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‣ Atividade antialérgica e estudos químicos das espécies Bidens gardneri Bak. e Bidens sulphurea (Cav.) Sch. Bip. (Asteraceae); Anti-allergic activity and chemistry studies from species Bidens gardneri Bak. and Bidens sulphurea (Cav.) Sch. Bip. (Asteraceae)

Silva, Denise Brentan da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/12/2009 Português
Relevância na Pesquisa
28.014539%
As análises dos voláteis por SPME/CG-EM das partes aéreas, flores e frutos de Bidens sulphurea e Bidens gardneri permitiram-nos constatar diferenças em suas composições químicas. Porém, em todas as frações analisadas os compostos majoritários foram os sequiterpenos b-cariofileno, germacreno D e biciclogermacreno. Apesar dos constituintes majoritários coincidirem nas frações analisadas das duas espécies, foi possível constatar a presença exclusiva de determinados metabólitos em cada fração. A partir das frações hexânicas, oriundas dos extratos etanólicos de B. sulphurea (partes aéreas e flores) e B. gardneri (partes aéreas), foram identificadas trinta e cinco, dezenove e vinte substâncias por CG-EM, respectivamente. Na fração hexânica das partes aéreas de B. sulphurea (BsfcEt/Hx) foram identificados, como constituintes majoritários, o óxido de cariofileno, espatulenol e _- cariofileno, enquanto que na fração hexânica de suas flores (BsflorEt/Hx) os principais constituintes identificados foram _-amirina e _-sitosterol e na fração hexânica das partes aéreas de B. gardneri (BgfcEt/Hx) foram os metabólitos _-estigmasterol e o trans-fitol. O estudo químico da espécie B. sulphurea (partes aéreas e flores) conduziu ao isolamento de um sesquiterpeno (1)...

‣ Incorporação de triciclo[6.2.1.02,7]undeca-4,9-dieno-3,6-diol como uma unidade de restrição conformacional de análogos peptídicos; Tricyclo[6.2.1.02,7] undeca-4,9- diene-3,6- diol incorporated in conformational constrained peptides analogues

Silva, Sandra Vieira da; Axt, Mariane; Costa, Valentim Emilio Uberti; Pohlmann, Adriana Raffin
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
68.021973%
O objetivo deste trabalho é a obtenção de um derivado peptídico incorporado da unidade triciclo[6.2.1.02,7]undeca-4,9-dieno-3,6-diol, obtida a partir da reação de Diels-Alder do ciclopentadieno e da pbenzoquinona, seguida de redução. A condensação em solução do tripeptídeo (Gly-L-AlaGly) com o diol produz um derivado capaz de assumir uma conformação de folheto paralelo.; The aim of this work is the synthesis of a peptide analog incorporating the unit tricyclo[6.2.1.02,7]undeca-4,9-diene-3,6-diol, which was obtained from the Diels-Alder reaction of cyclopentadiene and p-benzoquinone, followed by a reduction reaction. The tripeptide (Gly-L-AlaGly) condensed with the diol gives a derivative able to assume a parallel b-sheet conformation.

‣ Hidrogenação seletiva do adipato de dimetila a 1,6-hexanodiol em presença de catalisadores suportados de Ru e Sn

Adriana Maria da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/04/2004 Português
Relevância na Pesquisa
27.948042%
A seletividade a 1,6-hexanodiol foi avaliada a partir da hidrogenação do adipato de dimetila em presença de catalisadores RuSn suportados. Os parâmetros investigados foram: - natureza do suporte; - temperatura de calcinação; - razão Sn/Ru; - metodologia de preparação dos catalisadores e - temperatura de redução. A seletividade ao diol mostrou estar relacionada às fases oxidadas de Sn na superfície catalítica. Para os catalisadores impregnados RuSn/Al2O3, calcinados a 400 °C, a razão Sn/Ru = 2 foi a considerada ótima para a produção de diol (49 % de seletividade). Todavia, foi constatado que o aumento da temperatura de calcinação para 600 °C e o uso da metodologia sol-gel conduziram a sistemas totalmente não seletivos à produção de diol. Tal diferença é atribuída a um efeito de localização das espécies de Snn+, uma vez que os resultados de espectroscopia Mössbauer dos sistemas RuSn/Al2O3 mostraram uma quantidade muito alta em Snn+ (Sn4+ e Sn2+) em todas as amostras, enquanto que as análises de XPS evidenciaram que a concentração superficial dessas espécies óxidas é bastante distinta. O aumento da temperatura de calcinação promove a migração das fases Snn+ para a estrutura da alumina e, no caso do catalisador sol-gel...

