A natural combinatorial chemistry strategy in acylpolyamine toxins from Nephilinae orb-web spiders

The present study shows how nature combined a small number of chemical building blocks to synthesize the acylpolyamine toxins in the venoms of Nephilinae orb-web spiders. Considering these structures in four parts, it was possible to rationalize a way to represent the natural combinatorial chemistry involved in the synthesis of these toxins: an aromatic moiety is connected through a linker amino acid to a polyamine chain, which in turn may be connected to an optional tail. The polyamine chains were classified into seven subtypes (from A to G) depending on the way the small chemical blocks are combined. These polyamine chains may be connected to one of the three possible chromophore moieties: 2,4-dihydroxyphenyl acetic acid, or 4-hydroxyindole acetic acid, or even with the indole acetic group. The connectivity between the aryl moiety and the polyamine chain is usually made through an asparagine residue; optionally a tail may be attached to the polyamine chain; nine different types of tails were identified among the 72 known acylpolyamine toxin structures. The combinations of three chromophores, two types of amino acid linkers, seven sub-types of polyamine backbone, and nine options of tails results in 378 different structural possibilities. However, we detected only 91 different toxin structures, which may represent the most successful structural trials in terms of efficiency of prey paralysis/death.

New anti-Alzheimer drugs from biodiversity: the role of the natural acetylcholinesterase inhibitors

Alzheimer's disease (AD) is a progressive neurodegenerative pathology with severe economic and social impact. There is currently no cure, although cholinesterase inhibitors provide effective temporary relief of symptoms in some patients. Nowadays, drug research and development are based on the cholinergic hypothesis that supports the cognition improvement by regulation of the synthesis and release of acetylcholine in the brain. There are only four commercial medicines approved for treatment of AD, and natural products have played an important alternative role in the research for new acetylcholinesterase inhibitors, as exemplified through the discovery of galantamine. This profile conducts us to give in this paper an overview relating the several classes of natural products with anti-cholinesterasic activity as potential templates to the design of new selective and powerful anti-Alzheimer drugs.

Urea-Based Synthesis of Zinc Oxide Nanostructures at Low Temperature

The preparation of nanometer-sized structures of zinc oxide (ZnO) from zinc acetate and urea as raw materials was performed using conventional water bath heating and a microwave hydrothermal (MH) method in an aqueous solution. The oxide formation is controlled by decomposition of the added urea in the sealed autoclave. The influence of urea and the synthesis method on the final product formation are discussed. Broadband photoluminescence (PL) behavior in visible-range spectra was observed with a maximum peak centered in the green region which was attributed to different defects and the structural changes involved with ZnO crystals which were produced during the nucleation process.

Synthesis, characterization and thermal decomposition of [Pd2 (C2-dmba) (μ-SO4) (μ-SO4) SO22]

The bridged sulphate complex [Pd2 (C2,dmba) (μ-SO4) (SO2)2] has been obtained by reacting a saturated solution of SO2 in methanol and the cyclometallated compound [Pd(C2,N-dmba)(μ-N3)]2; (dmba = N,N-dimethylbenzylamine), at room temperature for 24 h. Reaction product was characterized by elemental analysis, NMR comprising 13C{1H} and 1H nuclei and I.R. spectrum's measurements. Thermal behavior has been investigated and residual products identified by X-ray powder diffraction.

Preconcentration and determination of mercury(II) at a chemically modified electrode containing 3-(2-thioimidazolyl)propyl silica gel

