The antioxidative capacity and structure-activity relationships of ten Schiff bases were investigated experimentally and theoretically. All compounds contain the aniline moiety, while the aldehyde part is either salicylaldehyde or vanillin. The DPPH assay was used to test the potential antioxidative activity of these compounds, and DFT study was used to investigate their electronic structures and provide insight into their structure-activity relationships. The effect of the position of the hydroxy, as well other groups present, on the antioxidative activity was examined. The possible radical scavenging mechanism was determined in polar (water and methanol), and nonpolar (benzene) solvents. Based on the experimental and computational results, compounds 7 and 8 exhibit the highest radical scavenging properties.

Compounds from the plant world that possess antioxidant abilities are of special importance for the food and pharmaceutical industry. Coumarins are a large, widely distributed group of natural compounds, usually found in plants, often with good antioxidant capacity. The coumarin-hydroxybenzohydrazide derivatives were synthesized using a green, one-pot protocol. This procedure includes the use of an environmentally benign mixture (vinegar and ethanol) as a catalyst and solvent, as well as very easy isolation of the desired products. The obtained compounds were structurally characterized by IR and NMR spectroscopy. The purity of all compounds was determined by HPLC and by elemental microanalysis. In addition, these compounds were evaluated for their in vitro antioxidant activity. Mechanisms of antioxidative activity were theoretically investigated by the density functional theory approach and the calculated values of various thermodynamic parameters, such as bond dissociation enthalpy, proton affinity, frontier molecular orbitals, and ionization potential. In silico calculations indicated that hydrogen atom transfer and sequential proton loss–electron transfer reaction mechanisms are probable, in non-polar and polar solvents respectively. Additionally, it was found that the single-electron transfer followed by proton transfer was not an operative mechanism in either solvent. The conducted tests indicate the excellent antioxidant activity, as well as the low potential toxicity, of the investigated compounds, which makes them good candidates for potential use in food chemistry.

No abstract

Recent reports have demonstrated that lipopolysaccharide (LPS)-induced depressive-like behaviour is mediated via NMDA receptor. In this study, we further investigated the role of GluN2A subunit of NMDA receptor in synaptic processes in the prefrontal cortex (PFC) and hippocampus of GluN2A knockout (KO) mice in LPS-induced depressive-like behavior. Our data suggest that LPS-treated mice, lacking GluN2A subunit, did not exhibit depressive-like behaviour. This was accompanied by unaltered levels of IL-6 and significant changes in neuroplasticity markers and glutamate receptor subunits composition in PFC and hippocampus. In particular, an immune challenge in GluN2A KO mice resulted in unchanged PSA-NCAM levels and proBDNF increase in both brain structures as well as in increase in BDNF levels in hippocampus. Furthermore, the absence of GluN2A resulted in increased levels of all NCAM isoforms in PFC upon LPS which was followed with a decrease in GluN1 and GluN2B subunits. The levels of AMPA receptor subunits (GluA1, GluA3, and GluA4) in the hippocampus of GluN2A mice were unaltered upon the treatment and abundantly present in the PFC of KO mice. These results indicate that the GluN2A subunit is critical in neuroinflammation-related depression, that its absence abolishes LPS-induced depressive phenotype, sustains PSANCAM levels,