LyeTx I, a potent antimicrobial peptide from the venom of the spider Lycosa erythrognatha.

LyeTx I, an antimicrobial peptide isolated from the venom of Lycosa erythrognatha, known as wolf spider, has been synthesised and its structural profile studied by using the CD and NMR techniques. LyeTx I has shown to be active against bacteria (Escherichia coli and Staphylococcus aureus) and fungi (Candida krusei and Cryptococcus neoformans) and able to alter the permeabilisation of L: -alpha-phosphatidylcholine-liposomes (POPC) in a dose-dependent manner. In POPC containing cholesterol or ergosterol, permeabilisation has either decreased about five times or remained unchanged, respectively. These results, along with the observed low haemolytic activity, indicated that antimicrobial membranes, rather than vertebrate membranes seem to be the preferential targets. However, the complexity of biological membranes compared to liposomes must be taken in account. Besides, other membrane components, such as proteins and even specific lipids, cannot be discarded to be important to the preferential action of the LyeTx I to the tested microorganisms. The secondary structure of LyeTx I shows a small random-coil region at the N-terminus followed by an alpha-helix that reached the amidated C-terminus, which might favour the peptide-membrane interaction. The high activity against bacteria together with the moderate activity against fungi and the low haemolytic activity have indicated LyeTx I as a good prototype for developing new antibiotic peptides.

Neutralizing properties of Musa paradisiaca L. (Musaceae) juice on phospholipase A2, myotoxic, hemorrhagic and lethal activities of crotalidae venoms.

The use of plants as medicine has been referred to since ancient peoples, perhaps as early as Neanderthal man. Plants are a source of many biologically active products and nowadays they are of great interest to the pharmaceutical industry. The study of how people of different culture use plants in particular ways has led to the discovery of important new medicines. In this work, we verify the possible activity of Musa paradisiaca L. (Musaceae) against the toxicity of snake venoms. Musa paradisiaca, an important source of food in the world, has also been reported to be popularly used as an anti-venom. Interaction of Musa paradisiaca extract (MsE) with snake venom proteins has been examined in this study. Phospholipase A2 (PLA2), myotoxic and hemorrhagic activities, including lethality in mice, induced by crotalidae venoms were significantly inhibited when different amounts of MsE were mixed with these venoms before assays. On the other hand, mice that received MsE and venoms without previous mixture or by separated routes were not protected against venom toxicity. Partial chemical characterization of MsE showed the presence of polyphenols and tannins and they are known to non-specifically inactivate proteins. We suggest that these compounds can be responsible for the in vitro inhibition of the toxic effects of snake venoms. In conclusion, according to our results, using mice as experimental model, MsE does not show protection against the toxic effects of snake venoms in vivo, but if was very effective when the experiments were done in vitro.

QSAR based on biological microcalorimetry.

In this paper we describe a QSAR based on biological microcalorimetry for a set of antimicrobial hydrazides acting against Saccharomyces cerivisiae and Escherichia coli. Results show that an extrathermodynamic relationship exists based upon partitioning (log P(TA)) and microcalorimetrically measured biopotencies using the same cell systems. Moreover, the extrathermodynamic relationship between drug potencies for these two cell systems shows that both cellular systems appear to behave in the same way with respect to the importance of partitioning. This means that the same set of congeneric compounds experience a similar environment in the two systems. This represents a lateral validation of the method and discloses the validity of the QSAR model.

A new cyclohexadecane derivative from Trixis vauthieri DC (Asteraceae).

The dichloromethane-methanol extract from the fresh leaves of Trixis vauthieri DC (Asteraceae) afforded trixol, a new cyclohexadecane derivative. The structural elucidation of this new compound, with a novel skeleton, was based on NMR studies of the natural product nd its derivatives.

The radioprotective effect of a new aminothiol (20-PRA).

We examined the radioprotective effect of aminothiol 2-N-propylamine-cyclo-hexanethiol (20-PRA) on a human leukemic cell line (K562) following various radiation doses (5, 7.5 and 20 Gy) using a source of 60Co gamma-rays. At 5 Gy and 1 nM 20-PRA, a substantial protective effect (58%) was seen 24 h after irradiation, followed by a decrease at 48 h (11%). At the high radiation dose (20 Gy) a low protective effect was also seen (35%). In addition, the antitumorigenic potential of 10 nM 20-PRA was shown by the inhibition of crown gall formation induced by Agrobacterium tumefaciens. The radioprotective potency of 20-PRA is 10(5)-10(6) times higher than that of the aminothiol WR-1065 (N-(2-mercaptoethyl)-1,3-diaminopropane) whose protective effect is in the 0.1 to 1.0 mM range.

Constituents of Brosimum potabile.

The ethanolic extract from the stem of Brosimum potabile afforded (-)-centrolobin (1), isolated for the first time in this genus. The identification of this compound included COSY and NOESY two-dimensional NMR data.

Characterization of synthetic polymers and speck impurities in cellulose pulp: a comparison between pyrolysis-gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy.

Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and Fourier transform infrared (FT-IR) spectroscopy were used for characterizing specks in cellulose pulp, polymeric materials and pitch formed during the cellulose extraction and paper production in the Brazilian mill. Three samples were analyzed and the pyrograms and infrared spectra obtained were compared. The results showed that the analytical pyrolysis more effectively differentiated between impurities (dirt specks) when compared to the infrared spectroscopy.

Synthesis of new N-alkyl-2-mercapto-1-octylamines and respective disulfides.

Four new N-alkyl-2-mercapto-1-octylamine hydrochlorides were synthesized via the reaction of 1,2-epithio-octane with corresponding amines following by conversion to the hydrochlorides. The disulfides were obtained by oxidation of the respective thiols. Upon biological assay of the products for activity against infection by Schistosoma mansoni, only 2,2'-dithiobis(N-isobutyl-1-octylamine) exhibited activity.

