Rosmarinic Acid and Its Methyl Ester as Antimicrobial Components of the Hydromethanolic Extract of Hyptis atrorubens

Primary biological examination of four extracts of the leaves and stems of Hyptis atrorubens Poit. (Lamiaceae), a plant species used as an antimicrobial agent in Guadeloupe, allowed us to select the hydromethanolic extract of the stems for further studies. It was tested against 46 microorganisms in vitro. It was active against 29 microorganisms. The best antibacterial activity was found against bacteria, mostly Gram-positive ones. Bioautography enabled the isolation and identification of four antibacterial compounds from this plant: rosmarinic acid, methyl rosmarinate, isoquercetin, and hyperoside. The MIC and MBC values of these compounds and their combinations were determined against eight pathogenic bacteria. The best inhibitory and bactericidal activity was found for methyl rosmarinate (0.3 mg/mL). Nevertheless, the bactericidal power of rosmarinic acid was much faster in the time kill study. Synergistic effects were found when combining the active compounds. Finally, the inhibitory effects of the compounds were evaluated on the bacterial growth phases at two different temperatures. Our study demonstrated for the first time antimicrobial activity of Hyptis atrorubens with identification of the active compounds. It supports its traditional use in French West Indies. Although its active compounds need to be further evaluated in vivo, this work emphasizes plants as potent sources of new antimicrobial agents when resistance to antibiotics increases dramatically

No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally

Martian dust storm impact on atmospheric H₂O and D/H observed by ExoMars Trace Gas Orbiter

Global dust storms on Mars are rare but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere, primarily owing to solar heating of the dust. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes, as well as a decrease in the water column at low latitudes. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere

The atmosphere of Venus: eleven Venusian years of observations by Venus Express

info:eu-repo/semantics/nonPublishe

Phosphine in Venus’ atmosphere: Detection attempts and upper limits above the cloud top assessed from the SOIR/VEx spectra

Context. Recent detection of phosphine (PH3) was reported from James Clerk Maxwell Telescope and Atacama Large Millimetre /submillimetre Array observations. The presence of PH3 on Venus cannot be easily explained in the Venus atmosphere and a biogenic source located at or within the clouds was proposed. Aims. We aim to verify if the infrared spectral signature of PH3 is present in the spectra of Solar Occultation at Infrared (SOIR). If it is not present, we then seek to derive the upper limits of PH3 from SOIR spectra. Methods. We analyzed the SOIR spectra containing absorption lines of PH3. We searched for the presence of PH3 lines. If we did not find any conclusive PH3 spectral signatures, we computed the upper limits of PH3. Results. We report no detection of PH3. Upper limits could be determined for all of the observations, providing strong constraints on the vertical profile of PH3 above the clouds. Conclusions. The SOIR PH3 upper limits are almost two orders of magnitude below the announced detection of 20 ppb and provide the lowest known upper limits for PH3 in the atmosphere of Venus

SOIR and NOMAD: Characterization of Planetary Atmospheres

info:eu-repo/semantics/nonPublishe

Sulfur dioxide in the Venus atmosphere measured by SOIR on board Venus Express

info:eu-repo/semantics/nonPublishe

Hydrogen Halides measurements in the Venus upper atmosphere retrieved from SOIR on board Venus Express

info:eu-repo/semantics/publishe