds 2 and 4 showed weak cytotoxicity against the human leukemic cell line HL-60 in vitro with IC50 s of 51.4 and 75.3 µM, respectively. Compounds 1 and 2 displayed weak activity against acetylcholinesterase with IC50 s around 61.3 and 52.6 µM, respectively.


Assuntos
Antifúngicos/isolamento & purificação , Alcaloides Indólicos/isolamento & purificação , Antifúngicos/química , Antifúngicos/farmacologia , Antifúngicos/toxicidade , Apocynaceae , Medicamentos de Ervas Chinesas , Fusarium/efeitos dos fármacos , Células HL-60 , Humanos , Alcaloides Indólicos/química , Alcaloides Indólicos/farmacologia , Alcaloides Indólicos/toxicidade , Testes de Sensibilidade Microbiana , Estrutura Molecular , Penicillium/efeitos dos fármacos , Rhizoctonia/efeitos dos fármacos
15.
IEEE J Biomed Health Inform ; 20(1): 333-42, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25361515

RESUMO

A novel accurate and fast optic disc (OD) detection method is proposed by using vessel distribution and directional characteristics. A feature combining three vessel distribution characteristics, i.e., local vessel density, compactness, and uniformity, is designed to find possible horizontal coordinate of OD. Then, according to the global vessel direction characteristic, a General Hough Transformation is introduced to identify the vertical coordinate of OD. By confining the possible OD vertical range and by simplifying vessel structure with blocks, we greatly decrease the computational cost of the algorithm. Four public datasets have been tested. The OD localization accuracy lies from 93.8% to 99.7%, when 8-20% vessel detection results are adopted to achieve OD detection. Average computation times for STARE images are about 3.4-11.5 s, which relate to image size. The proposed method shows satisfactory robustness on both normal and diseased images. It is better than many previous methods with respect to accuracy and efficiency.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Disco Óptico/anatomia & histologia , Vasos Retinianos/anatomia & histologia , Algoritmos , Bases de Dados Factuais , Humanos
16.
J Nat Prod ; 78(6): 1253-61, 2015 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-26024020

RESUMO

Nine new monoterpenoid indole alkaloids, ervatamines A-I (1-9), and five known ones (10-14), were isolated from Ervatamia hainanensis. The new structures were elucidated by extensive spectroscopic analysis and comparison to known compounds. Their absolute configurations were determined by various methods including computational methods, X-ray diffraction analysis, and electronic circular dichroism spectroscopy, as well as chemical transformations. Ervatamine A (1) is a ring-C-contracted ibogan-type monoterpenoid indole alkaloid with an unusual 6/5/6/6/6 pentacyclic rearranged ring system. Ervatamines B-E (2-5) display a nitrogen-containing 9/6 ring system, which is rarely observed in nature. The epimeric ervatamines B (2) and C (3) possess a 22-nor-monoterpenoid indole alkaloid carbon skeleton, which was only found in deformylstemmadenine. Compounds 10 and 14 exhibited significant anti-inflammatory activities, with IC50 values of 25.5 and 41.5 µM, respectively, while the IC50 value of indomethacin as a positive control was found to be 42.6 µM. Additionally, compound 9 showed mild activity against 786-O and HL-60 cell lines.


Assuntos
Anti-Inflamatórios/isolamento & purificação , Anti-Inflamatórios/farmacologia , Apocynaceae/química , Medicamentos de Ervas Chinesas/isolamento & purificação , Medicamentos de Ervas Chinesas/farmacologia , Alcaloides de Triptamina e Secologanina/isolamento & purificação , Alcaloides de Triptamina e Secologanina/farmacologia , Anti-Inflamatórios/química , Medicamentos de Ervas Chinesas/química , Células HL-60 , Humanos , Estrutura Molecular , Alcaloides de Triptamina e Secologanina/química
17.
Nat Prod Res ; 28(20): 1760-4, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25115794

RESUMO

Two new cyclic dipeptides, rhinocladin A (1) and rhinocladin B (2), were isolated from a fungal endophyte (Rhinocladiella sp. lgt-3) of Tripterygium wilfordii Hook. Their structures were elucidated by 1D and 2D NMR spectra. The monoamine oxidase inhibitory activity of 1 and 2 was also evaluated.


Assuntos
Dipeptídeos/química , Fungos Mitospóricos/química , Peptídeos Cíclicos/química , Tripterygium/microbiologia , Dipeptídeos/isolamento & purificação , Endófitos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Inibidores da Monoaminoxidase/química , Inibidores da Monoaminoxidase/isolamento & purificação , Peptídeos Cíclicos/isolamento & purificação
18.
Molecules ; 19(7): 9999-10010, 2014 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-25014530

RESUMO

Four new lycodine-type alkaloids, namely 16-hydroxyhuperzine B (1), N-methyl-11-acetoxyhuperzine B (2), 8,15-dihydrolycoparin A (3) and (7S,12S,13R)-huperzine D-16-O-ß-d-glucopyranoside (4), along with ten known analogues 5-14, were isolated from the whole plant of Lycopodiastrum casuarinoides. The structures of the new compounds were elucidated by means of spectroscopic techniques (IR, MS, NMR, and CD) and chemical methods. Compounds 1 and 2 possessed four connected six-membered rings, while compounds 3 and 4 were piperidine ring cleavage products. In particular, compound 4 was a lycopodium alkaloidal glycoside which is reported for the first time. Among the isolated compounds N-demethylhuperzinine (7), huperzine C (8), huperzine B (9) and lycoparin C (13) possessed significant inhibitory activity against acetylcholinesterase, and the new compound 1 showed moderate inhibitory activity. The structure activity relationships were discussed.


Assuntos
Alcaloides/farmacologia , Inibidores da Colinesterase/farmacologia , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Lycopodium/química , Extratos Vegetais/farmacologia , Acetilcolinesterase/metabolismo , Alcaloides/química , Inibidores da Colinesterase/química , Compostos Heterocíclicos de 4 ou mais Anéis/química , Concentração Inibidora 50 , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Extratos Vegetais/química
19.
Phys Rev Lett ; 112(5): 058501, 2014 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-24580631

RESUMO

We use a hybrid strategy to obtain anharmonic frequency shifts and lifetimes of phonon quasiparticles from first principles molecular dynamics simulations in modest size supercells. This approach is effective irrespective of crystal structure complexity and facilitates calculation of full anharmonic phonon dispersions, as long as phonon quasiparticles are well defined. We validate this approach to obtain anharmonic effects with calculations in MgSiO3 perovskite, the major Earth forming mineral phase. First, we reproduce irregular thermal frequency shifts of well characterized Raman modes. Second, we combine the phonon gas model (PGM) with quasiparticle frequencies and reproduce free energies obtained using thermodynamic integration. Combining thoroughly sampled quasiparticle dispersions with the PGM we then obtain first-principles anharmonic free energy in the thermodynamic limit (N→∞).

20.
Phys Rev Lett ; 112(9): 096805, 2014 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-24655271

RESUMO

We present, for the first time, an atomic-level and quantitative study of a strain-induced pseudomagnetic field in graphene nanoribbons with widths of hundreds of nanometers. We show that twisting strongly affects the band structures of graphene nanoribbons with arbitrary chirality and generates well-defined pseudo-Landau levels, which mimics the quantization of massive Dirac fermions in a magnetic field up to 160 T. Electrons are localized either at ribbon edges forming the edge current or at the ribbon center forming the snake orbit current, both being valley polarized. Our result paves the way for the design of new graphene-based nanoelectronics.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA