• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 45
  • 35
  • 8
  • 7
  • 2
  • Tagged with
  • 103
  • 36
  • 15
  • 11
  • 11
  • 10
  • 10
  • 10
  • 8
  • 8
  • 7
  • 7
  • 7
  • 6
  • 6
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Synthesis and properties of lignin epoxide

Nieh, Li-Shih World January 1986 (has links)
A lignin epoxide resin was synthesized and characterized. The epoxidation reaction was studied by reacting hydroxypropylated guaiacol (a lignin-like model compound) and epichlorohydrin using a catalyst system of potassium hydroxide and a phase transfer catalyst in toluene. The parameters studied were different epichlorohydrin level and temperature. The reaction was followed by HPLC and the structure of the product was identified with IR, ¹H and ¹³C NMR spectroscopy. The lignin epoxide was synthesized by reacting hydroxyalkylated (hydroxypropyl and hydroxybutyl) lignin with epichlorohydrin using the reaction conditions defined by the model compound studies. The reaction was studied at different epichlorohydrin level and at elevated and room temperature. The epoxy content of the lignin epoxide was determined by titration with HBr and its structure was identified with IR, ¹H and ¹³C NMR spectroscopy. Lignin epoxides were cured by crosslinking with a diamine and with phthalic anhydride. An amine-terminated rubber was added as toughening agent. Sol fraction and swelling behavior, stress-strain behavior and dynamic mechanical behavior of the cured lignin epoxides were studied in relation to cure conditions. / M.S.
42

Lignin acrylate derivatives and their behaviors in free radical copolymerizations

Wang, Hongxue January 1986 (has links)
Guaiacol and hydroxypropyl-guaiacol were taken as model compounds for lignins and hydroxypropyl lignins to study their vinylation and copolymerization behaviors. Lignin model compounds and lignin were subjected to reaction with isocyanatoethyl methacrylate (IEM) using dibutyltin dilaurate as catalyst. The acrylate derivatives were characterized by elemental analysis, UV, IR, <sup>1</sup>H-NMR, and <sup>13</sup>C-NMR spectroscopy. The acrylated lignin model compounds, guaiacol-IEM urethane (GIU) and hydroxypropyl-guaiacol-IEM urethane (HPGIU), were copolymerized with methyl methacrylate (MMA) and styrene (St) through free radical mechanism. Solution copolymerizations in 1,2-dichloroethane: ethanol were initiated by benzoyl peroxide. The monomer reactivity ratios were investigated for these copolymerization combinations. The copolymer compositions were analyzed by UV for GIU-co-MMA and HPGIU-co-MMA, while methoxyl content determination by HI-GC was used to determine compositions of styrene-based copolymers. The copolymers were characterized by gel permeation chromatography (GPC), and by IR and NMR spectroscopy. The reactivity ratios were computed by use of the Fineman-Ross linearization method, by the KelenTudos equation and by the Yezrielev-Brokhina-Roskin (YBR) numerical method. A comprehensive analysis with respect to the methods used to derive the ratios has shown that the Kelen-Tudos method and the YBR method produce diagnostic reactivity ratios. A great copolymerization tendency of lignins and hydroxypropylated lignins is predicted from the reactivity ratios of the lignin models. A statistical treatment of the model reactivity ratios lead to prediction for chain sequence length distribution of the copolymers formed. Hydroxybutyl lignin IEM urethanes (HBLIU's) were copolymerized with a vinyl-terminated poly(butadiene-acrylonitrile) macromer and MMA to study the copolymerization behaviors of macromolecular lignin acrylate derivatives. The crosslinked films with desired properties were cast from methylene chloride, with benzoyl peroxide as an initiator. The copolymerized network polymers were characterized by sol fraction measurements, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and by scanning electron microscopy (SEM). The influences of vinyl content in lignin acrylate derivatives and the ratio of lignin derivatives to vinyl monomer or macromer were studied with respect to structure-property relationship in the copolymers. / M.S.
43

