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Articles de revues sur le sujet "Flavonoidi naturali"
1
Choi, Roy C. Y., Judy T. T. Zhu, Amanda W. Y. Yung, Pinky S. C. Lee, Sherry L. Xu, Ava J. Y. Guo, Kevin Y. Zhu, Tina T. X. Dong et Karl W. K. Tsim. « Synergistic Action of Flavonoids, Baicalein, and Daidzein in Estrogenic and Neuroprotective Effects : A Development of Potential Health Products and Therapeutic Drugs against Alzheimer’s Disease ». Evidence-Based Complementary and Alternative Medicine 2013 (2013) : 1–10. http://dx.doi.org/10.1155/2013/635694.
Texte intégralRésumé :
Despite the classical hormonal effect, estrogen has been reported to mediate neuroprotection in the brain, which leads to the searching of estrogen-like substances for treating neurodegenerative diseases. Flavonoids, a group of natural compounds, are well known to possess estrogenic effects and used to substitute estrogen, that is, phytoestrogen. Flavonoid serves as one of the potential targets for the development of natural supplements and therapeutic drugs against different diseases. The neuroprotection activity of flavonoids was chosen for a possible development of anti-Alzheimer's drugs or food supplements. The estrogenic activity of two flavonoids, baicalein and daidzein, were demonstrated by their strong abilities in stimulating estrogen receptor phosphorylation and transcriptional activation of estrogen responsive element in MCF-7 breast cells. The neuroprotection effects of flavonoids againstβ-amyloid (Aβ) were revealed by their inhibition effects onin vitroAβaggregation and Aβ-induced cytotoxicity in PC12 neuronal cells. More importantly, the estrogenic and neuroprotective activities of individual flavonoid could be further enhanced by the cotreatment in the cultures. Taken together, this synergistic effect of baicalein and daidzein might serve as a method to improve the therapeutic efficacy of different flavonoids against Aβ, which might be crucial in developing those flavonoidsin treating Alzheimer's disease in the future.
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Arshad, Nasima, Naveed K. Janjua, Athar Y. Khan, Azra Yaqub, Torsten Burkholz et Claus Jacob. « Natural Flavonoids Interact with Dinitrobenzene System in Aprotic Media : An Electrochemical Probing ». Natural Product Communications 7, no 3 (mars 2012) : 1934578X1200700. http://dx.doi.org/10.1177/1934578x1200700309.
Texte intégralRésumé :
Three structurally related natural flavonoids (FlOH), quercetin (Q), rutin (R) and morin (M), were investigated by cyclic voltammetry to probe their interactions with hazardous 1,4-dinitrobenzene (1,4-DNB) using a glassy carbon electrode. Scavenging of 1,4-DNB by FlOH was inferred from a positive shift in reduction potential, decrease in anodic peak current, and irreversible electrochemical behavior of 1,4-DNB on increasing the flavonoid concentration. The homogeneous bi-molecular rate constant (k2) was determined using the Nicholson-Shain equation and found to be higher for the dianion. Morin posed a comparatively higher k2 value for its interaction with the 1,4-DNB electrochemical system owing to its more acidic nature and least intramolecular hydrogen bonding. The cyclic voltammetric (CV) results were further supported by HyperchemPM3 quantum mechanical semi-empirical calculations, which point towards ErCi interactions between flavonoids and 1,4-DNB. The present investigation is biologically significant in terms of natural flavonoidal scavenging activity toward toxins such as dinitroaromatics.
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Hurtová, Martina, David Biedermann, Zuzana Osifová, Josef Cvačka, Kateřina Valentová et Vladimír Křen. « Preparation of Synthetic and Natural Derivatives of Flavonoids Using Suzuki–Miyaura Cross-Coupling Reaction ». Molecules 27, no 3 (31 janvier 2022) : 967. http://dx.doi.org/10.3390/molecules27030967.
Texte intégralRésumé :
Herein, we report the use of the Suzuki–Miyaura cross-coupling reaction for the preparation of a library of synthetic derivatives of flavonoids for biological activity assays. We have investigated the reactivity of halogenated flavonoids with aryl boronates and with boronyl flavonoids. This reaction was used to prepare new synthetic derivatives of flavonoids substituted at C-8 with aryl, heteroaryl, alkyl, and boronate substituents. The formation of flavonoid boronate enabled a cross-coupling reaction with halogenated flavones yielding biflavonoids connected at C-8. This method was used for the preparation of natural compounds including C-8 prenylated compounds, such as sinoflavonoid NB. Flavonoid boronates were used for the preparation of rare C-8 hydroxyflavonoids (natural flavonoids gossypetin and hypolaetin). A series of previously unknown derivatives of quercetin and luteolin were prepared and fully characterized.
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Parwata, Adi, Putra Manuaba et Sutirta Yasa. « The Potency of Flavonoid Compounds in water Extract Gyrinops Versteegii Leaves as Natural Antioxidants Sources ». Biomedical and Pharmacology Journal 11, no 3 (17 septembre 2018) : 1501–11. http://dx.doi.org/10.13005/bpj/1517.
Texte intégralRésumé :
Flavonoids can provide antioxidant effects by preventing the formation of ROS, directly capture ROS, protect lipophilic antioxidants and stimulate the increase of enzymatic antioxidants. Flavonoids are phenolic compounds that are widely found in medicinal plants, one of which is Gyrinops versteegii leaves. In this research to determine the potential of flavonoids in water extract Gyrinop versteegii as one source of natural antioxidants was investigated. This research begins with maceration of Gyrinops versteegii leaves with some solvents such as ethyl acetate, ethanol, methanol and water. Each of the extracts obtained measured the total content of Phenol. The extract, which had the highest total phenol content, measured the total flavonoid content and antioxidant capacity. The active extract as antioxidant was further isolated and identified its flavonoid content. Flavonoids obtained measured antioxidant capacity in vitro. Total phenol (mg GAE/100 g) of ethyl acetate extract = 443, ethanol extract =1.510, methanol extract = 6.069 and water extract = 14.979, total flavonoid contens = 2298, 977 mg QE/100 gram, containing phenol, flavonoid, tannin, alkaloid and steroid compounds. Antioxidant capacity with IC50 = 3,45 ppm (5 min.) and 3,05 (60 min.). Identification of isolates with UV-Vis spectroscopy showed 2 absorption bands namely band I at 352 nm and band II at 256 nm. Addition of AlCl3 / HCl shear reagent showed band I undergoing a 2 nm batochromic shift. These results indicate that the resulting flavonoid is suspected to be a flavonoid group of flavonol substituted -OH group at C-5 or 5-hydroxy-flavonol. and its antioxidant capacity or IC50 = 17,14 ppm. These results indicate that the isolated flavonoid has very strong antioxidant activity and is potentially developed as a natural antioxidant.
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Brou, Kouassi Guy, Jean Luc Aboya Moroh, Sékou Diabaté, Boni N’zue, Goli Pierre Zouhouri, Janat Ackanovna Mamyrbekova-Bekro, II Nazaire Koffi Kouassi, Denézon Odette Dogbo et Yves-Alain Bekro. « Physiological mechanism of resistance antibiosis to anthracnose of different Manihot varieties ». International Journal of Biological and Chemical Sciences 14, no 8 (9 décembre 2020) : 2854–69. http://dx.doi.org/10.4314/ijbcs.v14i8.16.
Texte intégralRésumé :
Cassava is one of the main food crops in Africa, particularly in Côte d'Ivoire. However, the cultivated varieties are prone to attack by diseases. The present work focused on the role of phenolic and in particular flavonoid resistance markers in the Manihot esculenta-Colletotrichum gloeosporioides pathosystem. The aim was to elucidate the involvement of flavonoid antibiosis in the natural defense of three cultivars of M. esculenta when confronted with attacks by C. gloeosporioides. The quantitative dosage approach for total phenolics and flavonoids as well as the identification of flavonoid antibiosis have been carried out. The results revealed that the cultivars 9620A, TMS30572 and YACE of M. esculenta have, after the C. gloeosporioides inoculation tests, reacted early 2 days after inoculation (JAI) and accumulated relatively high levels of antibiosis phenolic and flavonoid 9JAI. The three cultivars accumulated constitutive flavonoid antibiosis and 3 neosynthesized antibiosis from 7JAI to 9JAI. The accumulation of flavonoid antibacterials neosynthesized in the stems and in the leaves testify to the expression of a systemic resistance of the cassava plants. The cultivars 9620A and TMS30572 are more tolerant than cultivar YACE. This study approach has made it possible to discriminate between cultivars and can therefore be used as a complementary selection tool to traditional selection tests.Keywords: Manihot esculenta, anthracnose, flavonoïd antibisis, glyphosate.
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Slámová, Kristýna, Jana Kapešová et Kateřina Valentová. « “Sweet Flavonoids” : Glycosidase-Catalyzed Modifications ». International Journal of Molecular Sciences 19, no 7 (21 juillet 2018) : 2126. http://dx.doi.org/10.3390/ijms19072126.