‣ Volatile composition of Vitis vinifera L. Fernão-Pires variety from Bairrada appellation : 1.

Ferreira, Paula Raquel da Silva Jorge Coutinho
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
27.94831%
A Bairrada é uma das regiões vitivinícolas mais antigas de Portugal, apesar de a Região Demarcada da Bairrada só ter sido oficialmente criada em 1979. A casta Fernão-Pires (FP) Vitis vinifera L. é a principal casta branca cultivada nesta região, onde é conhecida pelo nome de Maria-Gomes. As castas Bical (Bic), Arinto (Ari) e Cerceal (Cer), são outras castas brancas relevantes igualmente cultivadas na Região Demarcada da Bairrada. Estas quatro castas representam, respectivamente, 70%, 10%, 10% e 5% do total do encepamento de castas brancas nesta região. O conhecimento da composição volátil destas quatro variedades pode oferecer um meio de avaliar o seu potencial de aroma e melhorar a qualidade do aroma dos seus vinhos. No entanto, a composição volátil destas variedades ainda não se encontra caracterizada. Neste trabalho, o estudo foi centrado na casta FP, devido à sua importância no contexto da Região Demarcada da Bairrada, mostrando que esta casta apresenta um perfil significativamente diferente das outras castas brancas mais representativas (Bic, Ari e Cer), contendo um maior número de compostos voláteis e em maior concentração. As potencialidades de aroma da casta FP foram avaliadas pela análise da composição volátil das uvas...

‣ Transformações químicas do (+)-10b,14-diol-allo-aromadendrano, isolado de duguetia glabriuscula r. e. fries (r. e. fries) (annonaceae) e avaliações biológicas de alguns derivados obtidos

Lima,Dênis Pires de; Beatriz,Adilson; Ramos,Alexandre Ayoroa; Siqueira,João Máximo de; Oliveira,Celso Corrêa de; Marques,Maria Rita
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/1997 Português
Relevância na Pesquisa
37.282437%
The sesquiterpene (+)-allo-aromadendrane-10b-14-diol 1 was the lead compound to the preparation of several derivatives in order to test their biological activity against A. salina, C. sphaerospermum, E. coli and S. aureus. In this way the monoalcohols (+)-viridiflorol 4, 9 and 11 were synthesized from 1 together with the acetal 6, the ketal 7, and the ketone 8. The oxirane 3 and nitrile 5 were also prepared using as an intermediate the tosylate derivative 2.

‣ Accumulation of 3-Ketosteroids Induced by Itraconazole in Azole-Resistant Clinical Candida albicans Isolates

Marichal, Patrick; Gorrens, Jos; Laurijssens, Leen; Vermuyten, Karen; Van Hove, Carl; Le Jeune, Ludo; Verhasselt, Peter; Sanglard, Dominique; Borgers, Marcel; Ramaekers, Frans C. S.; Odds, Frank; Vanden Bossche, Hugo
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /11/1999 Português
Relevância na Pesquisa
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The effects of itraconazole on ergosterol biosynthesis were investigated in a series of 16 matched clinical Candida albicans isolates which had been previously analyzed for mechanisms of resistance to azoles (D. Sanglard, K. Kuchler, F. Ischer, J. L. Pagani, M. Monod, and J. Bille, Antimicrob. Agents Chemother., 39:2378–2386, 1995). Under control conditions, all isolates contained ergosterol as the predominant sterol, except two strains (C48 and C56). In isolates C48 and C56, both less susceptible to azoles than their parent, C43, substantial concentrations (20 to 30%) of 14α-methyl-ergosta-8,24(28)-diene-3β,6α-diol (3,6-diol) were found. Itraconazole treatment of C43 resulted in a dose-dependent inhibition of ergosterol biosynthesis (50% inhibitory concentration, 2 nM) and accumulation of 3,6-diol (up to 60% of the total sterols) together with eburicol, lanosterol, obtusifoliol, 14α-methyl-ergosta-5,7,22,24(28)-tetraene-3βol, and 14α-methyl-fecosterol. In strains C48 and C56, no further increase of 3,6-diol was observed after exposure to itraconazole. Ergosterol synthesis was less sensitive to itraconazole inhibition, as was expected for these azole-resistant isolates which overexpress ATP-binding cassette transporter genes CDR1 and CDR2. In addition to 3...