Antioxidant properties of flaxseed lignans using in vitro model systems

Hosseinian, Farah F.H 01 May 2006
The major objectives of this study were to investigate the antioxidant properties of flaxseed lignans secoisolariciresinol (SECO 2) and secoisolariciresinol diglycoside (SDG 1) and their major oxidative compounds using 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH 47) in an in vitro model of lipid peroxidation. This investigation was facilitated by the structural elucidation of the major oxidative compounds and the ability of flaxseed lignans to delay the onset of oxidation in two model systems. <p>This study showed that SECO 2 oxidation occurs at the aromatic (4-OH) and aliphatic (9-OH) hydroxyl groups. Conversely for SDG 1, only compounds derived from the oxidation of aromatic hydroxyl groups were obtained because the 9-OH position is glucosylated. <p>SECO 2 oxidation with AAPH 47 showed that the intermediate 2a is most likely involved in the generation of early-forming (48 and 52) and 2c for the formation of late-forming (49, 50 and 51) oxidation compounds. Compound 48 is formed from dimerization of 2a that is converted to 52 and then to 51. Compound 50 was formed by the addition of a carbon-centre free radical of AAPH (AP radical) to 2c. Compounds 50 and 51 trap carbon-centered AP radicals supporting SECO 2 as a chain-breaking antioxidant and AAPH 47 as a proper model for study of SECO 2 oxidation in vitro. <p>SDG 1 oxidation with AAPH 47 indicated that intermediates 1b and 1c are most likely involved for the formation of early forming compounds (55 and 58) and 1a leads to the late forming compounds (56 and 57). Compound 55 is a result of dimerization. Compound 56 may be directly formed via intermediate radical 1a by adding AP free radicals. Compound 56 was a stable non-radical compound that could trap AP free radicals, thereby supporting SDG 1 as a chain-breaking antioxidant. Hydrogen abstraction from 4-hydroxyl yielded the radical 1a and hydroxyl radical addition to 1a yielded 57. Compound 58 formed from the addition of OH or H2O to 1c. <p>This study demonstrated that AAPH 47 produces carbon-centred AP radicals upon thermal decomposition and mimics the formation of lipid peroxyl radicals. Interaction of carbon-centred AP radicals with SECO 2 and SDG 1 provides a good model to study the antioxidant reactions of SECO 2 in vitro. p*The relative antioxidant capacity of the flaxseed lignans versus BHT 17, in two model systems, was determined. The stoichiometric ratio for SECO 2 and SDG 1 were 1.5 and 1.1-1.2, respectively, compared to BHT 17 (2.0). The induction time by Rancimat analyzer measured inhibition of autoxidation mediated by flaxseed lignans SECO, SDG and SDG polymer in comparison with BHT 17. The induction time data demonstrated that SECO 2 protected canola oil better than either SDG 1 or SDG polymer 3. <p>These results are important for better understanding about the chemistry behind flaxseed lignan antioxidant activities. This study provided useful evidence that flaxseed lignans can be used as natural antioxidants.
44

Antioxidant properties of flaxseed lignans using in vitro model systems

Hosseinian, Farah F.H 01 May 2006 (has links)
The major objectives of this study were to investigate the antioxidant properties of flaxseed lignans secoisolariciresinol (SECO 2) and secoisolariciresinol diglycoside (SDG 1) and their major oxidative compounds using 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH 47) in an in vitro model of lipid peroxidation. This investigation was facilitated by the structural elucidation of the major oxidative compounds and the ability of flaxseed lignans to delay the onset of oxidation in two model systems. <p>This study showed that SECO 2 oxidation occurs at the aromatic (4-OH) and aliphatic (9-OH) hydroxyl groups. Conversely for SDG 1, only compounds derived from the oxidation of aromatic hydroxyl groups were obtained because the 9-OH position is glucosylated. <p>SECO 2 oxidation with AAPH 47 showed that the intermediate 2a is most likely involved in the generation of early-forming (48 and 52) and 2c for the formation of late-forming (49, 50 and 51) oxidation compounds. Compound 48 is formed from dimerization of 2a that is converted to 52 and then to 51. Compound 50 was formed by the addition of a carbon-centre free radical of AAPH (AP radical) to 2c. Compounds 50 and 51 trap carbon-centered AP radicals supporting SECO 2 as a chain-breaking antioxidant and AAPH 47 as a proper model for study of SECO 2 oxidation in vitro. <p>SDG 1 oxidation with AAPH 47 indicated that intermediates 1b and 1c are most likely involved for the formation of early forming compounds (55 and 58) and 1a leads to the late forming compounds (56 and 57). Compound 55 is a result of dimerization. Compound 56 may be directly formed via intermediate radical 1a by adding AP free radicals. Compound 56 was a stable non-radical compound that could trap AP free radicals, thereby supporting SDG 1 as a chain-breaking antioxidant. Hydrogen abstraction from 4-hydroxyl yielded the radical 1a and hydroxyl radical addition to 1a yielded 57. Compound 58 formed from the addition of OH or H2O to 1c. <p>This study demonstrated that AAPH 47 produces carbon-centred AP radicals upon thermal decomposition and mimics the formation of lipid peroxyl radicals. Interaction of carbon-centred AP radicals with SECO 2 and SDG 1 provides a good model to study the antioxidant reactions of SECO 2 in vitro. p*The relative antioxidant capacity of the flaxseed lignans versus BHT 17, in two model systems, was determined. The stoichiometric ratio for SECO 2 and SDG 1 were 1.5 and 1.1-1.2, respectively, compared to BHT 17 (2.0). The induction time by Rancimat analyzer measured inhibition of autoxidation mediated by flaxseed lignans SECO, SDG and SDG polymer in comparison with BHT 17. The induction time data demonstrated that SECO 2 protected canola oil better than either SDG 1 or SDG polymer 3. <p>These results are important for better understanding about the chemistry behind flaxseed lignan antioxidant activities. This study provided useful evidence that flaxseed lignans can be used as natural antioxidants.
45