Trypanocidal flavonoids from Trixis vauthieri.

The crude extract of Trixis vauthieri (Asteraceae) was active against the trypomastigote forms of Trypanosoma cruzi, the protozoan that causes Chagas' disease. Bioassay-guided fractionation of this extract afforded the trypanocidal flavonoids 5,4'-dihydroxy-7-methoxyflavanone (1) and 5,4'-dihydroxy-3,6,7-trimethoxyflavone (2) besides the inactive flavonoids 3,5,4'-trihydroxy-7-methoxyflavanone (3) and 5,4'-dihydroxy-3,6,7,8-tetramethoxy flavone (4). The trypanocidal activity of 1 and 2 and the presence of compounds 2 and 4 in Trixis vauthieri are reported here for the first time.

Chemical characterization of the lignins of corn and soybean agricultural residues

Corn (CR) and soybean (SR) culture wastes were submitted to extraction with organic solvents for lignin isolation (LGS). The obtained lignin was chemically characterized, and based on studies of functional groups and microanalyses, it was possible to determine the minimum formula. LGS of CR has characteristics that resemble wood and of bamboo lignin, possessing a larger amount of methoxyl groups and vanillin

Lignina isolada da palha de milho utilizada com indicador em ensaios de digestibilidade. Estudo comparativo / Lignin from corn crop residue used with indicator in experiment of apparent digestibility. Comparative study

Este experimento foi conduzido com o objetivo de comparar a lignina isolada da palha de milho (LPM-RM) com indicadores utilizados em ensaios de consumo e digestibilidade. Utilizaram-se além da LPM-RM, óxido crômico (Cr2O3), cloreto de itérbio (YbCl3.6H2O), fibra detergente ácido indigestível (FDA - ind), teor de metoxila da lignina (OCH3), lignina Klason (LK) e lignina determinada por espectroscopia no infravermelho (LIG-IV). O coeficiente de digestibilidade diferiu apenas entre a metoxila e os demais indicadores. Todos os indicadores foram semelhantes quanto à recuperaçäo fecal, exceto a metoxila que teve baixa recuperaçäo (44,6 por cento). Os dados de digestibilidade obtidos com LIG-IV, Cr2O3 e YbCl3.6H2O foram semelhantes entre si mas diferentes dos demais indicadores (21 por cento superior no caso do Cr2O3 e 24 por cento inferiores no caso da LIG-IV e do itérbio), quando comparados com a coleta total

The radioprotective effect of a new aminothiol (20-PRA)

We examined the radioprotective effect of aminothiol 2-N-propylamine-cyclo-hexanethiol (20-PRA) on a human leukemic cell line (K562) following various radiation doses (5, 7.5 and 20 Gy) using a source of (60)Co gamma-rays. At 5 Gy and 1 nM 20-PRA, a substantial protective effect (58 per cent) was seen 24 h after irradiation, followed by a decrease at 48 h (11 per cent). At the high radiation dose (20 Gy) a low protective effect was also seen (35 per cent). In addition, the antitumorigenic potential of 10 nM 20-PRA was shown by the inhibition of crown gall formation induced by Agrobacterium tumefaciens. The radioprotective potency of 20-PRA is 10(5)-10(6) times higher than that of the aminothiol WR-1065 N-(2-mercaptoethyl) - 1,3-diaminopropane) whose protective effect is in the 0.1 to 1.0 mM range.

Caracaterizaçäo microscópica da lignina dos resíduos agrícolas de milho e de soja submetidos à fermentaçäo ruminal e seus efeitos sobre a digestibilidade da fibra / Microscopic characterization of the lignins from both corn and soybean residues submitted to ruminal degradation, and its effect on fiber digestibility

O trabalho teve por objetico isolar e caracterizar microscopicamente as ligninas de resíduos agrícolas provenientes das culturas de soja (RS) e de milho (RM), bem como verificar o efeito das ligninas sobre a degradaçäo dos tecidos dos resíduos RM e RS. Por meio da microscopia eletrônica de varredura, estudou-se a ultra-estrutura das ligninas e dos tecidos vegetais de RM e RS. Verificou-se que as ligninas da palha moída do RM e da RS säo morfologicamente diferentes (ultra-estruturas diferentes) e que o desaparecimento dos tecidos digestíveis também é diferente, sendo mais prejudicado no RM

Isolamento e caracterizaçäo por espectroscopia no infravermelho da lignina dos resíduos agrícolas de milho e soja / Isolation and infrared spectroscopic characterization of lignin from both corn and soybean agricultural residues

Este trabalho teve por objetivo isolar e caracterizar ligninas de resíduos agrícolas das culturas de soja (Glycine max L.) (RS) e de milho (Zea mays) (RM). Para tanto, isolou-se a lignina da palha moída (LPM), após moagem em moinho de bolas, seguida de extraçäo por solventes orgânicos. As fraçöes assim obtidas foram analisadas por espectroscopia no infravermelho (IV). Nas fraçöes correspondentes às LPM de soja e milho pôde-se verificar absorçäo em 137Ocm elevado a -1 para RS e em 136Ocm elevado -1 para RM. Esses dados säo característicos de grupos siringila que apresentam absorçäo em torno de 137Ocm elevado a -1. Observou-se ainda em cada lignina a banda em 1265cm elevado a -1, indicativa da presença do grupo guaiacila. Finalmente, uma banda observada em 122Ocm elevada a -1 para RS e 1215cm elevado a -1 para RM pode caracterizar grupamento p-hidroxifenila