A mercury-sensitive chemically modified graphite paste electrode was constructed by incorporating modified silica gel into a conventional graphite paste electrode. The functional group attached to the (3-chloropropyl) silica gel surface was 2-mercaptoimidazole, giving a new product denoted by 3-(2-thioimidazolyl)propyl silica gel, which is able to complex mercury ions. Mercury was chemically adsorbed on the modified graphite paste electrode containing 3-(2-thioimidazolyl)propyl silica (TIPSG GPE) by immersion in a Hg(II) solution, and the resultant surface was characterized by cyclic and differential pulse anodic stripping voltammetry. One cathodic peak at 0.1 V and other anodic peak at 0.34 V were observed on scanning the potential from -0.1 to 0.8 V (0.01 M KNO3; ν = 2.0 mV s-1 νs. Ag/AgCl). The anodic peak at 0.34 V show an excellent sensitivity for Hg(II) ions in the presence of several foreign ions. A calibration graph covering the concentration range from 0.02 to 2 mg L-1 was obtained. The detection limit was estimated to be 5 μg L-1. The precision for six determinations of 0.05 and 0.26 mg L-1 Hg(II) was 3.0 and 2.5% (relative standard deviation), respectively. The method can be used to determine the concentration of mercury(II) in natural waters contaminated by this metal. 2005 © The Japan Society for Analytical Chemistry.

Efficacy of homeopathic treatment against natural infection of sheep by gastrointestinal nematodes.

The efficacy of the homeopathic treatment with the Fator Vermes, administered according to the manufacturer's recommendations, was evaluated against gastrointestinal nematodes infections in sheep. The experiment was divided into two phases: in the first phase (January/06/2004 to April/30/2004), the animals of the treated (n=10) and control (n=10) groups were treated individually with conventional anthelmintics to avoid deaths. In the second phase (April/30/2004 to July/06/2004), the sheep from the group that received the Fator Vermes were treated as they had been in the previous phase, while the control group animals were treated with conventional anthelmintics at 14 day intervals. In the first phase of the experiment, there was no significant difference (P>0.05) between group means regarding egg counts in feces (EPG), weight gain, or packed cell volume (PCV). Meanwhile, in the second phase, the control group sheep had a significantly higher weight gain, higher PCV values, and lower EPG counts. Infective larvae of Haemonchus spp., Trichostrongylus spp., Cooperia spp., and Oesophagostomum spp. were identified in the fecal cultures. After six months of daily treatment with the Fator Vermes, it was not possible to substantiate the product's benefits in both sheep health and productivity or in the prophylaxis of gastrointestinal nematode infections.

Evaluation of the anti-inflammatory, analgesic and antipyretic activities of the natural polyphenol chlorogenic acid

Phenolic compounds are numerous and ubiquitous in the plant kingdom, being particularly present in health-promoting foods. Epidemiological evidences suggest that the consumption of polyphenol-rich foods reduces the incidence of cancer, coronary heart disease and inflammation. Chlorogenic acid (CGA) is one of the most abundant polyphenol compounds in human diet. Data obtained from in vivo and in vitro experiments show that CGA mostly presents antioxidant and anti-carcinogenic activities. However, the effects of CGA on the inflammatory reaction and on the related pain and fever processes have been explored less so far. Therefore, this study was designed to evaluate the anti-inflammatory, antinociceptive and antipyretic activities of CGA in rats. In comparison to control, CGA at doses 50 and 100 mg/kg inhibited carrageenin-induced paw edema beginning at the 2nd hour of the experimental procedure. Furthermore, at doses 50 and 100 mg/kg CGA also inhibited the number of flinches in the late phase of formalin-induced pain test. Such activities may be derived from the inhibitory action of CGA in the peripheral synthesis/release of inflammatory mediators involved in these responses. On the other hand, even at the highest tested dose (200 mg/kg), CGA did not inhibit the febrile response induced by lipopolysaccharide (LPS) in rats. Additional experiments are necessary in order to clarify the true target for the anti-inflammatory and analgesic effects of CGA. © 2006 Pharmaceutical Society of Japan.

