The wide synthetic versatility of five membered rings containing phosphorus

The chemistry of cyclopentadiene rings has been widely studied. This review article deals with a similar chemistry of new compounds containing from 1 to 5 phosphorus atoms on the ring substituting the carbon atoms. The neutral rings containing one, two and three phosphorus atoms can be used as building blocks for the synthesis of new organic compounds containing phosphorus. These rings plus the anionic ones also show great potential as ligands in coordination chemistry. The aim of this article is to show how important this new area is and how diverse the chemistry related to a single type of ring can be.

Detecção de adulterações em produtos alimentares contendo leite e/ou proteínas lácteas

A critical review of the most relevant analytical methodologies for quality and authenticity control of dairy products and foods containing milk proteins is presented. Chromatographic, electrophoretic and immunological methods are used for: detection of cow's milk in ewe and goat milks, detection of whey added to milk, detection of caseins and/or whey proteins in non-lactic foods and study compounds resulting from milk proteins degradation. Techniques based on polimerase chain reaction are also suitable for detection of cow's milk on cheeses of ewe and goat milks.

Polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and polychlorinated biphenyls (PCB): main sources, environmental behaviour and risk to man and biota

Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofuranes (PCDF) and polychlorinated biphenyls (PCB) are types of persistent and bioaccumulating organic pollutants with enhanced chronic toxicity and carcinogenic properties and can be considered as environmental indicators of anthropogenic activities since their occurrence in the environment can always be linked to anthropogenic activities. The present paper reviews the main sources and behaviour of these compounds in the environment as well as the risks they represent to man and biota.

Constituintes químicos e avaliação do potencial alelopático de Adiantum tetraphyllum Humb. & Bonpl. Ex. Willd (Pteridaceae)

Chemical studies of green leaves of A. tetraphyllum afforded beta-sitosterol, a mixture containing the ethyl esters of long chain carboxylic acids, 30-normethyl-lupan-20-one, hopan-22-ol, phytol, phyten-3(20)-1,2-diol, quercetin and quercetin-3-O-beta-D-glucoside. The structures of the compounds were elucidated by spectroscopic and GC analysis. The allelopathic potentials of the crude ethanolic extract and fractions were evaluated against Lactuca sativa (letuce) and Allium cepa (onion) seeds.

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.

Antifungal derivatives from Piper mollicomum and P. lhotzkyanum (Piperaceae)

Bioguided fractionation of the extracts from leaves of Piper mollicomum and Piper lhotzkyanum against the fungi Cladosporium cladosporioides and C. sphaerospermum afforded seven bioactive compounds, four being chromenes: methyl 2,2-dimethyl-2H-chromene-6-carboxylate, methyl 8-hydroxy-2,2-dimethyl-2H-chromene-6-carboxylate, 2-methyl-2-[4'-methyl-3'-pentenyl]-2H-1-benzopyran-6-carboxylic acid, 2,2-dimethyl-2H-chromene-6-carboxylic acid, one a dihydrochalcone: 2',6'-dihydroxy-4'-methoxydihydrochalcone, and two flavanones: 7-methoxy-5,4'-dihydroxy-flavanone and 7,4'-dimethoxy-5-hydroxy-flavanone. The structures of the bioactive isolated derivatives were elucidated by interpretation of their NMR data [¹H and 13C (BBD, DEPT 135º)], and mass spectral data as well as by comparison with data described in the literature.

Antimycobacterial and cytotoxicity activity of synthetic and natural compounds

Antimycobacterial and cytotoxicity activity of synthetic and natural compounds. Secondary metabolites from Curvularia eragrostidis and Drechslera dematioidea, Clusia sp. floral resin, alkaloids from Pilocarpus alatus, salicylideneanilines, piperidine amides, the amine 1-cinnamylpiperazine and chiral pyridinium salts were assayed on Mycobacterium tuberculosis H37Rv. N-(salicylidene)-2-hydroxyaniline was the most effective compound with a minimal inhibitory concentration (MIC) of 8 µmol/L. Dihydrocurvularin was moderately effective with a MIC of 40 µmol/L. Clusia sp. floral resin and a gallocatechin-epigallocatechin mixture showed MIC of 0.02 g/L and 38 µmol/L, respectively. The cytotoxicity was evaluated for N-(salicylidene)-2-hydroxyaniline, curvularin, dihydrocurvularin and Clusia sp. floral resin, and the selectivity indexes were > 125, 0.47, 0.75 and 5, respectively.

Métodos de obtenção, reatividade e importância biológica de 4-tiazolidinonas

Molecules containing the 4-thiazolidinone ring are known to possess a wide range of biological properties including antimicrobial and anti-inflammatory activities among others. These compounds can be synthesized by cyclization reactions involving alpha-haloacetic acid or alpha-mercaptoacetic acid and employed in several chemoselective reactions. Comprehensive reviews have been written on 4-thiazolidinones in 1961 by Brown and in 1980 by Singh et al. In the recent literature, some new synthesis methods for 4-thiazolidinone derivatives and several reactions have been reported. These advances warrant to review the chemical and biological properties of compounds with this important heterocycle employed in synthetic organic chemistry and medicinal chemistry.

