Recent developments in the rapid analysis of plants and tracking their bioactive constituents

Natural products chemistry has witnessed many new developments in the last 5 years like extractions with subcritical water and ionic liquids, LC/HRMS and LC/SPE/cryo-NMR, UHPLC, TLC/MS, MS-based preparative HPLC, comprehensive chromatography (GC × GC, LC × LC), high-throughput screening, introduction of monolithic columns, miniaturisation, and automated structure identification. Nevertheless identifying bioactive constituents in complex plant extracts remains a tedious process. The classical approach of bioassay guided fractionation is time-consuming while off-line screening of extracts does not provide information on individual compounds and sometimes suffers from false positives or negatives. One way out of this is by coupling chromatography with chemical or biochemical assays, so called high resolution screening. An example is the development of HPLC on-line assays for antioxidants. By the post-column addition of a relatively stable coloured radical like DPPH¿ or ABTS¿+, radical scavengers are detected as negative peaks because in a reaction coil they reduce the model radical to its reduced, non-coloured form. When combined with LC/DAD/MS and LC/SPE/NMR, reliable identification of active constituents becomes possible without the necessity of ever isolating them in a classical sense. Also for finding leads for new drugs, combining HPLC with biochemical assays is interesting but technically more difficult. Most enzymes do not work at the organic modifier concentrations commonly encountered in RP-HPLC and the reaction time is often longer requiring dilution and lengthy coils respectively. Therefore, new techniques have to be implemented to gain the required sensitivity for on-line enzyme assays. For stable analytes, high temperature LC offers a solution to the organic modifier problem. When enzymes are highly expensive, like those used in the screening for Cytochrome P450 inhibitors, miniaturisation to chip format may offer a way out. Microreactors (chips) are not only useful for miniaturising larger assays but also offer completely new prospects in phytochemical analysis. One such application is in the sample clean-up of acids and bases like alkaloids. In a lay-out of three parallel channels of 100 ¿m width with the middle one containing organic phase and the two outer ones water of high pH (feed phase) and low pH (trapping phase) such a chip replaces two classical LLE steps but is much faster and requires less solvents and less manpower input

Ocean heat uptake processes: a model intercomparison

We compare the quasi-equilibrium heat balances, as well as their responses to 4×CO2 perturbation, among three global climate models with the aim to identify and explain inter-model differences in ocean heat uptake (OHU) processes. We find that, in quasi-equilibrium, convective and mixed layer processes, as well as eddy-related processes, cause cooling of the subsurface ocean. The cooling is balanced by warming caused by advective and diapycnally diffusive processes. We also find that in the CO2-perturbed climates the largest contribution to OHU comes from changes in vertical mixing processes and the mean circulation, particularly in the extra-tropics, caused both by changes in wind forcing, and by changes in high-latitude buoyancy forcing. There is a substantial warming in the tropics, a significant part of which occurs because of changes in horizontal advection in extra-tropics. Diapycnal diffusion makes only a weak contribution to the OHU, mainly in the tropics, due to increased stratification. There are important qualitative differences in the contribution of eddy-induced advection and isopycnal diffusion to the OHU among the models. The former is related to the different values of the coefficients used in the corresponding scheme. The latter is related to the different tapering formulations of the isopycnal diffusion scheme. These differences affect the OHU in the deep ocean, which is substantial in two of the models, the dominant region of deep warming being the Southern Ocean. However, most of the OHU takes place above 2000 m, and the three models are quantitatively similar in their global OHU efficiency and its breakdown among processes and as a function of latitude

Origin of the warm eastern tropical Atlantic SST bias in a climate model

The substantial warm sea surface temperature bias in the eastern Tropical Atlantic reported in most CMIP5 climate simulations with various models, in particular along the coast of Namibia and Angola, remains an issue in more recent and CMIP6-ready versions of climate models such as EC-Earth. A complete and original set of experiments with EC-Earth3.1 is performed to investigate the causes and mechanisms responsible for the emergence and persistence of this bias. The fully-developed bias is studied in a historical experiment that has reached quasi-equilibrium, while retrospective prediction experiments are used to highlight the development/growth from an observed initial state. Prediction experiments are performed at both low and high resolution to assess the possible dependence of the bias on horizontal resolution. Standalone experiments with the ocean and the atmosphere components of EC-Earth are also analyzed to separate the respective contributions of the ocean and atmosphere to the development of the bias. EC-Earth3.1 exhibits a bias similar to that reported in most climate models that took part in CMIP5. The magnitude of this bias, however, is weaker than most CMIP5 models by few degrees. Increased horizontal resolution only leads to a minor reduction of the bias in EC-Earth. The warm SST bias is found to be the result of an excessive solar absorption in the ocean mixed layer, which can be linked to the excessive solar insolation due to unrealistically low cloud cover, and the absence of spatial and temporal variability of the biological productivity in the ocean component. The warm SST bias is further linked to deficient turbulent vertical mixing of cold water to the mixed layer. Our study points at a need for better representation of clouds in the vicinity of eastern boundaries in atmosphere models, and better representation of solar penetration and turbulent mixing in the ocean models in order to eliminate the Tropical Atlantic biases.We would like to acknowledge the anonymous reviewer who provided constructive comments that led to a considerable improvement of the manuscript. We would also like to thank Aurore Voldoire and Anna-Lena Deppenmeier for the useful discussion, and Yann Planton for providing the code for implementing the tendency diagnostics in NEMO. This research has received funding from the EU Seventh Framework Programme FP7 (2007–2013) under grant agreements 308378 (SPECS), 603521 (PREFACE) and the Horizon 2020 EU program under grand agreements 641727 (PRIMAVERA). We acknowledge RES and ECMWF for awarding access to supercomput- ing facilities in the Barcelona Supercomputing Center in Spain and the ECMWF Supercomputing Center in the UK, through the HiResClim and SPESICCF projects, recpectively. We acknowledge the work of the developers of the s2dverification R-based package (http://cran.r-project. org/web/packages/s2dverification/index.html). The visualization of some of the figures was done with the NCAR Command Language (NCL, Version 6.3.0, 2016, Boulder, Colorado: UCAR/NCAR/CISL/TDD, http://dx.doi.org/10.5065/D6WD3XH5).Peer ReviewedPostprint (author's final draft

Role of wind stress in driving SST biases in the tropical Atlantic

Coupled climate models used for long-term future climate projections and seasonal or decadal predictions share a systematic and persistent warm sea surface temperature (SST) bias in the tropical Atlantic. This study attempts to better understand the physical mechanisms responsible for the development of systematic biases in the tropical Atlantic using the so-called Transpose-CMIP protocol in a multi-model context. Six global climate models have been used to perform seasonal forecasts starting both in May and February over the period 2000-2009. In all models, the growth of SST biases is rapid. Significant biases are seen in the first month of forecast and, by six months, the root-mean-square SST bias is 80% of the climatological bias. These control experiments show that the equatorial warm SST bias is not driven by surface heat flux biases in all models, whereas in the south-eastern Atlantic the solar heat flux could explain the setup of an initial warm bias in the first few days. A set of sensitivity experiments with prescribed wind stress confirm the leading role of wind stress biases in driving the equatorial SST bias, even if the amplitude of the SST bias is model dependent. A reduced SST bias leads to a reduced precipitation bias locally, but there is no robust remote effect on West African Monsoon rainfall. Over the south-eastern part of the basin, local wind biases tend to have an impact on the local SST bias (except in the high resolution model). However, there is also a non-local effect of equatorial wind correction in two models. This can be explained by sub-surface advection of water from the equator, which is colder when the bias in equatorial wind stress is corrected. In terms of variability, it is also shown that improving the mean state in the equatorial Atlantic leads to a beneficial intensification of the Bjerknes feedback loop. In conclusion, we show a robust effect of wind stress biases on tropical mean climate and variability in multiple climate models

CERTIFICATION REPORT: The certification of Deuterium-to-Hydrogen (D/H) amount-of-substance ratio in tetramethylurea (TMU): ERM®-AE003

