Dual effects of a 2-benzylquinuclidinium derivative on α7-containing nicotinic acetylcholine receptors in rat hippocampal interneurons

Synthesis of β-alkoxy-N-protected phenethylamines via one-pot copper-catalyzed aziridination and ring opening

A regioselective, copper-catalyzed, one-pot aminoalkoxylation of styrenes using primary and secondary alcohols and three different iminoiodanes as alkoxy and nitrogen sources respectively, is reported. The β-alkoxy-N-protected phenethylamines obtained were used to synthesise β-alkoxy-N-benzylphenethylamines which are interesting new compounds that could act as possible neuronal ligands.

An efficient, regioselective and rapid copper-catalyzed one-pot aminoalkoxylation of styrenes has been developed using different alcohols and phenyl iminoiodinanes.

Methylpiperidinium Iodides as Novel Antagonists for α7 Nicotinic Acetylcholine Receptors

The α7 nicotinic acetylcholine receptor (nAChR) is expressed in neuronal and non-neuronal cells and is involved in several physiopathological processes, and is thus an important drug target. We have designed and synthesized novel piperidine derivatives as α7 nAChR antagonists. Thus, we describe here a new series of 1-[2-(4-alkoxy-phenoxy-ethyl)]piperidines and 1-[2-(4-alkyloxy-phenoxy-ethyl)]-1-methylpiperidinium iodides (compounds 11a-11c and 12a-12c), and their actions on α7 nAChRs. The pharmacological activity of these compounds was studied in rat CA1 hippocampal interneurons by using the whole-cell voltage-clamp technique. Inhibition of the choline-induced current was less for 11a-11c than for the methylpiperidinium iodides 12a-12c and depended on the length of the aliphatic chain. Those compounds showing strong effects were studied further using molecular docking and molecular dynamics simulations. The strongest and non-voltage dependent antagonism was shown by 12a, which could establish cation–π interactions with the principal (+)-side and van der Waals interactions with the complementary (-)-side in the α7 nAChRs. Furthermore, compound 11a forms hydrogen bonds with residue Q115 of the complementary (-)-side through water molecules without forming cation–π interactions. Our findings have led to the establishment of a new family of antagonists that interact with the agonist binding cavity of the α7 nAChR, which represent a promising new class of compounds for the treatment of pathologies where these receptors need to be negatively modulated, including neuropsychiatric disorders as well as different types of cancer.

Effects of the antidepressant mirtazapine and zinc on nicotinic acetylcholine receptors

Nicotinic acetylcholine receptors (nAChRs) and zinc are associated with regulation of mood and related disorders. In addition, several antidepressants inhibit muscle and neuronal nAChRs and zinc potentiates inhibitory actions of them. Moreover, mirtazapine (a noradrenergic, serotonergic and histaminergic antidepressant) inhibits muscarinic AChRs and its effects on nAChRs are unknown. Therefore, we studied the modulation of muscle α1β1γd nAChRs expressed in oocytes and native α7-containing nAChRs in hippocampal interneurons by mirtazapine and/or zinc, using voltage-clamp techniques. The currents elicited by ACh in oocytes (at -60 mV) were similarly inhibited by mirtazapine in the absence and presence of 100 μM zinc (IC₅₀ ∼15 μM); however, the ACh-induced currents were stronger inhibited with 20 and 50 μM mirtazapine in the presence of zinc. Furthermore, the potentiation of ACh-induced current by zinc in the presence of 5 μM mirtazapine was 1.48 ± 0.06, and with 50 μM mirtazapine zinc potentiation did not occur. Interestingly, in stratum radiatum interneurons (at -70 mV), 20 μM mirtazapine showed less inhibition of the current elicited by choline (Ch) than at 10 μM (0.81 ± 0.02 and 0.74 ± 0.02 of the Ch-induced current, respectively). Finally, the inhibitory effects of mirtazapine depended on membrane potential: 0.81 ± 0.02 and 0.56 ± 0.05 of the control Ch-induced current at -70 and -20 mV, respectively. These results indicate that mirtazapine interacts with muscle and neuronal nAChRs, possibly into the ion channel; that zinc may increase the sensitivity of nAChRs to mirtazapine; and that mirtazapine decreases the sensitivity of nAChRs to zinc.

Organic Molecules from Biochar Leacheates Have a Positive Effect on Rice Seedling Cold Tolerance

Biochar is known to have a number of positive effects on plant ecophysiology. However, limited research has been carried out to date on the effects and mechanisms of biochar on plant ecophysiology under abiotic stresses, especially responses to cold. In this study, we report on a series of experiments on rice seedlings treated with different concentrations of biochar leacheates (between 0 and 10% by weight) under cold stress (10°C). Quantitative real-time PCR (qRT-PCR) and cold-resistant physiological indicator analysis at low temperatures revealed that the cold tolerance of rice seedlings increased after treatment with high concentrations of biochar leacheates (between 3 and 10% by weight). Results also show that the organic molecules in biochar leacheates enhance the cold resistance of plants when other interference factors are excluded. We suggest that the positive influence of biochar on plant cold tolerance is because of surface organic molecules which likely function by entering a plant and interacting with stress-related proteins. Thus, to verify these mechanisms, this study used gas chromatography-mass spectrometry (GC-MS) techniques, identifying 20 organic molecules in biochar extracts using the National Institute of Standards and Technology (NIST) library. Further, to illustrate how these organic molecules work, we utilized the molecular docking software Autodock to show that the organic molecule 6-(Methylthio)hexa-1,5-dien-3-ol from biochar extracts can dock with the stress-related protein zinc-dependent activator protein (ZAP1). 6-(Methylthio)hexa-1,5-dien-3-ol has a similar binding mode with the ligand succinic acid of ZAP1. It can be inferred that the organic molecule identified in this study performs the same function as the ZAP1 ligand, stimulating ZAP1 driving cold-resistant functions, and enhancing plant cold tolerance. We conclude that biochar treatment enhances cold tolerance in rice seedlings via interactions between organic molecules and stress related proteins.