Texte intégralRésumé :
Natural flavonoids, especially in their glycosylated forms, are the most abundant phenolic compounds found in plants, fruit, and vegetables. They exhibit a large variety of beneficial physiological effects, which makes them generally interesting in a broad spectrum of scientific areas. In this review, we focus on recent advances in the modifications of the glycosidic parts of various flavonoids employing glycosidases, covering both selective trimming of the sugar moieties and glycosylation of flavonoid aglycones by natural and mutant glycosidases. Glycosylation of flavonoids strongly enhances their water solubility and thus increases their bioavailability. Antioxidant and most biological activities are usually less pronounced in glycosides, but some specific bioactivities are enhanced. The presence of l-rhamnose (6-deoxy-α-l-mannopyranose) in rhamnosides, rutinosides (rutin, hesperidin) and neohesperidosides (naringin) plays an important role in properties of flavonoid glycosides, which can be considered as “pro-drugs”. The natural hydrolytic activity of glycosidases is widely employed in biotechnological deglycosylation processes producing respective aglycones or partially deglycosylated flavonoids. Moreover, deglycosylation is quite commonly used in the food industry aiming at the improvement of sensoric properties of beverages such as debittering of citrus juices or enhancement of wine aromas. Therefore, natural and mutant glycosidases are excellent tools for modifications of flavonoid glycosides.
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Fan, Xiaolan, Ziqiang Fan, Ziyue Yang, Tiantian Huang, Yingdong Tong, Deying Yang, Xueping Mao et Mingyao Yang. « Flavonoids—Natural Gifts to Promote Health and Longevity ». International Journal of Molecular Sciences 23, no 4 (16 février 2022) : 2176. http://dx.doi.org/10.3390/ijms23042176.
Texte intégralRésumé :
The aging of mammals is accompanied by the progressive atrophy of tissues and organs and the accumulation of random damage to macromolecular DNA, protein, and lipids. Flavonoids have excellent antioxidant, anti-inflammatory, and neuroprotective effects. Recent studies have shown that flavonoids can delay aging and prolong a healthy lifespan by eliminating senescent cells, inhibiting senescence-related secretion phenotypes (SASPs), and maintaining metabolic homeostasis. However, only a few systematic studies have described flavonoids in clinical treatment for anti-aging, which needs to be explored further. This review first highlights the association between aging and macromolecular damage. Then, we discuss advances in the role of flavonoid molecules in prolonging the health span and lifespan of organisms. This study may provide crucial information for drug design and developmental and clinical applications based on flavonoids.
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GEMMELL, CHRISTOPHER T., VALERIA R. PARREIRA et JEFFREY M. FARBER. « Controlling Listeria monocytogenes Growth and Biofilm Formation Using Flavonoids ». Journal of Food Protection 85, no 4 (4 janvier 2022) : 639–46. http://dx.doi.org/10.4315/jfp-21-135.
Texte intégralRésumé :
ABSTRACT The aim of this study was to investigate the ability of natural plant-derivate products (flavonoid compounds) to inhibit the growth and biofilm-forming ability of Listeria monocytogenes. A collection of 500 synthetic and natural flavonoids were tested individually on strains of L. monocytogenes for their antimicrobial and antibiofilm activity. The flavonoids were tested against a L. monocytogenes cocktail of five strains at a concentration of 100 μM to determine their effect on planktonic growth. The optical density was measured every hour for 24 h at 37°C, and every hour for 48 h at 22°C. A total of 17 flavonoids were chosen for further study because of their ability to significantly reduce the growth of L. monocytogenes up to 97%. An additional two flavonoids that increased planktonic growth were chosen as well to investigate whether they had the same effect on biofilm growth. A lower concentration of flavonoid compounds (50 μM) was selected to investigate the individual effects on L. monocytogenes biofilm formation using (i) stainless steel coupons to quantify biomass using crystal violet staining and (ii) glass slides using confocal laser scanning microscopic (CLSM) imaging to observe the biofilm architecture. The 19 flavonoids showed various levels of L. monocytogenes biofilm growth inhibition, ranging from 2 to 100% after 48 h of incubation at 22 or 10°C. This includes 18 of the 19 flavonoids significantly (P ≤ 0.05) inhibiting L. monocytogenes biofilm formation on stainless steel coupons under at least one of the testing conditions. However, only one flavonoid compound demonstrated significant biofilm inhibition (P ≤ 0.05) under all conditions tested. Furthermore, 8 of the selected 19 flavonoid compounds showed visible reductions through CLSM in L. monocytogenes biofilm formation. Overall, we identified five flavonoid compounds to be promising antibiofilm and antimicrobial agents against L. monocytogenes. HIGHLIGHTS
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Yan, Shiqiang, Mingxian Xie, Yujie Wang, Qiang Xiao, Ning Ding et Yingxia Li. « Semi-synthesis of a series natural flavonoids and flavonoid glycosides from scutellarin ». Tetrahedron 76, no 8 (février 2020) : 130950. http://dx.doi.org/10.1016/j.tet.2020.130950.
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Wisnumurti, Rafi Firdaus, Solmaz Aslanzadeh et Arli Aditya Parikesit. « COMPUTATIONAL EXAMINATION OF FLAVONOID COMPOUNDS : UTILIZATION OF MOLECULAR SIMULATION TO DISCOVER DRUG CANDIDATES FOR COVID-19 ». RASAYAN Journal of Chemistry 15, no 02 (2022) : 1132–36. http://dx.doi.org/10.31788/rjc.2022.1526877.
Texte intégralRésumé :
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the novel coronavirus disease 19 (COVID19) pandemic. Despite drugs had been deployed through intense research, none has been proven to cure the infection. Flavonoids, a natural substance, have been reported to exhibit various pharmaceutical and medical properties. The aim of this research is to discover lead compounds for covid-19 from flavonoid compounds through in silico study. Through computational examination, the potential of flavonoid compounds against SARS-CoV-2 has been examined and it shows that some flavonoids have potential against SARS-CoV-2.
Thèses sur le sujet "Flavonoidi naturali"
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Tangerina, Marcelo Marucci Pereira [UNESP]. « Extratos padronizados para o tratamento de doenças crônicas : Machaerium hirtium ». Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/97015.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O uso de fitoterápicos padronizados com assegurada comprovação de eficácia e segurança tem apresentado resultados terapêuticos surpreendentes em diversos países. Contudo, no Brasil, onde há grande potencial de produção de fitoterápicos devido a sua enorme biodiversidade, há deficiências na correta caracterização química das matérias-primas e escassez de ensaios farmacológicos e toxicológicos desses materiais, etapas essenciais para assegurar eficácia e segurança dos fitoterápicos. Machaerium hirtum (Fabaceae) é utilizada popularmente para o tratamento de diarréia, tosse e câncer. Um estudo químico que identifique as substâncias presentes nesta espécie e as quantifique pode fornecer subsídios para o entendimento destas atividades. A primeira etapa consistiu no isolamento das substâncias do extrato EtOH 70% das partes aéreas de M. hirtum por meio de cromatografia de permeação em gel seguida de purificação das substâncias por HPLC-RI. A identificação das substâncias foi feita por Ressonância Magnética Nuclear e por Espectrometria de Massas. O perfil químico do extrato foi estabelecido por HPLC-PDA e a quantificação das substâncias foi feita com base em suas agliconas, pelo método da calibração externa. Foi possível identificar as flavonas saponarina (8,69 ± 0,46 mg/g de extrato), isovitexina (6,44 ± 0,45 mg/g de extrato), isoorientina, que se apresentou abaixo do limite de quantificação (LOQ) e swertisina, presente no perfil cromatográfico em co-eluição com outra substância. Tais resultados são fundamentais para a padronização do extrato EtOH 70% das folhas de Machaerium hirtum
The use of standardized phytomedicines with proven efficacy and safety has shown surprising therapeutic results in various countries. Brazil has great potential for production of herbal medicine due to its enormous biodiversity. However, there are deficiencies in the correct characterization of chemical raw materials and few reliable pharmacological and toxicological tests of these materials, essential steps to ensure efficacy and safety of herbal medicines. Machaerium hirtum (Fabaceae) is popularly used to treat diarrhea, cough and cancer. A chemical study to identify the substances present in this species may provide and quantify contributions to the understanding of these activities. The first step was the isolation of substances of 70% EtOH extract of aerial parts of M. hirtum by gel permeation chromatography followed by purification of substances by HPLC-RI. The identification of substances was performed by Nuclear Magnetic Resonance and Mass Spectrometry. The chemical profile of the extract was established by HPLC-PDA and quantification of the substances was based on their aglycones by the method of external calibration. It was possible to identify the flavones saponarin (8,69 ± 0,46 mg/g of extract), isovitexin (6,44 ± 0,45 mg/g of extract), isoorientin, which was below the limit of quantification (LOQ) and swertisin, present in the chromatographic profile in co-elution with another substance. These results are fundamental to the standardization of the crude 70% EtOH extract from the leaves of Machaerium hirtum
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Arantes, Glenda Marqueti [UNESP]. « Bioprospecção em espécies do gênero Sclerolobium sp : busca de agentes quimiopreventivos ». Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/105818.
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A família Fabaceae é subdividida em 3 subfamílias: Faboideae, Caesalpinoideae e Mimosoideae, que englobam mais de 700 gêneros e 18000 espécies, bem distribuídas nas regiões tropicais e subtropicais. Inclui espécies de alta relevância econômica, como a soja, feijão, cerejeira, angelim e sucupira, além do pau-brasil, de importância histórica para o Brasil. Neste trabalho, os extratos etanólicos das folhas de Sclerolobium aureum, S. denudatum e S. paniculatum mostraram forte potencial antioxidante, sendo selecionados para investigação fitoquímica detalhada. O fracionamento cromatográfico destes extratos evidenciou sua composição química, destacando-se a presença de esqualeno, tocoferóis e lupenona, identificados por CG-EM, predominantes nas frações de baixa polaridade. O extrato hidroalcoólico de S. aureum foi submetido a etapas de purificação, incluindo o uso de CLAE-UV-DAD, evidenciando a presença majoritária de ácido gálico, flavonoides monoglicosilados e catequina, identificados por RMN, EM e UV. Os extratos hidroalcoólicos de S. denudatum e S. paniculatum foram submetidos a partição líquido-líquido e as frações resultantes foram analisadas por CLAE-UV-DAD e CLAE-EM-EM para identificação dos seus constituintes por desreplicação, ou seja, evitando-se procedimentos de purificação de substâncias conhecidas. Esta estratégia permitiu conhecer os metabólitos secundários das três espécies, que apresentaram perfis químicos semelhantes com a predominância de flavonoides monoglicosilados. As frações semipurificadas e substâncias isoladas mostraram elevado potencial de sequestro de radicais livres frente ao DPPH, destacando-se a presença de antioxidantes lipofílicos e hidrofílicos, atrativa para aplicações em cosméticos. Adicionalmente, foi observado potencial imunomodulador...