This report describes the production of ERM®-AE003, which is a 1,1,3,3-tetramethylurea (TMU) reference material certified for its deuterium-to-hydrogen (D/H) amount-of-substance ratio. This material was produced and certified in accordance with ISO 17034:2016 and ISO Guide 35:2017. ERM-AE003 was produced within the scope of ISO 17034 accreditation. TMU with a sufficiently high D/H amount-of-substance ratio (>120 x 10-6) was purchased, checked for sufficient chemical purity (> 99.0 %) and filled into amber glass bottles of 100 mL under argon atmosphere. Each bottle is individually placed in a multilayer pouch. Between unit-homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2017. The minimum sample size for one measurement using Nuclear Magnetic Resonance (NMR) tubes of 10 mm diameter is 1.3 mL (as prescribed by the official method OIV-MA-AS311-05). The certified value was calculated as the unweighted mean of 18 individual results obtained by three laboratories of demonstrated competence and adhering to ISO/IEC 17025:2017). The uncertainty of the certified value was calculated in accordance with ISO 17034:2016 and ISO Guide 35:2017 and include uncertainties related to the purity of the starting material, possible inhomogeneity, instability and characterisation. The material is intended for the use as internal standard in site-specific natural isotope fractionation – nuclear magnetic resonance (SNIF-NMR) spectrometry spectroscopy measurements for determining the D/H amount-of-substance ratio of distilled ethanol (method OIV-MA-AS311-05, International Organisation of Vine and Wine), an important measure in the authenticity testing of wines and spirits. Its use as internal standard applies also in the SNIF-NMR measurements of other food commodities like fruit juices, maple syrup, vanillin and vinegar. Before release of ERM-AE003, the certification project was subjected to peer-review involving both internal and external experts.JRC.F.6 - Reference Material

Allocation of the radio-frequency spectrum and satellite orbits : jurisprudential perspectives

Outer space is the new frontier for humankind. Its utilization depends on two distinct natural resources, the radio-frequency spectrum and the orbits around the Earth. The rapid advancement of technology in these fields simultaneously necessitates the introspection of principles upon which international law is construed. As the international policy and law makers face the future for the exploration of outer space and the capabilities of the radio spectrum, some conflicting considerations arise that can be scrutinized through the lens of jurisprudence. This paper discusses the allocation and distribution of those scarce natural resources between developed and developing countries, currently in the hands of international organizations, mainly the International Telecommunication Union. It critically reflects upon the in/ex-clusiveness of international law and the potential unequal relationships between developed and developing nations while managing some of the Global Commons. It examines the established practices from two neighbouring schools of thought and around two central concepts, fairness and efficiency

Antimicrobial and Efflux Pump Inhibitory Activity of Caffeoylquinic Acids from Artemisia absinthium against Gram-Positive Pathogenic Bacteria

Background: Traditional antibiotics are increasingly suffering from the emergence of multidrug resistance amongst pathogenic bacteria leading to a range of novel approaches to control microbial infections being investigated as potential alternative treatments. One plausible antimicrobial alternative could be the combination of conventional antimicrobial agents/antibiotics with small molecules which block multidrug efflux systems known as efflux pump inhibitors. Bioassay-driven purification and structural determination of compounds from plant sources have yielded a number of pump inhibitors which acted against gram positive bacteria. Methodology/Principal Findings: In this study we report the identification and characterization of 4′,5′-O-dicaffeoylquinic acid (4′,5′-ODCQA) from Artemisia absinthium as a pump inhibitor with a potential of targeting efflux systems in a wide panel of Gram-positive human pathogenic bacteria. Separation and identification of phenolic compounds (chlorogenic acid, 3′,5′-ODCQA, 4′,5′-ODCQA) was based on hyphenated chromatographic techniques such as liquid chromatography with post column solid-phase extraction coupled with nuclear magnetic resonance spectroscopy and mass spectroscopy. Microbial susceptibility testing and potentiation of well know pump substrates revealed at least two active compounds; chlorogenic acid with weak antimicrobial activity and 4′,5′-ODCQA with pump inhibitory activity whereas 3′,5′-ODCQA was ineffective. These intitial findings were further validated with checkerboard, berberine accumulation efflux assays using efflux-related phenotypes and clinical isolates as well as molecular modeling methodology. Conclusions/Significance: These techniques facilitated the direct analysis of the active components from plant extracts, as well as dramatically reduced the time needed to analyze the compounds, without the need for prior isolation. The calculated energetics of the docking poses supported the biological information for the inhibitory capabilities of 4′,5′-ODCQA and furthermore contributed evidence that CQAs show a preferential binding to Major Facilitator Super family efflux systems, a key multidrug resistance determinant in gram-positive bacteria.National Institutes of Health (U.S.) (grant R01GM59903)National Institutes of Health (U.S.) (grant R01AI050875)Netherlands Organization for Scientific Research (VICI grant 700.56.442)Massachusetts Technology Transfer Center (MTTC)National Institutes of Health (U.S.) (grant 5U54MH084690-02