Avaliação da atividade esquistossomicida in vitro do extrato hidroalcoólico bruto e metabólitos secundários dos frutos da Arctium lappa L. (Asteraceae) / Schistosomicidal a ctivity evaluation in vitro of the crude extract and secondary metabolites of the Arctium lappa L. (Asteraceae) fruit

Dias, Mirna Meana 30 July 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-07-11T19:21:39Z No. of bitstreams: 1 mirnameanadias.pdf: 4854720 bytes, checksum: 6e7eee98f8d74a58201a12af9346e6f8 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-08T15:34:44Z (GMT) No. of bitstreams: 1 mirnameanadias.pdf: 4854720 bytes, checksum: 6e7eee98f8d74a58201a12af9346e6f8 (MD5) / Made available in DSpace on 2017-08-08T15:34:44Z (GMT). No. of bitstreams: 1 mirnameanadias.pdf: 4854720 bytes, checksum: 6e7eee98f8d74a58201a12af9346e6f8 (MD5) Previous issue date: 2013-07-30 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / A esquistossomíase, causada por parasitos do gênero Schistosoma, é uma doença que afeta cerca de 240 milhões de pessoas no mundo. O Praziquantel é o fármaco de escolha para o tratamento desta parasitose e, devido principalmente aos casos de resistência do parasito a esta medicamento, se faz necessária a busca de novas moléculas e/ou protótipos com potencial atividade esquistossomicida. Neste contexto, a pesquisa com produtos naturais desponta como uma alternativa para o descobrimento de novos fármacos para o tratamento da esquistossomíase. Entre as espécies vegetais de interesse para a produção de substâncias esquistossomicidas, destaca-se a Arctium lappa L. (Asteraceae), a qual é reconhecida por biossintetizar lignóides, classe de metabólitos que tem demonstrado grande potencial esquistossomicida. O presente trabalho descreve o estudo fitoquímico do extrato hidroalcoólico dos frutos de A. lappa, bem como a avaliação da atividade esquistossomicida in vitro, frente aos vermes adultos de S. mansoni, do extrato e de seus metabólitos majoritários. O estudo fitoquímico de A. lappa L. resultou no isolamento de duas lignanas dibenzilbutirolactônicas, a arctiina e arctigenina. A análise dos resultados de avaliação esquistossomicida obtidos demonstrou que o extrato hidroalcoólico bruto na concentração de 200 mg/mL apresentou expressiva atividade esquistossomicida in vitro, sendo capaz de provocar a morte de 100% dos parasitos em até 24 horas de incubação. A arctiina, metabólito majoritário purificado do extrato, foi capaz de matar e provocar lesões tegumentares em 100% dos vermes adultos. Os resultados obtidos sugerem que a atividade esquistossomicida in vitro demonstrada pelo extrato hidroalcoólico pode estar relacionada à presença da arctiina, corroborando com o potencial esquistossomicida in vitro das lignanas dibenzilbutirolactônicas, frente aos vermes adultos de S. mansoni. / Schistosomiasis caused by the Schistosoma parasite is a disease that affects about 240 million people around the world. Praziquantel is the chosen drug for the treatment of this parasitosis. It is imperative to search for new molecules and / or prototypes with potential schistosomicidal activity. This requirement is due to the tough performance of the parasite against this medicine. In this context, the research with natural products has been recognized as an alternative to discover new pharmacos for Schistosoma treatment. Arctium lappa L. (Asteraceae) stands out among vegetal plants of interest for the production of schistosomicidal substances. This is recognized for being able to biosynthesize lignoid, a kind of metabolite that has performed great schistosomicidal potential. This master thesis describes the phytochemical study of the hydroalcoholic extract from A. lappa L. fruit, as well the evaluation of the schistosomicidal activity evaluation in vitro, facing the adult worms of S. mansoni from the extract and from its majority metabolite. The phytochemical study of A. lappa L. resulted in the isolation of two dibenzyl butyrolactone lignan, a arctiin e arctigenin. The results obtained schistosomicidal evaluation showed that hydroalcoholic extract crude in concentration of 200 mg/mL showed significant antischistosomal activity in vitro and is capable of causing the death of the 100% of the parasites within 24 hours of incubation. The arctiin a major purified metabolite from the extract, was capable of killing by causing tegumentary lesions en 100% of the adult worms. The obtained results suggest that the schistosomicidal activity in vitro showed by the hydroalcoholic extract can be related to arctiin presence, supporting the potencial schistosomicidal in vitro of dibenzyl butyrolactone lignan, against the adult worms of S. mansoni.
46

Application of gas chromatography and mass spectrometry for analysis of propolis from different geographic regions

Christov, Roumen January 2004 (has links)
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.
47

Avaliação do efeito leishmanicida de derivados de lignanas dibenzilbutirolactônicas / Evaluation of leishmanicidal effect in derivatives of dibenzylbutirolactonic lignans.

Rodrigues, Kelly Cristina 31 August 2009 (has links)
A leishmaniose é uma infecção causada pelo protozoário do gênero Leishmania, que causa um impacto social e econômico elevado, sendo a segunda maior incidência mundial de doença parasitária. Com o intuito de encontrar novas substâncias ou medicamentos de menor toxicidade e de custos inferiores que poderiam ser utilizados nos tratamentos de casos de infecção e, principalmente em situações de resistência parasitária, tem sido averiguada a possibilidade de utilização de substâncias de origem natural, tanto animal como vegetal, e substâncias sintéticas. Entre as que recentemente apresentaram propriedades biológicas úteis, estão alguns derivados de lignanas dibenzilbutirolactônicas que apresentam significativa ação tripanocida. Desse modo, propusemos avaliar a atividade biológica dessas lignanas em sistema in vitro, sobre formas promastigotas e amastigotas de Leishmania amazonensis. Os compostos utilizados foram (1) 7-O-N,N-dimetiletilamino cubebina, (3) cubebina, (D) 6-6´dinitroinoquinina e (H) hinoquinina. Para avaliação da atividade das substâncias foram utilizadas duas metodologias colorimétricas, MTT e Alamar Blue® e a contagem microscópica em hemocitômetro. Pelos resultados obtidos verificamos que pela contagem microscópica das formas promastigotas, as substâncias (1) 7-O-N,N-dimetiletilamino cubebina, (3) cubebina e (D) 6-6´dinitroinoquinina apresentaram potencial leishmanicida, sendo encontrados os seguintes valores de IC50: (1) = 19,4M; (3) 3,6M; (D) = 15,5M. Entretanto, os resultados obtidos com as mesmas substâncias em formas amastigotas do parasita não demonstraram atividade leishmanicida. Os métodos colorimétricos não apresentaram correspondência com a contagem microscópica, mostrando-se ineficazes para essa classe de substância. / Leishmaniasis is an infection caused by a protozoan parasite of the genus Leishmania, being the second great incidence of parasitic diseases in the world. In the search for new drugs or substances with low costs and low toxicity wich could be used in case of infection and situations of parasite resistance, being evaluated the possibility to use natural or synthetic substances. Dibenzylbutirolactonic lignans are substances with useful biological properties presenting significant trypanocidal effect. In this way we proposed to evaluate the in vitro biological activity of the lignans in of Leishmania amazonensis promastigote and amastigote forms . The compounds used were: (1) 7-O-N,N-dimethylamine cubebine, (3) cubebine, (D) 6-6´dinitroinokinine e (H) hinokinin. For the evaluation of these substances, two colorimetric methods were empoyed: MTT and Alamar Blue® , followed by microscopic counting in haemocytometer. After the results obtained after the couting of promastigote forms, we could verify that the substances (1) 7-O-N,N-dimethylamine cubebine, (3) cubebine, (D) 6-6´dinitroinokinine, and (H) hinokinin showed leishmanicidal potential, being fouded the followed values of IC50: (1) = 19.4M; (3) 3.6M; (D) = 15.5M. On the other hand the results obtained of the same substances in the parasite amastigote forms showed no leishmanicidal effect. The colorimetric methods showed no correspondence with microscopic couting demonstrating inefficacy of this substance class.
48

A distribuição de lignóides e policetídeos nos frutos de Virola elongata (Benth.) Warb. (Myristicaceae) / Distribution of lignoids and poliketides in fruits of Virola elongata (Benth.) Warb. (Myristicaceae)

