A Bioactive Olive Pomace Extract Prevents the Death of Murine Cortical Neurons Triggered by NMDAR Over-Activation

We have recently demonstrated that bioactive molecules, extracted by high pressure and temperature from olive pomace, counteract calcium-induced cell damage to different cell lines. Here, our aim was to study the effect of the same extract on murine cortical neurons, since the preservation of the intracellular Ca²⁺-homeostasis is essential for neuronal function and survival. Accordingly, we treated neurons with different stimuli in order to evoke cytotoxic glutamatergic activation. In these conditions, the high-pressure and temperature extract from olive pomace (HPTOPE) only abolished the effects of N-methyl-d-aspartate (NMDA). Particularly, we observed that HPTOPE was able to promote the neuron rescue from NMDA-induced cell death. Moreover, we demonstrated that HPTOPE is endowed with the ability to maintain the intracellular Ca²⁺-homeostasis following NMDA receptor overactivation, protecting neurons from Ca²⁺-induced adverse effects, including aberrant calpain proteolytic activity. Moreover, we highlight the importance of the extraction conditions used that, without producing toxic molecules, allow us to obtain protecting molecules belonging to proanthocyanidin derivatives like procyanidin B2. In conclusion, we can hypothesize that HPTOPE, due to its functional and nontoxic properties on neuronal primary culture, can be utilized for future therapeutic interventions for neurodegeneration.     

13C nuclear magnetic resonance spectroscopy to determine olive oil grades

¹³C nuclear magnetic resonance spectroscopy was used in a first attempt to differentiate olive oil samples by grades. High resolution ¹³C NMR Distortionless Enhancement by Polarization Transfer (DEPT) spectra of 137 olive oil samples from the four grades, extra virgin olive oils, olive oils, olive pomace oils and lampante olive oils, were measured. The data relative to the resonance intensities (variables) of the unsaturated carbons of oleate (C-9 and C-10) and linoleate (L-9, L-10 and L-12) chains attached at the 1,3- and 2-positions of triacylglycerols were analyzed by linear discriminant analysis. The 1,3- and 2- carbons of the glycerol moiety of triacylglycerols along with the C-2, C-16 and C-18 resonance intensities of saturated, oleate and linoleate chains were also analyzed by linear discriminant analysis. The three discriminanting functions, which were calculated by using a stepwise variable selection algorithm, classified in the true group by cross-validation procedure, respectively, 76.9, 70.0, 94.4 and 100% of the extra virgin, olive oil, olive pomace oil and lampante olive oil grades.     

A confocal study of mechanism of 5-hydroxytryptamino induced intracellular calcium dynamics in cultured rat stomach fundus smooth muscle cells with a new Ca2+ indicator STDln-AM

A new fluorescent Ca²⁺ indicator STDln-AM for detecting [Ca²⁺], transients in cultured smooth muscle cells is presented. By making a comparison, the difference between STDln and fluo-3 is discussed in detail. Using the new Ca²⁺ indicator, the mechanism of 5-hydroxytryptamino (5-HT) induced intracellular calcium dynamics in stomach fundus smooth muscle cells (SFSMC) of rats is investigated. It is shown that in contrast with fluo-3, STDln is uniformly distributed in the cytosolic compartment but excluded from the nucleus, when it is transfected into cells. This feature makes it a real cytosol Ca²⁺ indicator and can reflect changes of cytosol [Ca²⁺] more accurately than that of fluo-3. In addition, STDln responds to the [Ca²⁺], transients more sensitive and faster than fluo-3. The results also show that, the L-type Ca²⁺ channel inhibitor Mn9202 and the PLC inhibitor Compound 48/80 can significantly inhibit the [Ca²⁺], elevation induced by 5-HT, while the PKC inhibitor D-Sphingosine can enhance the effect of 5-HT. The results suggest that 5-HT acts by the way of 5-HT₂ receptors on SFSMC, then through 5-HT₂ receptors coupled IP₃/Ca²⁺ and GC/PKC double signal transduction pathways to make Ca²⁺ release from intracellular Ca²⁺ stores and Ca²⁺ influx possibly through L-type calcium channels.     

Radium removal from aqueous solutions by adsorption on non-treated and chemically modified biomass by-product

The adsorption efficiency of a biomass by-product (olive cake) regarding the removal of radium (²²⁶Ra) from aqueous solutions has been investigated prior and after its chemical treatment. The chemical treatment of the biomass by-product included phosphorylation and MnO₂-coating. The separation/removal efficiency has been studied as a function of pH, salinity (NaCl) and calcium ion concentration (Ca²⁺) in solution. Evaluation of the experimental data shows clearly that the phosphorylated biomass by-product presents the highest adsorption capacity and efficiency followed by the MnO₂-coated material and the non-treated biomass by-product. However, regarding the effect of salinity and the presence of competitive cations (e.g. Ca²⁺) on the adsorption/removal efficiency, the MnO₂-coated material shows the lowest decline in efficiency (only 2 % of the relative adsorption efficiency) followed by the non-treated and the phosphorylated biomass by-product. The results of the present study indicate that depending on the physicochemical characteristics of the radium-contaminated water, all three types of the biomass by-product could be effectively used for the treatment of radium-contaminated waters. Nevertheless, the MnO₂-coated material is expected to be the most effective adsorbent and an alternative to MnO₂ resins for the treatment of environmentally relevant waters.     

Calcium overload is essential for the acceleration of staurosporine-induced cell death following neuronal differentiation in PC12 cells

Differentiation of neuronal cells has been shown to accelerate stress-induced cell death, but the underlying mechanisms are not completely understood. Here, we find that early and sustained increase in cytosolic ([Ca²⁺]_c) and mitochondrial Ca²⁺ levels ([Ca²⁺]_m) is essential for the increased sensitivity to staurosporine-induced cell death following neuronal differentiation in PC12 cells. Consistently, pretreatment of differentiated PC12 cells with the intracellular Ca²⁺-chelator EGTA-AM diminished staurosporine-induced PARP cleavage and cell death. Furthermore, Ca²⁺ overload and enhanced vulnerability to staurosporine in differentiated cells were prevented by Bcl-X_L overexpression. Our data reveal a new regulatory role for differentiation-dependent alteration of Ca²⁺ signaling in cell death in response to staurosporine.     

Inhibition of Glutamate Release from Rat Cortical Nerve Terminals by Dehydrocorydaline,an Alkaloid from Corydalis yanhusuo

Excessive release of glutamate induces excitotoxicity and causes neuronal damage in several neurodegenerative diseases. Natural products have emerged as potential neuroprotective agents for preventing and treating neurological disorders. Dehydrocorydaline (DHC), an active alkaloid compound isolated from Corydalis yanhusuo, possesses neuroprotective capacity. The present study investigated the effect of DHC on glutamate release using a rat brain cortical synaptosome model. Our results indicate that DHC inhibited 4-aminopyridine (4-AP)-evoked glutamate release and elevated intrasynaptosomal calcium levels. The inhibitory effect of DHC on 4-AP-evoked glutamate release was prevented in the presence of the vesicular transporter inhibitor bafilomycin A1 and the N- and P/Q-type Ca²⁺ channel blocker ω-conotoxin MVIIC but not the intracellular inhibitor of Ca²⁺ release dantrolene or the mitochondrial Na⁺/Ca²⁺ exchanger inhibitor {"type":"entrez-protein","attrs":{"text":"CGP37157","term_id":"875406365","term_text":"CGP37157"}}CGP37157. Moreover, the inhibitory effect of DHC on evoked glutamate release was prevented by the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) inhibitor PD98059. Western blotting data in synaptosomes also showed that DHC significantly decreased the level of ERK1/2 phosphorylation and synaptic vesicle-associated protein synapsin I, the main presynaptic target of ERK. Together, these results suggest that DHC inhibits presynaptic glutamate release from cerebrocortical synaptosomes by suppressing presynaptic voltage-dependent Ca²⁺ entry and the MAPK/ERK/synapsin I signaling pathway.     

Lanthanum Chloride Promoted Proliferation with Enhanced S‐phase Entry and Inhibited Potassium Currents of NIH 3T3 Cells

The effects of La³⁺ on proliferation, cell cycles, apoptosis and ion channels were investigated in mouse embryo fibroblast NIH 3T3 cells and its possible mechanisms were explored. Our data showed that La³⁺ promoted cell proliferation with increased S‐phase entry and inhibited the outward potassium currents in a concentration‐dependent manner in NIH 3T3 cells. La³⁺ and Ca²⁺ had synergistic effect on cell proliferation and cell cycles. It showed that Ca²⁺ was needed for La³⁺‐promoted cell cycle progression. Using the whole‐cell voltage‐clamp technique, we found that La³⁺ blocked the outward potassium current in a concentration‐dependent manner in NIH 3T3 cells. Lanthanum ions can increase intracellular Ca²⁺ concentration through inhibition of potassium currents, which induce a series of physiological changes and improve proliferation of cells. This may be one of the molecular mechanisms of lanthanum ions induced cell proliferation. The present work provides a new perspective for understanding the biological and toxicological effects of lanthanum.     

Towards Understanding the Involvement of H+-ATPase in Programmed Cell Death of Psammosilene tunicoides after Oxalic Acid Application

Psammosilene tunicoides is a unique perennial medicinal plant species native to the Southwestern regions of China. Its wild population is rare and endangered due to over-excessive collection and extended growth (4–5 years). This research shows that H⁺-ATPase activity was a key factor for oxalate-inducing programmed cell death (PCD) of P. tunicoides suspension cells. Oxalic acid (OA) is an effective abiotic elicitor that enhances a plant cell’s resistance to environmental stress. However, the role of OA in this process remains to be mechanistically unveiled. The present study evaluated the role of OA-induced cell death using an inverted fluorescence microscope after staining with Evans blue, FDA, PI, and Rd123. OA-stimulated changes in K⁺ and Ca²⁺ trans-membrane flows using a patch-clamp method, together with OA modulation of H⁺-ATPase activity, were further examined. OA treatment increased cell death rate in a dosage-and duration-dependent manner. OA significantly decreased the mitochondria activity and damaged its electron transport chain. The OA treatment also decreased intracellular pH, while the FC increased the pH value. Simultaneously, NH₄Cl caused intracellular acidification. The OA treatment independently resulted in 90% and the FC led to 25% cell death rates. Consistently, the combined treatments caused a 31% cell death rate. Furthermore, treatment with EGTA caused a similar change in intracellular pH value to the La³⁺ and OA application. Combined results suggest that OA-caused cell death could be attributed to intracellular acidification and the involvement of OA in the influx of extracellular Ca²⁺, thereby leading to membrane depolarization. Here we explore the resistance mechanism of P. tunicoides cells against various stresses endowed by OA treatment.     

Kaempferol 3-Rhamnoside on Glutamate Release from Rat Cerebrocortical Nerve Terminals Involves P/Q-Type Ca2+ Channel and Ca2+/Calmodulin-Dependent Protein Kinase II-Dependent Pathway Suppression

Excess synaptic glutamate release has pathological consequences, and the inhibition of glutamate release is crucial for neuroprotection. Kaempferol 3-rhamnoside (KR) is a flavonoid isolated from Schima superba with neuroprotective properties, and its effecton the release of glutamate from rat cerebrocortical nerve terminals was investigated. KR produced a concentration-dependent inhibition of 4-aminopyridine (4-AP)-evoked glutamate release with half-maximal inhibitory concentration value of 17 µM. The inhibition of glutamate release by KR was completely abolished by the omission of external Ca²⁺ or the depletion of glutamate in synaptic vesicles, and it was unaffected by blocking carrier-mediated release. In addition, KR reduced the 4-AP-evoked increase in Ca²⁺ concentration, while it did not affect 4-AP-evoked membrane potential depolarization. The application of selective antagonists of voltage-dependent Ca²⁺ channels revealed that the KR-mediated inhibition of glutamate release involved the suppression of P/Q-type Ca²⁺ channel activity. Furthermore, the inhibition of release was abolished by the calmodulin antagonist, W7, and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) inhibitor, KN62, but not by the protein kinase A (PKA) inhibitor, H89, or the protein kinase C (PKC) inhibitor, GF109203X. We also found that KR reduced the 4-AP-induced increase in phosphorylation of CaMKII and its substrate synapsin I. Thus, the effect of KR on evoked glutamate release is likely linked to a decrease in P/Q-type Ca²⁺ channel activity, as well as to the consequent reduction in the CaMKII/synapsin I pathway.     