Fabaceae family comprises 3 subfamilies: Faboideae, Caesalpinoideae and Mimosoideae, with more than 700 genera and 18000 species, widespread in tropical and subtropical regions. It includes economically important species as soybean, beans, angelim, sucupira, in addition to pau-brasil (Caesalpinea echinata), which has historical importance in Brazil for its wood pigments. In this work, ethanol extracts of Sclerolobium aureum, S. denudatum and S. paniculatum leaves were investigated and showed strong antioxidant potential, and were selected for further investigation. Their chromatographic fractionation evidenced the presence of squalene, tocopherols and lupenone as major compounds in low polarity fractions, by GC-MS analysis. The hydroalcoholic extract of S. aureum was submitted to purification procedures, including the use of HPLC-UV-DAD, which evidenced gallic acid, flavonoid monoglucosides and catechin as major compounds, identified mainly by NMR, MS and UV techniques. HPLC-UV-DAD and LC-MS-MS analysis were further carried out on the hydroalcoholic extract of S. denudatum and S. paniculatum, leading to the identification of their major constituents by dereplication, avoiding the purification of known compounds. Such strategy evidenced a similar chemical profile for the three Sclerolobium species, with flavonoid monoglucosides as major compounds. Strong free radical scavenging potential was observed for the fractions and isolated compounds towards DPPH, evidencing the presence of lipophilic and hydrophilic antioxidants, which might be important for cosmetics development. In addition, the immunomodulatory potential of the hexane and ethyl acetate fractions from S. denudatum were evidenced through the dose-dependent inhibition of nitrite release by pre-treated macrophages, which might... (Complete abstract click electronic access below)
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Tangerina, Marcelo Marucci Pereira. « Extratos padronizados para o tratamento de doenças crônicas : Machaerium hirtium / ». Araraquara : [s.n.], 2012. http://hdl.handle.net/11449/97015.
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Orientador: Wagner VilegasCoorientador: Miriam Sannomiya
Banca: Alba Regina Monteiro Souza Brito
Banca: Elfriede Marianne Bacchi
Resumo: O uso de fitoterápicos padronizados com assegurada comprovação de eficácia e segurança tem apresentado resultados terapêuticos surpreendentes em diversos países. Contudo, no Brasil, onde há grande potencial de produção de fitoterápicos devido a sua enorme biodiversidade, há deficiências na correta caracterização química das matérias-primas e escassez de ensaios farmacológicos e toxicológicos desses materiais, etapas essenciais para assegurar eficácia e segurança dos fitoterápicos. Machaerium hirtum (Fabaceae) é utilizada popularmente para o tratamento de diarréia, tosse e câncer. Um estudo químico que identifique as substâncias presentes nesta espécie e as quantifique pode fornecer subsídios para o entendimento destas atividades. A primeira etapa consistiu no isolamento das substâncias do extrato EtOH 70% das partes aéreas de M. hirtum por meio de cromatografia de permeação em gel seguida de purificação das substâncias por HPLC-RI. A identificação das substâncias foi feita por Ressonância Magnética Nuclear e por Espectrometria de Massas. O perfil químico do extrato foi estabelecido por HPLC-PDA e a quantificação das substâncias foi feita com base em suas agliconas, pelo método da calibração externa. Foi possível identificar as flavonas saponarina (8,69 ± 0,46 mg/g de extrato), isovitexina (6,44 ± 0,45 mg/g de extrato), isoorientina, que se apresentou abaixo do limite de quantificação (LOQ) e swertisina, presente no perfil cromatográfico em co-eluição com outra substância. Tais resultados são fundamentais para a padronização do extrato EtOH 70% das folhas de Machaerium hirtum
Abstract: The use of standardized phytomedicines with proven efficacy and safety has shown surprising therapeutic results in various countries. Brazil has great potential for production of herbal medicine due to its enormous biodiversity. However, there are deficiencies in the correct characterization of chemical raw materials and few reliable pharmacological and toxicological tests of these materials, essential steps to ensure efficacy and safety of herbal medicines. Machaerium hirtum (Fabaceae) is popularly used to treat diarrhea, cough and cancer. A chemical study to identify the substances present in this species may provide and quantify contributions to the understanding of these activities. The first step was the isolation of substances of 70% EtOH extract of aerial parts of M. hirtum by gel permeation chromatography followed by purification of substances by HPLC-RI. The identification of substances was performed by Nuclear Magnetic Resonance and Mass Spectrometry. The chemical profile of the extract was established by HPLC-PDA and quantification of the substances was based on their aglycones by the method of external calibration. It was possible to identify the flavones saponarin (8,69 ± 0,46 mg/g of extract), isovitexin (6,44 ± 0,45 mg/g of extract), isoorientin, which was below the limit of quantification (LOQ) and swertisin, present in the chromatographic profile in co-elution with another substance. These results are fundamental to the standardization of the crude 70% EtOH extract from the leaves of Machaerium hirtum
Mestre
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Coqueiro, Aline [UNESP]. « Fracionamento bioguiado para selação de substâncias antioxidante, antimalárica e antibiótica potenciais nas espécies Kielmeyera variabilis (Clusiaceae) e Brosimum Glaziovii (Moraceae) ». Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/105815.
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Os testes biológicos realizados por pesquisadores colaboradores do NuBBE para as espécies selecionadas para este estudo Brosimum glaziovii e Kielmeyera variabilis indicaram K. variabilis como uma importante fonte de metabólitos especiais bioativos. O fracionamento bioguiado da fração AcOEt dos galhos de K. variabilis para isolamento de substâncias com potencial antimalárico foi realizado via teste químico com -hematina e in vitro com Plasmodium falciparum, levando a identificação das xantonas oxigenadas 3,6-diidroxi-1,4,8-trimetoxixantona, 3,5-diidroxi-4-metoxixantona, 3,4-diidroxi-6,8-dimetoxixantona, 3,4-diidroxi-2-metoxixantona, 5-hidroxi-1,3- dimetoxixantona, 2,3-dimetoxi-4-hidroxixantona, 3-hidroxi-2-metoxixantona e 2-hidroxi- 1-metoxi-xantona e o xantonolignóide kielcorina. Dentre as substâncias isoladas, o xatonolignóide kielcorina foi considerado ativo quando comparado ao padrão cloroquina. A avaliação do potencial tripanocida também foi realizada para as xantonas isoladas e dentre estas, a 3,4-diidroxi-2-metoxixantona foi a mais ativa, principalmente para a cepa resistente ao benzonidazol (cepa Bolívia). Na fração EHFB das folhas de B. glaziovii foi observado o potencial antichagásico desta espécie. Os resultados observados para os ensaios antioxidantes levaram ao isolamento dos flavonóides quercitrina, podocarpusflavona A e da mistura de quercetina-3-Oglicosídeo e quercetina-3-O-galactosídeo, evidenciando a importância dos grupos catecólicos na potencialização da ação antioxidante. O estudo bioguiado pela atividade antimicrobiana com seis cepas de Staphylococcus aureus resistentes à meticilina culminou no isolamento de um derivado prenilado do floroglucinol (HGK-1) o qual demonstrou ser responsável pela potente atividade demonstrada pela fração hexânica dos galhos de K. variabilis. As xantonas isoladas tiveram seu potencial antimicrobiano...
Several biological activities have been carried out by NuBBE’s collaborators aiming the identification of active extracts from plant species, and Brosimum glaziovii and Kielmeyera variables showed to be important sources of bioactive secondary metabolites. Bio-guided fractionation of the EtOAc bioactive fraction of the branches of K. variabilis by using of the chemical test -hematin, and in vitro by using of Plasmodium falciparum, led to the isolation and identification of oxygenated xanthones 3,6-dihydroxy-1,4,8-trimethoxyxanthone, 3,5-dihydroxy-4-methoxyxanthone, 3,4- dihydroxy-6,8-dimethoxyxanthone, 3,4-dihydroxy-2-methoxyxanthone, 1,3-dimethoxy- 5-hydroxyxanthone, 2,3-dimethoxy-4-hydroxyxantona, 3-hydroxy-2-methoxyxanthone and 2-hydroxy-1-methoxyxanthone and xantonolignoid kielcorin. Among the compounds isolated, the xatonolignoid keilcorine indicated activity when compared to the standard chloroquine. The assessment of potential trypanocidal was also a part of this work and among the isolated xanthones, 3,4-dihydroxy-2-methoxyxanthone showed to be the most active, especially against the resistant strain to benzonidazole (Bolivia strain). In hexane fraction of leaves from B. glaziovii was noted antichagasic potencial for this specie. The antioxidant test used in this study led to the isolation of several flavonoids with antioxidant activity: quercitrin, podocarpusflavone A and the mixture of quercetin-3-O-glucoside and quercetin-3-O-galactoside, showing the importance of catechol group for the potentiating of antioxidant activity. The bio-guided antimicrobial activity using six strains of methicillin-resistant Staphylococcus aureus resulted in the isolation of the prenylated phloroglucinol derivative (HGK-1), which proved to be responsible for the potent activity exhibited by the hexane extract of the branches of K. variabilis. The xanthones isolated were evaluated... (Complete abstract click electronic access below)
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Moura, Adriana Candido da Silva [UNESP]. « Uso sustentável da biodiversidade brasileira : avaliação químico-farmacológica de plantas superiores : Indigofera hirsuta (Fabaceae) ». Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/97958.
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As plantas medicinais utilizadas no tratamento de diversas doenças são fontes de uma infinidade de novas moléculas de interesse para a humanidade. Este trabalho investigou a composição química das partes aéreas do chá e do extrato metanólico de Indigofera hirsuta (Fabaceae), popularmente conhecida como “anileira” e encontrada no Cerrado brasileiro. O chá foi fracionado por cromatografia de permeação em gel e cromatografia líquida de média pressão, tendo-se isolado: kaempferol, ácido protocatecuico, kaempferol-3-O-β-D-glucopiranosideo, triptofano e uracila. O extrato metanólico foi fracionado por cromatografia líquida de alta pressão, que possibilitou o isolamento de: ácido gálico, galato de metila, rutina e kaempferol-3-O-β-D-glucopiranosideo. As substâncias foram identificadas por técnicas espectroscópicas (UV, IV e RMN) e as estruturas confirmadas pelo uso da técnica acoplada de HPLC-DAD-ESI-MS. O chá, extrato metanólico e as substâncias isoladas foram avaliados quanto à atividade antioxidante, utilizando-se DPPH. O extrato metanólico apresentou significativa atividade antioxidante, enquanto que o chá não apresentou atividade antioxidante considerável, quando comparados com o padrão ácido gálico. Das substâncias isoladas, o galato de metila apresentou a maior atividade antioxidante. O chá de I. hirsuta foi também avaliado quanto à atividade gastroprotetora em lesões induzida por etanol absoluto em 3 diferentes doses: 125 mg.Kg-1, 250 mg.Kg-1 e 500 mg.Kg-1, sendo a menor dose a que apresentou melhor efeito. Contudo, o chá de Indigofera hirsuta não apresentou atividade gastroprotetora
Medicinal plants used in the treatment of various diseases and are source of many new molecules. This work investigates the chemical composition of the aerial parts of the infusion and methanol extract of Indigofera hirsuta (Fabaceae), popularly known as “anileira” and found in the Brazilian Cerrado. The infusion was fractionated by gel permeation chromatography and medium pressure liquid chromatography, it was possible to isolate kaempferol, protocatecuic acid, kaempferol-3-O-β-D-glucopyranoside, tryptophan and uracil. The methanol extract was fractionated by high pressure liquid chromatography, which allowed the isolation of gallic acid, methyl gallate, rutin and kaempferol-3-O-β-D-glucopyranoside. The substances were identified by spectroscopic techniques (UV, IR and NMR) and confirmed by the use of HPLC-DAD-ESI-MS coupling. The infusion, methanol extract and isolated compounds were evaluated for their antioxidant activity using DPPH. The methanol extract showed significant antioxidant activity, while the tea did not show significant antioxidant activity, when compared to gallic acid. Among the isolated substances methyl gallate presented the highest antioxidant activity. The I. hirsuta was also evaluated for its gastroprotective activity in lesions induced by absolute ethanol in 3 different doses (125 mg.Kg-1, 250 mg.Kg-1 and 500 mg.Kg-1).The lowest dose showed the best effect. However, the infusion not active gastroprotective
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Coqueiro, Aline. « Fracionamento bioguiado para selação de substâncias antioxidante, antimalárica e antibiótica potenciais nas espécies Kielmeyera variabilis (Clusiaceae) e Brosimum Glaziovii (Moraceae) / ». Araraquara : [s.n.], 2010. http://hdl.handle.net/11449/105815.
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Orientador: Vanderlan da Silva BolzaniBanca: Marcia Nasser Lopes
Banca: José Angelo Slveira Zuanazzi
Banca: Horácio Adolfo Heinzen Gozález
Resumo: Os testes biológicos realizados por pesquisadores colaboradores do NuBBE para as espécies selecionadas para este estudo Brosimum glaziovii e Kielmeyera variabilis indicaram K. variabilis como uma importante fonte de metabólitos especiais bioativos. O fracionamento bioguiado da fração AcOEt dos galhos de K. variabilis para isolamento de substâncias com potencial antimalárico foi realizado via teste químico com -hematina e in vitro com Plasmodium falciparum, levando a identificação das xantonas oxigenadas 3,6-diidroxi-1,4,8-trimetoxixantona, 3,5-diidroxi-4-metoxixantona, 3,4-diidroxi-6,8-dimetoxixantona, 3,4-diidroxi-2-metoxixantona, 5-hidroxi-1,3- dimetoxixantona, 2,3-dimetoxi-4-hidroxixantona, 3-hidroxi-2-metoxixantona e 2-hidroxi- 1-metoxi-xantona e o xantonolignóide kielcorina. Dentre as substâncias isoladas, o xatonolignóide kielcorina foi considerado ativo quando comparado ao padrão cloroquina. A avaliação do potencial tripanocida também foi realizada para as xantonas isoladas e dentre estas, a 3,4-diidroxi-2-metoxixantona foi a mais ativa, principalmente para a cepa resistente ao benzonidazol (cepa Bolívia). Na fração EHFB das folhas de B. glaziovii foi observado o potencial antichagásico desta espécie. Os resultados observados para os ensaios antioxidantes levaram ao isolamento dos flavonóides quercitrina, podocarpusflavona A e da mistura de quercetina-3-Oglicosídeo e quercetina-3-O-galactosídeo, evidenciando a importância dos grupos catecólicos na potencialização da ação antioxidante. O estudo bioguiado pela atividade antimicrobiana com seis cepas de Staphylococcus aureus resistentes à meticilina culminou no isolamento de um derivado prenilado do floroglucinol (HGK-1) o qual demonstrou ser responsável pela potente atividade demonstrada pela fração hexânica dos galhos de K. variabilis. As xantonas isoladas tiveram seu potencial antimicrobiano... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Several biological activities have been carried out by NuBBE's collaborators aiming the identification of active extracts from plant species, and Brosimum glaziovii and Kielmeyera variables showed to be important sources of bioactive secondary metabolites. Bio-guided fractionation of the EtOAc bioactive fraction of the branches of K. variabilis by using of the chemical test -hematin, and in vitro by using of Plasmodium falciparum, led to the isolation and identification of oxygenated xanthones 3,6-dihydroxy-1,4,8-trimethoxyxanthone, 3,5-dihydroxy-4-methoxyxanthone, 3,4- dihydroxy-6,8-dimethoxyxanthone, 3,4-dihydroxy-2-methoxyxanthone, 1,3-dimethoxy- 5-hydroxyxanthone, 2,3-dimethoxy-4-hydroxyxantona, 3-hydroxy-2-methoxyxanthone and 2-hydroxy-1-methoxyxanthone and xantonolignoid kielcorin. Among the compounds isolated, the xatonolignoid keilcorine indicated activity when compared to the standard chloroquine. The assessment of potential trypanocidal was also a part of this work and among the isolated xanthones, 3,4-dihydroxy-2-methoxyxanthone showed to be the most active, especially against the resistant strain to benzonidazole (Bolivia strain). In hexane fraction of leaves from B. glaziovii was noted antichagasic potencial for this specie. The antioxidant test used in this study led to the isolation of several flavonoids with antioxidant activity: quercitrin, podocarpusflavone A and the mixture of quercetin-3-O-glucoside and quercetin-3-O-galactoside, showing the importance of catechol group for the potentiating of antioxidant activity. The bio-guided antimicrobial activity using six strains of methicillin-resistant Staphylococcus aureus resulted in the isolation of the prenylated phloroglucinol derivative (HGK-1), which proved to be responsible for the potent activity exhibited by the hexane extract of the branches of K. variabilis. The xanthones isolated were evaluated... (Complete abstract click electronic access below)
Doutor
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Vasconcelos, Paulo César de Paula [UNESP]. « Efeito da (-)-epicatequina presente nas folhas Mouriri pusa Gardin. (Melastomataceae) na prevenção e tratamento de colite ulcerativa em ratos ». Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/91671.
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vasconcelos_pcp_me_botib.pdf: 587894 bytes, checksum: ffe7b4603c76199083b6c290a52cfc05 (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A etiologia da colite ulcerativa ainda permanece desconhecida, porém atinge uma grande parcela da população mundial. A maioria das terapias disponiveis tem eficácia limitada e geram significativos clínicos efeitos adversos. A especie medicinal Mouriri pusa Gardn. (Melastomataceae) foi citada diversas vezes pela população local do Tocantins como útil no tratamento de distúrbios do trato digestório. Os estudos preliminares com essa planta tem apresentado efeitos gastroprotetores e cicatrizantes intensos. Estudos fitoquimicos de seu extrato metanólico revelaram presença de (-)- epicatequina, além de outros flavonóides, e taninos. Nesse projeto, induziu-se colite ulcerativa em ratos per injeção local de acido trinitrobenzenosulfonico (TNBS). Foram analisados parametros morfológicos, inflamatórios, imunohistoquimicos e Western Blot. 0 efeito da (-)-epicatequina foi avaliado em modele agudo nas doses de 5,10,25 e 50 mg/kg (p.o). Os animais receberam os tratamentos uma vez por dia durante 3 dias antes da indução de colite, 2 h e 24 h após a mesma. Observou-se macroscopicamente que as doses de 10 e 50 mg/kg (EC10 e ECSO)de epicatequina foram efetivas em reduzir 0 grau de seriedade da lesão, sendo confirmado pela análise microscópica para EC10. Nas quantificações do tecido intestinal, observou-se que a concentração de glutationa em EC10 foi maior que no controle, mostrando um possivel mecanismo de ação, já que a manutenção da glutationa no tecido inflamado pode indicar potencial antioxidante da substância. Observou-se diminuição de COX-2, um parametro inflamatório, e um aumento de PCNA, antigeno de proliferação celular, em EC10, dicando ação antiinflamatória e estimuladora de proliferação celular. EC10 e EC50 foram usadas então para o modelo crônico de colite, no qual os diferentes grupos de animais receberam, após indução de colite no primeiro dia...
