Membranostabilizing effect of CAPAH is demonstrated in vivo and in vitro. The preparation decreases experimental osmotic hemolysis and prevents elevation of blood enzymes in rats exposed to hypoxia. Infrared spectroscopy and electron paramagnetic resonance show that CAPAH is located in the superticial hydrophilic layer of modeled phosphatidylcholine membranes and interacts with lipid molecules.
The effect of original synthetic nootropic drugs (phosphorylacetohydrazides) on the physical properties of the dipalmitoyl phosphatidylcholine (DPPC) membranes was studied by 3lp nuclear magnetic resonance and Fourier transform infrared spectroscopies. Ir has been shown that the tested preparations reduce the phase transition temperature, widen the transition interval, suppress pretransition, render some condensing effect on the gel phase and essentially disorder the lipid bilayer in the liquid-crystalline state. The obtained results are in agreement with the suggested rnechanism of the primary pharmacological effect of nootropic preparations. According to this mechanism, the drug molecules penetrate into the hydrophilic region of the bilayer, interacting closely with the polar groups of DPPC, disturbing the bilayer organization and leading to polymorphism. By taking into account that the main property of nootropic preparations is to improve processes of training and memory, we suppose that the new lipid-drug organization of phospholipidic membranes and lipid polymorphism are the necessary steps of the nootropic activity. The similarity of molecular mechanisms of various nootropic drug effects on the lipid bilayer allows us to suppose that the positive effect of nootropics on the synaptic transmission may be governed by their influence on the phase transition of the lipid component of the synaptic membranes at the stage of the neurotransmitter release.
Statistical analysis of quantitative structure-property relationships (QSPR) for the phase transition gel-liquid crystal (main phase transition) temperatures (T m ) in hydrated vesicle bilayers of diacyl phosphatidylcholines (PC) and diacyl phosphatidylethanolamines (PE) with saturated acyl chains was carried out. Multiple regression equations relating the T m values to the volumes of the hydrocarbon fragments of the sn 1 and sn 2 acyl chains show that the acyl groups influence the transiton temperatures T m in different manner, the effect of the sn 2 group being predominant. The transition temperatures T m of saturated phosphatidylethanolamines and diacyl phosphatidylglycerols can be predicted using the T m values calculated for the corresponding diacyl phosphatidylcholines.Key words: diacyl phospholipids, quantitative structure-property relationships, main phase transition temperature.Glycerophospholipids, the most abundant components of biomembranes, are responsible for many of their physi cochemical and biological properties. In aqueous media, lipids usually form hydrated vesicles 1 existing as a highly ordered gel phase at low temperatures and as a less or dered liquid crystalline phase at elevated temperatures. The thermotropic gel-liquid crystal transition also called the main phase transition (MPT) or the chain melting transition has been the subject of intensive research in recent decades; the transition temperatures (T m ) are determined for many phospholipids. 2 The dependence of the T m values on the structure of 1,2 diacyl sn glycero 3 phosphocholines C(X) : C(Y)PC, where X and Y are the numbers of carbon atoms in the
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