Perfil químico de los tricomas urticantes de Cnidoscolus multilobus (“mala mujer”) y su actividad antimicrobiana

Cnidoscolus multilobus (Euphorbiacaeae) is a stinging plant widely distributed in the south of Mexico. The main objective of this work was to reveal the inflammatory-inducing toxins contained in the prickles of Cnidoscolus multilobus and its possible ecological role as antimicrobials. The chemical characterization and quantification of the toxins was performed by GC-MS and HPLC-DAD. Simultaneously, the endogenous fluid and its most abundant compounds were individually tested against opportunistic phytophatogens. According to our results, the fluid contained histamine (17.3-28.4 µg mL-1), dimethylethylamine (1.7-3.6 µg mL-1), acetylcholine (0.6-1.3 µg mL-1), serotonin (24.6-45.8 µg mL-1), oxalic acid (2.2-9.6 µg mL-1) and formic acid (0.9-4.7 µg mL-1). The in vitro growth of Pseudomonas syringae pv. tabaci TBR2004 (MIC, 122.2 µL mL-1), P. syringae pv. tomato DC3000 (MIC, 105.8 µL mL-1), Fusarium oxysporum ATCC 62506 (MIC, 97.4 µL mL-1) and Phytophthora capsici ATCC 15399 (MIC, 163.2 µL mL-1) was inhibited by the natural fluid whereas that of Clavibacter michiganensis AB299158 was not modified. The individual assessment of the main compounds dissolved in the fluid revealed histamine as an overlooked antimicrobial agent (145.1-219.5 µL mL-1). According to our results, the pain-inducing toxins from the prickles of C. multilobus are not only toxic for mammal species but also for some opportunistic phytopathogens.Cnidoscolus multilobus (Pax.) I.M. Johnst (Euphorbiaceae) es una planta con pelos urticantes ampliamente distribuida en el sur de México. En la actualidad, las propiedades químicas y biológicas del fluido endógeno de las espinas de C. multilobus se desconocen. De este modo, el objetivo de este trabajo fue identificar los compuestos tóxicos presentes en el fluido de los tricomas de Cnidoscolus multilobus y su posible actividad antimicrobiana. La determinación y cuantificación de las sustancias toxicas se efectuó por GC-MS y HPLC-DAD.  Simultáneamente, el fluido endógeno y sus compuestos más abundantes (adquiridos comercialmente), fueron individualmente ensayados contra fitopatógenos oportunistas mediante el método de microdilución en caldo con rezasurina y el método XTT anti-fúngico. De acuerdo a nuestros resultados, el fluido contuvo histamina (17.3-28.4 µg mL-1), dimetiletilamina (1.7-3.6 µg mL-1), acetilcolina (0.6-1.3 µg mL-1), serotonina (24.6-45.8 µg mL-1), ácido oxálico (2.2-9.6 µg mL-1) y ácido fórmico (0.9-4.7 µg mL-1). El crecimiento in vitro de Pseudomonas syringae pv. tabaci TBR2004 (MIC, 122.2 µL mL-1), P. syringae pv. tomato DC3000 (MIC, 105.8 µL mL-1), Fusarium oxysporum ATCC 62506 (MIC, 97.4 µL mL-1) y Phytophthora capsici ATCC 15399 (MIC, 163.2 µL mL-1) fue inhibido por el fluido natural. Contrariamente, el fluido natural no tuvo efecto sobre el crecimiento in vitro de Clavibacter michiganensis AB299158. El ensayo individual de los principales compuestos disueltos en el fluido reveló que la histamina posee una actividad antimicrobiana sustancial (145.1-219.5 µL mL-1). De acuerdo con nuestros resultados, las toxinas productoras de dolor en las espinas de C. multilobus no son dañinas solamente para especies de mamíferos, estas también exhiben propiedades inhibitorias contra fitopatógenos oportunistas

Zaluzania montagnifolia: essential oil composition and biological properties

The chemical composition of the seasonal essential oils (2015-2016) from the leaves and flowers of Zaluzania montagnifolia is presented. The chemical content of those oils showed quantitative and qualitative differences. Germacrene D (19.9-29.8%), camphor (12.4- 19.4%) and β-caryophyllene (13.7-18.5%) were the most abundant volatiles in the leaves. The essential oils from the flowers contained high amounts of camphor (32.7-37.2%) limonene (19.8-24.9%) and germacrene D (3.2-7.3%). All the seasonal essential oils showed a potent in vitro inhibition against HMG-CoA reductase. The essential oils from flowers (IC50, 40.5-55.1 μg mL-1) showed better inhibition properties than those of leaves (IC50, 84.4-123.5 μg mL-1). Camphor (IC50, 72.5 μg mL-1) and borneol (IC50, 84.4 μg mL-1) exerted a non-competitive inhibition on the enzyme. Additionally, the hydrodistillates exhibited antibacterial activity against the phytopathogenic Pseudomonas syringae pv. tabaci TBR2004 (MIC, 62.7-76.5 μg mL-1) P. syringae pv. tomato DC3000 (MIC, 45.4-50.4 μg mL-1) and P. syringae pv.phaseolicola NPS3121 (MIC, 26.7-31.9 μg mL-1). Germacrene D (MIC, 35.4-66.2 μg mL-1) and β-caryophyllene (MIC, 36.5-54.2 μg mL-1) were the strongest anti-Pseudomonas syringae agents

Alkaloid profile, antibacterial and allelopathic activities of Lupinus jaimehintoniana B.L. Turner (Fabaceae)

Herein we describe some aspects of the ethnobotanical use and the first alkaloid profile of Lupinus jaimehintoniana, the 5 to 8 m high arboreous lupine. Five quinolizidine alkaloids identified as sparteine, 5,6-dehydrolupanine, lupanine, nuttalline, and d-thermopsine, were characterized by the respective elution order according to their electronic impact spectra, lupanine being the most abundant in the four different tissues analyzed. Simultaneously, an antibacterial assessment of the four corresponding crude methanolic extracts, as well as the four semi-purified alkaloids was performed on specific Escherichia coli and Agrobacterium tumefaciens strains. These experiments resulted in MIC ranges of 37-61 µg mL-1 and 130-146 µg mL-1, respectively. for both bacterial species. Finally, the allelopathic activity of these extracts on the germination of Lactuca sativa seeds was demonstrated to be in the range of 50-300 µg mL-1 for both semi-purified alkaloid and methanolic extracts

Ciencia Odontológica 2.0

Libro que muestra avances de la Investigación Odontológica en MéxicoEs para los integrantes de la Red de Investigación en Estomatología (RIE) una enorme alegría presentar el segundo de una serie de 6 libros sobre casos clínicos, revisiones de la literatura e investigaciones. La RIE está integrada por cuerpos académicos de la UAEH, UAEM, UAC y UdeG

A Comparative Study of Gold Impregnation Methods for Obtaining Metal/Semiconductor Nanophotocatalysts: Direct Turkevich, Inverse Turkevich, and Progressive Heating Methods

ZnO nanostructures decorated with gold nanoparticles (Au-NPs) were synthesized by thermal decomposition of ZnO2 powders and their subsequent impregnation of metal nanoparticles using either the Direct Turkevich Method, the Inverse Turkevich Method, or the Progressive Heating Method. It was found that the impregnation approach influences the resulting microstructure and photocatalytic activity of the obtained materials. While the Direct Turkevich approach gave the highest yield of metal loading, the smallest Au-NPs were obtained by Inverse Turkevich and the Progressive Heating Method. The photocatalytic activity of the pristine support and gold-loaded samples was studied in the decolorization of Rhodamine B solutions using UV- and pure visible-light illumination. All Au-NPs/ZnO samples showed higher photocatalytic activity than the bare support when UV-light was used. This effect is attributed to a charge carrier separation due to electron transfer from ZnO to the metal nanoparticles and the built-in electric field at the interfaces. Contrarily to most reports, visible-light sensitization using plasmonic nanoparticles was not observed. The experimental evidence points against hot-electron injection from Au-NPs to the semiconductor component. This behavior is associated with the height of the Schottky barrier at the metal-semiconductor junctions. The differences in the photocatalytic performance among the samples under UV- and visible-light are explained in terms of the characteristics of the Au-NPs driven by the growth mechanism involved in each impregnation method and the physicochemical properties of the generated interfaces