Ulcerative colitis etiology is still not completely known, however, it is present among great portion of world's population. The majority of available therapies has limited efficacy and provides significant adverse effects. The medicinal species Mouriri pusa Gardn. (Melastomataceae) has been often mentioned by local population from Tocantins as useful in the treatment of gastrointestinal disorders. Previous studies with this plant have presented intense gastroprotective and cicatrizing effects. Phyochemical studies of its methanolic extract revealed presence of (-)-epicatechin, besides other flavonoids, and tannins, In this work, ulcerative colitis was induced in rats by local injection of TNBS (Trinitrobenzenesulphonic acid). We analyzed morphological, inflammatory, immunohistochemical and Western Blot parameters. (-)- Epicatechin effect was evaluated in acute model in 5, 10, 25 e 5Omg/kg doses (p.o). The animals received treatments once a day for 3 days before colitis induction, and 2 h and 24 h after it. The doses of 10 and 5Omg/kg (EC10 and EC5O) were macroscopically observed to be effective in reducing lesion seriousness, what was confirmed by microscopical analysis for EC10. By quantifications in the colon tissue, it was observed that glutathion concentration in EC10 was greater than in control, showing a possible echanism of action, since glutathione maintenance in the inflamed tissue may . dicate antioxidant potential from the compound. It was observed COX-2 reduction, an inflammatory parameter, and an increase in PCNA, proliferating cell antigen, in EClO, indicating anti-inflammatory and proliferation stimulating action. EC10 and EC were then used for chronic colitis model, in which the groups, after colitis induction in the first Day, treatments for 21 days. At the end of each week, some of the rats from each group were killed for accompaniment, and after the second week ... (Complete abstract click electronic access below)
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Arantes, Glenda Marqueti. « Bioprospecção em espécies do gênero Sclerolobium sp : busca de agentes quimiopreventivos / ». Araraquara [s.n.], 2011. http://hdl.handle.net/11449/105818.
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Orientador: Dulce Helena Siqueira SilvaBanca: Ana Marisa Fusco Almeida
Banca: Wilson Roberto da Cunha
Banca: Niege Araçari Jacometti Cardoso Furtado
Banca: Ana Luisa Lacava Lordello
Resumo: A família Fabaceae é subdividida em 3 subfamílias: Faboideae, Caesalpinoideae e Mimosoideae, que englobam mais de 700 gêneros e 18000 espécies, bem distribuídas nas regiões tropicais e subtropicais. Inclui espécies de alta relevância econômica, como a soja, feijão, cerejeira, angelim e sucupira, além do pau-brasil, de importância histórica para o Brasil. Neste trabalho, os extratos etanólicos das folhas de Sclerolobium aureum, S. denudatum e S. paniculatum mostraram forte potencial antioxidante, sendo selecionados para investigação fitoquímica detalhada. O fracionamento cromatográfico destes extratos evidenciou sua composição química, destacando-se a presença de esqualeno, tocoferóis e lupenona, identificados por CG-EM, predominantes nas frações de baixa polaridade. O extrato hidroalcoólico de S. aureum foi submetido a etapas de purificação, incluindo o uso de CLAE-UV-DAD, evidenciando a presença majoritária de ácido gálico, flavonoides monoglicosilados e catequina, identificados por RMN, EM e UV. Os extratos hidroalcoólicos de S. denudatum e S. paniculatum foram submetidos a partição líquido-líquido e as frações resultantes foram analisadas por CLAE-UV-DAD e CLAE-EM-EM para identificação dos seus constituintes por desreplicação, ou seja, evitando-se procedimentos de purificação de substâncias conhecidas. Esta estratégia permitiu conhecer os metabólitos secundários das três espécies, que apresentaram perfis químicos semelhantes com a predominância de flavonoides monoglicosilados. As frações semipurificadas e substâncias isoladas mostraram elevado potencial de sequestro de radicais livres frente ao DPPH, destacando-se a presença de antioxidantes lipofílicos e hidrofílicos, atrativa para aplicações em cosméticos. Adicionalmente, foi observado potencial imunomodulador... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Fabaceae family comprises 3 subfamilies: Faboideae, Caesalpinoideae and Mimosoideae, with more than 700 genera and 18000 species, widespread in tropical and subtropical regions. It includes economically important species as soybean, beans, angelim, sucupira, in addition to pau-brasil (Caesalpinea echinata), which has historical importance in Brazil for its wood pigments. In this work, ethanol extracts of Sclerolobium aureum, S. denudatum and S. paniculatum leaves were investigated and showed strong antioxidant potential, and were selected for further investigation. Their chromatographic fractionation evidenced the presence of squalene, tocopherols and lupenone as major compounds in low polarity fractions, by GC-MS analysis. The hydroalcoholic extract of S. aureum was submitted to purification procedures, including the use of HPLC-UV-DAD, which evidenced gallic acid, flavonoid monoglucosides and catechin as major compounds, identified mainly by NMR, MS and UV techniques. HPLC-UV-DAD and LC-MS-MS analysis were further carried out on the hydroalcoholic extract of S. denudatum and S. paniculatum, leading to the identification of their major constituents by dereplication, avoiding the purification of known compounds. Such strategy evidenced a similar chemical profile for the three Sclerolobium species, with flavonoid monoglucosides as major compounds. Strong free radical scavenging potential was observed for the fractions and isolated compounds towards DPPH, evidencing the presence of lipophilic and hydrophilic antioxidants, which might be important for cosmetics development. In addition, the immunomodulatory potential of the hexane and ethyl acetate fractions from S. denudatum were evidenced through the dose-dependent inhibition of nitrite release by pre-treated macrophages, which might... (Complete abstract click electronic access below)
Doutor
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Pacífico, Mariana [UNESP]. « Estudo químico e atividades mutagênica e antiulcerogênica de Syngonanthus nitens (Bong.) Ruhland ». Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/97968.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Neste trabalho, foi investigada a composição química de Syngonanthus nitens (Bong.) Ruhland, espécie pertencente à família Eriocaulaceae, conhecida popularmente como “capim dourado” e amplamente utilizada para o artesanato, sendo de grande importância econômica principalmente para populações do Tocantins e Minas Gerais. Espécies dessa família são conhecidas popularmente como “sempre-vivas” e a maioria delas ocorre em Campos Rupestres do Brasil. Foram preparados extratos de capítulos e de escapos, separadamente, por maceração utilizando hexano e diclorometano e por percolação com metanol. Os extratos metanólicos foram fracionados por colunas de permeação em gel, cromatografia líquida de média pressão (MPLC), cromatografia líquida de alta eficiência, com detector de arranjo de diodo (HPLC-DAD) e com detector de índice de refração (HPLC-RI) e cromatografia em contracorrente (HSCCC). As estruturas foram caracterizadas por espectroscopia na região do ultravioleta, técnicas mono e bidimensionais de RMN e por espectrometria de massas com fonte electrospray e analisador íon trap (modo de inserção direta). Foram isoladas as substâncias: 1,3,6-triidroxi-2-metoxixantona; 1,3,6-triidroxi-2,5-dimetoxixantona; 1,5,7-triidroxi-3,6-dimetoxixantona; 1,3,6,8-tetraidroxi-2,5-dimetoxixantona; 1,3,6,8-tetraidroxi-5-metoxixantona; 7-metoxiluteolina-6-C-β-D-glicopiranosideo, 7-metoxiluteolina-8-C-β-D-glicopiranosideo, 3`,7-dimetoxiluteolina-6-C-β-D-glicopiranosideo, 6-hidroxiluteolina e luteolina. Os extratos metanólicos de capítulos e escapos de S. nitens foram avaliados quanto à atividade antiulcerogênica e mutagênica. Através do modelo de lesão ulcerativa induzida por etanol absoluto, verificou-se que os dois extratos apresentaram atividade gastroprotetora. Na dose de 500 mg kg-1 do extrato de...
