Estudo fitoquímico de aristolochia esperanzae kuntze (Aristolochiaceae)

Exportado OPUSMade available in DSpace on 2019-08-14T01:23:40Z (GMT). No. of bitstreams: 1 estudo_fitoqu_mico_de_aristolochia_esperanzae_kuntze.pdf: 10173457 bytes, checksum: 9d3ebe37e69f124ad87a04655e9db281 (MD5) Previous issue date: 18Muitas das doenças reumáticas ocorridas na região de Minas Gerais envolvem o uso de Aristolochia esperanzae no seu tratamento. A literatura cita estudos fitoquímicos de folhas e raízes de Aristolochia esperanzae e este trabalho descreve o isolamento cromatográfico dos constituintes químicos do cerne e das cascas do cerne desta planta. O extrato etanólico das cascas do cerne apresentou hidrocarbonetos alifáticos, uma lignana, ácidos aristolóchicos e aristololactamas. O extrato etanólico do cerne apresentou uma cubebina, ácidos aristolóchicos e sitosterol-3-O-?-D-glucopiranosídeo. A análise estrutural destes compostos envolveu principalmente técnicas de ressonância magnética nuclear de hidrogênio e carbono-13, HSQC, HMBC, NOESY e COSY. Os compostos asarinin, ácido populifólico, ácido 2 oxo-populifólico, aristololactamas AIa e AII e sitosterol-3-O-?-D-glucopiranosídeo foram pela primeira vez citados nesta espécie. O extrato etanólico das cascas do cerne e as frações asarinin e ?-cubebina foram ativas frente a Bacillus cereus.Most of the rheumatic diseases in the Minas Gerais são popularmente tratadas com o uso de Aristolochia esperanzae.region involve the treatment using Aristolochia esperanzae. The literature records phytochemical studies of leaves and roots from A. esperanzae and this work describes the chromatographic isolation of stem bark and stem chemical constituents of this plant. The ethanolic stem bark extract presented aliphatic hydrocarbons, one lignan, two diterpenes, ristolochic acids and aristololactams. The ethanolic stem extract presented one cubebin, aristolochic acids and sitosterol-3- O-ß-D-glucopyranoside. Their complete structures have been establish mainly based on 2D NMRspectral HSQC, HMBC, NOESY and COSY. Compounds asarinin, populifolic acid, 2 oxo-populifolic acid, aristololactams AIa and AII and sitosterol-3-O-ß-D-glucopyranoside were first reports on thesespecies. The ethanolic stem bark and constituents asarinin (AE1) e (8R,8R,9S)-cubebin (AE2) were active towards Bacillus cereus

Estudo químico de constituintes das cascas do caule de Aristolochia esperanzae Kuntze (Aristolochiaceae), empregando métodos espectroscópicos e teóricos

Exportado OPUSMade available in DSpace on 2019-08-10T05:12:11Z (GMT). No. of bitstreams: 1 tese_alison_geraldo_pacheco.pdf: 4939781 bytes, checksum: be55881fe630dd35e41b9ac72109eeab (MD5) Previous issue date: 22A espécie Aristolochia esperanzae é utilizada amplamente para o tratamento de doenças reumáticas. Este trabalho descreve o isolamento por técnicas cromatográficas e caracterização de metabólitos secundários de cascas do caule desta planta e a determinação estrutural dos fitoconstituintes isolados. Das frações menos polares, obtidas após refracionamento cromatográfico do extrato etanólico das cascas do caule, foram isoladas lignanas, ácidos aristolóchicos, aristolactamas, diterpenos e triterpenos, relatados anteriormente pelo nosso grupo de pesquisa. Neste trabalho, deu-se continuidade ao estudo, sendo que, das frações de média polaridade, foram isoladas duas lignanas (a-cubebina e ß-cubebina), um ácido aristolóchico (ácido 3-hidróxi-4-metóxi-10-nitrofenantreno-1-carboxílico) e dois derivados fenólicos diméricos (2,2',6,6'-tetra-terc-butil-4,4'-etilenodifenol e 5,5´-di-hidróxi-1H,1H´-2,2´-biindeno-1,1´-diona). A análise estrutural dos compostos envolveu principalmente técnicas de ressonância magnética nuclear de hidrogênio e de carbono-13, HSQC, HMBC, NOESY e COSY. O ácido aristolóchico e a cetona dimérica não apresentam registros de isolamento na literatura, sendo, portanto, inéditos. A análise estrutural destes compostos e de triterpenos pentacíclicos foi realizada também por técnicas de modelagem molecular e química computacional.  The species Aristolochia esperanzae is widely used for the treatment of rheumatic diseases. This work describes the chromatographic isolation of the chemical constituents of the stem bark of this plant and structural analysis of the obtained phytochemicals. Chromatographic fractionation of less polar fractions of the ethanolic extract provides lignans, aristolochic acids, aristolactams, diterpenes, and triterpenes which were previously reported by the our research group. In this present work, the phytochemical study of medium polarity fractions was carried out, providing lignans (-and -cubebin), aristolochic acid (3-hydroxy-4-methoxy-10-nitrofenantreno 1 - carboxylic) and phenol derivatives dimer (2,2', 6,6'-tetra-tert-butyl-4,4'-etilenodifenol and 5,5'-dihydroxy-1H, 1H'-2, 2'-biindeno-1,1'-dione). Structural analysis of these compounds was mainly based on nuclear magnetic resonance of hydrogen and carbon-13, HSQC, HMBC, NOESY, and COSY techniques. Aristolochic acid and ketone dimer have not been recorded in the literature, being then new compounds. Structural analysis of these compounds and pentacyclic triterpenes was also performed by molecular modeling techniques

A DFT study of the chemical reactivity of cimetidine A, C and D in the gas, H2O, MeOH and EtOH solvents

% Fukui % DFT s KR nema In the present work, we have analyzed the chemical reactivity of cimetidine A, C and D in different solvents; through the evaluation of global and local DFT reactivity descriptors. In the gas, MeOH and EtOH phases, cimetidine A, C and D exhibit energy differences of 3-11 kcal mol-1. But, in the aqueous phase, cimetidine A and D are approximately isoenergetic. The values of the hardness indicate that cimetidine A, C and D are more reactive in the presence of a solvent than in the gas phase. Also, our results suggest that CimC and CimD are better nucleophiles that CimA. The Fukui Function values suggest that the more reactive sites of CimA are not modified in the different solvents. In the case of CimC, the more reactive sites to electrophilic and free radical attacks are located on the thioether sulfur. For CimD, the number and place of the electrophilic and free radical sites are independent of the solvent

DFT Study of Polythiophene Energy Band Gap and Substitution Effects

Polythiophene (PTh) and its derivatives are polymer-based materials with a π-conjugation framework. PTh is a useful photoelectric material and can be used in organic semiconductor devices, such as PLED, OLED, and solar cells. Their properties are based on molecular structure; the derivatives contain different substitutes in the 3 and 5 positions, such as electron-donating or electron-withdrawing groups. All molecular geometries were optimized at B3LYP/6-31G(d,p) level of theory. The energy gap (Egap) between the HOMO and LUMO levels is related to the π-conjugation in the PTh polymer backbone. In this study, the DFT calculations were performed for the nonsubstituted and 3,5-substituted variants to investigate the stability geometries and electrical properties. The theoretical calculations show that the substituted forms are stable, have low Egap, and are in good agreement with the experimental observations

C-NMR Data of Diterpenes Isolated from Aristolochia Species

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