Effect of addition of non-functionalized graphene oxide in a commercial epoxy resin used as coating

"The paper studies the effect of incorporating graphene oxide (GO) without surface functionalization on a commercial epoxy resin. GO was dispersed in a commercial epoxy resin at concentrations of 0 wt.%, 0.1 wt.%, 0.5 wt.%, 1 wt.%, and 3 wt.%. The resultant materials were deposited on carbon steel substrates, followed by the use of a 5 wt.% aqueous NaCl electrolyte, to evaluate the effectiveness of their anticorrosive coating function. Scanning electron microscopy (SEM) analysis showed that the GO was homogenously dispersed in the polymer matrix, resulting in flat a nd s mooth s urfaces. T he X -ray diffraction (XRD) results showed that although GO was highly dispersed in the polymer matrix, multilayer graphene was also obtained after curing. The anticorrosive properties were evaluated by electrochemical impedance spectroscopy (EIS) at various exposure periods. Analysis of the prepared samples indicated that the best anticorrosion performance among them was available with the 0.5 wt.% GO coating. The obtained results indicate that GO–polymer matrix composites provide improved corrosion protection properties even after 500 h exposure to the NaCl solution"

Improving the Shelf Life of Avocado Fruit against Clonostachys rosea with Chitosan Hybrid Films Containing Thyme Essential Oil

Hass avocadoes are one of the most popular fruits consumed worldwide because of their nutritional and nutraceutical content. Nevertheless, these fruits are susceptible to phytopathogen attacks that decrease fruit quality during the postharvest period. Herein we present the results of the in situ fungistatic activity of four hybrid films (FT1–FT4) manufactured with chitosan and different concentrations of the essential oil of thyme (TvEO). The films were evaluated as biodegradable materials to prevent fruit decay triggered by Clonostachys rosea which is considered an emergent phytopathogen of this crop. The in situ fungistatic strength, spectroscopic properties (FT-IR), optical features (transmittance/opacity), and consistency obtained by microscopic analysis (SEM), indicated that the films FT3 and FT4 possessed the best physicochemical properties to protect Hass avocadoes against the soft rot produced by C. rosea. Avocadoes treated with the films FT3 and FT4 significantly (p < 0.01) conserved fruit firmness and nutritional composition (protein, fat, fiber, and reducing sugars) as well as the nutraceutical content (oleic, palmitoleic, linoleic, and palmitic acids) of infected avocados for 21 days. Our results validate the potential use of the films FT3 and FT4 to prevent the soft rot caused by C. rosea and to improve the shelf life of Hass avocadoes

Aerożele krzemionkowe na bazie polimerowych mieszanin polipirolu i nanorurek węglowych

Novel silica aerogels were produced from carbon nanotubes/carbon black/polypyrrole (NTC/CB/PPy) blends, and their structure characterized by FT-IR analysis. X-ray diffraction analysis confirms the presence of amorphous silica and a new reflection at 2θ = 13°, which had not been reported before. SEM micrographs of the aerogels reveal the connectivity of the micropores of the material, along with the different fillers (NTC/CB/PPy), which allow to increase the water absorption of the aerogels and to increase thermal stability. The mechanical and thermal properties of the resulting aerogels are significantly better than those of similar materials reported in the literature.Otrzymano nowe aerożele krzemionkowe z wykorzystaniem mieszanin nanorurek węglowych, sadzy węglowej i polipirolu (NTC/CB/PPy). Strukturę wytworzonych aerożeli scharakteryzowano na podstawie widm FT-IR. Metodą dyfrakcji rentgenowskiej potwierdzono w nich obecność amorficznej krzemionki, stwierdzono też, wcześniej nieopisywane, odbicie przy 2θ = 13°. Mikrofotografie SEM aerożeli wykazały połączenia mikroporów krzemionki z cząstkami różnych napełniaczy (NTC/CB/PPy), pozwalające zwiększyć absorpcję wody przez aerożele i ich stabilność termiczną. Wykazano, że właściwości mechaniczne i termiczne powstałych aerożeli są znacznie lepsze niż właściwości podobnych materiałów opisanych w literaturze