Natural and Synthetic Xanthones as Monoamine Oxidase Inhibitors: Biological Assay and 3D‐QSAR

Fifty‐nine xanthones (=9H‐xanthen‐9‐ones) of natural or synthetic origin were investigated for their inhibitory activity toward monoamine‐oxidase A (MAO‐A) and MAO‐B. The compounds demonstrated reversible, time‐independent activities, with selectivity toward MAO‐A. The most active inhibitor had an IC₅₀ of 40 nM . Electron absorption spectroscopy revealed the formation of a 1 : 1 charge‐transfer complex between lumiflavine and xanthones. 3D‐QSAR Studies according to the CoMFA/GOLPE procedure provided information on the relationship between steric and electrostatic fields and MAO‐A inhibition. The ALMOND procedure yielded additional topographical information on structural factors favoring activity.     

Amino Alcohols from Eugenol as Potential Semisynthetic Insecticides: Chemical,Biological, and Computational Insights

A series of β-amino alcohols were prepared by the reaction of eugenol epoxide with aliphatic and aromatic amine nucleophiles. The synthesized compounds were fully characterized and evaluated as potential insecticides through the assessment of their biological activity against Sf9 insect cells, compared with a commercial synthetic pesticide (chlorpyrifos, CHPY). Three derivatives bearing a terminal benzene ring, either substituted or unsubstituted, were identified as the most potent molecules, two of them displaying higher toxicity to insect cells than CHPY. In addition, the most promising molecules were able to increase the activity of serine proteases (caspases) pivotal to apoptosis and were more toxic to insect cells than human cells. Structure-based inverted virtual screening and molecular dynamics simulations demonstrate that these molecules likely target acetylcholinesterase and/or the insect odorant-binding proteins and are able to form stable complexes with these proteins. Encapsulation assays in liposomes of DMPG and DPPC/DMPG (1:1) were performed for the most active compound, and high encapsulation efficiencies were obtained. A thermosensitive formulation was achieved with the compound release being more efficient at higher temperatures.     

Toxicological Stability of Ocimum basilicum Essential Oil and Its Major Components in the Control of Sitophilus zeamais

Essential oils (EOs) are widely recognized as efficient and safe alternatives for controlling pest insects in foods. However, there is a lack of studies evaluating the toxicological stability of botanical insecticides in stored grains in order to establish criteria of use and ensure your efficiency. The objective of this work was to evaluate the toxicological stability of basil essential oil (O. basilicum) and its linalool and estragole components for Sitophilus zeamais (Motschulsky) adults in corn grains by fumigation. The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass selective detector. Mortality of insects was assessed after 24 h exposure. After storage for six (EO) and two months (linalool and estragole) under different conditions of temperature (5, 20, and 35 °C) and light (with and without exposure to light), its toxicological stability was evaluated. Studies revealed that the essential oil of O. basilicum and its main components exhibited insecticidal potential against adults of S. zeamais. For greater toxicological stability, suitable storage conditions for them include absence of light and temperatures equal to or less than 20 °C.     

Monoclinic and triclinic forms of bis­[2‐hydroxy‐2,2‐bis(2‐pyridyl)­ethano­ato‐O1,N,N′]­nickel(II)

Reaction of pyridoin with nickel nitrate in methanol in air gives crystals of two forms of the title compound, [Ni(C₁₂H₉N₂O₃)₂]; a triclinic form with the Ni atom on an inversion centre and a monoclinic form with one mol­ecule in a general position in the asymmetric unit. Both forms show an octahedral nickel centre coordinated by two facial tridentate ligands with their O‐atom donors trans.     

Metrology for Chemical Measurements and the Position of INAA

Metrology systems are being established by various countries for the worldwide comparability of data related to trade, industrial products, health, and the environment. This has in turn led to an increased interest in methods that have the highest possible accuracy and precision. The relevance of instrumental neutron activation analysis (INAA) for metrological science has been evaluated. It is concluded that INAA is a suitable technique for method validation, proficiency testing, development of reference materials and reference methods. Moreover, it is concluded that INAA may comply with the CCQM definition of a definitive or primary ratio method provided that the uncertainty in the results is reduced to much lower levels compared to those currently encountered in most NAA laboratories.     

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