Host-guest complexation of a nitroheterocyclic compound with cyclodextrins: a spectrofluorimetric and molecular modeling study

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

Tillage and phosphorus management effects on enzyme-labile bioactive phosphorus availability in Cerrado Oxisols

Phosphorus (P) is an essential element in crop nutrition, which can be growth limiting or an environmental contaminant, if present in excess. Tillage practices have a direct effect on the behavior and availability of soil P. Sorption and availability of various P forms were evaluated in an incubation-fractionation study of three soils, a Typic Paleudults (CR soil) and two Cerrado Oxisols (Latossolo Vermelho-Amarelo [LVA] and Latossolo Vermelho [LV]) with distinct biogeochemical characteristics and tillage management history. Phosphate and myo-inositol hexakisphosphate (mIPH) were strongly sorbed by the soils. Maximum adsorption capacities (S(max)) were 2.2-6.9, 3.3-7.8, and 1.6-19.8 mmol kg(-1) for phosphate in the 0-40 cm depths of the CR, LV, and LVA soils, respectively. For mIPH, S. were 1.2-3.7, 3.7-5.5, and 4.6-5.2 mmol kg(-1). Saturation indices reflected the long-term effect of repeated manure applications on the Paleudults and the near saturation of its P holding capacity, in contrast to the recently cultivated Cerrado soils. Tillage method appeared to have altered P retention characteristics of the near-surface zone very slightly, while increases in ligand-exchangeable (EEP;) and enzyme-labile organic P (EDTA-PHP) forms were observed in no-till Oxisols. In the Paleudults, added manure P increased bioactive P fractions and P saturation of no-till near-surface soil zone. Estimates of all bioactive P fractions using the ligand-based enzymatic assay showed it to be an effective method for assessing P availability in soil and developing sustainable P management strategies, particularly in Cerrado Oxisols that were low in organic matter while having an extensive P-fixing capacity. Published by Elsevier B.V.

SnO2, ZnO and related polycrystalline compound semiconductors: An overview and review on the voltage-dependent resistance (non-ohmic) feature

The present review describes mainly the history of SnO2-based voltage-dependent resistors, discusses the main characteristics of these polycrystalline semiconductor systems and includes a direct comparison with traditional ZnO-based voltage-dependent resistor systems to establish the differences and similarities, giving details of the basic physical principles involved with the non-ohmic properties in both polycrystalline systems. As an overview, the text also undertakes the main difficulties involved in processing SnO2- and ZnO-based non-ohmic systems, with an evaluation of the contribution of the dopants to the electronic properties and to the final microstructure and consequently to the system's non-ohmic behavior. However, since there are at least two review texts regarding ZnO-based systems [Levinson, L. M., and Philipp, H. R. Ceramic Bulletin 1985;64:639; Clarke, D. R. Journal of American Ceramic Society 1999;82:485], the main focus of the present text is dedicated to the SnO2-based varistor systems, although the basic physical principles described in the text are universally useful in the context of dense polycrystalline devices. However, the readers must be careful of how the microstructure heterogeneity and grain-boundary chemistry are capable to interfere in the global electrical response for particular systems. New perspectives for applications, commercialization and degradation studies involving SnO2-based polycrystalline non-ohmic systems are also outlined, including recent technological developments. Finally, at the end of this review a brief section is particularly dedicated to the presentation and discussions about others emerging non-ohmic polycrystalline ceramic devices (particularly based on perovskite ceramics) which must be deeply studied in the years to come, specially because some of these systems present combined high dielectric and non-ohmic properties. From both scientific and technological point of view these perovskite systems are quite interesting. (c) 2007 Elsevier Ltd. All rights reserved.

Propolis Standardized Extract (EPP-AF (R)), an Innovative Chemically and Biologically Reproducible Pharmaceutical Compound for Treating Wounds

The aim of this study was to develop a formulation, containing the propolis standardized extract (EPP-AF (R)), which can assist in the healing of skin lesions. To achieve this objective the antimicrobial activity and chemical composition of the propolis extract was determined. The final product was subjected to in vitro and in vivo pre-clinical evaluation. The broth macrodi-lution method was used to determine the antimicrobial activity of the extracts and formulations against the microorganisms most commonly found in burns, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. Wistar rats with puncture wounded skin were used to evaluate the wound healing properties of propolis. The results of chemical and biological characterization demonstrated the batch-to-batch reproducibility of the standardized extract which is an unprecedented result. The antimicrobial and wound healing activity of the pharmaceutical studied showed the best results when samples contain 3.6% propolis, suggesting that this is the most promising composition.