In this work, the chemical composition of Syngonanthus nitens (Bong.) Ruhland was investigated. This plant belongs to Eriocaulaceae family, popularly known as “capim dourado” and widely used to make baskets and other handcraft products. It´s a very important economical specie to local communities in Tocantins ans Minas Gerais states, mainly. Plants of this family are known as “everlasting flower” and they can be found in “Campos Rupestres” vegetation in Brazil. Scapes and capitulae were extracted, sequentially, with hexane, dichloromethane and methanol. Methanol extract were fractionated by several chromatographic techniques, including gel permeation chromatography, Medium Pressure Liquid Chromatography (MPLC), High Pressure Liquid Chromatography (HPLC-DAD and HPLC-RI), High Speed Countercurrent Chromatography (HSCCC). Structures were determined by ultraviolet spectroscopy, as well as mono and bidimensional NMR techniques, besides electrospray – ion trap – mass spectrometry. The chemical study of S. nitens led to the identification of five xanthones: 1,3,6-trihydroxy-2-methoxyxanthone; 1,3,6- trihydroxy-2,5-dimethoxyxanthone; 1,5,7- trihydroxy -3,6-dimethoxyxanthone; 1,3,6,8-tetrahydroxy-2,5- dimethoxyxanthone e 1,3,6,8-tetrahyidroxyi-5-methoxyxanthone, and five flavones: 7-methoxyluteolin-6-C-β-D-glucopyranoside; 7-methoxyluteolin-8-C-β-D-glucopyranoside; 4`,7-dimethoxyluteolin-6-C-β-D-glucopyranoside; 6-hydroxyluteolin and luteolin. Pharmacological assays demonstrated that the methanol extract of capitulae and scape from S. nitens has presented gastroprotective activity in the ethanol induced ulcer model. According the results of Ames test, the mutagenicity was considered negative for all tested concentrations of the three methanol extracts, at all tested strains. The chemical data obtained in this work also added more data to the discussion of the taxonomy of Eriocaulaceae
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Pacífico, Mariana. « Estudo químico e atividades mutagênica e antiulcerogênica de Syngonanthus nitens (Bong.) Ruhland / ». Araraquara : [s.n.], 2010. http://hdl.handle.net/11449/97968.
Texte intégralRésumé :
Orientador: Lourdes Campaner dos SantosBanca: Lucienir Pains Duarte
Banca: Sidney Augusto Vieira Filho
Resumo: Neste trabalho, foi investigada a composição química de Syngonanthus nitens (Bong.) Ruhland, espécie pertencente à família Eriocaulaceae, conhecida popularmente como "capim dourado" e amplamente utilizada para o artesanato, sendo de grande importância econômica principalmente para populações do Tocantins e Minas Gerais. Espécies dessa família são conhecidas popularmente como "sempre-vivas" e a maioria delas ocorre em Campos Rupestres do Brasil. Foram preparados extratos de capítulos e de escapos, separadamente, por maceração utilizando hexano e diclorometano e por percolação com metanol. Os extratos metanólicos foram fracionados por colunas de permeação em gel, cromatografia líquida de média pressão (MPLC), cromatografia líquida de alta eficiência, com detector de arranjo de diodo (HPLC-DAD) e com detector de índice de refração (HPLC-RI) e cromatografia em contracorrente (HSCCC). As estruturas foram caracterizadas por espectroscopia na região do ultravioleta, técnicas mono e bidimensionais de RMN e por espectrometria de massas com fonte electrospray e analisador íon trap (modo de inserção direta). Foram isoladas as substâncias: 1,3,6-triidroxi-2-metoxixantona; 1,3,6-triidroxi-2,5-dimetoxixantona; 1,5,7-triidroxi-3,6-dimetoxixantona; 1,3,6,8-tetraidroxi-2,5-dimetoxixantona; 1,3,6,8-tetraidroxi-5-metoxixantona; 7-metoxiluteolina-6-C-β-D-glicopiranosideo, 7-metoxiluteolina-8-C-β-D-glicopiranosideo, 3',7-dimetoxiluteolina-6-C-β-D-glicopiranosideo, 6-hidroxiluteolina e luteolina. Os extratos metanólicos de capítulos e escapos de S. nitens foram avaliados quanto à atividade antiulcerogênica e mutagênica. Através do modelo de lesão ulcerativa induzida por etanol absoluto, verificou-se que os dois extratos apresentaram atividade gastroprotetora. Na dose de 500 mg kg-1 do extrato de... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In this work, the chemical composition of Syngonanthus nitens (Bong.) Ruhland was investigated. This plant belongs to Eriocaulaceae family, popularly known as "capim dourado" and widely used to make baskets and other handcraft products. It's a very important economical specie to local communities in Tocantins ans Minas Gerais states, mainly. Plants of this family are known as "everlasting flower" and they can be found in "Campos Rupestres" vegetation in Brazil. Scapes and capitulae were extracted, sequentially, with hexane, dichloromethane and methanol. Methanol extract were fractionated by several chromatographic techniques, including gel permeation chromatography, Medium Pressure Liquid Chromatography (MPLC), High Pressure Liquid Chromatography (HPLC-DAD and HPLC-RI), High Speed Countercurrent Chromatography (HSCCC). Structures were determined by ultraviolet spectroscopy, as well as mono and bidimensional NMR techniques, besides electrospray - ion trap - mass spectrometry. The chemical study of S. nitens led to the identification of five xanthones: 1,3,6-trihydroxy-2-methoxyxanthone; 1,3,6- trihydroxy-2,5-dimethoxyxanthone; 1,5,7- trihydroxy -3,6-dimethoxyxanthone; 1,3,6,8-tetrahydroxy-2,5- dimethoxyxanthone e 1,3,6,8-tetrahyidroxyi-5-methoxyxanthone, and five flavones: 7-methoxyluteolin-6-C-β-D-glucopyranoside; 7-methoxyluteolin-8-C-β-D-glucopyranoside; 4',7-dimethoxyluteolin-6-C-β-D-glucopyranoside; 6-hydroxyluteolin and luteolin. Pharmacological assays demonstrated that the methanol extract of capitulae and scape from S. nitens has presented gastroprotective activity in the ethanol induced ulcer model. According the results of Ames test, the mutagenicity was considered negative for all tested concentrations of the three methanol extracts, at all tested strains. The chemical data obtained in this work also added more data to the discussion of the taxonomy of Eriocaulaceae
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Livres sur le sujet "Flavonoidi naturali"
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Golubkina, Nadezhda, Elena Kekina, Anna Molchanova et Sergey Nadezhkin. Antioxidants of plants and methods of their definition. ru : INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1045420.
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The monograph presents the most simple and widely used methods for determining the most important of plant antioxidants: vitamin C, polyphenols, carotenoids, capsaicin, and belinovich photosynthetic pigments, flavonoids, anthocyanins, alkaloids, tannins, and minerals antioxidant: selenium and iodine. Special attention is paid to methods of extraction of antioxidants, providing maximum extraction of antioxidants from plant material, and the correct selection of the most appropriate method of analysis of one or another component. Provides detailed information developed by the authors method of using thin layer chromatography to assess the carotenoid composition of tomatoes and peppers.
The data presented here include results of research conducted on the basis of FICO, as well as the latest developments of foreign scientists devoted to natural antioxidants and methods of their determination. Presented in this monograph methodology was successfully tested in the laboratory and analytical Department of PNCO in 2012-2018.
For students and teachers and all interested in horticulture and agriculture.
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The handbook of natural flavonoids. Chichester : Wiley, 1999.
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Spectroscopic Properties of Natural Flavonoids. World Scientific Publishing Co Pte Ltd, 2018.
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HARBORNE. Hdbk to the Natural Flavanoids V 2. John Wiley and Sons Ltd, 1996.
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Kaempferol : Chemistry, Natural Occurrences and Health Benefits. Nova Science Pub Inc, 2013.
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Brunton, Nigel, Giovana B. Celli, Giovana B. Celli, Vasantha Rupasinghe et Monica Giusti. Anthocyanins from Natural Sources : Exploiting Targeted Delivery for Improved Health. Royal Society of Chemistry, The, 2019.
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Natural Products and Cancer Signaling : Isoprenoids, Polyphenols and Flavonoids. Elsevier, 2014. http://dx.doi.org/10.1016/c2013-0-12728-6.
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Tamanoi, Fuyuhiko, et S. Zahra Bathaie. Natural Products and Cancer Signaling : Isoprenoids, Polyphenols and Flavonoids. Elsevier Science & Technology Books, 2014.
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Dwight, Alexis J. Luteolin : Natural Occurrences, Therapeutic Applications and Health Effects. Nova Science Publishers, Incorporated, 2015.
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Tamanoi, Fuyuhiko, et S. Zahra Bathaie. Natural Products and Cancer Signaling Vol. 36 : Isoprenoids, Polyphenols and Flavonoids. Elsevier Science & Technology Books, 2014.
Trouver le texte intégralChapitres de livres sur le sujet "Flavonoidi naturali"
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Ribeiro, Tânia Bragança, Adma Melo, Ana A. Vilas-Boas et Manuela Pintado. « Flavonoids ». Dans Natural Secondary Metabolites, 73–105. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-18587-8_4.
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Harborne, J. B. « Flavonoids ». Dans Natural Products of Woody Plants, 533–70. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74075-6_16.
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Pandey, Ramesh Prasad, et Jae Kyung Sohng. « Genetics of Flavonoids ». Dans Natural Products, 1617–45. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-22144-6_52.
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Bligh, S. W. Annie, Olumuyiwa Ogegbo et Zheng-Tao Wang. « Flavonoids by HPLC ». Dans Natural Products, 2107–44. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-22144-6_97.
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Vauzour, David, Marcus Rattray, Robert J. Williams et Jeremy P. E. Spencer. « Potential Neuroprotective Actions of Dietary Flavonoids ». Dans Natural Products, 2617–40. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-22144-6_71.
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Heim, Kelly C. « Natural Polyphenol and Flavonoid Polymers ». Dans Antioxidant Polymers, 23–53. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118445440.ch2.
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Ninomiya, Masayuki, et Mamoru Koketsu. « Minor Flavonoids (Chalcones, Flavanones, Dihydrochalcones, and Aurones) ». Dans Natural Products, 1867–900. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-22144-6_62.
