Ligações hidrogênio fortes em ácidos dicarboxílicos e diaminas aromáticas

A very short-strong hydrogen bond (<2 Å, >20kcal/mol) is found in the monoanion of certain dicarboxylic acids derived from maleic and dialkylmalonic acids. Certain aromatic diamines that are known as proton sponge have exceptionally high basicity (pKa) and are only monoprotonated with strong acids like percloric acid. The closed proximity between the two basic centers provokes a strong steric interaction that is relieved upon protonation. Similar effects are found in dicarboxylic acids (hydrogen maleate and hydrogen dialkylmalonates) that present a very short distance between the two oxygens and a short-strong hydrogen bond.

Aplicação de lipases microbianas na obtenção de concentrados de ácidos graxos poliinsaturados

Several polyunsaturated fatty acids (PUFA) belonging to the ômega 6 series, such as cis-6,9,12 gamma-linolenic acid, as well as those of the ômega 3 series, such as cis-5,8,11,14,17-eicosapentaenoic acid and cis-4,7,10,13,16,19-docosahexaenoic acid are of considerable interest due to their nutritional and therapeutic properties. Methods used for the concentration of PUFA from natural sources include urea adduct formation, solvent winterization, supercritical fluid extraction and lipase-catalyzed reaction. Lipases are known to have little reactivity on PUFA and these acids can be enriched by selective hydrolysis, direct esterification of glycerol with PUFA and interesterification. Since lipase reactions are advantageous with respect to fatty acid, positional specificities and mild incubation condition, these enzymes are considered to be suitable for the production of PUFA concentrates for medical purposes.

Análise química quantitativa para a padronização do óleo de copaíba por cromatografia em fase gasosa de alta resolução

Quantitative GC-FID was evaluated for analysis of methylated copaiba oils, using trans-(-)-caryophyllene or methyl copalate as external standards. Analytical curves showed good linearity and reproducibility in terms of correlation coefficients (0.9992 and 0.996, respectively) and relative standard deviation (< 3%). Quantification of sesquiterpenes and diterpenic acids were performed with each standard, separately. When compared with the integrator response normalization, the standardization was statistically similar for the case of methyl copalate, but the response of trans-(-)-caryophyllene was statistically (P < 0.05) different. This method showed to be suitable for classification and quality control of commercial samples of the oils.

Determinação das propriedades catalíticas em meio aquoso e orgânico da lipase de Candida rugosa imobilizada em celulignina quimicamente modificada por carbonildiimidazol

Microbial lipase from Candida rugosa was immobilized by covalent binding on wood cellulignin (Eucaliptus grandis) chemically modified with carbonyldiimidazole. The immobilized system was fully evaluated in aqueous (olive oil hydrolysis) and organic (ester synthesis) media. A comparative study between free and immobilized lipase was carried out in terms of pH, temperature and thermal stability. A higher pH value (8.0) was found optimal for the immobilized lipase. The optimal reaction temperature shifted from 37 °C for the free lipase to 45 °C for the immobilized lipase. The pattern of heat stability indicated that the immobilization process tends to stabilize the enzyme. Kinetics tests at 37 °C following the hydrolysis of olive oil obeyed the Michaelis-Menten rate equation. Values for Km = 924.9 mM and Vmax = 198.3 U/mg were lower than for free lipase, suggesting that the affinity towards the substrate changed and the activity of the immobilized lipase decreased during the course of immobilization. The immobilized derivative was also tested in the ester synthesis from several alcohols and carboxylic acids.

Compostos organofosforados pentavalentes: histórico, métodos sintéticos de preparação e aplicações como inseticidas e agentes antitumorais

This paper is a review of the history, synthesis and application of organophosphorus compounds, especially of those of pentavalent phosphorus, such as phosphoramidates, phosphorothioates, phosphonates and phosphonic acids with insecticide and anticancer activities. The organophosphorus compounds with agrochemical applications show great structural variety, They include not only insecticides, but also fungicides, herbicides, and others. The large variety of commercially available organophosphorus pesticides is remarkable. Even more interesting is the high efficiency of some organophosphorus compounds as anticancer agents such as cyclophosphamide and its derivatives.