‣ Role of diaxial versus diequatorial hydroxyl groups in the tumorigenic activity of a benzo[a]pyrene bay-region diol epoxide.

Chang, R L; Wood, A W; Conney, A H; Yagi, H; Sayer, J M; Thakker, D R; Jerina, D M; Levin, W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1987 Português
Relevância na Pesquisa
28.022214%
Tumorigenic activities of the (7R,8S,9S,10R)-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro derivatives of benzo[a]pyrene [(+)-B[a]P diol epoxide-2] and 6-fluorobenzo[a]pyrene (6-FB[a]P diol epoxide-2) were evaluated in newborn CD-1 mice. A total dose of 14 nmol of either diol epoxide was administered to preweanling mice, and tumorigenic activity was determined when the mice were 32 to 36 weeks old. At the termination of the study, 13% of solvent-treated control mice had developed lung tumors with an average of 0.19 tumor per mouse. No other tumors were observed in control animals. (+)-B[a]P diol epoxide-2 induced pulmonary tumors in 60% of the mice with an average of 1.9 tumors per mouse, and 14% of the male mice developed hepatic tumors with an average of 0.18 tumor per mouse. In contrast, 6-FB[a]P diol epoxide-2 had no significant tumorigenic activity at the 14-nmol dose. Although both bay-region diol epoxides have the same absolute configuration, (7R,8S,9S,10R), the hydroxyl groups of (+)-B[a]P diol epoxide-2 prefer the pseudoequatorial conformation whereas the hydroxyl groups of 6-FB[a]P diol epoxide-2 prefer the pseudoaxial conformation. The tumorigenicity results reported here are the first direct demonstration that conformation of the hydroxyl groups in a bay-region diol epoxide...

‣ The structure of the inhibitory complex of alloxanthine (1H-pyrazolo[3,4-d]pyrimidine-4,6-diol) with the molybdenum centre of xanthine oxidase from electron-paramagnetic-resonance spectroscopy.

Hawkes, T R; George, G N; Bray, R C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/03/1984 Português
Relevância na Pesquisa
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Studies were carried out on the inhibitory complex of alloxanthine (1H-pyrazolo[3,4-d]pyrimidine-4,5-diol) with xanthine oxidase, in extension of the work of Williams & Bray [Biochem. J. (1981) 195, 753-760]. By suitable regulation of the reaction conditions, up to 10% of the functional enzyme could be converted into the complex in the Mo(V) oxidation state. The e.p.r. spectrum of the complex was investigated in detail with the help of computer simulation and substitution with stable isotopes. Close structural analogy of the signal-giving species to that of the Very Rapid intermediate in enzyme turnover is shown by g-values (2.0279, 1.9593 and 1.9442) and by coupling to 33S in the cyanide-labile site of the enzyme [A(33S) 0.30, 3.10 and 0.70mT]. However, whereas in the Very Rapid signal there is strong coupling to 17O [Gutteridge & Bray, Biochem. J. (1980) 189, 615-623], instead, in the Alloxanthine signal there is strong coupling to a single nitrogen atom [A(14N) 0.35, 0.35, 0.32 mT]. This is presumed to originate from the 2-position of the heterocyclic ring system. From this work and from earlier kinetic studies it is concluded that alloxanthine, after being bound reversibly at the active centre, reacts slowly with it, in a specific manner...

‣ The intermediary role of 5-pregnene-3β,20β-diol in the biosynthesis of 16-unsaturated C19 steroids in boar testis

Loke, K. H.; Gower, D. B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1972 Português
Relevância na Pesquisa
27.872913%
1. The possible involvement of 5-pregnene-3β,20β-diol in 16-unsaturated C19 steroid biosynthesis has been investigated. 2. 5,16-Androstadien-3β-ol (andien-β) formation from [4-14C]pregnenolone (3β-hydroxy-5-pregnen-20-one), 5-pregnene-3β,20α-diol and 5-pregnene-3β,20β-diol was studied in homogenates of boar testis and the mean yields obtained were 25.6, 2.7 and 16.0% respectively. 3. Short-term kinetic studies with pregnenolone and 5-pregnene-3β,20β-diol separately and together suggested that the latter compound might be an intermediate in the biosynthesis of andien-β. 4. In agreement with this interpretation, radioactive 5-pregnene-3β,20β-diol has been isolated during andien-β biosynthesis from [4-14C]pregnenolone in the presence of NADPH, more radioactivity being trapped under limiting conditions of andien-β formation with NADH present as cofactor. 5. Further, 5-pregnene-3β,20β-diol and andien-β have been shown to inhibit the formation of the 16-unsaturated C19 steroid from [4-14C]pregnenolone, the yield of radioactive 5-pregnene-3β,20β-diol increasing in the presence of added unlabelled andien-β. 6. It is concluded that there may be two pathways leading to 16-unsaturated C19 steroid formation from pregnenolone...

‣ 4,4′-(2,6-Dihydroxy­naphthalene-1,5-diyldimethyl­ene)dipyridinium bis­(per­chlorate)

Zhu, Wei-Feng; Xing, Zheng
Fonte: International Union of Crystallography Publicador: International Union of Crystallography
Tipo: Artigo de Revista Científica
Publicado em 30/05/2008 Português
Relevância na Pesquisa
36.734966%
The title compound, C22H20N2O2 2+·2ClO4 −, was synthesized by the reaction of naphthalene-2,6-diol with pyridine-4-carbaldehyde, 4-picolylamine and perchloric acid. There is a centre of symmetry at the mid-point of the central C—C bond of the cation. The two pyridine rings are parallel to each other, and the dihedral angle between the naphthalene ring system and the pyridine ring is 80.68 (11)°. All the bond lengths and angles are normal. Classical inter­molecular O—H⋯O and N—H⋯O hydrogen bonds connect cations and anions, forming a one-dimensional chain structure.

‣ Intrahippocampal Injection of 3α Diol (a Testosterone Metabolite ) and Indomethacin (3α-HSD Blocker), Impair Acquisition of Spatial Learning and Memory in Adult Male Rats

AssadianNarenji, Somayeh; Naghdi, Nasser; Oryan, Shahrbanoo; Azadmanesh, Kayhan
Fonte: Shaheed Beheshti University of Medical Sciences Publicador: Shaheed Beheshti University of Medical Sciences
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
27.96026%
Hippocampus is essentially involved in learning and memory processes, and is known to be a target for androgen actions. The high density of the androgen receptors in hippocampus shows that there must be some relationship between androgens and memory. Androgen effects on spatial memory are complex and contradictory. Some evidence suggests a positive correlation between androgens and spatial memory. While some other reports indicated an impairment effect. The present study was conducted to assess the effect of 3α diol on spatial discrimination of rats. Adult male rats were bilaterally cannulated into CA1 region of hippocampus and then received 3α diol (0.2, 1, 3 and 6 μg/ 0.5 μL/side), indomethacin (1.5, 3 and 6 μg/ 0.5 μL/side), indomethacin (3 μg/ 0.5 μL/side) + 3α diol (1μg/ 0.5 μL/side), 25-35 min before training in Morris Water Maze task. Our results showed that injection of 3α diol (1, 3 and 6 μg/ 0.5 μL/ side) and indomethacin (3 and 6 μg/ 0.5 μL/side) significantly increased the escape latency and traveled distance to find hidden platform. It is concluded that intra CA1 administration of 3α diol and indomethacin could impair spatial learning and memory in acquisition stage. However, intra hippocampal injection of indomethacin plus 3α diol could not change spatial learning and memory impairment effect of indomethacin or 3α diol in Morris Water Maze task.

‣ Protective activity of (1S,2E,4R,6R,7E,11E)-2,7,11-cembratriene-4,6-diol analogues against diisopropylfluorophosphate neurotoxicity: Preliminary structure-activity relationship and pharmacophore modeling

