Microstructural investigation of the PZT films prepared from the suspension of nanocrystalline powders

PZT thin films of composition Pb(Zr0.52Ti0.48)O-3 were prepared by a novel method from the suspension of nanocrystalline PZT powders. The powders were obtained by mechanochemical synthesis. Films were deposited on silicon (100) and platinum covered silicon substrates (Pt (111) /Ti/SiO2/Si) Using spin-on technique. Substrate type has influence on films crystallinity, orientation and can react with the films changing its phase composition. Films microstructure strongly depends on thermal treatment conditions due to phase and compositional changes of the films. (C) 2003 Elsevier Ltd. All rights reserved.

Isolation and structure elucidation of two new flavonoid glycosides from the infusion of Maytenus aquifolium leaves. Evaluation of the antiulcer activity of the infusion

Droplet countercurrent chromatography and high-performance liquid chromatography fractionation of the aqueous infusion from Maytenus aquifolium Martius leaves afforded two flavonoid tetrasaccharides: quercetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-O-[beta-D-glucopyranosyl(1-->3)-O-alpha-L-rhamnopranosyl( 1-->2)-O-beta-D-galactopyranoside and kaempferol 3-O-alpha-L-rhamnopyranosyl(1-->6)-O-[beta-D-glucopyranosyl( 1-->3)-O-alpha-L-rhamnopyranosy(1-->2-2)-O-beta-D-galactopyranoside. All structures were elucidated by spectroscopic methods. Pharmacological essays of the infusion showed antiulcer activity in rats.

A NEW SPECIES OF TAPINURUS FROM THE CAATINGA OF PIAUI, NORTHEASTERN BRAZIL (SQUAMATA, TROPIDURIDAE)

Tapinurus helenae sp. nov. is described from northeastern Brazil. The species is characterized by a dorsoventrally depressed body three bluish-white longitudinal stripes, the middorsal one interrupted at the scapular area, and an ochre colored dorsum that is lacking in larger males. Tapinurus helenae is easily distinguished from the other two known species, T. semitaeniatus and T. pinima, by its interrupted middorsal stripe. The new species inhabits calcareous massifs and sandstones in forested caatinga at the Toca de Cima dos Pilao, Sao Raimundo Nonato, Piaui, northeastern Brazil.

CRYSTALLIZATION AND PRELIMINARY DIFFRACTION DATA OF 2 MYOTOXINS ISOLATED FROM THE VENOMS OF BOTHROPS-ASPER (TERCIOPELO) AND BOTHROPS-NUMMIFER (JUMPING VIPER)

Two myotoxins isolated from B. asper (myotoxin II) and B. nummifer (myotoxin I) snake venoms have been crystallized and their diffraction properties are described. These myotoxins are phospholipase A2 variants which lack enzymatic activity; B. asper myotoxin II is a lysine-49 phospholipase. Crystals were obtained at room temperature by standard hanging-drop vapour diffusion methods. Crystals diffracted to a resolution of 2.8 and 2.3 angstrom, respectively.

Acylated flavonol glycosides and terpenoids from the leaves of Alibertia sessilis

Two novel acylated flavonol glycosides, along with iridoids, triterpenes, steroids and alpha-tocopherolquinone, were isolated from the leaves of Alibertia sessilis (Rubiaceae). The determination of the structures of the new compounds was based mainly on H-1- and C-13-NMR.

Liquid chromatography/electrospray ionization tandem mass spectrometry profiling of compounds from the infusion of Byrsonima fagifolia Niedenzu

A rapid analytical approach suitable to achieve a comprehensive characterization of the compounds present in the infusion prepared from the leaves of Byrsonima fagifolia Niedenzu (Malpighiaceae), a Brazilian plant used as an infusion to treat gastric disorders, was developed. The method was based on high-performance liquid chromatography coupled to electrospray negative ionisation multistage ion trap mass spectrometry (HPLC/ESI-ITMSn). The main ions in the ESI-ITMS spectra were attributed to a quinic acid core containing from one to five galloyl units. Quercetin derivatives containing one and two sugar moieties as well as galloyl esterification were also detected. These results indicated that HPLC/ESI-ITMSn is easily applicable to infusions of this plant and allows the rapid and direct identification of these compounds in crude plant extracts. Copyright (C) 2007 John Wiley & Sons, Ltd.

SEQUENCE OF A CDNA-ENCODING BOTHROPSTOXIN-I, A MYOTOXIN FROM THE VENOM OF BOTHROPS-JARARACUSSU

With the aim of further understanding the structure/function relationships in the membrane-damaging activity of the Lys(49) phospholipase A(2) (Lys(49)-PLA(2)) sub-family, we used PCR (polymerase chain reaction) on total venom gland cDNAs from Bothrops jararacussu with degenerate oligodeoxyribonucleotides encoding the N- and C-termini of myotoxin II, a Lys(49)-PLA(2) from Bothrops asper. A 350-bp cDNA coding for bothropstoxin I (BtxtxI) was amplified. Sequencing of the amplified fragment shows that BtxtxI has a Lys(49), and comparison with the known structure of myotoxin II showed that the amino acids involved in the formation of a novel dimeric structure in this protein were also conserved.

Crystallization of piratoxin I, a myotoxic LYS49-phospholipase A(2) homologue isolated from the venom of Bothrops pirajai

Fernanda Canduri, Lit C. Mancuso, Andreimar M. Soares, Jose R. Giglio, Richard J. Ward and Raghuvir K. Arni. Crystallization of piratoxin I, a myotoxic Lys49-phospholipase A(2) homologue isolated from the venom of Bothrops pirajai. Toxicon 36, 547-551, 1998.-Large single crystals of piratoxin I, a Lys49-PLA(2) homologue with low enzymatic activity, have been obtained. The crystals belong to the orthorhombic system space group p2(1)2(1)2(1) and diffract X-raps to a resolution of 2.8 Angstrom. Preliminary analysis reveals the presence of two molecules in the crystallographic asymmetric unit. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

New antioxidant C-glucosylxanthones from the stems of Arrabidaea samydoides

Three new C-glucosylxanthones, 2-(2'-O-trans-caffeoyl)-C-beta-D-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone (1), 2-(2'-O-trans-cinnamoyl)-C-beta-D-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone (2), and 2-(2'-O-trans-coumaroyl)-C-beta-D-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone (3), were isolated from the stems of Arrabidaea samydoides, in addition to three known C-glucosylxanthones, mangiferin (4), 2-(2'-O-benzoyl)-C-beta-D-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone (5), and muraxanthone (6). Their chemical structures were assigned on the basis of MS and 1D and 2D NMR experiments. Xanthones 1-6 showed moderate free radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) as well as antioxidant activity evidenced by redox properties measured on ElCD-HPLC.

Structure determination of an organometallic 1-(diazenylaryl)ethanol: A novel toxin subclass from the web of the spider Nephila clavipes

A novel chemical subclass of toxin, [1-(3-diazenylphenyl) ethanol]iron, was identified among the compounds present in the web of the spider Nephila clavipes. This type of compound is not common among natural products, mainly in spider-venom toxins; it was shown to be a potent paralytic and/or lethal toxin applied by the spider over its web to ensure prey capture only by topical application. The structure was elucidated by means of ESI mass spectrometry, H-1-NMR spectroscopy, high-resolution (HR) mass spectrometry, and ICP spectrometry. The structure of [1-( 3-diazenylphenyl)ethanol] iron and the study of its insecticidal action may be used as a starting point for the development of new drugs for pest control in agriculture.

Antifungal iridoids from the stems of Tocoyena formosa

A new antifungal iridoid compound, together with three active known iridoids, galioside, galioside aglucone, and apodanthoside, as well as 3-O-beta-D-glucopyranosyl-28-O-beta-D-glucopyranosyl quinovic acid and quercetin-3-O-methyl-3-O-beta-D-rhamnopyranoside, were isolated from the stems of Tocoyena formosa. This new compound was characterized by spectral data as 11-O-trans-feruloylteucrein.

Natural trans-crotonin: the antiulcerogenic effect of another diterpene isolated from the bark of Croton cajucara Benth.

The nor-clerodane diterpene trans-crotonin isolated from the bark of Croton cajucara BENTH. was investigated for its ability to prevent the formation of gastric-mucosa ulceration in different experimental models in mice. The results obtained from crotonin were compared with those obtained with another diterpene, DHC (trans-dehydrocrotonin) in the same models. When previously administered (p.o.) at the dose of 100 mg/kg, crotonin, as well as DHC, significantly reduced (p<0.05) gastric injury induced by stress (72, 67%), indomethacin/bethanechol (78, 29%) and pylorus ligature (35, 30%). In the HCl/ethanol-induced gastric ulcer model, at oral doses of 100 and 250 mg/kg, crotonin significantly prevented (p<0.05) the formation of gastric lesions by 51 and 56%, respectively, when compared to the control group. Gastric injury was also of significantly less magnitude in the DHC treatment group (p<0.05). In the pylorus-ligature model, crotonin (p.o.), like cimetidine, increased the volume of gastric juice when compared to the control group (p<0.05). No significant modifications where found in gastric parameters such as pH or total acid content after oral crotonin treatment. However, systemic alterations were observed when crotonin (100 mg/kg) was previously administered intraduodenally to mice. We observed significant changes (p<0.001) in gastric-juice parameters such as an increase in volume and a decrease in gastric acidity. Those pre-treated with crotonin as well as with DHC did not increase free mucus production (p>0.05). The results suggest that crotonin presents a significant anti-ulcer effect when assessed in these ulcer-induced models. As with DHC, the antiulcerogenic effects of crotonin are probably related to anti-secretory or/and gastroprotective properties of this substance. In light of results obtained with DHC and natural trans-crotonin in the present study, we concluded that the A-ring of both diterpenes is not directly involved in the antiulcerogenic activity.

Isolation and chemical characterization of PwTx-II: A novel alkaloid toxin from the venom of the spider Parawixia bistriata (Araneidae, Araneae)

Brazil has many species of spiders belonging to Araneidae family however, very little is known about the composition, chemical structure and mechanisms of action of the main venom components of these spiders. The main objective of this work was to isolate and to perform the chemical characterization of a novel beta-carboline toxin from the venom of the spider Parawixia bistriata, a typical species of the Brazilian 'cerrado'. The toxin was purified by RP-HPLC and structurally elucidated by using a combination of different spectroscopic techniques (UV, ESI-MS/MS and H-1 NMR), which permitted the assignment of the molecular structure of a novel spider venom toxin, identified as 1-4-guanidinobutoxy-6-hydroxy-1,2,3,4-tetrahydro-beta-carboline, and referred to here as PwTx-II. This compound is toxic to insects (LD50 = 12 +/- 3 eta g/mg honeybee), neurotoxic, convulsive and lethal to rats (LD50 = 9.75 mg/kg of male Wistar rat). (c) 2005 Elsevier Ltd. All rights reserved.

Native crystal structure of a nitric oxide-releasing lectin from the seeds of Canavalia maritima

Here, we report the crystallographic study of a lectin from Canavalia maritima seeds (ConM) and its relaxant activity on vascular smooth muscle, to provide new insights into the understanding of structure/function relationships of this class of proteins. ConM was crystallized and its structure determined by standard molecular replacement techniques. The amino acid residues, previously suggested incorrectly by manual sequencing, have now been determined as I17, I53, S129, S134, G144, S164, P165, S187, V190, S169, T196, and S202. Analysis of the structure indicated a dimer in the asymmetric unit, two metal binding sites per monomer, and loops involved in the molecular oligomerization. These confer 98% similarity between ConM and other previously described lectins, derived from Canavalia ensiformis and Canavalia brasiliensis. Our functional data indicate that ConM exerts a concentration-dependent relaxant action on isolated aortic rings that probably occurs via an interaction with a specific lectin-binding site on the endothelium, resulting in a release of nitric oxide. (C) 2005 Elsevier B.V. All rights reserved.

Eumenitin, a novel antimicrobial peptide from the venom of the solitary eumenine wasp Eumenes rubronotatus

A novel antimicrobial peptide, eumenitin, was isolated from the venom of the solitary eumenine wasp Eumenes rubronotatus. The sequence of eumenitin, Leu-Asn-Leu-Lys-Gly-Ile-Phe-Lys-Lys-Val-Ala-Ser-Leu-Leu-Thr, was mostly analyzed by mass spectrometry together with Edman degradation, and corroborated by solid-phase synthesis. This peptide has characteristic features of cationic linear a-helical antimicrobial peptides, and therefore, can be predicted to adopt an amphipathic a-helix secondary structure. In fact, the CD spectra of eumenitin in the presence of TFE or SDS showed a high content of alpha-helical conformation. Eumenitin exhibited inhibitory activity against both Gram-positive and Gram-negative bacteria, and moderately stimulated degranulation from the rat peritoneal mast cells and the RBL-2H3 cells, but showed no hemolytic activity against human erythrocytes. This antimicrobial peptide in the eumenine wasp venom may play a role in preventing potential infection by microorganisms during prey consumption by their larvae. (c) 2006 Elsevier B.V. All rights reserved.