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Hosseinzadeh, Hossein, et Marjan Nassiri-Asl. « Neuroprotective Effects of Flavonoids in Epilepsy ». Dans Neuroprotective Natural Products, 279–91. Weinheim, Germany : Wiley-VCH Verlag GmbH & Co. KGaA, 2017. http://dx.doi.org/10.1002/9783527803781.ch10.
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Varshney, Ritu, Neeladrisingha Das, Rutusmita Mishra et Partha Roy. « Structure-Function Elucidation of Flavonoids by Modern Technologies ». Dans Natural Medicines, 25–63. Boca Raton : Taylor & Francis, [2019] : CRC Press, 2019. http://dx.doi.org/10.1201/9781315187853-3.
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Hinton, Tina, et Graham A. R. Johnston. « Benzodiazepines, Flavonoids, and GABA ». Dans Naturally Occurring Benzodiazepines, Endozepines, and their Receptors, 117–26. Boca Raton : CRC Press, 2021. http://dx.doi.org/10.1201/9780367814373-11.
Texte intégralActes de conférences sur le sujet "Flavonoidi naturali"
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Hohmann, J., A. Hunyadi, MG Musat, A. Matei et M. Ciubotaru. « HIV-integrase inhibitory activity of natural flavonoids ». Dans GA 2017 – Book of Abstracts. Georg Thieme Verlag KG, 2017. http://dx.doi.org/10.1055/s-0037-1608116.
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Aksoy, Mine, İlhami Gülçin et Ö. İrfan Küfrevioğlu. « In vitro antioxidant profiles of some flavonoids ». Dans INTERNATIONAL CONFERENCE ON ADVANCES IN NATURAL AND APPLIED SCIENCES : ICANAS 2016. Author(s), 2016. http://dx.doi.org/10.1063/1.4945929.
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Kostikova, V. A., et T. N. Veklich. « Content of flavonoids and phenolcarboxylic acids in leaves and inflorescences of Spiraea salicifolia L. (Rosaceae) ». Dans Problems of studying the vegetation cover of Siberia. TSU Press, 2020. http://dx.doi.org/10.17223/978-5-94621-927-3-2020-20.
Texte intégralRésumé :
Comparative analysis of the content of the main groups of phenolic compounds (flavonoids and phenolic acids) was performed for the overground part of Spiraea salicifolia L. from natural habitats in Siberia and the Russian Far East. Populations of plants with the highest content of phenolic compounds were determined to reveal the potential of their use. It was found that the content of phenolcarboxylic acids in leaves (3,59–7,69 %) is higher than that in inflorescences (2,24–5,52 %), regardless of habitat. The distribution of flavonoids between leaves and inflorescences of S. salicifolia is ambiguous. The content of flavonoids ranges from 1,27 % to 5,48 % in leaves, and from 2,34 % to 6,26 % in inflorescences. The highest content of flavonoids and phenolcarboxylic acids was found in plants from Amur region, the Republic of Yakutia, the Republic of Buryatia and the Primorsky Territory. The content of the investigated substances is not high in samples of S. salicifolia from Irkutsk region, Sakhalin region, Khabarovsk region and Magadan region.
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Santos, Fernanda Barbosa Gomes dos. « Effects of euterpe oleracea Martius (açaí) consumption on the nervous system : a literature review ». Dans XIII Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1516-3180.279.
Texte intégralRésumé :
Background: Euterpe oleracea Martius is an abundant palm in the Amazon region. Its fruit is consumed after pulper processing, to obtain the açaí drink, whose flavonoid-rich composition draws attention to its antioxidant properties and can be used slowing the progression of dementia and others neurological disorders. Objectives: to list what is known at the time of this review regarding the effects of the consumption of the pulp, juice or extract of the fruits of Euterpe oleracea Mart. on the nervous system. DESIGN AND SETTING: literature scan carried out in the PubMed database. Methods: made using the descriptors provided by the DeCS platform: (effects) AND (euterpe oleracea) OR (açaí) AND (nervous system). A total of 33 results were obtained. Using inclusion and exclusion criteria, 24 articles were selected. Results: a positive action of this plant was observed in the modulation of free radicals and prevention of premature aging, which reveals the ability of açaí to delay the natural deterioration of cognitive function that occurs with advancing age. In addition, flavonoids act in the perivascular sheath, aiding in the growth of neuronal cells, containment of neurotoxin-induced neuronal lesions and protecting from others neurotoxical compounds. Conclusions: there is still a need for further studies on this topic to ratify the açaí potential, in order to opening the way for new strategies to protect the nervous system’s functions. As a literature scan, this study does not have a PROSPERO registration.
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Kravchenko, I. V., G. M. Kukurichkin et N. V. Nakonechniy. « QUANTITATIVE CONTENT OF PHOTOSYNTHETIC PIGMENTS IN SOME PLANTS OF NATURAL PARK «SIBERIAN UVALY» ». Dans Prirodopol'zovanie i ohrana prirody : Ohrana pamjatnikov prirody, biologicheskogo i landshaftnogo raznoobrazija Tomskogo Priob'ja i drugih regionov Rossii. Izdatel'stvo Tomskogo gosudarstvennogo universiteta, 2020. http://dx.doi.org/10.17223/978-5-94621-954-9-2020-44.
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Regularities of photosynthetic pigments accumulation (chlorophylls, carotenoids, and flavonoid compounds) in plants growing on the territory of the «Deep Sabun» base of the «Siberian Uvaly» Natural Park have been analyzed to evaluate the ecological and biochemical status of the most significant plant species.
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Syafni, N., AM Klemd, JK Reinhardt, O. Danton, C. Gründemann et M. Hamburger. « Immunosuppressant flavonoids from Scutellaria baicalensis ». Dans 67th International Congress and Annual Meeting of the Society for Medicinal Plant and Natural Product Research (GA) in cooperation with the French Society of Pharmacognosy AFERP. © Georg Thieme Verlag KG, 2019. http://dx.doi.org/10.1055/s-0039-3399888.
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Santos, Fernanda Barbosa Gomes dos. « Effects of Euterpe oleracea Martius (açaí) consumption on the nervous system : a literature review ». Dans XIII Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1516-3180.265.
Texte intégralRésumé :
Background: Euterpe oleracea Martius, popularly known as açaí, is an abundant palm in the Amazon region. Its fruit is consumed after pulper processing, to obtain the açaí drink, whose flavonoid-rich composition draws attention to its antioxidant properties and can be used in neurodegeneration processes, slowing the progression of dementia and neurological disorders. Objectives: to list what is known at the time of this review regarding the effects of the consumption of the pulp, juice or extract of the fruits of Euterpe oleracea Mart. on the nervous system. Methods: systematic review of the literature carried out in the PubMed database using the descriptors provided by the DeCS platform: (effects) AND (euterpe oleracea) OR (açaí) AND (nervous system). A total of 33 results were obtained. Using inclusion and exclusion criteria, 24 articles were selected. Results: a positive action of this plant was observed in the modulation of free radicals and prevention of premature aging, which reveals the ability of açaí to delay the natural deterioration of cognitive function that occurs with advancing age. In addition, flavonoids act in the perivascular sheath, aiding in the growth of neuronal cells, among other things, such as the containment of neurotoxin- induced neuronal lesions and protecting from others neurotoxical compounds. Finally, the Euterpe oleracea was able to attenuate depressive symptoms and epileptic seizures. Conclusions: there is a need for further studies on this topic, in order to ratify the findings that are known to date, opening the way for new strategies to protect the nervous system’s functions.
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Widyawaty, Loudfy Eka, I. Nyoman Ehrich Lister et Sukirman Lie. « Antioxidant Activity, Total Phenol, and Total Flavonoid of Syzygium Polyanthum ». Dans 2021 IEEE International Conference on Health, Instrumentation & Measurement, and Natural Sciences (InHeNce). IEEE, 2021. http://dx.doi.org/10.1109/inhence52833.2021.9537187.
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Laphookhieo, S., A. Raksat, W. Maneerat, RJ Andersen et SG Pyne. « Millexatins A-M, antibacterial flavonoids from Millettia extensa ». Dans 67th International Congress and Annual Meeting of the Society for Medicinal Plant and Natural Product Research (GA) in cooperation with the French Society of Pharmacognosy AFERP. © Georg Thieme Verlag KG, 2019. http://dx.doi.org/10.1055/s-0039-3399906.
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Prozhogina, Y. E., et M. A. Dzhavakhyan. « NATURAL DEEP EUTECTIC SOLVENTS AS ALTERNATIVE FLAVONOID EXTRACTANTS FROM THE SEDATIVE PLANT COMPOSITION ». Dans ОТ БИОХИМИИ РАСТЕНИЙ К БИОХИМИИ ЧЕЛОВЕКА. Москва : Федеральное государственное бюджетное научное учреждение "Всероссийский научно-исследовательский институт лекарственных и ароматических растений", 2022. http://dx.doi.org/10.52101/9785870191041_289.
Texte intégralRapports d'organisations sur le sujet "Flavonoidi naturali"
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Phillips, Donald, et Yoram Kapulnik. Using Flavonoids to Control in vitro Development of Vesicular Arbuscular Mycorrhizal Fungi. United States Department of Agriculture, janvier 1995. http://dx.doi.org/10.32747/1995.7613012.bard.