Eterović, Vesna A.; Valle-Rodriguez, Angelie Del; Pérez, Dinely; Carrasco, Marimée; Khanfar, Mohammad A.; El Sayed, Khalid A.; Ferchmin, Pedro A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.18837%
Diisopropylfluorophosphate (DFP) is an organophosphorous insecticide used as a surrogate for the more toxic chemical warfare nerve agent sarin. DFP produces neurotoxicity in vivo and irreversibly decreases the area of population spikes recorded from the CA1 region of acute hippocampal slices. (1S,2E,4R,6R,7E,11E)-2,7,11-Cembratriene-4,6-diol (1) is a neuroprotective natural cembranoid that reverses DFP-induced damage both in vivo and in the hippocampal slice. Cembranoid 1 acts by noncompetitive inhibition of the α7 nicotinic acetylcholine receptor. This study aims at establishing a preliminary structure-activity relationship to define the neuroprotective cembranoid pharmacophores using the hippocampal slice assay and pharmacophore modeling. Fourteen natural, semisyntheti or biocatalytic cembranoid analogues 2-15 related to 1 were tested for their capacity to protect the population spikes from DFP-induced damage and intrinsic toxicity. Twelve cembranoids caused significant reversal of DFP toxicity; only 3 active analogues displayed minor intrinsic toxicity at 10 μM. The C-4 epimer of 1 (2) and the 4-O-methyl ether analogue of 1 (3), were totally devoid of neuroprotective activity. The results suggested a model for cembranoid binding where the hydrophobic ring surface binds to a hydrophobic (Hbic) patch on the receptor molecule and an electronegative atom (oxygen or sulfur) in proper spatial relationship to the ring surface interacts with an electropositive group in the receptor binding site. A pharmacophore model consisting of 1 hydrogen bond acceptor (HBA)...

‣ Highly Sensitive Determination of 2,4,6-Trinitrotoluene and Related Byproducts Using a Diol Functionalized Column for High Performance Liquid Chromatography

Gumuscu, Burcu; Erdogan, Zeynep; Guler, Mustafa O.; Tekinay, Turgay
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 06/06/2014 Português
Relevância na Pesquisa
27.895203%
In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95–98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer...

‣ INHIBITORS OF CHOLESTEROL BIOSYNTHESIS: EFFECTS OF 14ALPHA-ETHYL-5ALPHA-CHOLEST-7-ENE-3BETA,15ALPHA-DIOL IN CULTURED MAMMALIAN CELLS. (VOLUMES I AND II) (OXYGENATED STEROLS)

IZUMI, AKIHIRO
Fonte: Universidade Rice Publicador: Universidade Rice
Português
Relevância na Pesquisa
27.800608%
14(alpha)-Ethyl-5(alpha)-cholest-7-ene-3(beta),15(alpha)-diol (0.5 uM) inhibited the synthesis of C(,27) sterols from radioactive acetate in Chinese hamster ovary (CHO-Kl) cells. This inhibition was accompanied by a striking accumulation of labeled lanosterol and 24,25-dehydrolanosterol which were characterized by chromatographic analyses on silicic acid-Super Cel columns and on alumina-Super Cel-silver nitrate columns and by the results of cocrystallization experiments. The inhibition of the metabolism of these two C(,30) sterols occurred after only 15 minutes of exposure of the cells to the 14(alpha)-ethylsteryl diol. Analyses of the labeled C(,27) sterols formed from radioactive acetate in CHO-Kl cells in the absence of the 14(alpha)-ethylsteryl diol revealed that, under the conditions employed, most of the radioactivity had the chromatographic mobility of 5(alpha)-cholesta-8,24-dien-3(beta)-ol and 5(alpha)-cholest-8-en-3(beta)-ol. The 14(alpha)-ethylsteryl diol (0.5 (mu)M) also caused the inhibition of the metabolism of lanosterol and 24,25-dihydrolanosterol in CRl, a mutant CHO line in which the levels of HMG-CoA reductase activity are not suppressed by 25-hydroxycholesterol, 14(alpha)-ethyl-5(alpha)-cholest-7-ene-3(beta),15(alpha)-diol and 5(alpha)-cholest-8(14)-en-3(beta)-ol-15-one. Incubations of CHO-Kl cells with low concentrations (0.1 (mu)M) of the 14(alpha)-ethylsteryl diol for longer periods of time (2-10 days) in lipid-deficient medium caused significant changes in sterol composition of the cells and of their plasma membranes. After two days of incubation...

