Abstract Background: Other tools for weed management should be considered in addition to the use of herbicides. In this context, the identification and use of allelopathic compounds deserves attention. Question: To quantify phenolic compounds and evaluate the allelopathic potential of extracts of Conyza sumatrensis on the germination of Bidens pilosa. Studied species: Conyza sumatrensis (Retz.) E.Walker, Bidens pilosa L. (Asteraceae) Study site: Palotina, state of Paraná, Brazil. Methods: The aqueous extracts were prepared with shoot and root portions of C. sumatrensis in concentrations: 0, 1, 5 and 10 %. Germination and germination speed index were evaluated. The total flavonoids and phenols of the tested extracts were also quantified. Results: With increasing concentrations of the extracts there was an increased inhibition of germination of B. pilosa and delays in the germination process. The extracts from the shoot of C. sumatrensis had a more expressive effect on seed germination when compared to the extracts obtained from the root. At concentration of 10 %, the extract from the shoot reduced in 83 % the percentage of germination. This may be related to the higher concentration of total flavonoids and phenols found. Conclusion: The allelopathic potential of C. sumatrensis plants can be considered since both shoot and root extracts inhibited and/or reduced the germination of B. pilosa.

Resumen Antecedentes: Se deben considerar otras herramientas para el manejo de malezas además del uso de herbicidas. En este contexto, la identificación y el uso de compuestos alelopáticos merece atención. Problema: Cuantificar compuestos fenólicos y evaluar el potencial alelopático de extractos de Conyza sumatrensis en la germinación de Bidens pilosa. Especies de estudio: Conyza sumatrensis (Retz.) E.Walker, Bidens pilosa L. (Asteraceae) Sitio de estudio: Palotina, estado de Paraná, Brasil. Métodos: Los extractos acuosos se prepararon con porciones de brotes y raíces de C. sumatrensis en concentraciones: 0, 1, 5 y 10 %. Se evaluaron la germinación y el índice de velocidad de germinación. También se cuantificaron los flavonoides y fenoles totales de los extractos probados. Resultados: Con el aumento de las concentraciones de los extractos hubo una mayor inhibición de la germinación de B. pilosa y retrasos en el proceso de germinación. Los extractos del brote de C. sumatrensis tuvieron un efecto más expresivo sobre la germinación de las semillas en comparación con los extractos obtenidos de la raíz. En la concentración de 10 %, el extracto del brote redujo en 83 % el porcentaje de germinación. Esto puede estar relacionado con la mayor concentración de flavonoides y fenoles totales encontrados. Conclusión: El potencial alelopático de las plantas de C. sumatrensis puede considerarse ya que tanto los extractos de brotes como los de raíz inhibieron y/o redujeron la germinación de B. pilosa.

The objective of this study was to evaluate the effect of extracts obtained from leaves of Jatropha curcas L. on germination and initial growth of wheat. The aqueous and alcohol (ethanol and methanol) extracts of dried leaves were prepared in the concentration of 50 mg/mL. From the crude extract were made dilutions and obtained different concentrations. Some of the aqueous extracts tested were autoclaved. Over seven days, the germination characteristics and growth of wheat seedlings were evaluated with the different treatments. There was no effect of aqueous extracts on percentage of seed germination, however the methanolic and ethanolic extracts 5% affected the germination of a cultivar in study. There was a decrease in the germination speed index when the seeds were incubated with crude aqueous extract and methanol extract. The extracts affected the growth of seedlings and the most phytotoxic was the ethanol extract 5%. The autoclaved extracts promoted a reduction in all parameters evaluated. The results presented here show the extracts of dried leaves of jatropha promoted allelopathic effects on wheat.

El objetivo de la investigación fue evaluar el efecto de los extractos obtenidos a partir de hojas de Jatropha curcas L. sobre la germinación y el crecimiento inicial del trigo. Las acuosas y alcohol (etanol y metanol) extractos de hojas secas se prepararon de la concentración de 50 mg/ml. A partir del extracto crudo se hicieron diluciones, obteniendo diferentes concentraciones. Algunos de los extractos acuosos ensayados se trataron en autoclave. Durante siete días, las características de germinación y crecimiento de plántulas de trigo fueron evaluados con los diferentes tratamientos. No hubo efecto de extractos acuosos en el porcentaje de germinación de las semillas; sin embargo, los extractos metanólicos y etanólicos 5% afectaba la germinación de un cultivar en estudio. Hubo una disminución en el índice de velocidad de germinación cuando las semillas se incubaron con extracto crudo acuoso y extracto de metanol. Los extractos afectaron el crecimiento de las plántulas y el más fitotóxico era el extracto en etanol 5%. Los extractos autoclave promovieron una reducción en todos los parámetros evaluados. Los resultados aquí presentados muestran los extractos de hojas secas de Jatropha que promueven efectos alelopáticos sobre el trigo.

Os fungos basidiomicetos do gênero Polyporus são fonte de metabólitos secundários de interesse medicinal como os compostos antibacterianos. Como estas substâncias são produzidas em pequenas quantidades pelos fungos, o estudo de condições de cultivo in vitro que otimizem sua produção, é de fundamental importância. Os efeitos da glicose e lactose, pH e agitação na concentração da biomassa e na velocidade específica de crescimento realizada pelo basidiomiceto Polyporus tricholoma foram investigados. O pH inicial (4.5, 6.5 e 8.5) foi autoregulado para pH 5.5, e a agitação aumentou o crescimento micelial e a velocidade específica de crescimento. A maior concentração das fontes de carbono (4%) incrementou a produção de biomassa. A concentração de lactose e a ausência de agitação foram determinantes na produção dos metabólitos antibacterianos. A caracterização da substância antibacteriana por CG-EM mostrou como componente majoritário o isodrimenediol, produzido pelo fungo Polyporus tricholoma, com atividade contra Staphylococcus aureus.

Basidiomycete fungi of the Polyporus genus are a source of secondary metabolites which are of medicinal interest as antibacterial compounds. As these substances are produced in a small amount by the fungi, the study of the cultivation conditions in vitro that could possibly optimize their production seems of major importance. The effects of glucose and lactose, pH and agitation on biomass concentration and on the specific growth rate caused by the basidiomycete Polyporus tricholoma were investigated. The initial pH (4.5, 6.5 and 8.5) was autoregulated at pH 5.5, and the agitation increased the mycelial growth and the specific growth rate. The high concentration of carbon sources (4%) increased biomass production. The lactose concentration and the absence of agitation were determinant in the production of antibacterial metabolites. The characterization of the antibacterial substance by GC-MS indicated a major compound, isodrimenediol, produced by the fungus Polyporus tricholoma with activity against Staphylococcus aureus.

Do fungo brasileiro Ganoderma australe foram isolados o ácido austrálico e o novo composto australado de metila, além de outros 9 compostos já conhecidos. Tanto o australado de metila quanto o ácido correpondente foram ativos contra fungos e bactérias Gram-positivas, sendo o éster metílico ainda ativo contra bactérias Gram-negativas.

In addition to nine known steroidal compounds, australic acid and the new methyl australate have been isolated from the Brazilian fungus Ganoderma australe. Both methyl australate and its corresponding acid were shown to be active against fungi and Gram-positive bacteria, the methyl ester being also active against Gram-negative bacteria.