Critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field.

The phase diagram and the critical behavior of the spin-1 and the spin-3/2 two-dimensional Baxter-Wu model in a crystal field are studied by conventional finite-size scaling and conformal invariance theory. The phase diagram of this model, for the spin-1 case, is qualitatively the same as those of the diluted 4-states Potts model and the spin-1 Blume-Capel model. However, for the present case, instead of a tricritical point one has a pentacritical point for a finite value of the crystal field, in disagreement with previous work based on finite-size calculations. On the other hand, for the spin-3/2 case, the phase diagram is much richer and can present, besides a pentacritical point, an additional multicritical end point. Our results also support that the universality class of the critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field is the same as the pure Baxter-Wu model, even at the multicritical points.

Effect of toothbrushing-mouthrinse-cycling on surface roughness and topography of nanofilled, microfilled, and microhybrid resin composites.

The purpose of this study was to evaluate the influence of toothbrushing-mouthrinse-cycling (TMC) on the surface roughness and topography of three resin composites with different filler particle systems (Z350, nanofilled [Nf]; Durafill, microfilled [Mf], and Empress Direct, microhybrid [Mh]). Twenty specimens of each resin composite (8.0 mm diameter and 2 mm height) were randomly divided into four groups (n=5) according to the mouthrinses: alcohol-free (Plax--P) and alcohol-containing (Listerine--L and Plax Fresh Mint--PM) and artificial saliva (control--AS). The specimens were submitted to TMC for nine weeks. A surface roughness tester and a three-dimensional profilometer were used to measure the roughness (Ra) and the topography (Sa) before and after TMC. The data were analyzed by multifactor analysis of variance and Tukey post hoc test (α=0.05). In all media, Mh presented greater roughness than Mf (p<0.05). The highest value of roughness was presented by Mh immersed in L (p<0.05). The lowest values of roughness were presented by Mf (p<0.05). The three resin composites presented the highest roughness after immersion in mouthrinses containing alcohol (PM and L) (p<0.05). For the three resin composites, the increase in roughness was noticeable after the fifth week. Topographic analysis showed that the smoothest surfaces were present after immersion in AS.

Trypanocidal and antimicrobial activities of Moquinia kingii.

A chloroform crude extract (aerial part) and two compounds, apigenin (1) and cynaropicrin (2), isolated from Moquinia kingii were evaluated against Trypanosoma cruzi trypomastigotes in vitro. Antimicrobial activity was also screened using twenty-two strains including gram-positive and gram-negative bacteria and the yeasts Candida albicans and C. tropicalis. The chloroform crude extract, fractions and isolated compounds from M. kingii were active for both activities. The IC50 values for trypanocidal activity obtained for cynaropicrin and apigenin were 93.5 microg/ml and 181 microg/ml, respectively, while the minimum inhibitory concentrations (MICs) varied from 100 microg/ml to 2500 microg/ml, against the strains of bacteria and yeasts evaluated.

Estudo comparativo da produção de metabólitos secundários em cultura de células e na planta in natura de Gomphrena globosa (Amaranthaceae)

A cultura de calos de Gomphrena globosa a partir de segmentos foliares foi estabelecida em meio contendo combinações dos fitoreguladores auxina/citocinina. Metabólitos secundários identificados através da fitoquímica da planta in natura, foram utilizados como padrões em análises por cromatografia líquida de alta eficiência e cromatografia de gás de extratos da cultura. O estudo comparativo revelou que os calos foram capazes de produzir alguns metabólitos sintetizados pela planta in natura.

The culture of calluses of Gomphrena globosa starting from segments foliate was established in half containing combinations of the phytoregulators auxina/citocinina. Identified secondary metabolites through the phytochemistry of the plant in natura were used as patterns in analyses for high performance liquid cromatography and gas cromatography of extracts of the culture. The comparative study revealed that the calluses were capable to produce some metabolite synthesized by the plant in natura.

Bioactivity of crude extracts and some constituents of Blutaparon portulacoides (Amaranthaceae).

Crude extracts (aerial parts and roots, both dried), methylenedioxyflavonol, and a mixture of acyl steryl glycosides isolated from Blutaparon portulacoides, were assayed for their toxicity against Trypanosoma cruzi trypomastigotes and Leishmania amazonensis amastigotes from axenic cultures. The antimicrobial activity was also investigated, in a screening conducted using fifteen strains of Gram-positive and Gram-negative bacteria, along with the yeasts, Candida albicans and Candida tropicalis. To assess the antibacterial activity of the isolated compounds, the minimum inhibitory concentrations (MICs) were determined. There are no reports of acyl steryl glycosides in the genus Blutaparon and their biological activities are being evaluated for the first time.

Inhibition of the lethal and myotoxic activities of Crotalus durissus terrificus venom by Tabernaemontana catharinensis: identification of one of the active components.

In Brazilian folk medicine, victims of bites by poisonous animals are usually treated with plant extracts derived from the diverse national flora. The chemical and pharmacological properties of most extracts were yet not investigated. In the rural community of Assis-SP, the root bark of Tabernaemontana catharinensis ("leiteiro", "cow milk") is applied to the site of the snake bite and believed to neutralize the effect of the venom. We report here the ability of the lyophilized aqueous extract (AE) and of a pure compound obtained from the ethanolic extract of T. catharinensis to inhibit the lethal and myotoxic activities of C. d. terrificus (South American rattlesnake) venom. Doses of 10 mg AE/100 g, injected (i.m., rat) 20 s after injecting (i.m.) the venom and that of 2.5 mg AE/100 g, incubated for 1 h at 25 degrees C with the venom before injection (i.m.) were able to neutralize the lethal activity of 2LD50. These data indicate that T. catharinensis could be used as a source of a model molecule able to neutralize the lethality and myotoxicity induced by C. d. terrificus venom. Its ethanolic extract was then fractionated on a silica gel 60 chromatography column affording fractions A to F. Fraction A consisted basically of non-polar compounds, terpenes and sterols. Fraction D showed a pronounced antiophidian activity which was later correlated with the presence of the quaternary alkaloid 12-methoxy-4-methylvoachalotine in this fraction. This alkaloid was isolated and inhibited 100% lethality when injected 20 s after 2 LD50 at 1.7 mg/100 g.

A methylenedioxyflavonol from aerial parts of Blutaparon portulacoides.

The aerial parts from Blutaparon portulacoides yielded a flavonol whose structure was established as 3,5,3'-trihydroxy-4'-methoxy-6,7-methylenedioxyflavone. In addition, the aerial parts yielded the isoflavone irisone B and the steroids stigmasterol, sitosterol and campesterol. The roots of B. portucaloides furnished sitosteryl, stigmast-7-enyl and spinasteryl beta-D-glucopyranosides as well as vanillic acid.