The pyrimidinones mhcpe, 2-methyl-3H-5-hydroxy-6-carboxy-4-pyrimidinone ethyl ester (mhcpe, 1), 2,3-dimethyl-5-benzyloxy-6-carboxy-4-pyrimidinone ethyl ester (dbcpe, 2) and ...N-methyl-2,3-dimethyl-5-hydroxy-6-carboxyamido-4-pyrimidinone (N-MeHOPY, 3), are synthesized and their structures determined by single crystal X-ray diffraction. The acid-base properties of 1 are studied by potentiometric and spectrophotometric methods, the pK(a) values being 1.14 and 6.35. DFT calculations were carried out to determine the most stable structure for each of the H2L(+), HL and L(-) forms (HL = mhcpe) and assign the groups involved in the protonation-deprotonation processes. The mhcpe(-) ligand forms stable complexes with V(IV)O(2+) in the pH range 2 to 10, and potentiometry, EPR and UV-Vis techniques are used to identify and characterize the V(IV)O-mhcpe species formed. The results are consistent with the formation of V(IV)O, (V(IV)O)L, (V(IV)O)L2, (V(IV)O)2L2H(-2), (V(IV)O)L2H(-1), (V(IV)O)2L2H(-3), (V(IV)O)LH(-2) species and V(IV)O-hydrolysis products. Calculations indicate that the global binding ability of mhcpe towards V(IV)O(2+) is similar to that of maltol (Hmaltol = 3-hydroxy-2-methyl-4H-pyran-4-one) and lower than that of 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdhp). The interaction of V(IV)O-complexes with human plasma proteins (transferrin and albumin) is studied by circular dichroism (CD), EPR and (51)V NMR spectroscopy. V(IV)O-mhcpe-protein ternary complexes are formed in both cases. The binding of V(IV)O(2+) to transferrin (hTF) in the presence of mhcpe involves mainly (V(IV)O)1(hTF)(mhcpe)1, (V(IV)O)2(hTF)(mhcpe)1 and (V(IV)O)2(hTF)(mhcpe)2 species, bound at the Fe(III) binding sites, and the corresponding conditional formation constants are determined. Under the conditions expected to prevail in human blood serum, CD data indicate that the V(IV)O-mhcpe complexes mainly bind to hTF; the formation of V(IV)O-hTF-mhcpe complexes occurs in the presence of Fe(III) as well, distinct EPR signals being clearly obtained for Fe(III)-hTF and to V(IV)O-hTF-mhcpe species. Thus this study indicates that transferrin plays the major role in the transport of V(IV)O-mhcpe complexes under blood plasma conditions in the form of ternary V(IV)-ligand-protein complexes.
Objective: The mood stabilizing drugs lithium, carbamazepine and valproate modulate brain adenosine monophosphate (cAMP) levels, which are assumed to be elevated in bipolar disorder patients. The ...aim of this work was to investigate how these three mood stabilizing agents affect the regulation of cAMP levels by dopamine D2‐like receptors in vitro in rat cortical neurons in culture and in vivo in the rat prefrontal cortex.
Methods: The production of cAMP was measured in the cultured cortical neurons or in microdialysis samples collected from the prefrontal cortex of freely moving rats using the 8‐3H and 125I radioimmunoassay kits.
Results: In vitro and in vivo data showed that the treatment with the mood stabilizing drugs had no effect on basal cAMP levels in vitro, but had differential effects in vivo. Direct stimulation of adenylate cyclase (AC) with forskolin increased cAMP levels both in vitro and in vivo, and this effect was significantly inhibited by all three mood stabilizers. Activation of dopamine D2‐like receptors with quinpirole partially inhibited forskolin‐induced increase in cAMP in untreated cultures, but no effect was observed in cortical neuron cultures treated with the mood stabilizing drugs. Similar results were obtained by chronic treatment with lithium and valproate in the prefrontal cortex in vivo. However, surprisingly, in carbamazepine‐treated rats the activation of dopamine D2‐like receptors enhanced the responsiveness of AC to subsequent activation by forskolin, possibly as a consequence of chronic inhibition of the activity of the enzyme.
