The MarR-Type Repressor MhqR Confers Quinone and Antimicrobial Resistance in Staphylococcus aureus

Aims: Quinone compounds are electron carriers and have antimicrobial and toxic properties due to their mode of actions as electrophiles and oxidants. However, the regulatory mechanism of quinone resistance is less well understood in the pathogen Staphylococcus aureus. Results: Methylhydroquinone (MHQ) caused a thiol-specific oxidative and electrophile stress response in the S. aureus transcriptome as revealed by the induction of the PerR, QsrR, CstR, CtsR, and HrcA regulons. The SACOL2531-29 operon was most strongly upregulated by MHQ and was renamed as mhqRED operon based on its homology to the Bacillus subtilis locus. Here, we characterized the MarR-type regulator MhqR (SACOL2531) as quinone-sensing repressor of the mhqRED operon, which confers quinone and antimicrobial resistance in S. aureus. The mhqRED operon responds specifically to MHQ and less pronounced to pyocyanin and ciprofloxacin, but not to reactive oxygen species (ROS), hypochlorous acid, or aldehydes. The MhqR repressor binds specifically to a 9–9 bp inverted repeat (MhqR operator) upstream of the mhqRED operon and is inactivated by MHQ in vitro, which does not involve a thiol-based mechanism. In phenotypic assays, the mhqR deletion mutant was resistant to MHQ and quinone-like antimicrobial compounds, including pyocyanin, ciprofloxacin, norfloxacin, and rifampicin. In addition, the mhqR mutant was sensitive to sublethal ROS and 24 h post-macrophage infections but acquired an improved survival under lethal ROS stress and after long-term infections. Innovation: Our results provide a link between quinone and antimicrobial resistance via the MhqR regulon of S. aureus. Conclusion: The MhqR regulon was identified as a novel resistance mechanism towards quinone-like antimicrobials and contributes to virulence of S. aureus under long-term infections

Naphthoquinone derivatives and lignans from the Paraguayan crude drug

Schmeda-Hirschmann,G. Laboratorio de Quımica de Productos Naturales,Instituto de Quımica de Recursos Naturales, Universidad de Talca, Casilla 747, Talca, Chile.The Paraguayan crude drug “tayı¨ pyta´” is used to treat cancer, wounds and inflammation. It consist of the bark and trunkwood of Tabebuia heptaphylla (Bignoniaceae). A phytochemical study of the crude drug gave, in addition to previously described naphthoquinones and the known lignans cycloolivil and secoisolariciresinol, three new lapachenol (lapachonone)-, two naphthofuran-, a chromone and a naphthalene derivative. The structures were elucidated by means of high field NMR spectroscopy. The biological activity of the main compound lapachol and the related α-lapachone as well as the lignans cycloolivil and secoisolariciresinol can explain, at least in part, the effect atributed to the crude drug in Paraguayan folk medicine

Naphthoquinone Derivatives and Lignans from the Paraguayan Crude Drug “Tayï Pytá” (Tabebuia heptaphylla, Bignoniaceae)

The Paraguayan crude drug “tayï pytá” is used to treat cancer, wounds and inflammation. It consist of the bark and trunkwood of Tabebuia heptaphylla (Bignoniaceae). A phytochemical study of the crude drug gave, in addition to previously described naphthoquinones and the known lignans cycloolivil and secoisolariciresinol, three new lapachenol (lapachonone)-, two naphthofuran-, a chromone and a naphthalene derivative. The structures were elucidated by means of high field NMR spectroscopy. The biological activity of the main compound lapachol and the related α-lapachone as well as the lignans cycloolivil and secoisolariciresinol can explain, at least in part, the effect atributed to the crude drug in Paraguayan folk medicine

Síntesis de nuevos derivados triazol-lapachol mediante reacción de cicloadición 1,3-dipolar

46 p.El lapachol, una naftoquinona de origen natural, que fue obtenido de extractos de la madera de Tabebuia heptaphylla (Lapacho). La síntesis de nuevos derivados de 1,4-naftoquinona es de particular importancia, ya que estos compuestos muestran importantes actividades como agentes antiparasitarios, antibacterianos, antifúngicos y anticancerígenos. Se llevo a cabo la síntesis de una serie de 13 derivados semisintéticos de la molécula lapachol, mediante la técnica de cicloadición 1,3-dipolar. Los compuestos sintetizados se caracterizarán por poseer un anillo triazol, obteniéndose mediante purificación con métodos cromatográficos, y además de la utilización de métodos espectroscópicos y espectrométricos para su identificación, añadiendo grupos químicos a los derivados

Nirs tools for prediction of main extractives compounds of teak (Tectona grandis L.) heartwood

