Antibacterial activity of cuticular components from heliotropium species, against staphylococcus aureus and salmonella tiphymurium / Actividad antibacteriana de componentes cuticulares de especies de heliotropium frente a staphylococcus aureus y salmonella tiphymurium

In this communication the antibacterial activity of filifolinol (1), naringenin (2) 3-O-methylgalangin (3) and pinocembrin (4) isolated from the resinous exudates of Heliotropium filifolium and H. sinuatum, were evaluated by flow cytometry against Staphylococcus aureus and Salmonella tiphymurium. The results showed that filifolinol (1) and naringenin (2) were inactive in the range of concentrations used (10 to 1000 ug/mL). On the other hand, pinocembrin (4) produced a decrease in cell surface at 500 ug/mL and the total disappearance of both bacterial populations at 1000 ug/mL. Also, 3-O-methylgalangin (3) showed the total disappearance at 1000 ug/mL of both bacterial populations and a decrease at 200 μg/mL for S. typhimurium and at 500 μg/mL for S. aureus.

En esta comunicación, la actividad antibacteriana de filifolinol (1), naringenina (2), 3-O-methylgalangina (3) y pinocembrina (4) aislados de los exudados resinosos de Heliotropium filifolium y H. sinuatum, fueron evaluados por citometría de flujo frente a Staphylococcus aureus y Salmonella tiphymurium. Los resultados mostraron que filifolinol (1) y naringenina (2) fueron inactivos en el intervalo de concentraciones usadas (10 a 1000 μg / mL). Por otro lado, pinocembrina (4) produce una disminución de la superficie de las células a 500 ug/mL y la desaparición total de ambas poblaciones bacterianas a 1.000 ug/mL. También, 3-O-metilgalangina (3) mostró la desaparición total a 1.000 ug / mL tanto de ambas poblaciones de bacterias y una disminución a 200 ug/mL para S. typhimurium y en 500 μg/mL para S. aureus.

Evaluation of the bactericidal activity of secondary metabolites isolated from Heliotropium genus against Piscirickettsia salmonis / Evaluación de la actividad bactericida de metabolitos secundarios aislados desde especies del género Heliotropiumcontra Piscirickettsia salmonis

The intracellular bacteria Piscirickettsia salmonis is the most prevalent pathogen in the Chilean salmon industry, responsible for 50 percent of losses in recent years. So far, there are no effective treatments to control infections by this pathogen due to the emergence of antibiotics resistance. Therefore, it is extremely important to conduct research to find successful antibacterial therapies. In this paper, we evaluated the in vitro bactericidal activity of flavonoids and aromatic geranyl derivatives isolated from the resinous exudate of species Heliotropium filifolium, H. sinuatum y H. huascoense. The results showed that the compounds Filifolinone, Naringenine and 3-O- methylgalangine cause different percentage of mortality of bacteria and therefore they are good candidates to continue its evaluation in vitro and in vivo.

La bacteria intracelular Piscirickettsia salmonis es el patógeno de mayor incidencia en la industria salmonera chilena siendo responsable de un 50 por ciento de las pérdidas en los últimos años. Hasta ahora no hay tratamientos efectivos para este patógeno que permitan controlar las infecciones provocadas por él debido a la aparición de resistencia a antibióticos. Por lo tanto, resulta de gran importancia investigar para encontrar terapias antibacterianas efectivas. En este trabajo nosotros evaluamos la actividad bactericida in vitro de flavonoides y derivados aromáticos geranilados aislados desde el exudado resinoso de las especies vegetales Heliotropium filifolium, H. sinuatum y H. huascoense. Los resultados mostraron que los compuestos Filifolinona, Naringenina y 3-O-metilgalangina provocan diferentes porcentajes de mortalidad de la bacteria y, por lo tanto, son candidatos para seguir siendo evaluados tanto in vitro como in vivo.

tlpA gene expression is required for arginine and bicarbonate chemotaxis in Helicobacter pylori

About half of the human population is infected with Helicobacter pylori, a bacterium causing gastritis, peptic ulcer and progression to gastric cancer. Chemotaxis and flagellar motility are required for colonization and persistence of H. pylori in the gastric mucus layer. It is not completely clear which chemical gradients are used by H. pylori to maintain its position. TlpA, a chemotaxis receptor for arginine/ bicarbonate, has been identified. This study aimed to find out whether tlpA gene expression is required for the chemotactic response to arginine/bicarbonate. Wild-type motile H. pylori ATCC 700392 and H. pylori ATCC 43504, a strain having an interrupted tlpA gene, were used. Also, a tlpA-knockout mutant of H. pylori 700392 (H. pylori 700-tlpA::cat) was produced by homologous recombination. Expression of tlpA was assessed by a Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay. Chemotaxis was measured as a Relative Chemotaxis Response (RCR) by a modified capillary assay. H. pylori 700392 presented chemotaxis to arginine and sodium bicarbonate. H. pylori 700-tlpA::cat showed neither tlpA gene expression nor chemotaxis towards arginine and bicarbonate. Besides confirming that TlpA is a chemotactic receptor for arginine/bicarbonate in H. pylori, this study showed that tlpA gene expression is required for arginine/bicarbonate chemotaxis.