Conclusions: It was shown that each of these drugs affects basal‐ and forskolin‐evoked cAMP levels in a distinct way, resulting in differential responses to dopamine D2‐like receptors activation.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
A new trinuclear oxovanadium(V) complex with the anionic dmpp ligand (Hdmpp = 3‐hydroxy‐1,2‐dimethyl‐4‐pyridinone), V3O6(dmpp)3(H2O)(H2O)2, was isolated from the reaction of Hdmpp, KOH and sodium ...metavanadate at pH 4.5. The solid state structure of the V3O6(H2O)(dmpp)3(H2O)2 complex, investigated by X‐ray diffraction methods, was found to contain a cyclic trinuclear metal cluster. This complex crystallises in the monoclinic system: P21/n, a = 9.5324(7) Å, b = 16.4107(11) Å and c = 18.0638(12) Å, β = 91.1010(10)°, V = 2825.3(3) Å3, Z = 4 and R1(wR2) = 0.0704 (0.2025). Two of the vanadium atoms (V1 and V3) are six‐coordinated, with distorted octahedral geometries, and the other one (V2) is five‐coordinated with a distorted square pyramidal geometry. The cyclic V3O4 framework has one oxygen atom bridging two vanadium atoms in two V−O−V groups, V1−O4−V2 and V2−O5−V3, and two oxygens bridging the V1−V3 atoms, V1−O6−V3 and V1−O12−V3. IR data confirm the crystallographic results, showing the characteristic V=O band in the 973−935 cm−1 frequency range. This compound has three bands corresponding to V=O stretching, indicative of different chemical environments around the vanadium atoms in the solid state. The ES mass spectrum in aqueous solution displays an intense peak corresponding to the V3O6(dmpp)3(H2O)+2H+2+ fragment. 51V and 1H NMR spectroscopy were used to study this complex in aqueous solution. The dissolution of the crystalline V3O6(dmpp)3(H2O)(H2O)2 compound in water, under aerobic conditions at pH 4.2, gave one intense broad signal at δ = −490 in the 51V NMR spectrum, which is attributed to a major species present in solution. The observation of only one 51V NMR signal, instead of the three expected from the different chemical environments of each vanadium atom present in the solid, is consistent with a fast (in the NMR timescale) dynamic equilibrium equalising their environments. This involves a fast exchange between O8, O10 and O12 as mono‐ or bifunctional oxygen atoms, as well as the H2O molecule, which acts in another fast equilibrium coordinating the vanadium atom that has a dmpp ligand with one bifunctional oxygen atom. The trinuclear oxovanadium(V) complex is relatively stable in water in the pH range 2.5−5.0. However, dissociation of the complex occurs at higher pH, leading to various hydrolysis products, which include mononuclear complex species with 1:1 and 1:2 metal‐to‐ligand stoichiometries, and monomeric and oligomeric species of free vanadium(V).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Objective: The mood stabilizing drugs lithium, carbamazepine and valproate modulate brain adenosine monophosphate (cAMP) levels, which are assumed to be elevated in bipolar disorder patients. The aim ...of this work was to investigate how these three mood stabilizing agents affect the regulation of cAMP levels by dopamine D sub(2)-like receptors in vitro in rat cortical neurons in culture and in vivo in the rat prefrontal cortex. Methods: The production of cAMP was measured in the cultured cortical neurons or in microdialysis samples collected from the prefrontal cortex of freely moving rats using the 8- super(3)H and super(125)I radioimmunoassay kits. Results: In vitro and in vivo data showed that the treatment with the mood stabilizing drugs had no effect on basal cAMP levels in vitro, but had differential effects in vivo. Direct stimulation of adenylate cyclase (AC) with forskolin increased cAMP levels both in vitro and in vivo, and this effect was significantly inhibited by all three mood stabilizers. Activation of dopamine D sub(2)-like receptors with quinpirole partially inhibited forskolin-induced increase in cAMP in untreated cultures, but no effect was observed in cortical neuron cultures treated with the mood stabilizing drugs. Similar results were obtained by chronic treatment with lithium and valproate in the prefrontal cortex in vivo. However, surprisingly, in carbamazepine-treated rats the activation of dopamine D sub(2)-like receptors enhanced the responsiveness of AC to subsequent activation by forskolin, possibly as a consequence of chronic inhibition of the activity of the enzyme. Conclusions: It was shown that each of these drugs affects basal- and forskolin-evoked cAMP levels in a distinct way, resulting in differential responses to dopamine D sub(2)-like receptors activation.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Tm(DOTP)5-, the thulium(III) complex of 1,4,7,10-tetraazacyclododecane-N,N',N',N'''-tetra(methylenephos p hon ate), is introduced as a 23Na+ shift agent for use in discrimination of the NMR ...resonances of intra- and extracellular 23Na+ ions in perfused rat hearts. The novel shift agent is directly compared to the widely used Dy(TTHA)3- (dysprosium(III) triethylenetetraminehexaacetate).
Lithium has been used clinically in the treatment of manic depression. However, its pharmacologic mode of action remains unclear. Characteristics of Li
+
interactions in red blood cells (RBCs) have ...been identified. We investigated Li
+
interactions on human neuroblastoma SH‐SY5Y cells by developing a novel
7
Li NMR method that provided a clear estimation of the intra‐ and extracellular amounts of Li
+
in the presence of the shift reagent thulium‐1,4,7,10‐tetrazacyclododecane‐
N,N
′,
N
″,
N
‴‐tetramethylene phosphonate (HTmDOTP
4−
). The first‐order rate constants of Li
+
influx and efflux for perfused, agarose‐embedded SH‐SY5Y cells in the presence of 3 m
M
HTmDOTP
4−
were 0.055 ± 0.006 (n = 4) and −0.025 ± 0.006 min
−1
(n = 3), respectively. Significant increases in the rate constants of Li
+
influx and efflux in the presence of 0.05 m
M
veratridine indicated the presence of Na
+
channel‐mediated Li
+
transport in SH‐SY5Y cells.
7
Li NMR relaxation measurements showed that Li
+
is immobilized more in human neuroblastoma SH‐SY5Y cells than in human RBCs.
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Magnesium is an essential element for all living systems. The quantification of free intracellular Mg 2+ concentration () is of utmost importance since changes in its basal value may be an indication ...of different pathologies due to abnormalities of Mg 2+ metabolism. In this work we used 31 P NMR and fluorescence spectroscopy to determine the resting in bovine chromaffin cells, a neuron‐like cellular model, as well as confocal laser scanning microscopy to study the free Mg 2+ spatial distribution in these cells. 31 P NMR spectroscopy did not prove to be effective for the determination of in this particular case due to some special morphological and physiological properties of this cell type. A basal value of 0.551 ± 0.008 mM was found for these cells using fluorescence spectroscopy and the Mg 2+ ‐sensitive probe furaptra; this value falls in the concentration range reported in the literature for neurons from different sources. This technique proved to be an accurate and sensitive tool to determine the . lntraceilular free Mg 2+ seems to be essentially localized in the nucleus and around it, as shown by confocal microscopy with the Mg 2+ ‐sensitive probe Magnesium Green. It was not possible to derive any conclusion about free Mg 2+ localization inside the chromaffin granules and/or in the cytoplasm due to the lack of sufficient spatial resolution and to probe compartmentalization.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Magnesium is an essential element for all living systems. The quantification of free intracellular Mg
2+
concentration (Mg
2+
i
) is of utmost importance since changes in its basal value may be an ...indication of
different pathologies due to abnormalities of Mg
2+
metabolism. In this work we used
31
P NMR and
fluorescence spectroscopy to determine the resting Mg
2+
i
in bovine chromaffin cells, a neuron-like cellular
model, as well as confocal laser scanning microscopy to study the free Mg
2+
spatial distribution in these cells.
31
P NMR spectroscopy did not prove to be effective for the determination of Mg
2+
i
in this particular case due to some special morphological and physiological properties of this cell type. A basal Mg
2+
i
value of
0.551 ± 0.008 mM was found for these cells using fluorescence spectroscopy and the Mg
2+
-sensitive probe
furaptra; this value falls in the concentration range reported in the literature for neurons from different
sources. This technique proved to be an accurate and sensitive tool to determine the Mg
2+
i
.
lntraceilular free Mg
2+
seems to be essentially localized in the nucleus and around it, as shown by
confocal microscopy with the Mg
2+
-sensitive probe Magnesium Green. It was not possible to derive any
conclusion about free Mg
2+
localization inside the chromaffin granules and/or in the cytoplasm due to the
lack of sufficient spatial resolution and to probe compartmentalization.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
: Lithium has been used clinically in the treatment of manic depression. However, its pharmacologic mode of action remains unclear. Characteristics of Li+ interactions in red blood cells (RBCs) have ...been identified. We investigated Li+ interactions on human neuroblastoma SH‐SY5Y cells by developing a novel 7Li NMR method that provided a clear estimation of the intra‐ and extracellular amounts of Li+ in the presence of the shift reagent thulium‐1,4,7,10‐tetrazacyclododecane‐N,N′,N″,N‴‐tetramethylene phosphonate (HTmDOTP4−). The first‐order rate constants of Li+ influx and efflux for perfused, agarose‐embedded SH‐SY5Y cells in the presence of 3 mM HTmDOTP4− were 0.055 ± 0.006 (n = 4) and −0.025 ± 0.006 min−1 (n = 3), respectively. Significant increases in the rate constants of Li+ influx and efflux in the presence of 0.05 mM veratridine indicated the presence of Na+ channel‐mediated Li+ transport in SH‐SY5Y cells. 7Li NMR relaxation measurements showed that Li+ is immobilized more in human neuroblastoma SH‐SY5Y cells than in human RBCs.
Full text
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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