Estudos Cinéticos da aquação do trans-[Co(en)2Cl2]Cl

The trans-dichlorobis(ethylenediamine)cobalt(III) chloride was synthesized in an undergraduate laboratory and its aquation reaction was carried out at different temperatures. This reaction follows pseudo-first-order kinetics and the rate constants, determined at 25, 35, 45, 55 and 70 º C, are 1.44 x 10-3; 5.14 x 10-3; 1.48 x 10-2; 4.21 x 10-2 and 2.21 x 10-1 s-1, respectively. The activation energy is 93.99 ± 2.88 kJ mol-1.

Extração, estruturas e propriedades de alfa- e beta-quitina

The fact that alpha- and beta-chitin adopt different arrays in the solid state is explored to emphasize their different properties and distinct spectral characteristics and X ray diffraction patterns. The methods for their extraction from the biomass in view of the preservation of their native structures and aiming to fulfill the claims of purity and uniformity for potential applications are discussed. The different arrays adopted by alpha- and beta-chitin also result in distinct reactivities toward the deacetylation reaction. Thus, the deacetylation of beta-chitin is more efficient owing to the better accessibility to amide groups due to the lower crystallinity of this polymorph.

Preparação e caracterização físico-química de complexos de inclusão entre anestésicos locais e hidroxipropil-beta-ciclodextrina

S(-) Bupivacaine (S(-)BVC) and Lidocaine (LDC) are widely used local anesthetics (LA). Hydroxypropyl beta-cyclodextrin (HP-beta-CD) is used as a drug-carrier system. The aim of this work was to characterize inclusion complexes between LA and HP-beta-CD. The affinity constants determined at different pHs show favourable complexation. The release kinetics experiments showed that S(-)BVC and LDC changed the released profiles in the presence of HP-beta-CD. Nuclear magnetic resonance experiments gave information about the interaction between LA and the cyclodextrin cavity. This study focused on the physicochemical characterization of drug-delivery formulations that come out as potentially new therapeutic options for pain treatment.

Chemical constituents from Bakeridesia pickelii Monteiro (Malvaceae) and the relaxant activity of kaempferol-3-O-beta-D-(6"-E-p -coumaroyl) glucopyranoside on guinea-pig ileum

The phytochemical investigation of Bakeridesia pickelii Monteiro led to the isolation of seven compounds: beta-sitosterol, a mixture of sitosteryl-3-O-beta-D-glucopyranoside and stigmasteryl-3-O-beta-D-glucopyranoside, vanillic acid, p-coumaric acid, quercetin 3-O-beta-D-glucopyranoside (isoquercitrin) and kaempferol-3-O-beta-D-(6"-E-p -coumaroyl) glucopyranoside (tiliroside), which was isolated as the major component. Their structures were elucidated on the basis of spectroscopic data such as IR, ¹H and 13C NMR, including two-dimensional techniques. Tiliroside relaxed the guinea-pig ileum pre-contracted with KCl 40 mM (EC50 = 9.5 ± 1.0 x 10-5 M), acetylcholine 10-6 M (EC50 = 2.3 ± 0.9 x 10-5 M) or histamine 10-6 M (EC50 = 4.1 ± 1.0 x 10-5 M) in a concentration-dependent manner.

Caracterização do complexo de inclusão ropivacaína: beta-ciclodextrina

Characteriza of the inclusion complex ropivacaine: beta-cyclodextrin. Ropivacaine (RVC) is a widely used local anesthetic. The complexation of RVC with beta-cyclodextrin (beta-CD) is of great interest for the development of more efficient local anesthetic formulations. The present work focuses on the characterization of the RVC:beta-CD complex by nuclear magnetic resonance (NMR). The stoichiometry of the complex is 1:2 RVC:beta-CD. DOSY-NMR shows that the association constant is 55.5 M-1. Longitudinal relaxation time results show that RVC changes its mobility in the presence of beta-CD. This study is focused on the physicochemical characterization of inclusion complexes that are potentials options for pain treatment.

Síntese de amidas e sulfonamidas de beta-D-galactopiranosilamina e beta-lactosilamina e avaliação de suas interações com lectinas de Erythrina cristagalli e de Ricinus communis

We report herein the synthesis of some beta-D-galactopyranosylamine and beta-lactosylamine amides and sulfonamides. The interactions of these compounds with lectins from the seeds of Erythrina cristagalli (LEC) and Ricinus communis (RCA120) were evaluated in a hemagglutination inhibitory activity assay. D-Galactose and lactose were used as reference compounds. The beta-lactosylamine amides and sulfonamides were nearly as active as lactose in inhibiting LEC mediated hemagglutination and were less active against RCA120 agglutinin. The beta-D-galactopyranosylamine amides and sulfonamides were, with one exception, considerably less active than D-galactose in the assay with both lectins.

Interesterificação química: alternativa para obtenção de gorduras zero trans

The function of lipids in human nutrition has been intensively debated in the last decade.This context reinforces the concern about controlling the trans fat ingestion, due to its negative implications on health. Interesterification provides an important alternative to modify the consistency of oils and fats without causing formation of trans isomers. This article reports research done towards production of zero trans fats by chemical interesterification, for different industrial purposes. Aspects related to the effect of trans fats on diet, their impact on health and modifications in Brazilian legislation are also covered.

Compostos polifenólicos do kino de Eucalyptus citriodora

Phytochemical analysis of the kino of Eucalyptus citriodora led to the isolation of 1-O,2-O-digaloil-6-O-trans -p-cumaroil-beta-D-glucopyranoside, 1-O-trans-p-cumaroil-6-O -cinamoil-beta-D-glucopyranoside, alpha and beta 6-O-trans-p-cumaroil-D-glucopyranoside, 7-methylaromadendrin-4'-O-6''- trans-p-cumaroil-beta-D-glucopyranoside, aromadendrin, aromadendrin-7-methyl-ether, naringenin, sakuranetin, kaempferol-7-methyl-ether and galic acid. Structural elucidation of the isolated compounds was established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift correlated NMR pulse sequences (¹H,¹H-COSY, HMQC, HMBC).

Indução assimétrica 1,5-Anti na adição de enolatos de boro de metilcetonas beta-oxigenadas a aldeídos

High levels of substrate-based 1,5-stereoinduction are obtained in the boron-mediated aldol reactions of beta-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products. At present, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on a hydrogen bonding between the alkoxy oxygen and the formyl hydrogen has been recently proposed.

Caracterização físico-química de complexo de inclusão entre hidroximetilnitrofurazona e hidroxipropil-beta-ciclodextrina

Hydroxymethylnitrofurazone (NFOH) is a prodrug that is active against Trypanosoma cruzi. It however presents low solubility and high toxicity. Hydroxypropyl-beta-cyclodextrin (HP-beta-CD) can be used as a drug-delivery system for NFOH modifying its physico-chemical properties. The aim of this work is to characterize the inclusion complex between NFOH and HP-beta-CD. The rate of NFOH release decreases after complexation and thermodynamic parameters from the solubility isotherm studies revealed that a stable complex is formed (deltaGº= 1.7 kJ/mol). This study focuses on the physico-chemical characterization of a drug-delivery formulation that comes out as a potentially new therapeutic option for Chagas disease treatment.

Síntese de beta-N-acetilglicosaminídeos de arila modificados em C-6 como potenciais agentes antimicrobianos

We report herein the synthesis of aryl beta-N-acetylglucosaminides containing azido, amino and acetamido groups at C-6 as potential antimicrobial agents. It was expected that these compounds could interfere with the biosynthesis and/or biotransformation of N-acetylglucosamine in fungi and bacteria. None of the compounds showed antimicrobial activity against bacteria (Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa), filamentous fungus (Aspergillus niger) and yeasts (Saccharomyces cerevisae, Candida albicans and Candida tropicallis), at the concentration of 1 mg/mL in agar diffusion assay.

Ondas ultrassônicas e pérolas de vidro: um novo método de extração de beta-galactosidase para uso em laboratório

The optimization of a traditional technique of cellular disruption by abrasion was carried out and a process using ultrasonic waves associated with glass pearls to extract beta-galactosidase from Kluyveromyces marxianus proposed. In the first case, the effects of the diameter and weight of the pearls in relation to the volume of cellular suspension and amount of time for cellular disruption were evaluated. The efficiency of the new process of cellular disruption was evaluated by varying the length of time of sonification and comparing with the method of abrasion under the same conditions. The proposed method can be efficiently applied to obtain beta-galactosidase at laboratory scale.

Purificação e caracterização da beta-lapachona e estudo de estabilidade dos cristais em diferentes condições de armazenamento

The beta-lapachone is a product obtained from the Ipê Roxo tree [Tabebuia avellandae], which has proved its excellent antineoplasic potential acting through a particular mechanism of apoptosis against various cancer types. This study aims at determining the identity card of beta-lapachone by means of physico-chemical and pharmaco-technical characterization. A purifying process has been performed, as well as the isolation of a contaminant, its isomer alpha-lapachone. A stability study was also performed, determining the ideal storing conditions for beta-lapachone, essential for the ongoing pre-formulation studies for obtaining the different classic pharmaceutical forms and modified release systems.

Constituintes químicos de Ipomoea subincana Meisn. (Convolvulaceae)

The chloroform extract of aerial parts of Ipomoea subincana was submitted to different chromatographic procedures which afforded methyl caffeate, ethyl caffeate, methyl 3,4-dimethoxycinnamate, lupeol, alpha-amyrin, beta-amyrin, 3-beta-O-beta-D-glycopiranosyl-sitosterol, beta-sitosterol, stigmasterol, scopoletin, aromadendrane-4beta,10alpha-diol, n-docosyl-cis-p-coumarate and n-icosyl-trans-p-coumarate, vanilin, cinamic acid and vanillic acid. However, from the ethyl acetate extract besides quercetin and 3-O-beta-D-glycopiranosyl-quercetin were isolated methyl 4-O-E-feruloyl-5-O-E-caffeoyl-quinate, methyl 3,5-di-O-E-caffeoyl-quinate and methyl 4-O-E-caffeoyl-quinate. The structures of the compounds were established on the basis of spectral data.

Polarizabilidades e primeira hiperpolarizabilidades elétricas dipolares de ésteres E-4-amino-trans-1,3-butadienil-(1',2'-di-hidroxibenzeno) de boro, alumínio e gálio

Static electric dipole polarizabilities and first hyperpolarizabilites have been calculated for the title molecules and their 3' and 4'-nitro derivatives at ab-initio Hartree- Fock/6-31G(d, p) level. The influence of the pivotal p vacant 3A elements (B, Al or Ga) substitution on the electrical properties of these molecules is detailed. The axial vector components of the first hyperpolarizabilities β(0) of the push-pull 4'-nitro derivatives, -18.2×10-32 esu (B), -21.1×10-32 esu (Al) and -20.8×10-32 esu (Ga) are calculated to be as much as fourfold larger then that calculated for the p-nitroaniline, a reference organic molecule for comparison for this type of molecular property.