[GABA-ergic mechanism of cerebrovascular and antiischemic effects of docosahexaenoic acid].

In experiments on rats, measurements of the local blood flow in the cortex of cerebrum with the aid of a laser Doppler flow meter showed that docosahexaenoic acid (DHA) enhanced the local cerebral circulation in animals with global transient cerebral ischemia, while not influencing that in intact animals. This vasodilatory effect of DHA in ischemized rats is blocked by bicuculline (specific GABA(A) receptor blocker), which is indicative of a GABA-ergic mechanisms of the vascular tone regulation. The results of radioligand binding assay in vitro showed the possibility of direct DHA interaction with cerebrovascular GABA(A) receptors.

[A new fluorescent analogue for the investigation of anandamide transport in cell cultures].

For the first time a new fluorescent analogue of anadamide incorporating BODIPY®-FL-fluorophore, attached to arachidonic acid via 2,2'-(ethylenedioxy)-bis(ethylenediamine), was prepared. Using rat glioma C6 cells it was demonstrated that the fluorescent analogue is a substrate of the cellular anandamide uptake system (Km 4.5 ± 0.9 µM, Vmax 20 ± 1 amol/(min x cell)).

[Antiaggregation activity of arachidonic acid conjugates with neurotropic peptides proglyprol and semax].

The influence two original derivatives of a therapeutically important peptide, bearing arachidonic acid residue with semax and proglyprol, upon platelet aggregation have been studied in vitro. It is established that both derivatives, in contrast to the parent peptide, possess moderate anti-aggregant properties and produce a dose-dependent decrease in the interplatelet interaction induced by ADP, epinephrine, and arachidonic acid within the concentration range of 0.018 - 1.8 mM. This activity was more pronounced for arachidonoylsemax in comparison with arachidonoylproglyprol.

[Cerebrovascular effects of GABA-prostaglandin E2 conjugate in comparison with prostaglandin E2].

Experiments have shown that GABA conjugate with prostaglandin E2 enhances cerebral blood flow in rats after global transient ischemia, while not affecting the cerebral hemoperfusion in intact animals. It is established that cerebrovascular activity of the GABA conjugate with prostaglandin E2 under conditions of cerebral ischemia is based on GABAergic mechanisms of vascular tone regulation, since it is removed by GABA(A)-receptor blocker bicuculline. At the same time, cerebral blood flow of intact rats and rats after global transient ischemia of brain is equally enhanced by prostaglandin E2 alone. This effect is not neutralized by bicuculline.

[Peculiarities of cerebrovascular effects of GABA conjugate with docosahexaenoyl dopamine under conditions of separate and combined vascular pathology of brain and heart].

A GABA conjugate with docosahexaenoyl dophamine (DHED) enhanced local cerebral blood flow in rats under conditions of global transient cerebral ischemia, experimental myocardial infarction, and combined vascular pathology of brain and heart. At the same time, the GABA-DHED conjugate did not influence brain hemoperfusion in intact animals. The cerebrovascular effect of this conjugate is determined by its direct action on the vascular tone, since no changes in blood pressure have been observed. Under conditions of the combined vascular pathology of brain and heart, the cerebrovascular effect of GABA-DHED conjugate is inhibited by bicuculline, which is evidence for the involvement of GABAergic mechanisms in the drug action upon cerebrovascular tone.

[Cerebrovascular effects of GABA conjugate with arachidonic acid under conditions of separate and combined vascular pathology of brain and heart].

Experiments on rats showed that, under conditions of global transient ischemia, a conjugate of GABA with arachidonic acid enhances the local cerebral blood flow due to a decrease in the vascular tone. In intact rats, the examined neurolipin did not show unidirectional changes in the cerebral perfusion. Under conditions of experimental myocardial infarction and combined vascular pathology of brain and heart, the GABA conjugate with arachidonic acid increased the blood flow in the parietal region of brain cortex in most experiments, while decreasing the level of blood pressure.

[The study of peptide stability during hydrolysis by rat gastroenteric tract fragments].

The hydrolytic stability of therapeutic peptides such as dalargin, stemokin and some others, including cyclic tripeptides modified by ibuprofen and aspirin, was studied. Two experimental systems were used, one containing purified enzymes pepsin, trypsin and chymotrypsin and other based on fragments of rat stomach and ileum. It was found that linear peptides without D-aminoacids are hydrolyzed by fragments of stomach and ileum but resistant to hydrolysis with purified enzymes. The peptides with D-aminoacids and cyclic peptides are stable in all experimental conditions used, however, peptides modified with aspirin lost acetyl moiety of aspirin residue in acidic medium, the process is accelerated in presence of pepsin.

