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Search Results: 1 - 10 of 308508 matches for " Alaíde B.; "
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An Interesting Backbone Rearrangement and Novel Derivatives from the Biotransformation of Trachyloban-19-oic Acid by Rhizopus stolonifer
Silva, Eliane A.;Takahashi, Jacqueline A.;Oliveira, Alaíde B.;
Journal of the Brazilian Chemical Society , 2002, DOI: 10.1590/S0103-50532002000100016
Abstract: a biotransformation experiment of trachyloban-19-oic acid (2) was carried out with rhizopus stolonifer. after twenty days of reaction, four metabolites were extracted, isolated and characterized: two trachylobane type compounds, the 7b (3) and the 17 (5) hydroxyl derivatives, and two rearranged ent-kaur-11-en-19-oic acids, the 16b (4) and the 9a,16b (6) hydroxylated compounds. products 4 and 5 were isolated as their methyl esters (4a and 5a) after esterification of a mixture containing their corresponding acids. the rearrangement of a trachylobane diterpene leading to ent-16b-hydroxy-kaur-11-ene derivatives gives support to the biogenetic proposal based on the occurrence of this rare group of kaurenes only in plants containing trachylobane representatives. by the best of our knowledge, this is the first report on the isolation of compounds 5 and 6.
An Interesting Backbone Rearrangement and Novel Derivatives from the Biotransformation of Trachyloban-19-oic Acid by Rhizopus stolonifer
Silva Eliane A.,Takahashi Jacqueline A.,Oliveira Alaíde B.
Journal of the Brazilian Chemical Society , 2002,
Abstract: A biotransformation experiment of trachyloban-19-oic acid (2) was carried out with Rhizopus stolonifer. After twenty days of reaction, four metabolites were extracted, isolated and characterized: two trachylobane type compounds, the 7beta (3) and the 17 (5) hydroxyl derivatives, and two rearranged ent-kaur-11-en-19-oic acids, the 16beta (4) and the 9alpha,16beta (6) hydroxylated compounds. Products 4 and 5 were isolated as their methyl esters (4a and 5a) after esterification of a mixture containing their corresponding acids. The rearrangement of a trachylobane diterpene leading to ent-16beta-hydroxy-kaur-11-ene derivatives gives support to the biogenetic proposal based on the occurrence of this rare group of kaurenes only in plants containing trachylobane representatives. By the best of our knowledge, this is the first report on the isolation of compounds 5 and 6.
Novel Derivatives of Kaurenoic Acid
Vieira Henriete S.,Takahashi Jacqueline A.,Oliveira Alaíde B. de,Chiari Egler
Journal of the Brazilian Chemical Society , 2002,
Abstract: Kaurenoic acid, a kauranic diterpenoid, presents in vitro activity against trypomastigote forms of Trypanosoma cruzi, showing, however, lytic activity on blood erythrocytes, as a side effect. The syntheses of twelve new derivatives of kaurenoic acid, four amides, four amines (and three hydroclorides) and four oximes, was carried out aiming at the improvement of the therapeutic activity and without the side effect. Among the derivatives prepared, one compound showed enhanced trypanocidal activity in vitro towards Trypanosoma cruzi trypomastigote erythrocytic forms, when compared to kaurenoic acid, but continued to show discrete lytic activity on erythrocytes; another compound showed a level of activity similar to that of kaurenoic acid, but without lysis.
Identification of Some Chemical Components of the Essential Oil from Molasses Grass (Melinis minutiflora Beauv.) and their Activity Against Cattle-Tick (Boophilus microplus)
Prates, Hélio T.;Leite, Romário C.;Craveiro, Afranio A.;Oliveira, Alaíde B.;
Journal of the Brazilian Chemical Society , 1998, DOI: 10.1590/S0103-50531998000200013
Abstract: the essential oil of molasses grass (melinis minutiflora beauv.) has shown virtually 100% lethal effect on larvae of the cattle-tick (boophilus microplus) within 10 min exposure. gc/ms analysis of the essential oil led to the identification of six major components: propionic acid, butyric acid, phenylethyl alcohol, hexanal, 1,8-cineole and 9 -e-eicosene. two of those components (1,8-cineole and n-hexanal) have also shown individually 100% lethal effect on cattle-tick larvae within 10 min. the presence of 2,6-di-t-butyl-4-methylphenol was assigned to a contaminant from commercially supplied diethyl ether used for the essential oil extraction.
Cytotoxicity of Wedelia paludosa D.C. extracts and constituents
Batista, Ronan;Brand?o, Geraldo C.;Braga, Fern?o C.;Oliveira, Alaíde B.;
Revista Brasileira de Farmacognosia , 2009, DOI: 10.1590/S0102-695X2009000100009
Abstract: wedelia paludosa d.c. (asteraceae) is an ornamental species occurring in many regions of brazil. aiming to find new cytotoxic compounds, the hydromethanol extract of w. paludosa (hme), as well as the dichloromethane (df) and water (wf) fractions resulting from its partition, were submitted to the brine shrimp lethality bioassay (bslb) in order to evaluate their cytotoxicity. dichloromethane fraction (df) was shown to be the most cytotoxic fraction (lc50 = 140.6 μg/ml), and its analysis by reversed phase high performance liquid chromatography (rp-hplc) revealed ent-kaurenoic (1, 6.22 ± 0.23%) and grandiflorenic (2, 3.22 ± 0.31%) acids as important constituents. hme (lc50 = 980 μg/ml), df (lc50 = 140.6 μg/ml), 1 (lc50 = 15.9 μg/ml) and 2 (lc50 = 29.8 μg/ml) were found to be cytotoxic, while the water fraction (wf, lc50 >> 1000 μg/ml) was inactive. as conclusion, the cytotoxicity observed for hme and df is mainly due to the presence of 1 and 2 in their constitution.
