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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11800
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Item Caracterização química do “pitch” em indústria de celulose e papel de Eucalyptus(Química Nova, 2006-05) Cruz, Mariluze P.; Barbosa, Luiz C. A.; Maltha, Célia R. A.; Gomide, José L.; Milanez, Augusto F.The chemical analysis of the acetone, chloroform, toluene and methanol extracts of a pitch sample was carried out by IR and GC-MS, leading to the identification of sixty nine compounds, including fatty acids, alcohols and hydrocarbons. Analysis of the acetone extractive of a eucalyptus wood used in Brazil for pulp production was also carried out, resulting in identification of fifty nine compounds, including mainly fatty acids, phenolic compounds, b-sitosterol and other steroids. This analysis showed that pitch formation had a contribution from wood extractives and other sources of contamination. The results obtained and the methodology applied can be used by the pulp industry to develop new methods of pitch control.Item Síntese de novas fitotoxinas derivadas do 8- oxabiciclo[ 3. 2. 1] oct- 6- en- 3- ona(Química Nova, 2005-05) Barbosa, Luiz C. A.; Maltha, Célia R. A.; Demuner, Antônio J.; Ganen, Flávia R.; Silva, Antônio A. daThe [4+3] cycloaddition was utilized in order to prepare 8-oxabicyclo[3.2.1]oct-6-en-3-one (1) derivatives. The correspondent acetonide 6 was converted into several alcohols (11-16). Addition of aryllithium reagents to 6 resulted in 3-(2-fluorophenyl)-6,7-exo-isopropylidenedioxy -8-oxabicyclo[3.2.1]octan-3a-ol (11, 72%) and 3-(2,4-dimethoxyphenyl)-6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan -3a-ol (16, 20%). The 3-butyl-6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3 a-ol (15, 56%) was obtained through a Grignard reaction. Reduction of 6 resulted in 6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3 b-ol (7, 62%) and 6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3 a-ol (8, 20%). The alcohols were treated with thionyl chloride in pyridine, and the corresponding alkenes were obtained with 31-80% yield. The effect of these compounds on the development of radicle and aerial parts of Sorghum bicolor was evaluated.Item Constituintes químicos de Melaleuca alternifolia (Myrtaceae)(Química Nova, 2004-07) Vieira, Tatiana R.; Barbosa, Luiz C. A.; Maltha, Célia R. A.; Paula, Vanderlúcia F.; Nascimento, Evandro A.he first chemical study of non-volatile constituents from the bark and stem of Melaleuca alternifolia (Myrtaceae) led to the isolation and identification of 3,3’-O- dimethylellagic acid (1) and five pentacyclic triterpenes: 2α,3β,23-trihydroxyolean-12-en-28-oic acid (arjunolic acid, 2), 3β- hydroxylup-20(29)-en-27,28-dioic acid (melaleucic acid, 3), betulinic acid (4), betuline (5), 3β-O-acetylurs-12-en-28-oic acid (6), a mixture of fatty acids and esters, and several hydrocarbons. For 2α,3β,23-trihydroxyolean-12-en-28-oic acid (2) and 3β-O- acetylurs-12-en-28-oic acid (6) a first detailed assignment of 1 H NMR is presented.Item Determinação da relação siringila/guaiacila da lignina em madeiras de eucalipto por pirólise acoplada à cromatografia gasosa e espectrometria de massas ( PI - CG/ EM)(Química Nova, 2008) Barbosa, Luiz C. A.; Maltha, Célia R. A.; Silva, Vanessa Lopes; Colodette, Jorge LuizThe use of analytical pyrolysis combined with gas chromatography/mass spectrometry (Py-GC/MS) to determine the syringyl/guaiacyl ratio (S/G) in lignins from Eucalyptus spp woods was investigated. Sample of E. grandis and "E. urograndis" wood, with and without extractives, were subjected to pyrolysis from 300 ºC to 600 ºC. The products that results from pyrolysis were identified by mass spectrometry and the S/G ratio was determined based on the areas of the peaks corresponding to the guaiacyl and syringyl derivatives. The best S/G estimation is achieved when pyrolysis is carried out at 550 ºC. Extractives and carbohydrate present in the woods do not interfere with the results.Item Síntese de 2-( 2- piridil) quinolinas promovida por micro- ondas e suas atividades antifúngicas(Química Nova, 2017-09) Borel, Carmindo R.; Barbosa, Luiz C. A.; Maltha, Célia R. A.; Fernandes, Sergio A.; Santos, Larissa B.; Takahashi, Jacqueline A.In this work a series of 2-(2- pyridyl)quinolines were prepared via a Povarov reaction between anilines, 2-pyridinocarbadehyde and ethyl vinyl ether under microwaves heating conditions. The optimized conditions herein reported allowed the preparation of several pyridylquinolines in yields in the range of 30-83%, some of them not previously accessible by this multicomponent process. The reported methodology has advantage over previous report due to its larger scope and short reaction time (2 hours). All quinolines obtained were assayed against five species of clinically important yeasts Candida sp and against Cryptococcus neoformans. Some of them possessed a broad spectrum of action including 2-(2-pyridyl)quinoline (20) and 6,8-dimethoxy-2-(pyridin-2-yl)quinolone (22) that were highly effective in inhibiting Candida species (IC50 < 1.95 µg/mL against C. tropicalis and C. krusei). Some compounds were more potent than commercial drugs Nistatin and Miconazole.Item Síntese e avaliação da atividade antimicrobiana de furanonas halogenadas e de compostos análogos aos nostoclídeos(Química Nova, 2010) Barbosa, Luiz C. A.; Maltha, Célia R. A.; Demuner, Antônio J.; Pinheiro, Patrícia F.; Varejão, Jodieh O. S.; Montanari, Ricardo M.; Andrade, Nélio J.Considering the broad spectrum of biological activity of gamma-butyrolactone derivatives, we presented the synthesis of 3,4-dihalo-5-arylidenefuran-2(5H)-ones (17-21) and analogues (24-28) of the natural product nostoclide (7,8). Furanones 17-21 were synthesized from the condensation of aromatic aldehydes with lactones 14 and 15, that were obtained from mucobromic and mucochloric acids. Lactone 15 was converted into the intermediate 23 in 36% overall yield. Compound 23 was then transformed into the nostoclide analogues 24-28. Some of the compounds prepared showed antimicrobial activities against Escherichia coli, Staphylococcus aureus and Bacillus cereus comparable to commercial antibiotics.Item Synthesis, molecular properties and DFT studies of new phosphoramidates as potential urease inhibitors(Medicinal Chemistry Research, 2014-06-28) Oliveira, Fabricio M.; Barbosa, Luiz C. A.; Demuner, Antônio J.; Maltha, Célia R. A.; Pereira, Silvana R.; Horta, Lı́via P.; Modolo, Luzia V.In this work, new phosphoramidates were prepared and screened for their putative urease inhibitory activity. The importance of this class of compounds is related to the wide range of biological activities which they exhibit. Consequently, higher activity shown by phosphoramidates 3a, 4b, 5a, 5b, 5c, and 9a suggests that they could serve as lead substances for the development of novel synthetic compounds with enhanced inhibitory ureolitic activity. Their predicted ADMET properties are also in accordance with the general requirements for drug-like compounds. Structure–activity relationship analyses suggest that the presence of cyclohexylamine group is an important structural feature associated with enhanced activities. DFT calculations were performed to obtain the energy values of HOMO and LUMO, and dipole moment.