Synthesis and biological evaluation of biaryl analogs of antitubulin compounds

This paper reports the synthesis of methanones and esters bearing different substitution patterns as spacer groups between aromatic rings. This series of compounds can be considered phenstatin analogs. Two of the newly synthesized compounds, 5a and 5c, strongly inhibited tubulin polymerization and the binding of [³H] colchicine to tubulin, suggesting that, akin to phenstatin and combretastatin A-4, they can bind to tubulin at the colchicine site.

A fração volátil das aguardentes de cana produzidas no Brasil

The volatile fraction of sugar cane spirits plays a key role in the quality and acceptance of these beverages. The composition of this fraction is dependent on the way sugar cane collection, fermentation, distillation and aging are carried out. The materials used in these processes strongly influence chemical composition. Acetic acid, acetaldehyde, ethyl acetate, ethanol, 2.3-butanedione, n-propanol, 3-methyl-buthanol and isobuthanol were the major volatiles in spirits. Dimethyl sulfide and n-propanol impaired beverage flavor. Ethyl octanoate, 1.1-diethoxy-ethane, 2-phenylethanol and 3-methyl-butanol were important aroma contributors. Ageing allows the extraction of flavor-active components (e.g., phenolic compounds) from wood.

Montagem de uma prensa para fios de sódio metálico

Several organic chemistry labs in Brazil suffers from the absence of a safe method to extrude sodium wire, used to obtain anhydrous solvents such as THF or ethyl ether. This technical note presents the assembly instructions for a sodium wire press, similar to the one that has been used for the past four years in our laboratory without any maintenance.

Novas N-benzoiltiraminas de Swinglea glutinosa (Rutaceae)

Phytochemical studies of the leaves and fruits have led to the identification of the known amides (E)-N-methyl-cinnamamide, N-benzoyltyramine, N-benzoyl-O-geranyltyramine, N-benzoyl-O-(4-acetoxyl)-geranyltyramine, in addition to the new N-{2-[4-(butoxyl-3-one)phenyl]ethyl}benzamide, N-{2-[4-(2,3-dihydroxy-2-methyl-butoxylanal)phenyl]ethyl}benzamide, N-{2-[4-(2,3-dihydroxy-2-methyl-butoxyloic)phenyl]ethyl}benzamide, N-benzoyl-O-(4-acetoxyl-6,7-epoxy)-geranyltyramine, N-benzoyl-O-(4-acetoxyl-6,7-dihydroxy)-geranyltyramine and N-benzoyl-O-(6-acetoxyl-4,7-dihydroxy)-geranyltyramine. The isolated compounds clearly point to Swinglea phytochemical affinities with other Aurantioideae species.

Sesquiterpenos produzidos pelo fungo endofítico Phomopsis cassiae com atividade antifúngica e inibidora de acetilcolinesterase

SESQUITERPENES PRODUCED BY ENDOPHYTIC FUNGUS Phomopsis cassiae WITH ANTIFUNGAL AND ACETYLCHOLINESTERASE INHIBITION ACTIVITIES. Two new diastereoisomeric cadinanes sesquiterpenes 3,9-dihydroxycalamenene (1-2), along with the known 3-hydroxycalamen-8-one (3) and aristelegone-A (4), were isolated from ethyl acetate extract of Phomopsis cassiae, an endophytic fungus in Cassia spectabilis. Their structures, including relative stereochemistry, were determined on the basis of detailed interpretation of 2D NMR spectra and comparison with related known compounds. Compounds 1-4 displayed antifungal activity against the phytopathogenic fungi Cladosporium cladosporioides and C. sphaerospermum, as well as inhibition of acetylcholinesterase.

Isolamento e avaliação do potencial citotóxico de derivados fenólicos de Schinus terebinthifolius Raddi (Anacardiaceae)

The EtOH extract from leaves of S. terebinthifolius was subjected to partition between EtOH:H2O and hexane, CH2Cl2, and EtOAc. The phases obtained were evaluated in vitro against human tumoral cell lines and the EtOAc phase exhibited activity. Chromatographic procedures afforded gallic acid (1), methyl (2) and ethyl (3) gallates, trans-catechin (4), quercitrin (5), and afzelin (6), being the first occurrence of 1, 4 and 6 in S. terebinthifolius.In vitro cytotoxic evaluation of 1 - 6 indicated that gallic acid (1) displayed higher activity than ethyl gallate (3) against HL-60 and HeLa cells, while compounds 2, 4 - 6 were inactive.

Chemical characterization by GC-MS and phytotoxic potential of non-polar and polar fractions of seeds of Dioteryx odorata (Aubl.) Willd. from Venezuelan regions

Dipteryx odorata (Aubl.) Willd. is a tall arboreal species native to Central and Northern South America. This paper describes the chemical characterization and phytotoxic potential of polar and non-polar extracts from D. odorata seeds. Structural determinations were accomplished by chemical derivatization and analyzed by GC/MS. The chemical composition of the non-polar fraction (hexane and dichloromethane) presented fatty acids as major constituent. Medium polar and polar fractions (ethyl acetate and ethanol: water) contained carboxylic acid and high 6,7-Dyhidroxycoumarin-β-D-glucopyranoside content, not previously reported for seeds of D. odorata. Extracts showed a significant level of phytotoxic activity, correlated to the content of coumarin derivatives, predominantly in the polar fraction.

Constituintes químicos de Vernonia scorpioides (Lam) Pers. (Asteraceae)

The chemical investigation of hexane and ethanol extracts from the aerial parts of Vernonia scorpioides resulted in the isolation and characterization of a new polyacetylene lactone, rel-4-dihydro-4β-hydroxy-5a-octa-2,4,6-triynyl-furan-2-(5H)-one, along with the new ethyl 3,4-dihydroxy-6,8,10-triynyl-dodecanoate, and seven known compounds: taraxasteryl acetate, lupeyl acetate, lupeol, lupenone, β-sitosterol, stigmasterol and luteolin. The structure of all compounds was determined by spectrometric techniques (HR-ESI-MS, ¹H and 13C NMR and IV) and comparison with published spectral data.

Estudo do comportamento da lipase comercial Lipozyme RM IM em reações de esterificação para obtenção de biodiesel

The aim of this work was to study monoalkyl ester synthesis catalyzed by immobilized lipase Lipozyme RM IM via the esterification reaction. Yields of over 90% were obtained with butanol in esterification reactions with oleic acid. In the reactions with deodorizer distillates of vegetable oils and butanol, the conversion obtained was greater than 80% after 2.5 h. For the esterification reaction of palm fatty acid deodorizer distillate (PFAD) and butanol, seven reuse cycles of Lipozyme RM IM were carried out and the final conversion was 42% lower than the initial conversion.

Preparative separation and purification of bufadienolides from ChanSu by high-speed counter-current chromatography combined with preparative HPLC

Eight bufadienolides were successfully isolated and purified from ChanSu by high-speed counter-current chromatography (HSCCC) combined with preparative HPLC (prep-HPLC). First, a stepwise elution mode of HSCCC with the solvent system composed of petroleum ether - ethyl acetate - methanol - water (4:6:4:6, 4:6:5:5, v/v) was employed and four bufadienolides, two partially purified fractions were obtained from 200 mg of crude extract. The partially purified fractions III and VI were then further separated by prep-HPLC, respectively, and another four bufadienolides were recovered. Their structures were confirmed by ESI-MS and ¹H-NMR spectra.

Determinação simultânea de topiramato, carbamazepina, fenitoína e fenobarbital em plasma empregando cromatografia a gás com detector de nitrogênio e fósforo

Topiramate and the other frequently co-administered antiepileptic drugs carbamazepine, phenytoin and phenobarbital were determined in 100 µL plasma samples by gas chromatography with nitrogen phosphorus detection (GC-NPD), after a one-step liquid-liquid extraction with ethyl acetate, followed by flash methylation with trimethylphenylammonium hydroxide. Total chromatographic run time was 12.5 min. Intra-assay and inter-assay precision was 2.5-7.3% and 1.6-5.2%, respectively. Accuracy was 100.1-104.2%. The limit of quantitation was 1 µg mL-1 for all analytes, proving suitable for routine application in therapeutic drug monitoring of antiepileptic drugs.

Decaimento de íons cianato e a formação de carbamato de etila

Cyanate ion stability was studied in aqueous/ethanolic solutions, pH = 4.5 (CH3COOH/NaCH3COO), at different temperatures. Following the decay [(OCN)-] versus time, in the presence of excess C2H5OH, the rate constant for this reaction (k1) was calculated as (2.5 ± 0.3) x 10-4 s-1 at 25 ºC, for 0 < [C2H5OH] < 13.7 x 10-1 mol L-1. For [C2H5OH] > 2.0 mol L-1 a decrease in the numerical value of k1 was observed, reaching 5.2 x 10-5 s-1 when [CH3CH2OH] = 13.7 mol L-1. Variations in the kinetic parameter values ΔH1‡, ΔS1‡ and ΔG1‡ for the cyanate ion decay reaction were observed for solutions at different ethanol concentrations.

A general A³: coupling reaction based on functionalized alkynes

A range of hydroxypropargylpiperidones were efficiently obtained by a one-pot three-component coupling reaction of aldehydes, alkynols, and a primary amine equivalent (4-piperidone hydrochloride hydrate) in ethyl acetate using copper(I) chloride as a catalyst. The developed protocol proved to be equally efficient using a range of aliphatic aldehydes, including paraformaldehyde, and using protected and unprotected alkynols.

Preparative separation of C19-diterpenoid alkaloids from Aconitum carmichaelii Debx by pH‑zone-refining counter-current chromatography

The technique of pH-zone-refining counter-current chromatography was successfully applied to preparatively separate three C19-diterpenoid alkaloids from the crude extracts of Aconitum carmichaelii for the first time using a two-phase solvent system of petroleum ether-ethyl acetate-methanol-water (5:5:1:9, v/v/v/v). Mesaconitine (I), hypaconitine (II), and deoxyaconitine (III) were obtained from 2.5 g of the crude alkaloids in a one-step separation; the yields were 4.16%, 16.96%, and 5.05%, respectively. The purities of compounds I, II, and III were 93.0%, 95%, and 96%, respectively, as determined by HPLC. The chemical structures of the three compounds were identified by electrospray ionization mass spectrometry (ESI-MS) and NMR.

Ésteres de cloropropanóis e de glicidol em alimentos

Chloropropanols are a well-known group of food processing contaminants. They are formed through the reaction between lipids and chlorides when submitted to thermal treatment, and can be found in free and bound form. Although free chloropropanols were identified around 30 years ago, the occurrence of bound forms, especially 3-MCPD, and glycidyl fatty acid esters, has only recently been reported in several food products. Dietary exposure to these ester-bound compounds has been considered a priority food safety issue since free forms can be potentially released through the action of gut lipases, representing a major toxicological concern.