[Docosahexaenoyl dopamine in freshwater hydra: effects on regeneration and metabolic changes].

The effects of docosahexaenoyl dopamine and docosahexaenoic acid on the regeneration of hydra gastric and basal fragments are studied. Docosahexaenoyl dopamine induced morphogenetic abnormalities such as single ectopic tentacles in the gastric region and projections in the gastric and basal regions. Docosahexaenoic acid had no effect on the morphogenesis except for a mild slowing of the regeneration rate. Since no hydrolysis of docosahexaenoyl dopamine was detected in hydra extract, it was assumed that the morphogenetic effect could be associated with the dopamine component of this complex.

[Influence of derivatives of arachidonic and docosohexaenic acids on AMPA receptors in Purkinje neurons and cognitive functions in mice].

The effect of derivatives of arachidonic and docosahexaenoic acids on AMPA receptors in Purkinje cells from the rat cerebellum was studied using the patch-clamp electrophysiological method. It was shown that derivatives of arachidonic acid-arachidonoyl dopamine and docosahexaenoic acid-docosahexaenoyl dopamine and ester of docosahexaenoic acid with ethylene glycol in nanomolar concentrations effectively potentiated the ionic currents caused by activation of AMPA receptors of kainic acid. Ester of docosahexaenoic acid with nitroethylene glycol blocked AMPA receptors, and anandamide (ethanolamide of arachidonic acid) was not effective. A behavioral test showed that docosahexaenoyl dopamine in doses of 0.1-20 mg/kg had no effect on the learning and memory abilities of the animals tested.

[Some regularities of dimer II formation in BODIPY-FL-labeled lipids].

Some regularities of dimer II formation from BODIPY-FL-labeled lipid probes using mono-, bis-, and tris-BODIPY-FL derivatives of gangliosides G(M1) and G(D1a) and mono- and bis-BODIPY-FL derivatives of triglycerides have been defined. BODIPY-FL-labeled glycolipids were shown in phospholipid layers to reveal a greater disposition towards dimer II formation than BODIPY-FL-labeled glycerides. The formation of dimer 11 was also shown to depend on the label position in the probe molecule. Probes bearing a label in the polar head area are more prone to dimer II formation than probes labeled in the apolar part of the molecule.

[BODIPY-labeled ganglioside probes for membrane and biological studies].

A series of new fluorescent ganglioside G(M1) derivatives bearing the residue of 4,4-difluoro-4-bora-3a,4a-diaza-s-indecene (BODIPY) either in the polar or nonpolar part of the molecule have been synthesized. Gangliosides G(M1) labeled with the residues of (4,4-difluoro-5-styryl-4-bora-3a,4a-diaza-s-indecenyl)-5-pentanoic (564/570-BODIPY-pentanoic) acid and (4,4-difluoro-5-butadienylphenyl-4-bora-3a,4a-diaza-s-indecenyl)-11-undecanoic (581/591-BODIPY-undecanoic) acid at the polar part of the molecule or with the residue of (4,4-difluoro-5-butadienylphenyl-4-bora-3a,4a-diaza-s-indecenyl)-5-pentanoic (581/591-BODIPY-pentaoic) acid at the nonpolar part of the molecule have been synthesized. The spectral characteristics of the resulting probes and their behavior in ganglioside G(M1) micelles and in sphingomyelin-cholesterol enriched bilayers containing BODIPY-FL-labeled gangliosides G(M1) have been studied. The localization of the probe in the ganglioside molecule has been demonstrated to affect the efficiency of energy transfer in the case of the corresponding donor-acceptor pairs.

[Modification of recombinant proteins by covalent polysialation illustrated with the example of human insulin].

Methods of selective and nonselective covalent immobilization of genetically engineered proteins on molecules of natural polysialic acid are described by the example of human insulin. Such modification increases insulin lifetime in vivo.

[Cerebrovascular and antiaggregative effects of GABA-docosahexaenoyldopamine conjugate].

The effects of GABA - docosahexaenoyldopamine (DHED) conjugate on the cerebral haemodynamics and thrombocyte aggregation were evaluated and compared to these of docosahexaenoyldopamine alone. The GABA - DHED conjugate was shown to significantly enhance the cerebral circulation in rats with a model of global transient cerebral ischemia, as compared to the intact animals. Administered alone, DHED increased the blood supply of both intact and ischemic brains to an equal extent. The GABA-DHED conjugate demonstrated the antiaggregative activity, but the effect was less expressed than that of DHED alone.

