Aplicações sintéticas do ácido mucobrômico e da 3,4-dibromofuran-2(5H)-ona

This review describes the use of two biomass-derivate butenolides as intermediates in organic synthesis, mucobromic acid and its reduced derivative 3,4-dibromofuran-2(5H)-one. The ambiphilic and ambident character of such butenolides make them versatile starting materials in the synthesis of natural and/or bioactive compounds. Thus, the reactions of mucobromic acid with C-nucleophiles and heteronucleophiles are described, as well as the nucleophilic addition to carbonyl reactions of 3,4-dibromofuran-2(5H)-one. Besides, both compounds are active in diverse metal cross-coupling reactions, manly with palladium in Suzuki and Sonogashira reactions.

Estudo espectroscópico de compósito obtido da reação no estado sólido entre um complexo mononuclear de vanádio(IV) e caulinita

The use of probes, such as paramagnetic species diluted in diamagnetic materials in EPR spectroscopy, and mathematical tools such, as the Kubelka-Munk function in DRUV-VIS spectroscopy are strategies in the analysis of complex mixtures of solid materials. The results obtained here show that the solid state reaction between the complex, [VO(acac)(BMIMAPY)] [ClO4], BMIMAPY = [(bis(1-methylimidazole-2-yl)methyl)(2-(pyridyl-2-yl)ethyl) amine] and acac = acetilacetonate, with kaolinite turns possible to obtain anisotropic EPR spectrum of the complex with a reasonable level of resolution. The study by DRUV-VIS using the method of second derivative mode of the Kubelka-Munk function revealed new complex structural arrangements, a solid hitherto unknown.

Classificação de biodiesel na região do visível

Classification of biodiesel by oilseed type using pattern recognition techniques is described. The spectra of the samples were performed in the Visible region, requiring noise removal by use of a first derivative by the Savitzky-Golay method, employing a second-order polynomial and a window of 21 points. The characterization of biodiesel was performed using HCA, PCA and SIMCA. For HCA and PCA methods, one can observe the separation of each group of biodiesel in a spectral region of 405-500 nm. SIMCA model was used in a test group composed of 28 spectral measurements and no errors are obtained.

Determinação simultânea de olanzapina e cloridrato de fluoxetina em formulações farmacêuticas por espectrofotometria derivativa

Simple, sensitive and accurate spectrophotometric derivative methods were developed for the simultaneous determination of olanzapine and fluoxetine hydrochloride in pharmaceutical formulations by derivative spectrophotometry. On all orders of derivative studied, the linear response range was 10 to 60 mg L-1, with limit of quantitation (LoQ) ranging from 0.73 to 1.49 mg L-1 for fluoxetine hydrochloride and from 0.18 to 0.96 mg L-1 for olanzapine. The best orders for derivative analyses showed recoveries ranging from 99 to 103% and from 98 to 100%, and inter-day accuracy < 2.1% and < 2.8%, for fluoxetine hydrochloride and olanzapine, respectively.

Nitro derivatives and other constituents of Aristolochia melastoma

A phytochemical study of Aristolochia melastoma Manso has led to the isolation and identification of 20 known compounds, including aristolochic acids, sodium aristolochates, lignan, flavonoids, and nitro phenylethyl derivatives. Their structures were established by spectroscopic analysis. The presence of thalictricoside and secoisolariciresinol dimethyl ether diacetate is reported for the first time in the Aristolochiaceae family. In addition, the presence of nitro compounds in this species is significant.

Synthesis and characterization of Fe(III)-piperazine-derived complexes encapsulated in zeolite Y

Zeolite-encapsulated complexes have been widely applied in hydrocarbon oxidation catalysis. The "ship-in-a-bottle" encapsulation of iron(III) complexes containing piperazine and piperazine-derivative ligands in zeolite-Y is described. The flexible ligand methodology was employed and the efficiency and reproducibility of the procedure was investigated. The catalysts were characterized employing several techniques and the results indicate the presence of coordinated and uncoordinated iron(III) ions inside and outside the zeolitic cage.

Constituintes químicos das folhas de Riedeliella graciliflora Harms (Leguminosae)

A new salicylic acid derivative, pentacosanyl salicylate, was isolated from the leaves of the plant toxic to cattle, Riedeliella graciliflora, in addition to a digalactosyldiacylglycerol (DGDG), 1,2-di-O-α-linolenoyl-3-O-α-D-galactopyranosyl-(1→6)-β-D-galactopyranosyl-glycerol, kaempferol-3-O-β-D-glucopyranoside, kaempferol-3-O-α-L-rhamnopyranoside, quercetin-3-O-α-L-rhamnopyranoside, rutin, (+)-catechin and the dimer (+)-catechin-(4β-8)-catechin, glutinol, squalene, β-sitosterol, stigmasterol, phytol, β-carotene, α-tocopherol and ficaprenol-12. Their structures were determined using spectral techniques (MS, IR, and NMR-1D and 2D) and based on literature data.

Ácido myrsinoico a e derivado: inibidores da fotossíntese in vitro

Myrsinoic A acid, isolated from Myrsine cuneifolia and its hydrogenated derivative had their effect on photosynthesis tested. The compounds inhibited the electron flow (basal, phosphorylating and uncoupled) from water to methylviologen; therefore, they act as Hill reaction inhibitors in spinach thylakoids. They inhibited partial reactions of PSII electron flow from water to 2,5-dichloro-1,4-benzoquinone, from water to sodium silicomolybdate, and partially electron flow from diphenylcarbazide to 2,6-dichloroindophenol. Their inhibition sites were at the donor and acceptor sides of PSII, between P680 and Q A. Chlorophyll a fluorescence measurements confirmed the behavior of the compounds (pool of quinones).