‣ Reações Multicatalíticas Sequenciais envolvendo Hidroformilação de Olefinas

Almeida, Ana Rita Matos de
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
27.872913%
O trabalho apresentado nesta tese orientou-se no sentido de desenvolver processos multicatalíticos sequenciais, partindo da hidroformilação de olefinas como reação central. Os aldeídos obtidos através da hidroformilação foram, subsequentemente, submetidos in situ a reações sequenciais, com o intuito de sintetizar diferentes famílias de compostos com grupos funcionais diversos e, desta forma, obter produtos de valor acrescentado. No Capítulo 1 apresenta-se uma revisão crítica da literatura focada nas principais temáticas desenvolvidas no decurso do trabalho experimental. No Capítulo 2, encontram-se apresentados os estudos de otimização da reação de hidroformilação catalítica de diferentes tipos de olefinas que, posteriormente, foram selecionadas como substratos nos processos catalíticos sequenciais. Estes estudos, em conjunto com a otimização das reações seguintes, permitiram identificar os sistemas catalíticos mais ativos e seletivos para se obter os aldeídos pretendidos e, assim, prosseguir com a metodologia proposta. No que concerne à reação tandem de hidroformilação/arilação, o sistema catalítico Rh/dppp permitiu obter seletivamente álcoois do tipo 1,2-diarilpropan-1-ol, em resultado da derivatização dos correspondentes aldeídos ramificados...

‣ Chemical Constituents from Bombacopsis glabra (Pasq.) A. Robyns: Complete ¹H and 13C NMR Assignments and X Ray Structure of 5-Hydroxy-3,6,7,8,4'-pentamethoxyflavone

Paula,Vanderlúcia F.; Barbosa,Luiz C. A .; Errington,William; Howarth,Oliver W.; Cruz,Mariluze P.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2002 Português
Relevância na Pesquisa
37.50099%
The flavone 5-hydroxy-3,6,7,8,4'-pentamethoxyflavone (1) and the triterpenes lupenone, 9,19-cyclolanost-23-ene-3beta,25-diol (2), (24R)-9,19-cyclolanost-25-ene-3beta,24-diol (3) and (24S)-9,19-cyclolanost-25-ene-3beta,24-diol (4) were isolated from the hexane extract of the stem bark of Bombacopsis glabra (Bombacaceae). The structures were determined by 13C and ¹H NMR (1D and 2D) and mass spectrometry, and by comparison with literature data for triterpenes. The structure of the flavone 1 was unambiguously confirmed by a X-ray diffraction study. The five substances were isolated for the first time from Bombacaceae species.

‣ Síntesis de 6-tia, aziridino y sulfamido pregnanos análogos de esteroides neuroactivos; Synthesis of 6-thia, aziridino and sulfamido pregnane analogues of neuroactive steroids

Durán, Fernando Javier
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2005 Português
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n esta tesis se describe la síntesis de análogos de esteroides neuroactivos por dos vías: i) adición de nitreno a dobles enlaces en C-2/C-3 y C-5/C-6 a partir de un sulfamato en posición 19, ii) síntesis estereoselectiva de 5αH-6tiapregnanos. Se desarrollo la metodología de aziridinación intramolecular, a partir de sulfamatos olefínicos, derivados de alcoholes primarios y secundarios, posteriormente se los sometió condiciones de aziridinación intramolecular en presencia de iodosilbenceno y catálisis de complejos de Cu(II) para la obtención de aziridinas bicíclicas fusionadas. Se realizaron aperturas de las aziridinas con nucleófilos nitrogenados, oxigenados y azufrados, la apertura en todos los casos fue en el carbono más sustituido. Se realizó la segunda sustitución sobre el carbono que contenía al oxígeno mediante activación del nitrógeno del sulfamidato. Se aplicó la metodología en esteroides utilizando como primer sustrato 3β-acetiloxi-19- hidroxi-5-pregnen-20-ona, se sintetizó 3β-acetiloxi-5β,6β-iminopregnan-20-ona N,19- sultona y se realizaron aperturas de la aziridina con fluoruro, cianuro y acetato, observándose la apertura en C-5. En el caso del acetato a altas temperaturas se observó regioselectividad inversa en C-6 debido a la migración del acetato. A partir del 5β...

‣ Síntesis de 6-tia, aziridino y sulfamido pregnanos análogos de esteroides neuroactivos; Synthesis of 6-thia, aziridino and sulfamido pregnane analogues of neuroactive steroids

Durán, Fernando Javier
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: Tesis Doctoral Formato: text; pdf
Publicado em //2005 Português
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n esta tesis se describe la síntesis de análogos de esteroides neuroactivos por dos vías: i) adición de nitreno a dobles enlaces en C-2/C-3 y C-5/C-6 a partir de un sulfamato en posición 19, ii) síntesis estereoselectiva de 5αH-6tiapregnanos. Se desarrollo la metodología de aziridinación intramolecular, a partir de sulfamatos olefínicos, derivados de alcoholes primarios y secundarios, posteriormente se los sometió condiciones de aziridinación intramolecular en presencia de iodosilbenceno y catálisis de complejos de Cu(II) para la obtención de aziridinas bicíclicas fusionadas. Se realizaron aperturas de las aziridinas con nucleófilos nitrogenados, oxigenados y azufrados, la apertura en todos los casos fue en el carbono más sustituido. Se realizó la segunda sustitución sobre el carbono que contenía al oxígeno mediante activación del nitrógeno del sulfamidato. Se aplicó la metodología en esteroides utilizando como primer sustrato 3β-acetiloxi-19- hidroxi-5-pregnen-20-ona, se sintetizó 3β-acetiloxi-5β,6β-iminopregnan-20-ona N,19- sultona y se realizaron aperturas de la aziridina con fluoruro, cianuro y acetato, observándose la apertura en C-5. En el caso del acetato a altas temperaturas se observó regioselectividad inversa en C-6 debido a la migración del acetato. A partir del 5β...

‣ 4,6-O-[1-Cyano-2-(2-iodophenyl)ethylidene] Acetals. Improved Second Generation Acetals for the Stereoselective Formation of β-d-Mannopyranosides and Regioselective Reductive Radical Fragmentation to β-d-Rhamnopyranosides. Scope and Limitations

Crich, David; Bowers, Albert A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 28/04/2006 Português
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The [1-cyano-2-(2-iodophenyl)]ethylidene group is introduced as an acetal protecting group for carbohydrate thioglycoside donors. The group is easily introduced under mild conditions, over short reaction times, and in presence of a wide variety of other protecting groups by the reaction of the 4,6-diol with triethyl (2-iodophenyl)orthoacetate and trimethylsilyl triflate, followed by trimethylsilyl cyanide and boron trifluoride etherate. The new protecting group conveys strong β-selectivity with thiomannoside donors and undergoes a tin mediated radical fragmentation to provide high yields of the synthetically challenging β-rhamnopyranosides. The method is also applicable to the glucopyranosides when high α-selectivity is observed in the coupling reaction and α-quinovosides are formed selectively in the radical fragmentation step. In the galactopyranoside series, α-glycosides are formed selectively on coupling to donors protected by the new system, but the radical fragmentation is unselective and gives mixtures of the 4- and 6-deoxy products. Variable temperature NMR studies for the glycosylation step, which helped define an optimal protocol, are described.

‣ NSC302357; (-)-Heroin hydrochloride; Diacetylmorphine hydrochloride; Diamorphine hydrochloride; Diamorphine, hydrochloride; Heroin hydrochloride; Heroin, hydrochloride; Heroine hydrochloride; Morphinan-3,6.alpha.-diol, 7,8-didehydro-4, 5.alpha.-epoxy-17-methyl-, diacetate (ester), hydrochloride (8CI); Morphinan-3,6.alpha.-diol, 7,8-didehydro-4, 5.alpha.-epoxy-17-methyl-, diacetate (ester) hydrochloride; Morphinan-3,6.alpha.-diol, 7,8-didehydro-4, 5.alpha.-epoxy-17-methyl-, diacetate (ester), hydrochloride (8CI); Morphinan-3,6.alpha.-diol, 7,8-didehydro-4, 5.alpha.-epoxy-17-methyl-, diacetate (ester) hydrochloride; Morphinan-3,6-diol, 7,8-didehydro-4,5-epoxy-17-methyl- (5.alpha., 6.alpha.)-,diacetate (ester), hydrochloride (9CI); Morphinan-3, 6-diol, 7,8-didehydro-4,5-epoxy-17-methyl- (5.alpha.,6.alpha.)-, diacetate (ester), hydrochloride (9CI); Morphinan-3,6-diol, 7, 8-didehydro-4,5-epoxy-17-methyl-, diacetate (ester), hydrochloride, (5.alpha.,6.alpha.)-; Morphine, diacetate (ester), hydrochloride; WLN: T B6566 B6/CO 4ABBC R BX HO PN DU GHT&&TTJ FOV1 JOV1 P1 &GH

US National Cancer Institute
Fonte: Unilever Center for Molecular Informatics, Cambridge University Publicador: Unilever Center for Molecular Informatics, Cambridge University
Tipo: Outros Formato: 8853 bytes; 7964 bytes; chemical/x-cml; chemical/x-cml
Português
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