Composição química e atividades biológicas das folhas de Cynara scolymus L. (alcachofra) cultivada no Brasil

The present paper describes the chemical composition and biological activities of artichoke cultivated in Brazil. Our studies demonstrated that glycosyl flavonoids (cynaroside and scolymoside), are the major constituents, along with cynaropicrin, a sesquiterpene lactone, and the triterpene lupeol. Cynarin, which is the main compound described for artichoke, was detected in very low concentration. Hexanic fraction exhibited considerable cytotoxicity and diuretic activities.

Determinação de compostos de massa molecular alta em folhas de plantas da Amazônia

The fractIons of dichloromethane extracts of leaves from andiroba (Carapa guianensis - Meliaceae), caapi (Banisteriopsis caapi - Malpighiaceae), cocoa (Theobroma cacao - Sterculiaceae), Brazil nut (Bertholletia excelsa - Lecytidaceae), cupuaçu (Theobroma grandiflorum - Sterculiaceae), marupá (Simaruba amara - Simaroubaceae) and rubber tree (Hevea brasiliensis - Euphorbiaceae), were analyzed by HT-HRGC and HT-HRGC-MS. Esters of homologous series of fatty acids and long chain alcohols, phytol, amyrines and tocopherols were characterized. The characterization of the compounds was based mainly in mass spectra data and in addition by usual spectrometric data (¹H and 13C NMR, IR).

A química dos ésteres de fosfato

This work summarizes important aspects of the chemistry of phosphate esters, with special emphasis on: i) advances in the design of enzymatic models for phosphatases; and ii) nerve agents and currently used strategies for detoxification. The physical organic chemical aspects that are responsible by the reactivity of phosphate esters are also discussed.

Sucroquímica: síntese e potencialidades de aplicações de alguns derivados químicos de sacarose

The interest on the use of sucrose as raw material increased in the last years. In this work, the synthesis and applications of sucrose derivatives as esters, ethers, and other products are discussed in a concise manner aiming to presenting the sucrochemistry as a promising field in organic chemistry from a rather accessible, low-priced, ecological, and renewable source.

Dirhamnosyl flavonoid and other constituents from Brillantaisia palisatii

A mixture containing sitosterol and stigmasterol; a new triterpene 3-epi-ursolic acid; another triterpene mixture comprising a-amyrin, b-amyrin and lupeol; verbascoside, a phenylpropanoid glycoside; and lespedin, a glycosyl flavonoid, were isolated. The less polar compounds (steroids and triterpenoids) were isolated from the hexane partition of the crude ethanolic extract while the more polar ones (phenylpropanoid glycoside and glycosyl flavonoid) were isolated from the ethyl acetate partition of the same extract. The structures of all compounds were established using modern spectrometric methods of elucidation. The spectroscopic data of Lespedin, a rare dirhamnosylflavonol with hypotensor activity and of the triterpene, 3-epi-ursolic acid, are also reported.

Síntese de enaminonas

The general term "enaminone" is applied to any compound bearing the conjugated system N-C=C-C=O. Enaminones are typical capto-dative ethylenes, showing particular properties due to pi-electron delocalization. Their reactivity can be predicted by structural patterns of substitution, conformation and configuration, making them versatile synthetic building blocks. In this review, a variety of methods for the synthesis of enaminones is described. The methods were divided into condensation of amines to beta-dicarbonyl compounds, addition of amines to a,b-unsaturated carbonyl compounds, condensation between carbonyl compounds and N-unsaturated functions and other methods, covering the period from 1993 to 2001.

Lignanas de Strychnos guianensis (Aublet) Mart.

The present communication reports the isolation and identification of three lignans from metanolic root extracts of Strychnos guianensis (Aublet) Mart.: olivil (1), cycloolivil (2) and the unknown derivative cycloolivil carbonate (3). From hexane extracts was identified a long chain fatty acid mixture and the triterpene lupeol. The analyses were based on chromatographic and spectroscopy techniques (IR, MS, GC/MS, ¹H-NMR and 13C-NMR, 1D (BB, DEPT 135) and 2D (¹H, ¹ H-COSY, ¹H, 13C-COSY, ¹H, 13C-COSY-LR, HMQC, HMBC and NOESY) and comparison with literature data.

Caracterização química do óleo da amêndoa de Sterculia striata St. Hil. et Naud

This paper describes total lipid content, unsaponifiable fraction and the acid, refractive, saponification and iodine indices of the oil of Sterculia striata nuts. The fatty acids, the sterols and the triterpene alcohols were determined. The percentage of cyclopropenoid fatty acids (CPFA), determined by NMR ¹H (15,5%), makes the nuts of this species unsuitable for human consumption.