Kato, Massuo Jorge 30 January 1989 (has links)
Este trabalho descreve os isolamentos e as determinações estruturais dos metabólitos secundários das diferentes partes dos frutos (pericarpos, arilos, tegumentos e amêndoas) de Virola elongata. 0 material foi coletado em Humaitá (AM) e no Km 96 da Rodovia Santarém-Cuiabá (PA). Os constituíntes químicos foram isolados por cromatografias de adsorção e tiveram suas estruturas identificadas ou determinadas por técnicas espectrométricas usuais (IV, UV, RMN e EM). As configurações absolutas dos metabólitos foram deduzidas a partir de medidas espectropolarimétricas, ou auxiliadas pela obtenção de derivados mais informativos. As substâncias foram agrupadas nas seguintes subclasses: lignanas furofurânicas [(+)-sesamina (LF-1), (+)-epifargesina (LF-2), (+)-eudesmina (LF-3), (+)-fargesina (LF-4), (+)-filigenina (LF-5) e (+)-epieudesmina (LF-6)]; lignanas tetraidrofurânicas [(+)-magnostelina-A (LT-1), (+)-magnostelina-C (LT-2), (±)-4\'-metil-5\'-metoxi-lariciresinol (LT-3), (±)-4,4\'-dimetil-5\'- metoxi-lariciresinol (LT-4) e (±)-4-4\'-dimetil-5\'-hidroxi-5-metoxi-lariciresinol (LT-5)]; Lignana diarilbutanólica [(-)-4,4\'-dimetil-5-metoxi-secolariciresinol (LD-1)]; e lignanas dibenzilbutirolactâmicas [(-)-hinokinina (DB-1), (-)-kusunokinina (DB-2), (-)-dimetilmatairesinol (DB-3), (-)-metiltujaplicatina (DB-4), (-)-dimetil-5-hidroximatairesinol (DB-5) e (-)-dimetil-5-metoxi-matairesinol (DB-6)]; neolignanas diarilbutânicas [ND-1, ND-2 e ND-3], neolignana ariltetralínica: galbulina (NA-1) e neolignanas ariltetralônicas [(-) e (+)-oxoisogalcatina (NA-2), (+)-hidroxi-isogalcatina (NA-3), diidroxi-oxoisogalcatinas epiméricas inéditas (NA-4 e NA-5), NA-6, NA-7, (+)-otobanona (NA-8), hidroxi-otobanonas epiméricas (NA-9 e NA-10)]; neolignanas secoariltetralínicas (ND-5 e seu acetato ND-6]; uma neolignana dimérica [NA-11] e ainda diversos policetídeos acilresorcinólicos e acifloroglucinôlicos [AR-1 a AR-8]. 0 padrão 3,4-dioxigenado nos anéis aromáticos é predominante na maioria dos lignóides isolados. 0 padrão 3,4,5-trioxigenado observado nos anéis aromáticos de lignanas dibenzilbutirolactônicas (DB-4 e DB-5), diarilbutanólica (LD-1) e tetraidrofurânicas (LT-3, LT-4 e LT-5) e, o padrão 2,4,5-trioxigenado observado para neolionanas ariltetralônicas (NA-6, NA-7), conferem para algumas o caráter inédito. A maior variação no padrão de substituição de esqueletos foi observada para neolignanas ariltetralônicas, o que motivou a elaboração de experimentos especíificos em RMN- 1H (ENO e uso de reagente de deslocamento) associados a análise dos dados de RMN- 13C para proposições de constituições e de configurações relativas. Foi constatada a presença das neolionanas NA-2, NA-9 e NA-10 nos extratos dos tegumentos e de seus enantiômeros nos extratos das amêndoas de V. elongata (PA). Algumas classes de substâncias isoladas foram correlacionadas biossinteticamente a partir de suas configurações absolutas. A quantificação aproximada das substâncias identificadas foi efetuada, através das quantidades isoladas e análises de espectros de RMN-1H de frações impuras. Nos pericarpos e arilos foi constatada a presença exclusiva e alternada de lignanas furofurâanicas e lignanas dibenzilbutirolactônicas entre os frutos de diferentes localidades. Essas lignanas, também presentes nos tegumentos, ocorrem em maior teor com maior diversidade de substituição nos anéis aromáticos, mas são completamente ausentes nos extratos das amêndoas, onde o perfil é baseado na presença de neolignanas ariltetralônicas e policetídeos. Os policetídeos com anéis aromáticos di- e triidroxilados foram isolados, principalmente, dos tegumentos e amêndoas. A análise do extrato de uma das amêndoas foi baseada na análise conjunta do espectro de RMN-1H, dos cromatogramas em camada delgada e dos dados obtidos por cromatografia gasosa acoplada a espectrometria