[New aspects of biosynthesis and metabolism of N-acyldopamines in rat tissues].

Possible biosynthetic pathways of N-acyldopamines in rat tissues were compared. It was shown that an insignificant amount of the conjugation products was formed during the incubation of arachidonic acid and dopamine, whereas the substitution of tyrosine for dopamine resulted in the productive biosynthesis of N-arachidonoyldopamine. The biosynthesis presumably involves several closely conjugated enzymatic stages, and free fatty acids rather than their CoA esters served as the starting substrates. The decarboxylation stage probably precedes the stage of catechol system formation, because N-acetyltyramine (a probable intermediate) was easily oxidized by monophenol monooxygenase to N-acyldopamine, whereas N-acyltyrosine is hydrolyzed under these conditions. Biosynthesis of N-acyldopamines in a cell-free medium was accompanied by their methylation. The possibility of oxidative metabolism of N-acyldopamines, which could serve as co-substrates or inhibitors of different oxidoreductases, was shown for the first time.

[Arachidonoyl amino acids and arachidonoyl peptides: synthesis and properties].

N-Arachidonoyl (AA) derivatives of amino acids (glycine, phenylalanine, proline, valine, gamma-amino butyric acid (GABA), dihydroxyphenylalanine, tyrosine, tryptophan, and alanine) and peptides (Semax, MEHFPGP, and PGP) were synthesized in order to study the biological properties of acylamino acids. The mass spectra of all the compounds at atmospheric pressure electrospray ionization display the most intense peaks of protonated molecular ions; the detection limits for these compounds are 10 fmol per sample. AA-Gly showed the highest inhibitory activity toward fatty acid amide hydrolase from rat brain (IC50 6.5 microM) among all the acylamino acids studied. AA-Phe, AA-Tyr, and AA-GABA exhibited a weak but detectable inhibitory effect (IC50 55, 60, and 50 microM, respectively). The acylated amino acids themselves, except for AA-Gly, were stable to the hydrolysis by this enzyme. All the arachidonoylamino acids inhibited cabbage phospholipase D to various degrees; AA-GABA and AA-Phe proved to be the most active (IC50 20 and 27 microM, respectively). Attempts to detect the biosynthesis of AA-Tyr in homogenates of rat liver and nerve tissue showed no formation in vitro of either this acylamino acid or AA-dopamine and AA-Phe, the products of its metabolism. The highest contents of these metabolites were detected in liver homogenate and in the brain homogenate, respectively. Acylamino acids exert no cytotoxic effect toward the glioma C6 cells. It was shown that N-acylation of Semax with arachidonic acid results in enhancement of its hydrolytic stability and increases its affinity for the sites of specific binding in rat cerebellum membranes. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru.

[Fluorescent-labeled lipophilic analogues of serotonin, dopamine, and acetylcholine: synthesis, mass spectrometry, and biological activity]. / Fluorestsentnomechenye lipofil'nye analogi serotonina, dofamina i atsetilkholina: sintez, mass-spektrometriia i biologicheskaia aktivnost'.

4,4-Difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-dodecanoyl derivatives of serotonin, dopamine, choline, and N,N-dimethylaminoethanol, with the fluorescence maximum at 512 nm (lambda(exc) 470 nm), and 4,4-difluoro-5,7-diphenyl-4-bora-3a,4a-diaza-s-indacene-3-dodecanoyl derivatives of choline and N,N-dimethylaminoethanol, with the fluorescence maximum at 554 nm (lambda(exc) 470 nm), were synthesized. These compounds yield protonated molecular ions of 100% intensity upon mass spectrometry with electrospray ionization at atmospheric pressure. The fragmentation of molecular ions under the conditions of secondary mass spectrometry mainly proceeds through the elimination of hydrogen fluoride from the fluorescent core of the molecules. Experiments on sea urchin Lytechinus variegatus embryos and larvae showed that these compounds easily penetrate into the cells and are accumulated in the cytoplasm. They do not differ in their biological activity from similar derivatives of arachidonic acid described previously and are agonists of serotonin or acetylcholine or antagonists of nicotinic acetylcholine receptors. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 5; see also http: // www.maik.ru.

[The possible functional interaction of serotonin and neuropeptides in embryogenic regulatory processes (experiments on embryos of the mollusk Tritona diomedea)]. / O vozmozhnom funktsional'nom vzaimodeistvii serotonina i neiropeptidov v reguliatornykh protsessakh émbriogeneza (opyty na zarodyshakh molliuska Tritona diomeda).

Ritanserin and inmecarb hydrochloride, antagonists of serotonin, act cytostatically and teratogenically on early embryos of Tritonia diomedea, a nudibranch mollusk. On the basis of a pharmacological analysis and the type of developmental abnormalities observed, this action appears to be due to disturbances in the functional activity of endogenous serotonin and is associated with damage of to the cytoskeleton. The effects of ritanserin and inmecarb are prevented or attenuated by lipophilic serotonin analogs (serotoninamides of polyenoic fatty acids), as well as by polypeptides isolated from neurons Pd5 and Pd6 of the pedal ganglia of the adult Tritonia. In late embryos (stage of veligers), serotonin and to a lesser extent its lipophilic analogs strongly increase embryonic motility. This effect of serotonin is potentiated by some neuropeptides and inhibited by others. These results provide evidence for functional interaction between serotonin and neuropeptides in the control processes of embryogenesis.

[Effects of the novel synthetic fatty acid dinitroglycerol esters on aggregation of the human platelets in vitro]. / Deistvie novykh sinteticheskikh dinitroglitserinovykh éfirov zhirnykh kislot na agregatsiiu trombotsitov cheloveka in vitro.

A series of six new synthetic dinitroglycerol esters of fatty acids on the human platelet aggregation was studied in vitro. Inclusion of the dinitroglycerol moiety into the molecule of arachidonic acid deprived this acid from pro-aggregant activity. All six compounds produced moderate (dose-dependent) inhibition of the platelet aggregation process induced by arachidonic acid (1 x 10(-3) M). Platelet aggregation was most significantly affected by dinitroglycerol esters of arachidonic and docosahexaenoic acids. This is probably explained by the influence of these esters on the oxidative metabolism of arachidonic acid to eicosanoids playing the role of proaggregants. In the presence of vessel wall (rat aorta fragments), dinitroglycerol esters of arachidonic and docosahexaenoic acids incubated with platelets (5 min, 37 degrees C) significantly reduced their aggregation induced by arachidonic acid (1 x 10(-3) M) or docosahexaenoic acid (1 x 10(-5) M) under the conditions of endothelial cyclooxygenase suppressed by acetylsalicylic acid (10 mg/ml). The pronounced antiaggregant effect of the synthetic dinitroglycerol esters studied is probably related to their ability to act as NO donors suppressing the activity of thrombocytes (provided that the NO production activity is present in the system).

[Effect of dopamineamides of polyunsaturated fatty acids on blood coagulation system and cerebral circulation]. / Vliianie dofaminamidov polinenasyshchennykh zhirnykh kislot na svertyvaiushchuiu sistemu krovi i mozgovoe krovoobrashchenie.

A series of original dopaminamides of polyunsaturated fatty acids were synthesized and characterized with respect to antiaggregant and cerebrovascular stimulant properties. It was established that dopaminamides of linolic, dimethyllinolic, docosapentaenoic, docosahexaenoic (DHEA) and stearidonic (C18:4 and C18:3) acids decrease ADP and arachidonic acid (AA) induced human thrombocyte aggregation in vitro. The most pronounced antiaggregant effect was observed for DHEA dopaminamide: in a dose of 10 mg/kg, this agent produced a significant decrease in the AA induced thrombocyte aggregation. DHEA per se in the same dose increases the activated partial thromboplastin time (APTT), while not affecting the prothrombin time. The synthesized dopaminamides of arachidonic, eicosapentaenoic, and docosahexaenoic acids stimulate local circulation in the cerebral cortex. The most pronounced cerebrovascular effect was also produced by DHEA dopaminamide.

[The influence of docosahexaenoic acid moiety on cytotoxic activity of 1,2,4-thiadiazole derivatives].

Among 3-(2-aminopropyl)-1,2,4-thiadiazole derivatives contatining substitution-ready secondary amino group and exhibiting cytotoxic towards rat C 6 glioma cells three compounds with LD 50 values ranged from 6 to 48 мM were chosen. For these compounds amides with docosahexaenoic acid were synthetised and their cytotoxic activity was studied. It was shown that, although docosahexaenoic acid itself was not toxic for C 6 glioma cells, its addition to the amino derivatives of 1,2,4-thiadiazole increased or decreased resultant cytotoxicity. The effect depended on the structure of 1,2,4-thiadiazole substituents. The obtained data show that the acylation of cytotoxic compounds with docosahexaenoic acid does not necessarily lead to the increase of their activity, but sometimes can inactivate a compound. This fact should be taken into account, especially in the case of anti-cancer drug development.