Structure and Neuroprotector Properties of a Complex Compound of Lithium with Comenic Acid

The structure, antioxidant and neuroprotective properties of lithium comenate (lithium 5-hydroxy-4-oxo-4H-pyran-2-carboxylate) were studied. Lithium comenate was obtained by reacting comenic acid (H2Com) with lithium hydroxide in an aqueous solution. The structure of lithium comenate was confirmed via thermal analysis, mass spectrometry, IR, NMR and UV spectroscopy. The crystal structure was studied in detail via X-ray diffraction. The compound crystallized in a non-centrosymmetric space group of symmetry of the orthorhombic system Pna21 in the form of a hydrate, with three water molecules entering the first coordination sphere of the cation Li+ and one molecule forming a second environment through non-valent contacts. The gross formula of the complex compound was established [Li(HCom)(H2O)3]·H2O. It has been established that lithium comenate has a pronounced neuroprotective activity under the excitotoxic effect of glutamate, increasing the survival rate of cultured rat cerebellar neurons more than two-fold. It has also been found that the pre-stress use of lithium comenate at doses of 1 and 2 mg/kg has an antioxidant effect, which is manifested in a decrease in oxidative damage to the brain tissues of mice subjected to immobilization stress. Based on the data available in the literature, we believe that the high neuroprotective and antioxidant efficacy of lithium comenate is a consequence of the mutual potentiation of the pharmacological effects of lithium and comenic acid.

Study of the Magnesium Comenate Structure, Its Neuroprotective and Stress-Protective Activity

The crystal structure and the biological activity of a new coordination compound of magnesium ions with comenic acid, magnesium comenate, was characterized and studied. Quantitative and qualitative analysis of the compound was investigated in detail using elemental X-ray fluorescent analysis, thermal analysis, IR-Fourier spectrometry, UV spectroscopy, NMR spectroscopy, and X-ray diffraction analysis. Based on experimental analytical data, the empirical formula of magnesium comenate [Mg(HCom)₂(H₂O)₆]·2H₂O was established. This complex compound crystallizes with eight water molecules, six of which are the hydration shell of the Mg²⁺ cation, and two more molecules bind the [Mg(H₂O)₆]²⁺ aquacation with ionized ligand molecules by intermolecular hydrogen bonds. The packing of molecules in the crystal lattice is stabilized by a branched system of hydrogen bonds with the participation of solvate water molecules and oxygen atoms of various functional groups of ionized ligand molecules. With regard to the biological activity of magnesium comenate, a neuroprotective, stress-protective, and antioxidant effect was established in in vitro and in vivo models. In in vitro experiments, magnesium comenate protected cerebellar neurons from the toxic effects of glutamate and contributed to the preservation of neurite growth parameters under oxidative stress caused by hydrogen peroxide. In animal studies, magnesium comenate had a stress-protective and antioxidant effect in models of immobilization-cold stress. Oral administration of magnesium comenate at a dose of 2 mg/kg of animal body weight for 3 days before stress exposure and for 3 days during the stress period led to a decrease in oxidative damage and normalization of the antioxidant system of brain tissues against the background of induced stress. The obtained results indicate the advisability of further studies of magnesium comenate as a compound potentially applicable in medicine for the pharmacological correction of conditions associated with oxidative and excitotoxic damage to nerve cells.

Neurotrophic Action of Comenic Acid and Its Derivatives Potassium Comenate and Calcium Comenate

Using the model of cultured spinal ganglia, we demonstrated high neurotrophic activity of comenic acid and its derivatives potassium comenate and calcium comenate both under normal conditions and during oxidative stress. Calcium comenate in the norm as well as potassium and calcium comenates during oxidative stress demonstrate greater neurotrophic potency than comenic acid.

Modulation of the transducer function of Na+,K+-ATPase: new mechanism of heart remodeling

Endogenous digitalis-like factors were found in the mammalian and human blood. It was the starting point for the elucidation of the new non-pumping function of the Na⁺,K⁺-ATPase. It was previously well known that Na⁺,K⁺-ATPase is a pharmacological target receptor for cardiac glycosides (J.C. Skou. 1957. Biochim. Biophys. Acta, 23: 394-401). We have investigated the trophotropic effects of such agents as ouabain, epinephrine, norepinephrine, atenolol, and comenic acid using the organotypic tissue culture combined with the reconstruction of optical cross sections and confocal microscopy. It was shown that the growth zone of organotypic culture forms a multidimensional structure. Our results indicate that the cardiac glycoside ouabain applied in endogenous concentrations (10^-8, 10^-10 mol/L) can modulate transducer function of Na⁺,K⁺-ATPase and control the cell growth and proliferation. It was also shown that Src-kinase is involved in "endogenous" ouabain activated intracellular pathways as a series unit. Epinephrine (10^-9-10^-14 mol/L) and comenic acid (10^-6-10^-10 mol/L) were demonstrated to modulate the growth of 10- to 12-day-old chicken embryo cardiac tissue explants in a dose-dependent manner. Epinephrine and comenic acid regulate growth and proliferation of the cardiac tissue via receptor-mediated modulation Na⁺,K⁺-ATPase as a signal transducer. The trophotropic effects of the investigated agents specifically control the heart remodeling phenomenon.

Comparative Analysis of Antioxidant Properties of Comenic Acid and Potassium Comenate in Modeled Immobilization Stress

We studied antioxidant protective effect of comenic acid and potassium comenate in doses of 2, 4, and 8 mg/kg under conditions of oxidative stress in the brain of mice exposed to immobilization stress. Administration of potassium comenate and comenic acid in the above doses for 3 days before stress prevented the development of oxidative processes in the brain of stressed animals. The antioxidant effect of potassium comenate more pronounced.