Texte intégralRésumé :
Vesicular-arbuscular mycorrhizal (VAM) fungi and other beneficial rhizosphere microorganisms, such as Rhizobium bacteria, must locate and infect a host plant before either symbiont profits. Although benefits of the VAM association for increased phosphorous uptake have been widely documented, attempts to improve the fungus and to produce agronomically useful amounts of inoculum have failed due to a lack of in vitro production methods. This project was designed to extend our prior observation that the alfalfa flavonoid quercetin promoted spore germination and hyphal growth of VAM fungi in the absence of a host plant. On the Israeli side of the project, a detailed examination of changes in flavonoids and flavonoid-biosynthetic enzymes during the early stages of VAM development in alfalfa found that VAM fungi elicited and then suppressed transcription of a plant gene coding for chalcone isomerase, which normally is associated with pathogenic infections. US workers collaborated in the identification of flavonoid compounds that appeared during VAM development. On the US side, an in vitro system for testing the effects of plant compounds on fungal spore germination and hyphal growth was developed for use, and intensive analyses of natural products released from alfalfa seedlings grown in the presence and absence of microorganisms were conducted. Two betaines, trigonelline and stachydrine, were identified as being released from alfalfa seeds in much higher concentrations than flavonoids, and these compounds functioned as transcriptional signals to another alfalfa microsymbiont, Rhizobium meliloti. However, these betaines had no effect on VAM spore germination or hyphal growth i vitro. Experiments showed that symbiotic bacteria elicited exudation of the isoflavonoids medicarpin and coumestrol from legume roots, but neither compound promoted growth or germination of VAM fungi in vitro. Attempts to look directly in alfalfa rhizosphere soil for microbiologically active plant products measured a gradient of nod-gene-inducing activity in R. meliloti, but no novel compounds were identified for testing in the VAM fungal system in vitro. Israeli field experiments on agricultural applications of VAM were very successful and developed methods for using VAM to overcome stunting in peanuts and garlic grown in Israel. In addition, deleterious effects of soil solarization on growth of onion, carrot and wheat were linked to effects on VAM fungi. A collaborative combination of basic and applied approaches toward enhancing the agronomic benefits of VAM asociations produced new knowledge on symbiotic biology and successful methods for using VAM inocula under field conditions
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Prusky, Dov, Noel Keen et Rolf Christoffersen. Involvement of Epicatechin in the Regulation of Natural Resistance of Avocado Fruit against Postharvest Pathogens. United States Department of Agriculture, janvier 1997. http://dx.doi.org/10.32747/1997.7613028.bard.
Texte intégralRésumé :
In this project it was found that the activation of the mechanism of resistance in avocado fruits to Colletotrichum gloeosporioides depends on the increase of the level of the preformed antifungal diene. This increase is regulated by the synthesis of the flavonoid epicatechin present in the fruit peel. Epicatechin is an inhibitor of the enzyme lipoxygenase whose activity catalyze the breakdown of the antifungal diene. Increase in epicatechin concentration inhibits the breakdown of the antifungal compound and since the compound is continuously synthesized, both combined processes result in the increase of the antifungal level. Biotic and abiotic elicitors affecting the mechanism of resistance, all activate the synthesis of epicatechin. As abiotic elicitors were tested wounding, ethylene and CO2 treatments. As biotic elicitors were tested challenge inoculation with C. gloeosporioides, Colletotrichum magna (a non pathogen of avocado) and also non pathogenic strain of C. magna. In all the cases activation of the key enzymes of the phenylpropanoic pathway is followed by an enhance in the level of epicatechin and the antifungal diene. In order to determine the level of regulation by the different elicitors of the mechanism, the genes encoding for key enzymes of the phenylpropanoic pathway were cloned and it was found that the different elicitors regulate the expression of those genes at a translational level. Modulation of the mechanism of resistance could also be done by activation of lipoxygenase gene expression. For this purpose lipoxygenase from avocado was cloned and its over-expression, under the effect of methyl jasmonate, determined.
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Phillips, Donald A., Yitzhak Spiegel et Howard Ferris. Optimizing nematode management by defining natural chemical bases of behavior. United States Department of Agriculture, novembre 2006. http://dx.doi.org/10.32747/2006.7587234.bard.
Texte intégralRésumé :
This project was based on the hypothesis that nematodes interacting with plants as either parasites or beneficial saprophytes are attracted to their host by natural products. This concept was supported by numerous observations that parasitic nematodes are attracted to root exudates. Our overall goal was to identify nematode sensory compounds from root exudates and to use that information for reducing nematicide applications. We applied skills of the investigators to achieve three specific objectives: 1) Identify nematode behavioral cues (e.g., attractants or repellents) in root exudates; 2) Identify new natural nematicidal compounds; and 3) Combine a natural attractant and a nematicide into a nematode trap. Because saprophytic nematodes benefit plants by mineralizing organic matter, we sought compounds attractive primarily to parasitic nematodes. The project was constructed on several complementary foundations. First, data from Dr. Spiegel’s lab showed that under aseptic conditions Ditylenchus dipsaci, a parasite on onion, is attracted to certain fractions of onion root exudates. Second, PI Phillips had a sizeable collection of natural plant products he had identified from previous work on Rhizobium-legume interactions, which could be tested “off the shelf”. Third, Dr. Ferris had access to aseptic and natural populations of various saprophytic and parasitic nematodes. The project focused on five nematode species: D.dipsaci, Heterodera avenae, and Tylenchulussemipenetransat ARO, and Meloidogyne javanicand Caenorhabditis elegans at UCD. Ten pure plant compounds, mostly flavonoids, were tested on the various nematode species using six different assay systems. Results obtained with assorted test systems and by various scientists in the same test systems were essentially irreproducible. Many convincing, Many convincing, i.e. statistically significant, results in one system or with one investigator could not be repeated with other assays or different people. A recent report from others found that these compounds, plus another 30, were inactive as attractants in three additional parasitic nematode species (Wuyts et al. Nematology 8:89- 101, 2006). Assays designed to test the hypothesis that several compounds together are required to attract nematodes have thus far failed to find a reproducibly active combination. In contrast to results using pure plant compounds, complex unfractionated exudates from aseptic onion root reproducibly attracted D. dipsaci in both the ARO and UCD labs. Onion root exudate collection, separation into HPLC fractions, assays using D. dipsaci and MS-MS experiments proceeded collaboratively between ARO and UCD without any definitive identification of an active compound. The final active fraction contained two major molecules and traces of several other compounds. In the end, analytical studies were limited by the amount of onion root exudate and the complexity of the purification process. These tests showed that aseptic plant roots release attractant molecules, but whether nematodes influence that release, as insects trigger release of attractants from plants, is unknown. Related experiments showed that the saprophyte C. elegans stimulates its prey, Pseudomonas bacteria, to increase production of 2, 4-diacetylphloroglucinol (DAPG) a compound that promotes amino acid exudation by plant roots. It is thus possible that saprophytic nematodes are attracted primarily to their bacterial or fungal prey and secondarily to effects of those microorganisms on root exudation. These observations offer promising avenues for understanding root-zone interactions, but no direct routes to controlling nematodes in agriculture were evident. Extracts from two plant sources, Chrysanthemum coronarium and Sequoia sempervirens, showed nematicidal activity at ARO and UCD, respectively. Attempts to purify an active compound from S. sempervirens failed, but preliminary results from C. coronarium are judged to form a potential basis for further work at ARO. These results highlight the problems of studying complex movement patterns in sentient organisms like nematodes and the issues associated with natural product isolation from complex mixtures. Those two difficulties combined with complications now associated with obtaining US visas, slowed and ultimately limited progress on this project. As a result, US investigators expended only 65% of the $207,400 originally planned for this project. The Israeli side of the project advanced more directly toward its scientific goals and lists its expenditures in the customary financial report.
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Kapulnik, Yoram, et Donald A. Phillips. Isoflavonoid Regulation of Root Bacteria. United States Department of Agriculture, janvier 1996. http://dx.doi.org/10.32747/1996.7570561.bard.
Texte intégralRésumé :
The overall objective of this project was to develop a conceptual framework for enhancing root colonization by beneficial bacteria. To accomplish this aim we tested the hypothesis that production and excretion of the plant phytoalexin medicarpin can be used for creation of a special niche along the legume roots, where beneficial microorganism, such as rhizobium, will have a selective advantage. On the Israeli side it was shown that higher medicarpin levels are exuded following the application of Rhizobium meliloti to the rhizosphere but the specific biochemical pathway governing medicarpin production was not induced significantly enough to support a constant production and excretion of this molecule to the rhizosphere. Furthermore, pathogenic bacteria and chemical elicitors were found to induce higher levels of this phytoalexin and it became important to test its natural abundance in field grown plants. On the US side, the occurrence of flavonoids and nucleosides in agricultural soils has been evaluated and biologically significant quantities of these molecules were identified. A more virulent Agrobacterium tumefaciens strain was isolated from alfalfa (Medicago sativa L.) which forms tumors on a wide range of plant species. This isolate contains genes that increase competitive colonization abilities on roots by reducing the accumulation of alfalfa isoflavonoids in the bacterial cells. Following gene tagging efforts the US lab found that mutation in the bacterial efflux pump operons of this isolate reduced its competitive abilities. This results support our original hypothesis that detoxification activity of isoflavenoids molecules, based on bacterial gene(s), is an important selection mechanism in the rhizosphere. In addition, we focused on biotin as a regulatory element in the rhizosphere to support growth of some rhizosphere microorganisms and designed a bacterial gene construct carrying the biotin-binding protein, streptavidin. Expressing this gene in tobacco roots did not affect the biotin level but its expression in alfalfa was lethal. In conclusion, the collaborative combination of basic and applied approaches toward the understanding of rhizosphere activity yielded new knowledge related to the colonization of roots by beneficial microorganisms in the presence of biological active molecules exuded from the plant roots.