Síntese e avaliação preliminar da atividade antibacteriana e antifúngica de derivados N-acilidrazônicos

We describe the synthesis and evaluation of N-acylhydrazone compounds bearing different electron-donating groups in one of its aromatic rings, obtained using a four-step synthetic route. IC50 values against pathogenic fungi and bacteria were determined by serial microdilution. Compounds showed low activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. By contrast, a derivative with a meta-oriented electron-donating group showed significant activity (IC50) against Candida albicans (17 µM), C. krusei (34 µM) and C. tropicalis (17 µM). Results suggest this is a promising lead-compound for synthesis of potent antifungal agents.

Phaeophytins from Thyrsacanthus ramosissimus Moric. with inhibitory activity on human dna topoisomerase II-α

Our study reports the extraction and isolation of a new phaeophytin derivative 15¹-hydroxy-(15¹-S)-porphyrinolactone, designated anamariaine (1) herein, isolated from the chloroform fraction of aerial parts of Thyrsacanthus ramosissimus Moric. along with the known 15¹-ethoxy-(15¹-S)-porphyrinolactone (2). These compounds were identified by usual spectroscopic methods. Both compounds were subjected to in vitro (inhibitory activity) tests by means of supercoiled DNA relaxation techniques and were shown to display inhibitory activity against human DNA topoisomerase II-α at 50 µM. Interconversion of these two pigments under the mild conditions of the isolation techniques should be highly unlikely but cannot be entirely ruled out.

Anti-trypanosomal activity of 1,2,3,4,6-penta-O-galloyl-β -D-glucose isolated from Plectranthus barbatus Andrews (Lamiaceae)

MeOH extract from the leaves of Plectranthus barbatus Andrews (Lamiaceae), showed in vitro anti-trypanosomal activity. The bioassay-guided fractionation resulted in the isolation of a gallic acid derivative, identified as 1,2,3,4,6-penta-O-galloyl-β-D-glucose (PGG), after thorough NMR and MS spectral analysis. Finally, this compound was tested against trypomastigote forms of T. cruzi and displayed an EC50 value of 67 µM, at least 6.6-fold more effective than the standard drug benznidazole. This is the first occurrence of PGG in the Plectranthus genus and the first anti-parasitic activity described for PGG in the literature.

Flavonoides e terpenoides de Croton muscicarpa (Euphorbiaceae)

A new sesquiterpene and twelve known compounds comprising eight flavonoids and four terpenoids, were isolated from the leaves, stems, roots and exudate of Croton muscicarpa Müll. Arg.. Their structures were identified as the terpenoids 6α-methoxy-cyperene, dammaradienol, squalene, acetyl aleuritolic acid and spathulenol, and as the flavonoids retusin, 3,7,4'-trimethoxy kaempferol, ombuine, pachipodol, kaempferol, casticin, 5-hydroxy-3,6,7,4'-tetramethoxyflavone and artemetin. All isolated compounds were characterized based on IR, MS, ¹H and 13C NMR, including 2D analyses (COSY, HSQC, HMBC, NOESY) and comparison with data from the literature.

Imobilização e caracterização de lacase e seu uso na biodegradação de efluentes de indústrias papeleiras

Laccase from Aspergillus sp was immobilized on glutaraldehyde-activated chitosan beads. A comparative study between free and immobilized laccase was conducted and the potential of the resulting immobilized derivative in the biodegradation of pulp and paper mill effluent was evaluated. The immobilized laccase is more resistant to various denaturing conditions, which allows for the reduction of 65% of the phenols (total and low molecular weight) and loss of 60% of total color in the effluent. These results show the potential of the immobilized laccase in the biodegradation of phenols, the chemical agents responsible for the high toxicity of the effluent generated in cellulose pulp industries.

Nanopartículas de poli-hidroxibutirato-co-valerato como suporte para a imobilização da lipase de Candida antarctica fração B

This work evaluates the immobilization of Candida antarctica lipase (Fraction B) using poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanoparticles as support. The effects of immobilization time (30-150 min) and pH (5-10) on lipase loading were evaluated. The stability of the immobilized enzyme towards temperature (40, 60, and 80 ºC), reuse and storage (at 4 ºC) were also determined. Furthermore, to assess its potential application in a system of interest, the immobilized lipase was used as a catalyst in the esterification of geraniol with oleic acid. The results indicated a time of 120 minutes and pH of 7 as optimal for immobilization. A 21 hour exposure of the PHBV-lipase derivative to 60 ºC showed a 33% reduction of the initial activity while storage at 4 ºC led to a residual activity (5% of the original activity). The derivative was used without significant loss of activity for 4 successive cycles. The use of the immobilized lipase as a catalyst in the production of geranyl oleate led to about 88% conversion of the initial reactants to products.

Interacciones de la glicina en soluciones acuosas de tetrafluoroborato de 1-butil, 3-metilimidazolio a diferentes temperaturas

Densities of glycine in aqueous solutions of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate were determined at temperatures ranging from 283.15 to 313.15 K. The apparent molar volume, infinite dilution apparent molar volume, second derivative of the infinite dilution partial molar volume with respect to temperature, partial molar volume of transfer at infinite dilution, and the number of hydration were determined. It was found that the apparent molar volume at infinite dilution was positive, but decreased with increasing ionic liquid concentration and increased with increasing temperature. On the other hand, the partial molar volume of transfer at infinite dilution behaved in a similar manner, but was negative.