EPR investigation of the influence of side chain protecting groups on peptide-resin solvation of the Asx and Glx model containing peptides

In spite of all progressive efforts aiming to optimize SPPS, serious problems mainly affecting the assembly of aggregating sequences have persisted. Following the study intended to unravel the complex solvation phenomenon of peptide-resin beads, the XING and XAAAA model aggregating segments were labeled with a paramagnetic probe and studied via EPR spectroscopy. Low and high substituted resins were also comparatively used, with the X residue being Asx or Glx containing the main protecting groups used in the SPPS. Notably, the cyclo-hexyl group used for Asp and Glu residues in Boc-chemistry induced greater chain immobilization than its tert-butyl partner-protecting group of the Fmoc strategy. Otherwise, the most impressive peptide chain immobilization occurred when the large trytil group was used for Asn and Gln protection in Fmoc-chemistry. These surprising results thus seem to stress the possibility of the relevant influence of the amino-acid side chain protecting groups in the overall peptide synthesis yield. (C) 2007 Elsevier Ltd. All rights reserved.

Limonoids showing selective toxicity to DNA repair-deficient yeast and other constituents of Trichilia emetica

Bioactivity-directed fractionation of the MeCOEt extract of Trichilia emetica (Meliaceae) resulted in the isolation of the limonoids nymania 1 (1), drageana 4 (3), trichilin A (4), rohituka 3 (5),and Tr-B (7) and the novel seco-A protolimonoid 8. of these, nymania 1 and Tr-B showed selective inhibitory activity toward DNA repair-deficient yeast mutants. The isolation, structure elucidation, C-13 NMR spectral assignments, and biological activities of:these compounds are reported.

Thiobacillus ferrooxidans response to copper and other heavy metals: growth, protein synthesis and protein phosphorylation

Respirometric experiments demonstrated that the oxygen uptake by Thiobacillus ferrooxidans strain LR was not inhibited in the presence of 200 mM copper. Copper-treated and untreated cells from this T. ferrooxidans strain were used in growth experiments in the presence of cadmium, copper, nickel and zinc. Growth in the presence of copper was improved by the copper-treated cells. However, no growth was observed for these cells, within 190 h of culture, when cadmium, nickel and zinc were added to the media. Changes in the total protein synthesis pattern were detected by two-dimensional polyacrylamide gel electrophoresis for T. ferrooxidans LR cells grown in the presence of different heavy metals. Specific proteins were induced by copper (16, 28 and 42 kDa) and cadmium (66 kDa), whereas proteins that had their synthesis repressed were observed for all the heavy metals tested. Protein induction was also observed in the cytosolic and membrane fractions from T. ferrooxidans LR cells grown in the presence of copper. The level of protein phosphorylation was increased in the presence of this metal.

beta-carotene and other carotenoids as antioxidants

Carotenoids are natural pigments which are synthesized by plants and are responsible for the bright colors of various fruits and vegetables. There are several dozen carotenoids in the foods that we eat, and most of these carotenoids have antioxidant activity. beta-carotene has been best studied since, in most countries it is the most common carotenoid in fruits and vegetables. However, in the U.S., lycopene from tomatoes now is consumed in approximately the same amount as beta-carotene. Antioxidants (including carotenoids) have been studied for their ability to prevent chronic disease, beta-carotene and others carotenoids have antioxidant properties in vitro and in animal models. Mixtures of carotenoids or associations with others antioxidants (e.g. vitamin E) can increase their activity against free radicals. The use of animals models for studying carotenoids is limited since most of the animals do not absorb or metabolize carotenoids similarly to humans.Epidemiologic studies have shown an inverse relationship between presence of various cancers and dietary carotenoids or blood carotenoid levels. However, three out of four intervention trials using high dose beta-carotene supplements did not show protective effects against cancer or cardiovascular disease. Rather, the high risk population (smokers and asbestos workers) in these intervention trials showed an increase in cancer and angina cases. It appears that carotenoids (including beta-carotene) can promote health when taken at dietary levels, but may have adverse effects when taken in high dose by subjects who smoke or who have been exposed to asbestos. It will be the task of ongoing and future studies to define the populations that can benefit from carotenoids and to define the proper doses, lengths of treatment, and whether mixtures, lather than single carotenoids (e.g. beta-carotene) are more advantageous.

BIOACTIVE AND OTHER PIPERIDINE ALKALOIDS FROM CASSIA-LEPTOPHYLLA

Four new piperidine alkaloids, leptophyllin A (4), 3-acetylleptophyllin A (5), leptophyllin B (8), and (-)-spectaline (1), and 3 known piperidine alkaloids, (-)-spectalinine (2), canavaline (3), and iso-6-canavaline (7), were isolated by a bioassay-guided fractionation of a leaf extract of Cassia leptophylla. The alkaloids 1 - 3 were active in a mechanism-based DNA-modifying yeast assay and 2 was moderately active in Vero monkey and Chinese hamster ovary cell cytotoxicity assays.