Bioactive coating on titanium implants modified by Nd:YVO4 laser

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The in vitro antiviral activity of an aliphatic nitro compound from Heteropteris aphrodisiaca

We investigated the antiviral activity of an aliphatic nitro compound (NC) isolated from Heteropteris aphrodisiaca O. Mach. (Malpighiaceae), a Brazilian medicinal ptant. The NC was tested for its antiviral activity against poliovirus type 1 (PV-1) and bovine herpes virus type 1 (BHV-1) by plaque reduction assay in cell culture. The NC showed a moderate antiviral activity against PV-1 and BHV-1 in HEp-2 celts, and the 50% inhibitory concentration (IC50) were 22.01 mu g/ml (selectivity index (SI) = 2.83) and 21.10 mu g/mi (SI = 2.95), respectivety. At the highest concentration of the drug (40 mu g/ml) a reduction of approximately 80% in plaque assay was observed for both viruses. The treatment of cells or virus prior to infection did not inhibit the replication of virus strains. (C) 2006 Elsevier GmbH. All rights reserved.

Effect of non-steroidal anti-inflammatory drugs (NSAID) on the histamine release induced by compound 48/80 and cardiac anaphylaxis in guinea-pig isolated heart

Histamine release from guinea pig heart treated with compound 48/80 was potentiated by the cyclooxygenase inhibitors indomethacin and piroxicam but not by aspirin or phenylbutazone. This differential effect suggests that the potentiation is not merely due to an inhibition of prostaglandin synthesis. Piroxicam potentiated the histamine release induced by cardiac anaphylaxis whereas indomethacin reduced this effect. The SRS-A antagonist FPL 55712 inhibited histamine release induced by cardiac anaphylaxis, but not that evoked by compound 48/80, and also prevented the potentiation due to indomethacin and piroxicam. In total, these data suggest that the potentiation of histamine release by piroxicam and indomethacin is probably due to a diversion of arachidonic acid metabolism from the cyclooxygenase to the lipoxygenase pathways. The resulting lipoxygenase products may then regulate histamine release, with the secretion due to antigen being more sensitive to such modulation than that evoked by compound 48/80.

Bioactive guanidine alkaloids from Pterogyne nitens

Bioactivity-guided fractionation of a methanolic CHCl 3 extract of the leaves of Pterogyne nitens afforded the known guanidine alkaloid pterogynidine [2] and three new guanidine alkaloids, nitensidines A [3], B [4], and C [5], all of which exhibited selective activity towards the DNA repair-deficient yeast mutant RS 321 (IC 12=9.3-20.0 μg/ml); 3,4, and 5 were moderately cytotoxic to CHO Aux B 1 cells (IC 50=8.5-13.0 μg/ml).

Linamarin - The toxic compound of cassava

Cassava is a widely grown root crop which accumulates two cyanogenic glucosides, linamarin and lotaustralin. Linamarin accounts for more than 80% of the cassava cyanogenic glucosides. It is a β-glucoside of acetone cyanohydrin and ethyl-methyl-ketone-cyanohydrin. Linamarin β-linkage can only be broken under high pressure, high temperature and use of mineral acids, while its enzymatic break occurs easily. Linamarase, an endogenous cassava enzyme, can break this β-linkage. The enzymatic reaction occurs under optimum conditions at 25°C, at pH 5.5 to 6.0. Linamarin is present in all parts of the cassava plant, being more concentrated on the root and leaves. If the enzyme and substrate are joined, a good detoxification can occur. All the cassava plant species are known to contain cyanide. Toxicity caused by free cyanide (CN-) has already been reported, while toxicity caused by glucoside has not. The lethal dose of CN- is 1 mg/kg of live weight; hence, cassava root classification into toxic and non-toxic depending on the amount of cyanide in the root. Should the cyanide content be high enough to exceed such a dose, the root is regarded as toxic. Values from 15 to 400 ppm (mg CN-/kg of fresh weight) of hydrocyanic acid in cassava roots have been mentioned in the literature. However, more frequent values in the interval 30 to 150 ppm have been observed. Processed cassava food consumed in Brazil is safe in regard to cyanide toxicity.

A description of ligand field effects in the Di-μ-Azido-Bis [{Azido(N,N-diethylethylenediamine)}Copper(II)] compound by the simple overlap model

We present a theoretical description of ligand field effects in the di-μ-azido- bis[{azido(N,N-diethylethylenediamine)} copper(II)] compound by the Simple Overlap Model. The ligand field Hamiltonian is expressed in terms of irreducible tensor operators for an assumed D3h site symmetry occupied by the copper ion. The ligand field parameters, calculated from the available structural data, indicate that the copper ion is under the influence of a very strong ligand field. The energy of the d-d absorption band is well reproduced phenomenologically by the model.

Helivypolide G. A novel dimeric bioactive sesquiterpene lactone

Helivypolide G was isolated from leaves of Helianthus annuus L. cv. Stella. In the course of our ongoing research for new allelochemicals from Helianthus annuus, a novel dimeric bioactive sesquiterpene lactone, helivypolide G has been isolated and characterized from the medium polar active fractions of the leaves of cultivar variety Stella. The monomers are connected through carbons C-15 of each unit and an oxygen bridge, forming an enolic oxane ring. © 2004 Elsevier Ltd. All rights reserved.