Novel Derivatives of Kaurenoic Acid
Vieira, Henriete S.;Takahashi, Jacqueline A.;Oliveira, Alaíde B. de;Chiari, Egler;Boaventura, Maria Amélia D.;
Journal of the Brazilian Chemical Society , 2002, DOI: 10.1590/S0103-50532002000200004
Abstract: kaurenoic acid, a kauranic diterpenoid, presents in vitro activity against trypomastigote forms of trypanosoma cruzi, showing, however, lytic activity on blood erythrocytes, as a side effect. the syntheses of twelve new derivatives of kaurenoic acid, four amides, four amines (and three hydroclorides) and four oximes, was carried out aiming at the improvement of the therapeutic activity and without the side effect. among the derivatives prepared, one compound showed enhanced trypanocidal activity in vitro towards trypanosoma cruzi trypomastigote erythrocytic forms, when compared to kaurenoic acid, but continued to show discrete lytic activity on erythrocytes; another compound showed a level of activity similar to that of kaurenoic acid, but without lysis.
Synthesis and trypanocidal activity of 7, 2'-dioxygenated isoflavones and oxypropanolamine derivatives
Faria, Terezinha de J.;Silva, Luiz G. Fonseca e;Souza Filho, José D. de;Chiari, Egler;Oliveira, Alaíde B. de;
Journal of the Brazilian Chemical Society , 2005, DOI: 10.1590/S0103-50532005000800020
Abstract: 7, 2'-dihydroxyisoflavone was shown to be active against the bloodstream trypomastigote form of trypanosoma cruzi, the etiologic agent of chagas' disease. amphiphilic derivatives of this isoflavone were synthezised aiming to obtain hydrosoluble compounds of potential use as prophylactic agents to be added to blood for transfusion. this isoflavone was obtained by demethylation of 7-hydroxy-2'-methoxyisoflavone that was synthesized via the intermediate deoxybenzoin. its reaction with epichlorohydrin, followed by aminolysis with diethylamine, afforded the 7-oxypropanolamine which on treatment with methyl iodide gave the corresponding ammonium salt. the 7-hydroxy-2'-methoxyisoflavone was inactive in the in vitro assays, the 7-oxypropanolamine was more active than 7, 2'-dihydroxyisoflavone while the ammonium salt has not eliminated the parasite from the blood besides causing total lysis of the erythrocytes. the simple synthetic procedures described in the present paper can be used to provide gram quantities of 7, 2'-dihydroxyisoflavone and its 7-oxypropanolamine derivative that should be further investigated in in vivo murine models as potential chemotherapeutic agents for treatment of chagas' disease.
Mono and diterpenes from seeds of Xylopia sericea
Takahashi, Jacqueline A.;Vieira, Henriete S.;Boaventura, Maria Amélia D.;Hanson, James R.;Hitchcock, Peter B.;Oliveira, Alaíde B. de;
Química Nova , 2001, DOI: 10.1590/S0100-40422001000500008
Abstract: a monoterpene, 3b,6b-dihydroxy-p-menth-1-ene has been isolated from the seeds of xylopia sericea along with four kaurane, one beyerene, one atisene and four trachylobane diterpenoids, including the trachyloban-18- and 19-methyl esters. the x-ray crystal structure of methyl ent-trachyloban-18-oate was determined in order to make an unambiguous distinction between the 18- and 19-esters. the 13c nmr data for ent-15a-hydroxy-trachyloban-19-oic acid has been revised.
Electrochemical Properties of Biologically Active Heterocyclic Naphthoquinones
Tonholo, Josealdo;Freitas, Luciano R.;Abreu, Fabiane C. de;Azevedo, Dayse C.;Zani, Carlos L.;Oliveira, Alaíde B. de;Goulart, Marília O. F.;
Journal of the Brazilian Chemical Society , 1998, DOI: 10.1590/S0103-50531998000200008
Abstract: a series of natural and synthetic heterocyclic naphthoquinones, some of them with anti-plasmodial and trypanocidal activities, were studied by cyclic voltammetry in aprotic media (dmf/tbap). in this solvent, the voltammograms of the quinones show two pairs of waves, corresponding to reversible or quasi-reversible one-electron transfer processes to form the semiquinone anion radical (q·) and the dianion (q2-). within the studied series, ortho-quinones undergo reduction easier than isomeric para-quinones. however, para-naphthoquinones fused to an aromatic heterocyclic ring are more easily reduced than the corresponding ortho-naphtoquinones with a non aromatic heterocycle. substituents effects correlated very well with the first reduction potential (epc1) and the half wave potential (e1/2). high yield reductive acetylation was achieved by electrolyses in the presence of acetic anhydride. comparison of electrochemical data with reported antimalarial activities showed no correlation, differently from the already reported trend in relation to trypanocidal activities.
New oxidized ent-kaurane and ent-norkaurane derivatives from kaurenoic acid
Batista, Ronan;García, Pablo A.;Castro, Maria A.;del Corral, José M. Miguel;San Feliciano, Arturo;Oliveira, Alaíde B. de;
Journal of the Brazilian Chemical Society , 2007, DOI: 10.1590/S0103-50532007000300020
Abstract: new oxidized ent-kaurane and ent-norkaurane derivatives were synthezised starting from kaurenoic acid. the spectroscopic characterization of all compounds is reported.
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