Safranal Induces Vasorelaxation by Inhibiting Ca2+ Influx and Na+/Ca2+ Exchanger in Isolated Rat Aortic Rings

Introduction: Safranal, which endows saffron its unique aroma, causes vasodilatation and has a hypotensive effect in animal studies, but the mechanisms of these effects are unknown. In this study, we investigated the mechanisms of safranal vasodilation. Methods: Isolated rat endothelium-intact or -denuded aortic rings were precontracted with phenylephrine and then relaxed with safranal. To further assess the involvement of nitric oxide, prostaglandins, guanylate cyclase, and phospholipase A₂ in safranal-induced vasodilation, aortic rings were preincubated with L-NAME, indomethacin, methylene blue, or quinacrine, respectively, then precontracted with phenylephrine, and safranal concentration–response curves were established. To explore the effects of safranal on Ca²⁺ influx, phenylephrine and CaCl₂ concentration–response curves were established in the presence of safranal. Furthermore, the effect of safranal on aortic rings in the presence of ouabain, a Na⁺-K⁺ ATPase inhibitor, was studied to explore the contribution of Na⁺/Ca²⁺ exchanger to this vasodilation. Results: Safranal caused vasodilation in endothelium-intact and endothelium-denuded aortic rings. The vasodilation was not eliminated by pretreatment with L-NAME, indomethacin, methylene blue, or quinacrine, indicating the lack of a role for NO/cGMP. Safranal significantly inhibited the maximum contractions induced by phenylephrine, or by CaCl₂ in Ca²⁺-free depolarizing buffer. Safranal also relaxed contractions induced by ouabain, but pretreatment with safranal totally abolished the development of ouabain contractions. Discussion/Conclusion: Inhibition of Na⁺-K⁺ ATPase by ouabain leads to the accumulation of Na⁺ intracellularly, forcing the Na⁺/Ca²⁺ exchanger to work in reverse mode, thus causing a contraction. Inhibition of the development of this contraction by preincubation with safranal indicates that safranal inhibited the Na⁺/Ca²⁺ exchanger. We conclude that safranal vasodilation is mediated by the inhibition of calcium influx from extracellular space through L-type Ca²⁺ channels and by the inhibition of the Na⁺/Ca²⁺ exchanger.     

New Calcium‐Selective Smart Contrast Agents for Magnetic Resonance Imaging

Calcium plays a vital role in the human body and especially in the central nervous system. Precise maintenance of Ca²⁺ levels is very crucial for normal cell physiology and health. The deregulation of calcium homeostasis can lead to neuronal cell death and brain damage. To study this functional role played by Ca²⁺ in the brain noninvasively by using magnetic resonance imaging, we have synthesized a new set of Ca²⁺‐sensitive smart contrast agents (CAs). The agents were found to be highly selective to Ca²⁺ in the presence of other competitive anions and cations in buffer and in physiological fluids. The structure of CAs comprises Gd³⁺‐DO3A (DO3A=1,4,7‐tris(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane) coupled to a Ca²⁺ chelator o‐amino phenol‐N,N,O‐triacetate (APTRA). The agents are designed to sense Ca²⁺ present in extracellular fluid of the brain where its concentration is relatively high, that is, 1.2–0.8 mM . The determined dissociation constant of the CAs to Ca²⁺ falls in the range required to sense and report changes in extracellular Ca²⁺ levels followed by an increase in neural activity. In buffer, with the addition of Ca²⁺ the increase in relaxivity ranged from 100–157 %, the highest ever known for any T₁‐based Ca²⁺‐sensitive smart CA. The CAs were analyzed extensively by the measurement of luminescence lifetime measurement on Tb³⁺ analogues, nuclear magnetic relaxation dispersion (NMRD), and ¹⁷O NMR transverse relaxation and shift experiments. The results obtained confirmed that the large relaxivity enhancement observed upon Ca²⁺ addition is due to the increase of the hydration state of the complexes together with the slowing down of the molecular rotation and the retention of a significant contribution of the water molecules of the second sphere of hydration.     