Influence of natural polymer derived from starch as a sensory modifier in sunscreen formulations

Background: Nowadays, there has been increased incidence of skin cancer, which is mainly related to increased sun exposure. Although sunscreen products may prevent the appearing of this disease, consumers may not use them due to some factors, including the sensory properties. The Aluminum Starch Octenylsuccinate (Dry-Flo® Pure, Akzo Nobel), an aluminum salt produced by the reaction of anhydride octenylsuccinic with starch, is able to improve the spreadability on the skin and reduce the oiliness of the formulation. Objective: To verify volunteers' acceptance for sunscreen formulation with natural polymer, compared with a control formulation (without polymer). Methods: To carry out the sensory analysis a formulation with or without 2. 0% Aluminum Starch Octenylsuccinate was prepared. Formulations had FPS 15, with critical wavelength of 353 nm, determined by testing in silico using the BASF® Sunscreen Simulator. Sensory analysis was performed on 60 students of both sexes, aged between 18 and 25 years, regular users of sunscreen products. Results: The results suggested that the polymer was able to promote a very soft and velvety feel on the skin when used in a sunscreen formulation, and it was able to mitigate and noticeably reduce the oiliness of the skin. Of the 60 volunteers who participated in the study, 45 volunteers (75%) considered that the polymer formulation provides little brightness or did not notice the difference in brightness of the skin after application. Conclusions: It was able to improve the sensory of the product, contributing to greater volunteers' acceptance.

The natural absence of RPA1N domain did not impair Leishmania amazonensis RPA-1 participation in DNA damage response and telomere protection.

We have previously shown that the subunit 1 of Leishmania amazonensis RPA (LaRPA-1) alone binds the G-rich telomeric strand and is structurally different from other RPA-1. It is analogous to telomere end-binding proteins described in model eukaryotes whose homologues were not identified in the protozoan's genome. Here we show that LaRPA-1 is involved with damage response and telomere protection although it lacks the RPA1N domain involved with the binding with multiple checkpoint proteins. We induced DNA double-strand breaks (DSBs) in Leishmania using phleomycin. Damage was confirmed by TUNEL-positive nuclei and triggered a G1/S cell cycle arrest that was accompanied by nuclear accumulation of LaRPA-1 and RAD51 in the S phase of hydroxyurea-synchronized parasites. DSBs also increased the levels of RAD51 in non-synchronized parasites and of LaRPA-1 and RAD51 in the S phase of synchronized cells. More LaRPA-1 appeared immunoprecipitating telomeres in vivo and associated in a complex containing RAD51, although this interaction needs more investigation. RAD51 apparently co-localized with few telomeric clusters but it did not immunoprecipitate telomeric DNA. These findings suggest that LaRPA-1 and RAD51 work together in response to DNA DSBs and at telomeres, upon damage, LaRPA-1 works probably to prevent loss of single-stranded DNA and to assume a capping function.

Characterization of natural rubber/gold nanoparticles SERS-active substrate

Natural rubber/gold nanoparticles membranes (NR/Au) were studied by ultrasensitive detection and chemical analysis through surface-enhanced Raman scattering and surface-enhanced resonance Raman scattering in our previous work (Cabrera et al., J. Raman Spectrosc. 2012, 43, 474). This article describes the studies of thermal stability and mechanical properties of SERS-active substrate sensors. The composites were prepared using NR membranes obtained by casting the latex solution as an active support (reducing/establishing agents) for the incorporation of colloidal gold nanoparticles (AuNPs). The nanoparticles were synthesized by in situ reduction at different times. The characterization of these sensors was carried out by thermogravimetry, differential scanning calorimetry, scanning electron microscopy (SEM) microscopy, and tensile tests. It is suggested an influence of nanoparticles reduction time on the thermal degradation of NR. There is an increase in thermal stability without changing the chemical properties of the polymer. For the mechanical properties, the tensile rupture was enhanced with the increase in the amount of nanoparticles incorporated in the material. © 2013 Wiley Periodicals, Inc.

Fontes e doses de nitrogênio na nutrição, produção e qualidade do feijoeiro

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudos sobre a síntese de piperidinas funcionalizadas através de reações pentacomponentes, utilizando compostos de nióbio como catalisadores

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

Produção de exopolissacarídeos por Lactobacillus helveticus autócne isoldao de soro-fermento natural

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparação e caracterização de tecidos tratados com polianilina condutora recobertos com borracha natural

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise isotópica da variabilidade natural do carbono-13 e avaliação energética em néctares de pêssego – Prunus persica (L.) Batsch

Pós-graduação em Agronomia (Energia na Agricultura) - FCA