Biochemical and physiological process which occurred during heartwood formation have consequences on wood properties such as colour, natural durability and some mechanical properties. However, it is very time-consuming to take measurements of extractives contents. Teak has been reported to contain 1-hydroxy- 2-methyl-anthraquinone, 2-hydroxy-methyl-anthraquinone, 2-methyl- anthraquinone, lapachol, 1,4-naphthoquinone for the main compounds. In teak, natural durability is ascribed to extractives. Consequently, it's possible to estimate natural durability by measurement of extractives indirectly. For the purposes of selection for the production of improved varieties, the number of samples to be measured rapidly exceeds the capacity of a traditional laboratory. Near-infrared spectroscopy approach, based on spectral data and reference data, is a tool enabling many of the chemical properties of wood to be predicted and the number of laboratory measurements to be reduced exponentially. The issue here is a question of checking the effectiveness of NIRS tool to build models and predict the main extractive compounds of teak wood from Ivory Coast. We try to calibrate these chemical properties with Nirs spectral information measured on grounded wood. The results show the possible use of NIRS to predict total phenol content and some main extractive compounds of teak heartwood as tectoquinone, 2-hydroxymethylanthraquinone,Consequently, after verification on other sets of teak samples, which may or may not be included in the prediction model, NIRS can be used to predict extractive compounds accurately for a large number of samples, making it possible to estimate natural durability indirectly and to include these characteristics in the selection criteria for classifying wood and high throughput phenotyping. (Résumé d'auteur

Les espèces du genre Tabebuia susceptibles de fournir le bois d'ipé

Il s'avère que le prestigieux " bois d'ipé ", issu d'espèces du genre Tabebuia, domine le marché du matériau bois en extérieur haut de gamme depuis plusieurs années, ce qui est justifié par les remarquables propriétés physiques, mécaniques et de durabilité des espèces commercialisées sous cette appellation. Mais, du fait de l'engouement industriel pour ce type de matériau, l'offre sur le marché devient de plus en plus disparate avec la présence d'espèces ou d'essences n'ayant pas les propriétés attendues et recherchées. Cette note, basée sur l'ensemble du genre botanique Tabebuia, identifie les espèces dont les bois ont la capacité et les caractéristiques technologiques dévolues à l'appellation ipé. Une liste a été définie comprenant onze espèces du genre Tabebuia susceptibles de répondre aux exigences de qualité escomptées et de figurer ainsi sous l'appellation commerciale d'ipé. Quoi qu'il en soit, la dérive commerciale qui se fait jour pour l'ipé et ses ersatz représente une première alarme de raréfaction de la diversité biologique de certaines espèces du genre Tabebuia et demande que la plus grande prudence soit accordée aux risques de mélanges d'essences dans les lots commerciaux. (Résumé d'auteur

Fraccionamiento y caracterización química del extracto en butanol obtenido de la corteza interna de Tabebuia rosea (Bertol.) DC

Tabebuia rosea (Bertol.) DC. es un árbol conocido en Colombia como guayacán morado o flor rosado, nativo de centro y sur América, perteneciente a la familia Bignoniácea. De esta especie se han reportado compuestos como naftoquinonas, quinonas, flavonoides, alcanos, aldehídos aromáticos y actividades biológicas como antibacteriana, antifúngica y antiinflamatoria. El grupo de Polifenoles de la Universidad Tecnológica de Pereira llevo a cabo una investigación de los extractos obtenidos a partir de la corteza interna de Tabebuia rosea, evaluando la presencia de los principales grupos de metabolitos secundarios asociados con actividad biológica. Para el extracto en butanol (BuOH) el estudio de actividad antinflamatoria presentó inhibición de TNF-α y PGE2. El extracto en butanol fue sometido a tres fraccionamientos mediante cromatografía en columna (CC), realizando un análisis cromatográfico a las fracciones obtenidas mediante cromatografía en capa delgada (CCD), cromatografía de gases acoplada a espectroscopia de masas (CG-EM) y espectrometría UV-VIS. Los perfiles cromatográficos (CG-EM) permitieron caracterizar compuestos como lapachol, naftoquinona reportada para el género Tabebuia. Se desarrollaron pruebas de caracterización de núcleos químicos en placa revelando la posible presencia de terpenos, cumarinas, antronas, flavonoides, fenoles, carbohidratos, taninos entre otros

Chemical composition and antioxidant potentials of Kigelia pinnata root oil and extracts

The chemical composition of Kigelia pinnata root oil extracted with n-hexane was analyzed by GC/GCMS. The antioxidant potential of the oil was compared to that of ethyl acetate and methanol extracts of the root. UV and IR spectroscopic techniques were used to carry out partial characterization of the oil and extracts. The free radical scavenging activity by spectrophotometric assay on the reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH) was examined while the total antioxidant activity (TAA) and relative antioxidant activity (RAA) were compared with standard antioxidant, α-tocopherol. The antioxidant activity (which correlated with the total phenolic content of the extracts) was assumed to be from the total phenolic content of the extracts. TAA was found to be higher in methanol extract (at 0.25 mg/mL). We hereby report for the first time the major component of the oil from the root of Kigelia pinnata to be elaidic acid (56.12 %). It is a reported toxicant which thereby underscores the risk in the use of the plant in traditional therapies