八肋游仆虫中心蛋白N-端半分子与Tb3+，Ca2+的结合

用分子生物学方法表达、纯化了游仆虫中心蛋白及N-端半分子，用铽荧光探针法、离子竞争法研究了pH 7.4，0.01 mol· L^-1 Hepes条件下中心蛋白与铽、钙的结合性质。结果表明中心蛋白有4个铽结合部位，其中2个为高亲合结合部位、2个为低亲合结合部位。具有2个低亲合结合部位的中心蛋白半分子与铽结合的条件常数是(2.13±0.10)×10⁵ L·mol^-1，与钙结合的条件常数是(7.52±0.02)×10² L·mol^-1。     

Novel Ca-selective merocyanine-type chromoionophore derived from calix[4]arene-diamide

The synthesis and calcium-selective chromogenic ion binding properties of benzothiazolium derivative of calix[4]arene are described. The merocyanine-type ionophore derived from calix[4]arene-diamide showed selective chromogenic properties toward Ca²⁺ ions in aqueous methanol. The compound showed significant Ca²⁺ ion dependent changes in UV-vis spectral properties in the presence of other physiologically important metal ions (Na⁺, K⁺, and Mg²⁺). The pH sensitive chromogenic behavior also suggests that the compound can be used as a sensitive pH indicator around pH 6.5.     

A model for cation adsorption to clays and membranes

A cation adsorption model is presented and its recent applications are discussed. The model combines electrostatic equations with specific binding, and considers neutral and positively charged complexes between the negative surface sites and organic cations in a closed system. Extensions in the model account for dye aggregation in solution, and for the formation of solution complexes of inorganic cations, such as [M⁺⁺ Cl^–]⁺. The amounts of 45Ca²⁺ adsorbed to vesicles extracted from the plasma membranes of melon root cells could be adequately simulated and predicted. The binding coefficients determined for Ca²⁺, Na⁺, and Mg²⁺ are in the range of values previously deduced for binding to phospholipid components. Model calculations were applied to the test of hypotheses on the effect of salt stress on the growth of roots. The adsorption of monovalent organic cations to montmorillonite is characterized by binding coefficients that are at least six orders of magnitude larger than those of Na⁺, Mg²⁺, Ca²⁺, and Cd²⁺, or those of CdCl⁺ or CaCl⁺. Monovalent organic cations were found to adsorb 140–200% of the cation exchange capacity of the clay and to cause charge reversal. Deductions from adsorption results of acriflavin are consistent with those drawn from the application of other experimental methods. Preliminary results on the adsorption of divalent organic cations are presented. Agro-environmental applications of organo-clays are discussed.     

希土化合物对离体巨噬细胞的影响

本文应用细胞培养法和单细胞阳离子测定系统研究了希土化合物以地巨噬细胞的影响，结果表明，在培养介质中ＳｍＣｌ３和Ｙｃｌ３的浓度大于１ｍｍｏｌ．ｄｍ＾－３时，有明显的细胞毒性，Ｙｃｌ３的细胞毒性大于ＳｍＣｌ３，ＳｍＣｌ３和ＹＣｌ３的细胞毒性明显大于Ｓｍ（Ａｌａ）３Ｃｌ３和Ｙ（Ａｌａ）２Ｃｌ３。希土化合物的作用使细胞（Ｃａ＾２＋ｉ）升高；毒性越大，Ｃａ＾２＋ｉ升高越甚。低浓度Ｓｍ＾３＋和Ｙ６３＋对细胞膜     

Phenylethylidene-3,4-dihydro-1H-quinoxalin-2-ones: promising building blocks for Cu recognition

A series of sulfonamido-substituted phenylethylidene-3,4-dihydro-1H-quinoxalin-2-one derivatives in which both of the fluorophore and ionophore are integrated into one structural unit, have been investigated. They all exhibit high selectivity toward Cu²⁺ in ethanol in the presence of other metallic ions (Zn²⁺, Mg²⁺, Co²⁺, Ni²⁺, Mn²⁺, Ca²⁺, and Ag⁺), as well as fast, stable, and reversible binding, as is evidenced by the observation of a red shift in the UV-vis spectrum, ‘ON-OFF’ fluorescence response. In addition, titration and MALDI-TOF measurements indicated that a 1:1 (and possibly also 2:1 (organic ligand: Cu²⁺) complexes were formed, depending on the relative amount of Cu²⁺ added to the solution of the organic ligand. It was also found that the binding constant could be tuned by modifying the nature and position of the substituents attached to the central benzene ring in the quinoxalone derivative. In acetonitrile, unlike in ethanol, these ligands undergo oxidation-decomposition by Cu²⁺ and therefore, no UV-vVis absorption bands could be observed. However, due to color change (from yellow to transparent) they could be useful as dosimeters in this solvent.     