Constituintes químicos das cascas do caule de Cenostigma macrophyllum: ocorrência de colesterol

Phytochemical investigation of the bark of Cenostigma macrophyllum (Leguminosae-Caesapinioideae) resulted in the isolation and identification of valoneic acid dilactone, ellagic acid, lupeol, alkyl ferulate, four free sterols (cholesterol, campesterol, stigmasterol and sitosterol), a mixture of sitosteryl ester derivatives of fatty acids, sitosterol-3-O-beta-D-glucopyranoside, stigmasterol-3-O-beta-D-glucopyranoside and saturated and unsaturated fatty acids. The structures of the isolated compounds were identified by ¹H and 13C NMR spectral analysis and comparison with literature data. The mixtures of 3-beta-hydroxysterols and fatty acids were analysed by GC/MS.

Estudio analitico de especies oxigenadas en el aceite de teobroma ozonizado

Ozonization of theobroma oil at different applied ozone dosages was carried out with measurement of peroxide index values, oxygen percentage content and fatty acids composition. The comparison of peroxide values with percentage content of oxygen at different applied ozone dosages showed good correlation (r=0.9923). Unsaturated fatty acids and triacylglycerols decrease with ozone applied dosage due to ozone reaction with double bonds. Small amounts of oleic acid were consumed with applied ozone dosage at 35 mg/g, which demonstrated that peroxide values and oxygen content were not principally increased by the ozone attack on the double bonds, but other mechanisms could be involved in the reaction system.

Determinação simultânea dos ácidos orgânicos tartárico, málico, ascórbico e cítrico em polpas de acerola, açaí e caju e avaliação da estabilidade em sucos de caju

The aim of the present study was determining the main organic acids in pulp and juices, as well as evaluating their stability, after opening the package, by liquid chromatography in a C18 column with isocratic elution and UV detection. In açaí pulp tartaric, malic and citric acids were found. Cashew samples presented all of the organic acids evaluated, besides high concentrations of ascorbic and malic acids. Acerola pulp had the highest ascorbic acid concentration. A small decrease in organic acid content during storage was observed. Malic and citric acids seem to be more stable than tartaric and ascorbic acids.

químicos das folhas de Qualea grandiflora: atribuição dos dados de RMN de dois flavonóides glicosilados acilados diastereoisoméricos

Phytochemical investigation from leaves of the Qualea grandiflora (Vochysiaceae) resulted in the isolation and identification of kaempferol-3-O-α-L-(4"-E-p-coumaroyl)-rhamnoside, kaempferol-3-O-α-L-(4"-Z-p-coumaroyl)-rhamnoside, squalene, phytol, lupeol, α-amyrin, β-amyrin, sitosterol, sitostenone, sitosterol-3-O-β-D-glucopyranoside, ursolic and oleanolic acids. The structures of the compounds were identified by 1D- and 2D-NMR experiments, mass and UV spectrometry and comparison with literature data.

Constituintes químicos e avaliação do potencial antiinflamatório e antioxidante de extratos das folhas de Chomelia obtusa Cham. & Schltdl. (Rubiaceae)

The phytochemical investigation of Chomelia obtusa leaves led to the isolation of four triterpenes (3-O-β-D-quinovopyranosyl-28-O-β-D-glycopyranosyl quinovic acid, 3-O-β-D-quinovopyranosyl-28-O-β-D-glycopyranosyl cincholic acid, and a mixture of ursolic and oleanolic acids), two flavonoids (3-O-β-D-glycopyranosyl quercetin, 3-O-[α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranoside] quercetin), besides bornesitol and a mixture of 3,5- and 4,5-O-dicaffeoyl quinic acids. The structures of the isolated compounds were assigned on the basis of spectroscopic data, including two-dimensional NMR methods. The anti-inflammatory and antioxidant activities of the crude methanolic extract and of its fractions were evaluated. This is the first report on the chemical and biological investigation of the Chomelia genus.