de massas. A metodologia foi tentativamente aplicada á análise das diversas partes dos frutos de V. sebifera coletada em Roraima. Os dados obtidos sobre as estruturas e distribuição dos metabólitos são confrontados com os descritos na literatura para espécies taxonomicamente afins. / This work describes isolations and structural determinations of secondary metabolites in parts of fruits (pericarps, arils, teguments and kernels) from Virola elongata. Material was collected in Humaita (AM) and Km 96 of Santarém-Cuiabá Road (PA). The chemical constituents were isolated by chromatographic processes and their structures identified or elucidated by usual spectrometric techniques (IR, UV, NMR, and MS). Absolute configuration were deduced through spectropolarimetric measures, or based on data from derivatives. The compounds were classified in the following classes: furofuran lignans [(+)-sesamin (LF-1), (+)-epifargesin (LF-2), (+)-eudesmin (LF-3), (+)- fargesin (LF-4), (+)-phylligenin (LF-5) and (+)-epieudesmin (LF-6)]; tetrahydrofuran lignans [(+)-magnostelin-A (LT-1), (+)-magnostelin-C (LT-2), (±)-5\'-methox y -4\'-methyl-lariciresinol (LT-3), (±)-5\'-methoxy-4,4\'-dimethyl-lariciresinol (LT-4) and (±)-5\'-hydroxy-5-methoxy-4,4\'-dimethvl-lariciresinol (LT-5)]; diarylbutanol lignan [(-)-4,4\'-dimethvl-5-methoxy-secolariciresinol (LD-1)]; and dibenzylbutyrolactone lignans [(-)-hinokinin (DB-1), (-)-kusunokinin (DB-2), (-)-dimethylmatairesinol (DB-3), (-)-methylthujaplicatin (DB-4)]; diarylbutane neolignans (ND-1, ND-2 and ND-3); aryltetralin neolignans [galbulin (NA-1) and aryltetralone neolignans [(-)- and (+)-oxoisogalcatin (NA-2), (+)-hydroxyisogalcatin (NA-3), unpublished epimeric dihydroxy-isogalcatins (NA-4 and NA-5), (+)-otobanone (NA-8), epimeric hydroxy-otobanones (NA-9 and NA-10)]; secoaryltetralin neolignans [ND-5 and its acetate (NA-6).1; dimeric neolignan (NA-11) and several acylresorcinol and acylphloroglucinol polyketides (AR-1 to AR-8). The 3,4-dioxygenated pattern was observed in aromatic rings of the majority isolated lignans. The 3,4,5-trioxygenated pattern observed in dibenz y lbutyrolactone lignans (DB-4 e DB-5), diarylbutanol (LD-1), and tetrahydrofuran lignans (LT-3, LT-4, LT-5), and the 2,4,5-pattern observed in aryltetralone neolignans, confer to some of them the unusual character. The main variation in the substitution pattern was observed in aryltetralone neolignans, which needed more detailed study involving 1H-NMR experiments (NOE and LIS reagent) and refined analysis of 13C-NMR data. It was observed the presence of NA-2, NA-9 and NA-10 neolignans in teguments and its enantiomers in kernels of fruits from Virola elongata (PA). The biosynthetic relationships among several classes of lignoids are discussed under their absolute configurations. The near concentration of identified compounds was obtained from isolated quantities and analysis of 1H-NMR spectra of mixtures. In pericarps and arils was determined the exclusive and alternated presence of furofuran and dibenzylbutyrolactone lignans between fruits from different localities. These last two subclasses, also present in teguments, occur in higher concentrations and substitution diversifications in aromatic rings, but are completely absent in kernels whose profile is based on the presence of aryltetralone lignans. The poliketide with di- and trihydroxylated aromatic rings were isolated mainly from teguments and kernels. The analysis from kernels extract was performed by combined analysis involving 1H-NMR spectra, thin layer chromatography, and gas chromatography coupled to mass spectrometry. This methodology was tested to analyse the parts of fruits from Virola sebifera collected in Roraima. The obtained informations about structures of metabolites and their distributions in fruits was compared with those data described for taxonomically closed species.
49

Caracterização e identificação de compostos com atividade antioxidante de própolis orgânica brasileira / Caracterization and identification of compounds with antioxidant activity in Brazilian organic propolis

Tiveron, Ana Paula 20 March 2015 (has links)
A própolis é uma substância resinosa complexa e que apresenta diversas propriedades biológicas como antiviral, antifúngica, antioxidante, anti-inflamatória, antitumoral, entre outras. Estas atividades têm sido atribuídas principalmente à presença de compostos fenólicos e/ou derivados. Entretanto, a composição química da própolis pode variar significativamente com a vegetação ao redor da colmeia. Neste estudo, foram coletadas 78 amostras de própolis orgânica produzidas em áreas de preservação permanente e reflorestamento, devidamente certificadas, localizadas no sul do Paraná e norte de Santa Catarina. Assim, o objetivo desse trabalho foi avaliar a composição química da própolis orgânica, bem como isolar os compostos responsáveis pela atividade antioxidante. Também foram avaliadas a composição de voláteis e a aplicação dos extratos etanólicos de própolis (EEP) e microcápsulas de própolis orgânica, produzidas por coacervação complexa, em óleo de soja sem adição de antioxidante. Dentre as 78 amostras analisadas, foram encontrados sete perfis cromatográficos distintos. Utilizando critérios como recorrência e atividade antioxidante, o perfil 1 foi selecionado para a etapa de isolamento dos compostos bioativos. O EEP do perfil 1 foi então fracionado pela técnica de extração líquido-líquido, originando as frações hexano, acetato de etila, butanol e água. As frações acetato de etila e butanol foram as que apresentaram as maiores atividades antioxidantes pelos métodos de sequestro dos radicais DPPH, ABTS e peroxil, bem como semelhança na composição química. Portanto, estas frações foram reunidas e na sequencia, recromatografadas em uma coluna aberta de vidro com sílica C18, a qual gerou 19 subfrações. As subfrações 2 e 5 foram as que apresentaram maior atividade antioxidante, que variou de 16,25 a 26,26 ?mol Trolox/mg e 2,28 a 5,71 ?mol Trolox/mg para os métodos ORAC e ABTSo+, respectivamente. Assim, a partir dessas subfrações foram isolados sete compostos com atividade antioxidante, sendo dois precursores de lignanas, álcool coniferil e aldeído coniferil, e cinco lignanas, as quais foram identificadas como pinoresinol, lariciresinol, secoisolariciresinol, matairesinol e balajaponina D, sendo as quatro últimas compostos inéditos em própolis. A aplicação das microcápsulas contendo a própolis orgânica do perfil 1 em óleo de soja não foi eficiente para evitar a oxidação. Na fração volátil dos sete perfis, foram encontrados terpenos, cetonas, aldeídos e alcoóis, sendo os compostos ? e ?-pinenos predominantes. Os resultados obtidos mostraram uma composição química bastante peculiar da própolis orgânica quando comparada à outras própolis brasileiras. De acordo com os resultados obtidos pode-se afirmar que a própolis orgânica é uma boa fonte de compostos bioativos a ser explorada / Propolis is a complex resinous substance and has many biological properties, such as antiviral, antifungal, antioxididant, anti-inflamatory, antitumor, among others. These activities have been attributed mainly due to the presence of phenolic compounds and/ or derivatives. However, propolis chemical composition depends on the vegetation around the hive. In this study, 78 samples of organic propolis were collected in permanent preservation and reflorestation areas, properly certified, in southern Paraná and north of Santa Catarina. The aim of this work was to evaluate the chemical composition of organic propolis as well as isolate the compounds responsible for the antioxidant activity. The volatile composition and application of ethanol extracts of propolis (EEP) and microcapsules of organic propolis, produced by complex coacervation, in soybean oil with no antioxidant addition were also evaluated. Among the 78 samples analysed, seven different chromatographic profiles were found. Using criteria such as recurrence and and antioxidant activity profile 1 was selected for isolation of bioactive compounds. The profile 1 was then fractionated by the technique of liquid-liquid extraction, resulting in hexane, ethyl acetate, butanol and water fractions. Fractions ethyl acetate and butanol were the ones that showed the highest antioxidant activity by radicals DPPH, ABTS and peroxyl scavenging methods, as well as similarity in chemical composition. Therefore, these fractions were pooled and rechromatographed in sequence in an open glass column with silica C18, yelding 19 subfractions. The subfractions 2-5 showed the highest antioxidant activity, ranging from 16,25 to 26,26 ?mol Trolox/mg e and 2,28 to 5,71 ?mol Trolox/mg for ORAC and ABTSo+ methods, respectively. Thus, from this subfractions were isolated seven compounds with antioxidant activity, two lignans precursors, such as coniferyl alcohol and coniferyl aldehyde and five lingans, wich were identified as pinoresinol, lariciresinol, secolariciresinol, matairesinol and balajaponin D. These four last lignans are novel in propolis. The application of microcapsules containing profile 1 of organic propolis in soybean oil was no effective to prevent oxidation. In the volatile fraction of the seven profiles, terpenoids, ketones, aldehydes and alcohols were found, and ? and ?-pinenes were the predominant compounds. The results obtained showed a very peculiar chemical composition of organic propolis when compared to other Brazilian ones. According to the results its possible to conclude that OP1 is a good source of bioactive compounds to be explored
50

Caracterização e identificação de compostos com atividade antioxidante de própolis orgânica brasileira / Caracterization and identification of compounds with antioxidant activity in Brazilian organic propolis

Ana Paula Tiveron 20 March 2015 (has links)
A própolis é uma substância resinosa complexa e que apresenta diversas propriedades biológicas como antiviral, antifúngica, antioxidante, anti-inflamatória, antitumoral, entre outras. Estas atividades têm sido atribuídas principalmente à presença de compostos fenólicos e/ou derivados. Entretanto, a composição química da própolis pode variar significativamente com a vegetação ao redor da colmeia. Neste estudo, foram coletadas 78 amostras de própolis orgânica produzidas em áreas de preservação permanente e reflorestamento, devidamente certificadas, localizadas no sul do Paraná e norte de Santa Catarina. Assim, o objetivo desse trabalho foi avaliar a composição química da própolis orgânica, bem como isolar os compostos responsáveis pela atividade antioxidante. Também foram avaliadas a composição de voláteis e a aplicação dos extratos etanólicos de própolis (EEP) e microcápsulas de própolis orgânica, produzidas por coacervação complexa, em óleo de soja sem adição de antioxidante. Dentre as 78 amostras analisadas, foram encontrados sete perfis cromatográficos distintos. Utilizando critérios como recorrência e atividade antioxidante, o perfil 1 foi selecionado para a etapa de isolamento dos compostos bioativos. O EEP do perfil 1 foi então fracionado pela técnica de extração líquido-líquido, originando as frações hexano, acetato de etila, butanol e água. As frações acetato de etila e butanol foram as que apresentaram as maiores atividades antioxidantes pelos métodos de sequestro dos radicais DPPH, ABTS e peroxil, bem como semelhança na composição química. Portanto, estas frações foram reunidas e na sequencia, recromatografadas em uma coluna aberta de vidro com sílica C18, a qual gerou 19 subfrações. As subfrações 2 e 5 foram as que apresentaram maior atividade antioxidante, que variou de 16,25 a 26,26 ?mol Trolox/mg e 2,28 a 5,71 ?mol Trolox/mg para os métodos ORAC e ABTSo+, respectivamente. Assim, a partir dessas subfrações foram isolados sete compostos com atividade antioxidante, sendo dois precursores de lignanas, álcool coniferil e aldeído coniferil, e cinco lignanas, as quais foram identificadas como pinoresinol, lariciresinol, secoisolariciresinol, matairesinol e balajaponina D, sendo as quatro últimas compostos inéditos em própolis. A aplicação das microcápsulas contendo a própolis orgânica do perfil 1 em óleo de soja não foi eficiente para evitar a oxidação. Na fração volátil dos sete perfis, foram encontrados terpenos, cetonas, aldeídos e alcoóis, sendo os compostos ? e ?-pinenos predominantes. Os resultados obtidos mostraram uma composição química bastante peculiar da própolis orgânica quando comparada à outras própolis brasileiras. De acordo com os resultados obtidos pode-se afirmar que a própolis orgânica é uma boa fonte de compostos bioativos a ser explorada / Propolis is a complex resinous substance and has many biological properties, such as antiviral, antifungal, antioxididant, anti-inflamatory, antitumor, among others. These activities have been attributed mainly due to the presence of phenolic compounds and/ or derivatives. However, propolis chemical composition depends on the vegetation around the hive. In this study, 78 samples of organic propolis were collected in permanent preservation and reflorestation areas, properly certified, in southern Paraná and north of Santa Catarina. The aim of this work was to evaluate the chemical composition of organic propolis as well as isolate the compounds responsible for the antioxidant activity. The volatile composition and application of ethanol extracts of propolis (EEP) and microcapsules of organic propolis, produced by complex coacervation, in soybean oil with no antioxidant addition were also evaluated. Among the 78 samples analysed, seven different chromatographic profiles were found. Using criteria such as recurrence and and antioxidant activity profile 1 was selected for isolation of bioactive compounds. The profile 1 was then fractionated by the technique of liquid-liquid extraction, resulting in hexane, ethyl acetate, butanol and water fractions. Fractions ethyl acetate and butanol were the ones that showed the highest antioxidant activity by radicals DPPH, ABTS and peroxyl scavenging methods, as well as similarity in chemical composition. Therefore, these fractions were pooled and rechromatographed in sequence in an open glass column with silica C18, yelding 19 subfractions. The subfractions 2-5 showed the highest antioxidant activity, ranging from 16,25 to 26,26 ?mol Trolox/mg e and 2,28 to 5,71 ?mol Trolox/mg for ORAC and ABTSo+ methods, respectively. Thus, from this subfractions were isolated seven compounds with antioxidant activity, two lignans precursors, such as coniferyl alcohol and coniferyl aldehyde and five lingans, wich were identified as pinoresinol, lariciresinol, secolariciresinol, matairesinol and balajaponin D. These four last lignans are novel in propolis. The application of microcapsules containing profile 1 of organic propolis in soybean oil was no effective to prevent oxidation. In the volatile fraction of the seven profiles, terpenoids, ketones, aldehydes and alcohols were found, and ? and ?-pinenes were the predominant compounds. The results obtained showed a very peculiar chemical composition of organic propolis when compared to other Brazilian ones. According to the results its possible to conclude that OP1 is a good source of bioactive compounds to be explored

Page generated in 0.4273 seconds