Comparison of Ca2+ and Mg2+ binding to calmodulin. An enthalpy,entropy, and gibbs free energy analysis

A consistent set of G _B , H _B , and S _B parameters have been determined from ion specific electrode, calorimetric, and spectrophotometric studies for the binding of Ca²⁺ and Mg²⁺ to bovine calmodulin at pH=7.0 and an ionic strength I of 0.113M. A non-linear least squares analysis of calcium specific ion electrode data yields, on a molar basis, four calcium dissociation constants: 10^–7 for the first site, 10^–5 for the fourth site, and two constants between these values. Both calorimetric experiments and an indicator method provide evidence that Mg²⁺ binds to calmodulin, probably at the same sites as Ca²⁺, but with affinities about 100 times smaller: 4×10^–5 for the first site and 2×10^–3 for the fourth. Calorimetric titrations on Ca²⁺ binding to calmodulin in three buffers are consistent with 0.46 protons released upon binding at all four sites and yield an average H _B per site of 5.6 and 7.9 kJ-mol^–1 for Ca²⁺ and Mg²⁺, respectively. The entropy of the system increases by 524 and 361 J-K^–1-mol^–1 when Ca²⁺ and Mg²⁺, respectively, bind to four sites on calmodulin, i.e., the selectivity of calmodulin for Ca²⁺ is primarily derived from entropy effects. Further analysis based on elimination of the entropy term for the metal ions demonstrates that calmodulin bound to Ca²⁺ has a larger entropy than the unbound calmodulin; the opposite is true for calmodulin bound to Mg²⁺. These analyses are consistent with the hypothesis that Ca²⁺ forms tight complexes at all sites on calmodulin and that release of waters of hydration upon binding is the source of the increase of entropy in the system.     

Imidazo-benzo-15-crown-5 ethers bearing arylthienyl and bithienyl moieties as novel fluorescent chemosensors for Pd and Cu

Novel fluorescent ionophores bearing imidazo-arylthienyl or imidazo-bithienyl π-conjugated bridges functionalized with one or two fused benzo-15-crown-5 ethers as receptor units are reported. The sensing ability of the compounds in the presence of metallic cations (Li⁺, Na⁺, K⁺, Ca²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Pd²⁺, and Hg²⁺) and fluoride ion was studied in MeCN/DMSO solutions by absorption and emission spectroscopy. The experimental results indicate that all compounds could act as selective fluorimetric sensors for Cu²⁺ and Pd²⁺ and also for the fluoride ion, in the case of the bis-substituted crown ether derivatives.     

A Thermodynamic Study Between 18-Crown-6 with Mg2+, Ca2+, Sr2+and Ba2+ Cations in Water–Methanol and Water–Ethanol Binary Mixtures Using The Conductometric Method

The complexation reactions between Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ cations with the macrocyclic ligand, 18-Crown-6 (l8C6) in water–methanol (MeOH) binary systems as well as the complexation reactions between Ca²⁺ and Sr²⁺ cations with 18C6 in water–ethanol (EtOH) binary mixtures have been studied at different temperatures using conductometric method. The conductance data show that the stoichiometry of all the complexes is 1:1. It was found that the stability of 18C6 complexes with Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ cations is sensitive to solvent composition and in all cases, a non-linear behaviour was observed for the variation of log K _f of the complexes versus the composition of the mixed solvents. In some cases, the stability order is changed with changing the composition of the mixed solvents. The selectivity order of 18C6 for the metal cations in pure methanol is: Ba²⁺ > Sr²⁺ > Ca²⁺ > Mg²⁺. The values of thermodynamic parameters (Δ H _c ° and Δ S _c °) for formation of 18C6–Mg²⁺, 18C6–Ca²⁺, 18C6–Sr²⁺ and 18C6–Ba²⁺complexes were obtained from temperature dependence of the stability constants. The obtained results show that the values of (Δ H _c ° and Δ S _c °) for formation of these complexes are quite sensitive to the nature and composition of the mixed solvent, but they do not vary monotonically with the solvent composition.This revised version was published online in July 2005 with a corrected issue number.