A DNA-damaging sesquiterpene and other constituents from Frullania nisquallensis

Bioassay-guided fractionation of an MeCOEt extract of Frullania nisquallensis Sull. has furnished a DNA-damaging sesquiterpene, costunolide (1), and two inactive compounds, a sesquiterpene (-)-frullanolide (2) and a tridepside tenuiorin (3). C-13-NMR data of 3 are reported.

Radiative properties of the skin and haircoat of cattle and other animals

Radiative properties (reflectance rho, transmittance tau, and absorptance alpha) were determined for wavelengths from 300 to 850 nm in the haircoat and the skin of water buffalo, deer (Pantanal deer, Blastocerus dichotomus), and cattle of the Holstein, Simmental, Canchim, Brangus, and Nelore breeds. The results showed that white hairs have higher rho (0.60 to 0.67) than the other coat colors, but the gray coats (mixed white and dark hair) of the Nelore cattle presented higher rho than that of the white coats of the European breeds at wavelengths lower than 600 nm. The light gray colored skin of the Canchim cattle had higher rho (0. 66) than the non-pigmented skin of Holstein (0.53). Red skins presented rho values higher than those of dark gray and black skins. Buffalo skin (dark gray) presented an average rho of 0.23+/-0.02 and alpha of 0.77+/-0.02. The red haircoat of the deer presented rho lower (0.37) than that of cattle of the same color (0.58). However, there was little difference between deer and cattle with respect to reflectance and absorptance of the skin. As for the spectral transmittance of the skin, it was very low and about the same for both species, until 600 nm. In the range 600 to 850 nm, the tau values for cattle rose to 0. 17, while those for deer increased only to 0.12.

Increased Levels of NOTCH1, NF-kappa B, and Other Interconnected Transcription Factors Characterize Primitive Sets of Hematopoietic Stem Cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Correlation of electrical conductivity and other vigor tests with field emergence of soybean seedlings

Seeds from six soybean cultivars (Cristalina, IAC 31-Foscarin, IAC-15, UFV-10, IAC-14 and IAS-5) and from five soybean cultivars (IAC 31-Foscarin, IAC-15, IAC-14, IAS-5 and Iguacu) were evaluated in 1993 and 1994, respectively, in terms of physiological seed quality by the mechanical damage (MD), standard germination (SG), accelerated aging (AA), electrical conductivity (EC), and seedling field emergence (FE) tests. Significant correlations were detected between SG, AA and EC and FE. However, in terms of the cultivar or the year, the degree of association among these parameters can change based on the environmental conditions of each year.

β-carotene and other carotenoids as antioxidants

Carotenoids are natural pigments which are synthesized by plants and are responsible for the bright colors of various fruits and vegetables. There are several dozen carotenoids in the foods that we eat, and most of these carotenoids have antioxidant activity. β-carotene has been best studied since, in most countries it is the most common carotenoid in fruits and vegetables. However, in the U.S., lycopene from tomatoes now is consumed in approximately the same amount as β-carotene. Antioxidants (including carotenoids) have been studied for their ability to prevent chronic disease. β-carotene and others carotenoids have antioxidant properties in vitro and in animal models. Mixtures of carotenoids or associations with others antioxidants (e.g. vitamin E) can increase their activity against free radicals. The use of animals models for studying carotenoids is limited since most of the animals do not absorb or metabolize carotenoids similarly to humans. Epidemiologic studies have shown an inverse relationship between presence of various cancers and dietary carotenoids or blood carotenoid levels. However, three out of four intervention trials using high dose β- carotene supplements did not show protective effects against cancer or cardiovascular disease. Rather, the high risk population (smokers and asbestos workers) in these intervention trials showed an increase in cancer and angina cases. It appears that carotenoids (including β-carotene) can promote health when taken at dietary levels, but may have adverse effects when taken in high dose by subjects who smoke or who have been exposed to asbestos. It will be the task of ongoing and future studies to define the populations that can benefit from carotenoids and to define the proper doses, lengths of treatment, and whether mixtures, rather than single carotenoids (e.g. β-carotene) are more advantageous.

Effect of micelles, microemulsions and other supramolecular aggregates on the hydrolysis of β-lactam antibiotics

A critical revision of the literature was made regarding the stability of β-lactam antibiotics in the presence of surfactants. The factors involved in the drug decomposition were analyzed in the development of the discussion. The analysis has indicated that some organized systems obtained from surfactants can be used to control rates and mechanisms of antibiotic decomposition. These organized systems can also be used to obtain specific information about the drug reactivity in a microenvironment similar to the site of pharmacological effect.