Estudio del efecto solvatocrómico en derivados fenólicos naturales

Se describen las características espectrofluorimétricas de dos derivados de quercetina aislados de las hojas deFlaveria bidentis, un derivado de 6-prenilpinocembrina, aislado de las raíces de Dalea elegans y un compuesto deestructura antraquinónica aislado de las hojas de Heterophyllaea pustulata. Todos ellos presentan espectros deabsorción con máximos en la región UV-visible acordes con los grupos cromóforos presentes en su estructura. Loscuatro compuestos estudiados presentan fluorescencia nativa. La posición de los máximos de emisión de fluorescenciase modifica en función del disolvente. Los desplazamientos producidos están relacionados con el diferente gradode solvatación de las moléculas en estado excitado según la polaridad del disolvente. La adición de ácidos mineralesprovoca desplazamientos en los máximos de fluorescencia concordantes con los ya descritos para compuestos deestructura similar. Estas modificaciones espectrales tienen un gran interés analítico desde el punto de vista de laidentificación y caracterización de productos naturales de estructura fenólica

Incidence of the nordihydroguaiaretic acid content on the in vitro antiviral activity of extracts obtained from larrea divaricata cav. (Zygophyllaceae)

The South American species Larrea divaricata Cav. (Zygophyllaceae) has been widely used in folk medicine against infectious diseases. In previous studies, we reported that several extracts obtained from the aerial parts of this species and the nordihydroguaiaretic acid (NDGA), its main lignan, inhibited Junin Virus (JUNV) in vitro. In this work, the objective was to assess whether NDGA is truly responsible for the antiviral activity produced by the extracts. Therefore, the presence and amount of NDGA in extracts were determined by HPLC. We established that NDGA in the extracts analyzed is required to inhibit JUNV and observed that some components of the bioactive extracts would increase the antiviral effect of NDGA. On the other hand, we estimated the selectivity index for NDGA against JUNV. Thus, NDGA and extracts containing this lignan exhibited potential therapeutic effects against the etiologic agent of the Argentine Hemorrhagic Fever, an endemo-epidemic illness in this country.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Determination of non-toxic and subtoxic concentrations of potential antiviral natural anthraquinones

Anthraquinones-rich extracts of Heterophyllaea pustulata Hook f. (Rubiaceae) exhibited in vitro antiviral activity against Herpes Simplex Virus Type I, from which several anthraquinones (AQs) were isolated and identified. The Maximum Non-Cytotoxic Concentration (MNCC), the subtoxic concentration (SubTC), and the CC50 of each AQ were determined on a mammalian eukaryotic cell line (Vero cells) by means of Neutral Red uptake assay; the cytopathic effect was simultaneously evaluated by optical microscopy. The range of concentrations where each AQ did not exhibit cytotoxicity was established, which is limited by the MNCC: rubiadin 1-methyl ether, damnacanthol and pustuline were found to be markedly less cytotoxic. To the remaining AQs, we could estimate a SubTC (about 10 μg/mL) that assures 80 % cellular viability. Therefore, we determined a concentration range which could be used to evaluate the antiviral effect of each AQ since it ensures the viability of the host cell.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Study of the solvatochromic effect on natural phenolic compounds

Se describen las características espectrofluorimétricas de dos derivados de quercetina aislados de las hojas de Flaveria bidentis, un derivado de 6-prenilpinocembrina, aislado de las raíces de Dalea elegans y un compuesto de estructura antraquinónica aislado de las hojas de Heterophyllaea pustulata. Todos ellos presentan espectros de absorción con máximos en la región UV-visible acordes con los grupos cromóforos presentes en su estructura. Los cuatro compuestos estudiados presentan fluorescencia nativa. La posición de los máximos de emisión de fluorescencia se modifica en función del disolvente. Los desplazamientos producidos están relacionados con el diferente grado de solvatación de las moléculas en estado excitado según la polaridad del disolvente. La adición de ácidos minerales provoca desplazamientos en los máximos de fluorescencia concordantes con los ya descritos para compuestos de estructura similar. Estas modificaciones espectrales tienen un gran interés analítico desde el punto de vista de la identificación y caracterización de productos naturales de estructura fenólica.The spectrofluorimetric behaviour of two derivatives of quercetin isolated from the leaves of Flaveria bidentis, a derivative of 6-prenylpinocembrin isolated from the roots of Dalea elegans and an anthraquinonic derivative isolated from the leaves of Heterophyllaea pustulata, is described. The UV-visible absorption spectra of these compounds exhibit the maximum values corresponding to the chromophores present in each structure. All of the compounds studied show native fluorescence in different solvents. The maximum shift in fluorescence emission to the red spectral region when the polarity of the solvents is increased, can be attributed to varying degrees of solvation in the excited state in the different solvents. Additions of small amounts of H2SO4 cause shifts in excitation and emission wavelengths, in agreement with those described for compounds with similar chemical structures. Such fluorescent spectral changes are of considerable analytical interest, given that they allow the presence of phenolic compounds in the extracts of natural plant material to be detected easily.Program for University Co-operation conve- ned in 2001 by Agencia Española de Cooperación Internacional (AECI)

Seasonal drought limits tree species across the Neotropics

Within the tropics, the species richness of tree communities is strongly and positively associated with precipitation. Previous research has suggested that this macroecological pattern is driven by the negative effect of water-stress on the physiological processes of most tree species. This process implies that the range limits of taxa are defined by their ability to occur under dry conditions, and thus in terms of species distributions it predicts a nested pattern of taxa distribution from wet to dry areas. However, this ‘dry-tolerance’ hypothesis has yet to be adequately tested at large spatial and taxonomic scales. Here, using a dataset of 531 inventory plots of closed canopy forest distributed across the Western Neotropics we investigated how precipitation, evaluated both as mean annual precipitation and as the maximum climatological water deficit, influences the distribution of tropical tree species, genera and families. We find that the distributions of tree taxa are indeed nested along precipitation gradients in the western Neotropics. Taxa tolerant to seasonal drought are disproportionally widespread across the precipitation gradient, with most reaching even the wettest climates sampled; however, most taxa analysed are restricted to wet areas. Our results suggest that the ‘dry tolerance’ hypothesis has broad applicability in the world's most species-rich forests. In addition, the large number of species restricted to wetter conditions strongly indicates that an increased frequency of drought could severely threaten biodiversity in this region. Overall, this study establishes a baseline for exploring how tropical forest tree composition may change in response to current and future environmental changes in this region

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

Estimating the global conservation status of more than 15,000 Amazonian tree species

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality