Navegando por Autor "Perry, Katia da Silva Peixoto"
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Item Complete assignments of 1h and 13c nmr data for trypanocidal eremantholide c oxide derivatives.(2007) Guimarães, Dênia Antunes Saúde; Perry, Katia da Silva Peixoto; Raslan, Delio Soares; Chiari, Egler; Barrero, Alejandro Fernández; Oltra, Juan EnriqueThe chemical transformations of eremantholide C (1), a trypanocidal sesquiterpene lactone isolated from Lychnophora trichocarpha Spreng., gave five new oxide derivatives: 3 -hydroxyeremantholide C (2), 1 -formyleremantholide C (3), 1 -carboxyeremantholide C (4), 1 -carbomethoxyeremantholide C (5) and sodium 1 -carboxylate of eremantholide C (6). The 1H and 13C NMR data of all these derivatives were assigned based on 1D and 2D techniques. The derivatives were evaluated against Y and CL strains of Trypanosoma cruzi. All of them were inactive against the Y strain. Compounds 2 and 5 displayed 100% activity on the CL strain while compounds 4 and 6were partially active on the CL strain. Copyright 2007 John Wiley & Sons, Ltd.Item Conformational study of naringenin in the isolated and solvated states by semiempirical and AB Initio methods.(1999) Perry, Katia da Silva Peixoto; Nagem, Tanus Jorge; Almeida, Wagner Batista deNaringenin is a natural widespread flavanone occurring in different foodstuffs that presents several important biological activities. Although its properties are well documented, its mechanisms of action are still controversial. The present article reports a conformational analysis of naringenin, using the semiempirical AM1 and ab initio methods, at the Hartree-Fock level of theory. The 3-21G, 3-21G*, 6-31G, and 6-31G** basis sets were used. The electron correlation effects were included through the M011er-Plesset second-order perturbation theory. The solvation of naringenin has been investigated through the standard SCRF, the supermolecule (SM), and the combined SM/SCRF models. The results have shown that there are two degenerate forms of naringenin, differing mainly by the orientation of a hydroxyl group (C4'—OH). The energy barrier for the interconversion between them is ca. 6 kcal.mol-1, suggesting some conjugation between the p-system of the aromatic B ring and the hydroxyl group (C4'—OH).