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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11847
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Item Unprecedented one-pot sequence for the synthesis of tetrahydroquinoline alkaloids and preliminary evaluation of their antibacterial activity(Journal of the Brazilian Chemical Society, 2018-12) Purgato, Gislaine A.; Diaz, Marisa A. N.; Diaz-Muñoz, Gaspar; Miranda, Izabel L.; Sartori, Suélen K.; Dias, Gabriel N. S.; Kohlhoff, MarkusA novel one-pot sequence (in 2 or 3 steps) was developed for the synthesis of the tetrahydroquinoline alkaloids (±)-galipinine, (±)-cuspareine, (±)-galipeine and (±)-angustureine, and the derivative (±)-11-methoxy-5,6,6a,7,8,13-hexahydro-13a-aza-benzo[5,6]cyclohepta [1,2-a]naphthalene-12-ol from their respective Wittig adducts in moderate and high yields. The solvolytic N-methylation reaction was shown to be catalyzed by Pt0, generated in situ by reduction of PtO2. The evaluation of biofilm inhibition and antibacterial activity of the compounds against Staphylococcus aureus strains isolated from cows with mastitis revealed that the alkaloid derivative is a promising candidate for an antibiotic drug.Item Synthesis approaches to (−)-cytoxazone, a novel cytokine modulator, and related structures(Molecules, 2016-09) Diaz, Marisa A. N.; Miranda, Izabel L.; Lopes, Ítala K. B.; Diaz, Gaspar(−)-Cytoxazone, originally isolated from cultures of a Streptomyces species has an oxazolidin-2-one 4,5-disubstituted ring. It is known that this natural product presents a cytokine modulator effect through the signaling pathway of Th2 cells (type 2 cytokines), which are involved in the process of growth and differentiation of cells. From this, the interest in the development of research aimed at the total synthesis of this molecule and its analogs has remained high, which can be confirmed by the large number of publications on the topic, more than 30 to date. This review focuses on the various creative methods for the synthesis of (−)-cytoxazone and its congeners. The assessment of the preparation of this oxazolidinone and related structures serves as a treatise on the efforts made in the synthesis of this important class of compound from its first total synthesis in 1999.Item Screening of medicinal plants for antibacterial activities on Staphylococcus aureus strains isolated from bovine mastitis(Revista Brasileira de Farmacognosia, 2009-11-21) Diaz, Marisa A. N.; Rossi, Ciro C.; Mendonça, Vítor R.; Silva, Danielle M.; Ribon, Andréa de O. B.; Aguilar, Ananda P.; Muñoz, Gaspar D.Staphylococcus aureus is the main causative agent of bovine mastitis. The activity of several extracts from ten medicinal plants traditionally used in Brazil as antiseptic was investigated against fifteen strains of Staphylococcus aureus isolated from animals with mastitis manifestation by the disc diffusion method and broth microdilution assay. The interference of the extracts on cell in the form of adherent colonies was also evaluated. MIC values ranged from 0.5 mg/mL to 1.0 mg/mL and biofilm inhibitory concentration (BIC) were between 0.25 mg/mL and 0.8 mg/mL. Results revealed the potential of extracts of Senna macranthera, Artemisia absinthium, Cymbopogon nardus and Baccharis dracunculifolia as antibacterial agents against S. aureus strains isolated from bovine mastitis and support the possible use of these phytotherapic agents in the clinical management of the disease.Item Easy access to evans’ oxazolidinones. Stereoselective synthesis and antibacterial activity of a new 2-oxazolidinone derivative(Molecules, 2014-06-06) Diaz, Gaspar; Freitas, Michelle A. A. de; Ricci-Silva, Maria E.; Diaz, Marisa A. N.An interesting new approach was developed for the synthesis of Evans’ chiral auxiliaries with excellent yields. In turn, another new stereoselective and efficient strategy has also allowed for the preparation of a 2-oxazolidinone derivative in 34% overall yield from the Morita-Baylis-Hillman adduct. The antibacterial activity of this oxazolidinone was tested against Staphylococcus aureus strains isolated from animals with mastitis infections.