Abstract Background: Gunnera tinctoria has been collected by Mapuche-Pewenche people for food and medicinal purposes. The high polyphenol content of methanolic extract from G. tinctoria leaves with chemical constituents such as ellagic acid and quercetin derivatives suggests its application to prevent endothelial dysfunction and oxidative stress. The aim of this study was to provide evidence of the protective effect of this extract on endothelial function by reducing oxidative stress induced by high D-glucose and H2O2, as well as by stimulating nitric oxide (NO) levels in human umbilical vein endothelial cells (HUVECs). Results: A methanolic extract with a high content of polyphenols (520 ± 30 mg gallic acid equivalents/g dry extract) was obtained from G. tinctoria leaves. Its main constituent was ellagic acid. The results of Ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays of the extract confirmed its antioxidant activity by inhibition pathway of radical species. The incubation of HUVECs with the extract decreased the apoptosis and reactive oxygen species (ROS) synthesis induced by high extracellular concentration of D-glucose or hydrogen peroxide. The extract increased endothelial NO levels and reduced vasoconstriction in human placental vessels. Conclusions: This study provides evidence about the antioxidant and endothelial protective properties of methanolic G. tinctoria leaf extract. The extract improves the availability of NO in HUVECs, inhibiting the production of ROS and vasoconstriction.

Abstract The effect of molecular weights and hydrolysis degrees (HD) of polyvinyl alcohol (PVA) on thermal and mechanical properties and crystallinity of polylactic acid (PLA)/PVA blends was investigated. Blends were prepared by the melt blending method using PLA/PVA ratios: 80/20, 90/10 and 97/3 wt. %. A single glass transition temperatures was observed for all PLA/PVA blends, suggesting the formation of binary compatible blends at concentration range studied. Thermogravimetric analysis results showed a better thermal stability for PLA/PVA blends containing PVA of higher Mw and HD. According to mechanical properties, low quantities of PVA (3 wt. %) do not affect the tensile strength of blends (irrespective of Mw and HD). However, as the PVA content increases, tensile strength tends to lower values, especially for blends with 20 wt.% of PVA, with 98% of HD.

Selenium is required and essential for the growth and metabolism of several biological systems. Its transformation in the environment occurs mainly by the activity of microorganisms, able to reduce selenite into elemental Selenium. Pantoea agglomerans UC-32 reduces selenite to nanoparticles of elemental Selenium. The aims of this work were to determine the kinetics of selenite reduction and to determine the cellular localization of this activity in P. agglomerans UC-32. The selenite reducing activity of P. agglomerans UC-32 was assayed in the presence of different selenite concentrations and the decrease of selenite and appearance of elemental Selenium were evaluated. The location of this activity was studied by cellular fractioning and zymography. Results indicated that the selenite reducing enzyme saturates at low concentrations of this compound and the zymogram localized this activity in the cytoplasmic fraction and showed that NADPH is required as coenzyme. In conclusion, P. agglomerans reduces, under aerobic conditions, selenite into insoluble elemental Selenium, immobilized in the biomass and that the enzyme catalyzing this reduction is cytoplasmatic. These characteristics would allow the "green synthesis" of selenium nanoparticles which have application in the bioremediation of different contaminated matrices, such as soil or water.

El selenio es esencial y requerido por distintos sistemas biológicos para su crecimiento y metabolismo. Su transformación en el ambiente ocurre principalmente por microorganismos que reducen el selenito a selenio elemental. Pantoea agglomerans UC-32 reduce el selenito a nanopartículas de selenio elemental. El objetivo de este trabajo fue determinar la cinética de reducción de selenito a selenio elemental y la ubicación celular de la actividad reductora en Pantoea agglomerans UC-32. Se ensayó la actividad reductora de P. agglomerans frente a diferentes concentraciones de selenito, evaluándose la disminución de selenito y aparición de selenio elemental. La ubicación de la actividad reductora fue estudiada por fraccionamiento celular y zimograma. Al ensayar la actividad reductora de selenito se encontró que la enzima se satura a concentraciones bajas de este compuesto y el zimograma localizó esta actividad en la fracción citoplasmática y que requiere NADPH como coenzima. En conclusión, P. agglomerans es capaz de reducir selenito a selenio elemental insoluble inmovilizado en la biomasa en condiciones aeróbicas y que la enzima que cataliza esta reducción se localiza en la fracción de citoplasmática. Estas características permitirían la "síntesis verde" de nanopartículas de selenio las cuales tienen aplicación en la biorremediación de diferentes matrices, como suelo o agua contaminadas.

The effect of virgin heterophasic PP copolymer (vPP) content on moisture absorption, as well as on thermal and mechanical properties of recycled polyethylene/ wood flour composites was investigated. The polymer matrix of recycled post-consumed plastic waste (rPE) was composed of a matrix of LDPE and a part of PP. Wood flour of Pinus radiata was used as filler at a constant loading of 45 wt.%. rPE/vPP blends and their composites were manufactured by melt blending, and then by injection molding. The morphology of the blends and composites was analyzed by means of scanning electron microscopy. The addition of vPP improved tensile and flexural moduli and flexural strength of wood plastic composites (WPC). The highest increase of these properties was observed for a WPC sample with a rPE/vPP ratio of 19. WPC made with higher virgin PP content (rPE/vPP ratio = 9 and 5.7) showed lower increase of mechanical properties compared to polymer matrix and WrPE samples. The moisture uptake of WPC made of rPE/vPP blend was higher than those of rPE, and their mechanical properties were more adversely affected by immersion in water. TGA results indicate that rPE are thermally more stable than rPE/vPP blends. The incorporation of heterophasic PP copolymer into the recycled polymer matrix of WPC delays the starting of wood flour degradation.

Polypropylene/starch blends were prepared using starch of different botanical source. The influence of starch type and starch content on thermal properties and morphology of polypropylene/starch blends was studied. Corn and potato starches were used as starch source. The starch content in the blends was 7 and 15 wt-%. Characterization of PP and PP/starch blends by (DSC), (TGA), and (SEM) was carried out to obtain information on miscibility among PP and starch. The starch domains exhibited characteristic voids be due to thermal degradation. Two types of PP, PP1 poly(propylene-co-ethylene), random copolymer, and PP3 poly(propylene-co-ethylene), heterophasic copolymer were studied.