Constituintes químicos de Melaleuca alternifolia (Myrtaceae)

The 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: 2alpha,3beta,23-trihydroxyolean-12-en-28-oic acid (arjunolic acid, 2), 3beta-hydroxylup-20(29)-en-27,28-dioic acid (melaleucic acid, 3), betulinic acid (4), betuline (5), 3beta-O-acetylurs-12-en-28-oic acid (6), a mixture of fatty acids and esters, and several hydrocarbons. For 2alpha,3beta,23-trihydroxyolean-12-en-28-oic acid (2) and 3beta-O-acetylurs-12-en-28-oic acid (6) a first detailed assignment of ¹H NMR is presented.

Análise de ácidos graxos não-esterificados de plasma humano por cromatografia gasosa capilar com injeção sem divisão de fluxo

The aim of the present work was to test the combination of non-esterified fatty acid (NEFA) isolation using fumed silicon dioxide with capillary gas-chromatography (C-GC) with splitless injection for the analysis of NEFAs in human plasma. Injection volume, solvent re-condensation and split purge flow-rate were the parameters evaluated for the analysis of fatty acid methyl esters by C-GC. The use of a solvent re-condensation technique, associated with 1.0 µL injection and a split purge flow rate of 80 mL/min resulted in satisfactory analysis of NEFAs. Fourteen fatty acids were identified in plasma samples, ranging from 2.03 to 184.0 µmol/L. The combination of both techniques proved useful for routine analyses of plasma NEFAs.

Biodiesel de soja: taxa de conversão em ésteres etílicos, caracterização físico-química e consumo em gerador de energia

Biodiesel was produced by the transesterification of neutral soybean oil and anhydrous ethanol using NaOH as catalyst. Combinations of biodiesel and diesel in the proportions of 0, 5, 10, 20, 40, 60, 80 and 100% were tested, respectively, as fuel in an energy generator. The average consumption and mixture performance were analysed. The tests showed a reduction in Diesel oil consumption when mixed with up to 20% of biodiesel. The quality characteristics of these fuels were analyzed.

Estudo da influência do solvente, carboidrato e ácido graxo na síntese enzimática de ésteres de açúcares

The aim of this work was to gain knowledge of enzymatic processes for the synthesis fatty acid esters of sugar, with the objective to develop an enzymatic process for the preparation of non-toxic biodegradable surface-active agents derived entirely from renewable resources. A wide range of data were collected for reaction conditions involving different sugars (glucose, fructose and sucrose), fatty acids (oleic, palmitic, lauric), solvents (hexane, heptane and t-butanol) and different sources of lipases in both free and immobilized forms. As a solvent t-butanol provided the best conditions to create a catalytic liquid phase in which the reaction occurs. Sugars were preferentially esterified in the following order: fructose > glucose > sucrose, depending on the enzyme preparation. For fructose no influence was found concerning de acyl donor and similar rates were achieved for all tested fatty acids. Ester synthesis was maximized for substrates containing fructose, lauric or oleic acids, t-butanol and lipase from porcine pancreas immobilized on polysiloxane-polyvinyl alcohol particles. Under such conditions molar conversions were higher than 50%.

Constituintes químicos de Luehea divaricata Mart. (Tiliaceae)

Chemical studies of the leaves of L. divaricata afforded 3beta-p-hydroxybenzoyl-tormentic acid, a triterpene with an ursene-type skeleton, a mixture whose main compound was an oleanene derivative, the maslinic acid, a C-glycoside flavone, vitexin and glucopyranosylsitosterol. A flavonoid, characterized as (-)-epicatechin, which belongs to the flavan-3-ol class, was isolated from the stem's bark. The structures of the compounds were elucidated by spectroscopic analysis. The antibacterial, antifungal and antiproliferative activities of the crude methanolic extracts of leaves and bark were evaluated and the antibacterial properties of the fractions of the barks were also investigated.

Triterpenóides pentacíclicos das folhas de Terminalia brasiliensis

Eleven oleanane, ursane and lupane-type triterpenes were isolated from the leaves of Terminalia brasiliensis Camb, daturadiol (3b,6beta-dihydroxy-olean-12-ene), 3beta-hydroxy-30-norlupan-20-one, lupenone, beta-amyrenone, alpha-amyrenone, lupeol, beta-amyrin, alpha-amyrin, betulin, erythrodiol and uvaol, in addition to squalene, sitosterol and alpha-tocopherol. The structures of these compounds were identified by ¹H and 13C NMR spectral analysis and comparison with literature data.

Emprego do carvão ativado para remoção de cobre em cachaça

Copper content is of great concern among sugarcane-spirit producers. It is released from copper-made distillers, during the distillation process. Activated carbon has been used to remove copper. However, depending on the amount of carbon and the duration of reaction, it can also remove higher alcohols and esters, which are important in the final product. A sugarcane spirit with 9 mg L-1 of copper was shaken with 2 to 26 g L-1 of activated carbon, during 10 to 1440 minutes. Then, copper and organic compounds were measured. At least 12 g L-1 of carbon and 60 min shaking time were necessary to decrease copper bellow 5 mg L-1. However, other components of the product were also affected.