Synthesis, structure and physicochemical properties of zinc and copper complexes based on sulfonamides containing 8-aminoquinoline ligands

Sulfonamides obtained by reaction of 8-aminoquinoline with 4-nitrobenzenesulfonylchloride and 2,4,6-triisopropylbenzenesulfonyl chloride were used to synthesize coordination compounds with CuII and ZnII with a ML2 composition. Determination of the crystal structures of the resulting zinc and copper complexes by X-ray diffraction show a distorted tetrahedral environment for the [Cu(qnbsa)2], [Cu(qibsa)2] and [Zn(qibsa)2] complexes in which the sulfonamide group acts as a bidentate ligand through the nitrogen atoms from the sulfonamidate and quinoline groups. The complex [Zn(qnbsa)2] crystallizes with a water molecule from the solvent and the Zn is five-coordinated and shows a bipyramidal-trigonal geometry. The electrochemical and electronic spectroscopy properties of the copper complexes are also discussed.

Volatile compounds in the thermoplastic extrusion of bovine rumen

The volatile compounds of raw and extruded bovine rumen, extracted by dynamic headspace, were separated by gas chromatography and analyzed by GC-MS. Raw and extruded materials presented thirty-two volatile compounds. The following compounds were identified in raw bovine rumen: heptane, 1-heptene, 4-methyl-2-pentanone, toluene, hexanal, ethyl butyrate, o-xylene, m-xylene, p-xylene, heptanal, limonene, nonanal, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octadecane. The following compounds were identified in the extruded material: 1-heptene, 2,4-dimethylhexane, toluene, limonene, undecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane and nonadecane. Mass spectra of some unidentified compounds indicated the presence of hydrocarbons with branched chains or cyclic structure.

Estudo da adsorção de compostos sulfurados empregando zeólitas contendo zinco

This paper deals with an adosrption of sulphur compounds employing zeolites containing zinc. The zeolites employed were commercial NaY and Beta. The zinc was incorporated in three levels: 0.5; 1.0 and 5%. The sulphur compounds studied were benzothiophene and dibenzothiofene. The results showed that both zeolites can be employed for adsorption of benzothiophene and dibenzothiophene. The Zn incorporation (0.5%) promotes an increase in zeolites adsorption ability. The DBT adsorbs more than BT, probably because it strongly interacts with zeolite structure. The BT adsorbs more in NaY than in beta probably because the NaY zeolite has a high intern volume. This is not observed for DBT.

Steroidal and phenolic compounds from Sidastrum paniculatum (L.) Fryxell and evaluation of cytotoxic and anti-inflammatory activities

Sidastrum paniculatum (L.) Fryxell belongs to the family Malvaceae and is popularly known as "malva roxa" or "malvavisco". The phytochemical study of the hexane, CHCl3 and EtOAc phases from the crude ethanol extract of S. paniculatum led to the isolation of six compounds: a mixture of β-sitosterol and stigmasterol, 4-methoxy-3-hydroxybenzoic acid, 4-methoxy-3-hydroxybenzaldehyde, N-trans-feruloyltyramine and kaempferol-3-O-β-D-(6''-E-p -coumaroyl) glucoside. The structural identification of the compounds was made on the basis of spectroscopic methods such as IR, ¹H and 13C NMR with the aid of including two-dimensional techniques, besides comparison with literature data. The β-sitosterol and stigmasterol mixture showed a significant anti-inflammatory activity.

In vitro study of antioxidant and scavenger properties of phenolic compounds from Lychnophora species

This paper describes the antioxidant effects of thirteen phenolic compounds isolated from plants of the genus Lychnophora. Two assays were performed to evaluate these effects: a cellular test that measured the luminol-enhanced chemiluminescence produced by neutrophils stimulated with opsonized zymosan and a cell-free test involving horseradish peroxidase-H2O2-luminol. In both assays, the antioxidant activity of the phenolic compounds was dependent on their concentration and chemical structure. Our results suggest that the ability of phenolic compounds from Lychnophora species to scavenge and inhibit the generation of ROS may be a mechanism underlying the anti-inflammatory activity of extracts from Lychnophora spp.

Phenolic compounds from Sidastrum micranthum (A. St.-Hil.) fryxell and evaluation of acacetin and 7,4'-Di-O-methylisoscutellarein as motulator of bacterial drug resistence

From the aerial parts of Sidastrum micranthum (A. St.-Hil.) Fryxell (Malvaceae) were isolated m-methoxy-p-hydroxy-benzaldehyde, o-hydroxy-benzoic acid, acacetin, quercetin, 7,4′-Di-O-methylisoscutellarein, genkwanin and tiliroside. These compounds were identified by data analyses of spectroscopic methods. Although acacetin and 7,4′-Di-O-methylisoscutellarein did not display relevant antibacterial activity (MIC = 256 µg/mL), they modulated the activity of antibiotics, i.e. in combination with antibiotics at 64 µg/mL (¼ MIC), a two-fold reduction in the MIC was observed for norfloxacin and ethidium bromide; regarding tetracycline and erythromycin a two-fold reduction in the MIC was observed only with 7,4′-Di-O-methylisoscutellarein.

Integração das técnicas de triagem virtual e triagem biológica automatizada em alta escala: oportunidades e desafios em P&D de fármacos

High-throughput screening (HTS) and virtual screening (VS) are useful methods employed in drug discovery, allowing the identification of promising hits for lead optimization. The efficiency of these approaches depends on a number of factors, such as the organization of high quality databases of compounds and the parameterization of essential components of the screen process. This brief review presents the basic principles of the HTS and VS methods, as well as a perspective of the utility and integration of these drug design approaches, highlighting current opportunities and future challenges in medicinal chemistry.