Flavonóides, norisoprenóides e outros terpenos das folhas de Tapirira guianensis

From hexane fraction of methanol extract of leaves of Tapirira guianensis (Anacardiaceae) were obtained lupeol, 24-methylenecycloartan-3-ol, phytol, α-amyrin, β-amyrin, sitosterol, sitostenone, glycosyl sitosterol, as well as sitosterol esterified with palmitic and stearic acids. Phytol, α-amyrin and β-amyrin esterified with fatty acids were also identified from same extract. The EtOAc extract besides the norisoprenoids (6S,7E,9S)-6,9-dihydroxy-megastigma-4,7-dien -3-one 9-O-β-glucopyranoside and (6S,7E,9R)-6,9-dihydroxy-megastigma-4,7-dien-3-one 9-O-β-glucopyranoside also afforded kaempferol 3-O-rhamnoside, kaempferol 3-O-arabinofuranoside, quercetin 3-O-rhamnoside, and kaempferol. The structural elucidation of isolated compounds were based on UV, IR, MS, ¹H and 13C NMR data analysis.

Compostos bioativos e atividade antioxidante do café conilon submetido a diferentes graus de torra

The bioactive compounds and antioxidant activity presented by Conilon coffee (C. Canephora) variety, produced in the Espírito Santo State, Brazil, were quantified. The light roast coffee showed the highest level of total phenols, trigonelline, caffeic and chlorogenic acids. The proanthocyanidin level was the highest for dark roast coffee, while caffeine level didn't show significative changes for the light and middle roast coffees. All the Conilon coffee extracts showed antioxidant activity depending on bioactive compounds concentration and roasting degree. The coffee samples submitted to a light roasting degree showed the highest antioxidant activity.

Derivados oleananos e ursanos e sua importância na descoberta de novos fármacos com atividade antitumoral, anti-inflamatória e antioxidante

Oleanolic and ursolic acids are triterpenes that exist abundantly in the plant kingdom. They show antitumor activity and their cytotoxic activity was already evaluated against a broad range of cell lines. The inhibition of enzymes involved in the metabolism of DNA and the induction of apoptosis are known events that have been related to the antitumour activity of these triterpenes. The antiinflamatory and antioxidant activities also seem to play an important role in their antitumour activity. In this review, it is presented an overview of the importance of the potential antitumour, antiinflamatory and antioxidant activities of these triterpenoid derivatives. Also, we propose a structural-activity relationship to triterpenes containing oleanane or ursane skeleton and their cytotoxic activity.

Cromatografia de afinidade por íons metálicos imobilizados (IMAC) de biomoléculas: aspectos fundamentais e aplicações tecnológicas

Immobilized Metal Ion Affinity Cromatography - IMAC - is a group-specific based adsorption applied to the purification and structure-function studies of proteins and nucleic acids. The adsorption is based on coordination between a metal ion chelated on the surface of a solid matrix and electron donor groups at the surface of the biomolecule. IMAC is a highly selective, low cost, and easily scaled-up technique being used in research and commercial operations. A separation process can be designed for a specific molecule by just selecting an appropriate metal ion, chelating agent, and operational conditions such as pH, ionic strength, and buffer type.

Hidrólise do óleo de Azadirachta indica em água subcrítica e determinação da composição dos triacilglicerídeos e ácidos graxos por cromatografia gasosa de alta resolução a alta temperatura e cromatografia gasosa de alta resolução acoplada à espectrometria de massas

The development of modern analytical tools plays an important role in quality control. The main purpose of this study was to explore the use of subcritical water as a versatile analytical tool, employed simultaneously as a reagent and solvent, as well as the application of high temperature-high resolution gas chromatography (HT-HRGC) to develop a procedure for the analysis of triacylglycerides and fatty acids in Azadirachta indica A. Juss. (Neem) oil without the need for solvents, chemical reagents, or catalytic agents. The developed method presented satisfactory results and is in agreement with the concepts of Green Analytical Chemistry (GAC).