Synthesis, structural analysis and anticonvulsant activity of a ternary Cu(II) mononuclear complex containing 1,10-phenanthroline and the leading antiepileptic drug valproic acid

The synthesis and characterization of the binary complex of copper(II) with the antiepileptic drug valproic acid sodium salt (Valp) and the related ternary complex with 1,10-phenanthroline (phen) are reported, as well as the anticonvulsant properties of the latter. The characterization was carried out by means of elemental analyses, infrared (IR), UV-visible (UV-vis) spectrophotometry and Electron Paramagnetic Resonance (EPR). The X-ray crystal structure of the mononuclear complex bis(2-propylpentanoate)(1,10-phenanthroline)copper(II) [Cu(Valp)(2)phen] is showed for the first time. It crystallized in C2/c space group with unit cell dimensions of a = 14.939(1) A, b = 19.280(1) A, c = 9.726(1) A, beta = 97.27(2) degrees , V = 2778.8(4) A(3) and Z = 8. The carboxylates bond in an asymmetric chelating mode and the copper atom adopts a highly distorted octahedral coordination, characterized by the sum of the angles of 365.9 degrees around Cu(II) and its nearest atoms in the CuN(2)O(2) + O(2) chromophore instead of the expected 360 degrees for a basal square planar geometry found in most Cu(II) complexes. Molecules assemble three by three through slipped pi-pi stacking of the aromatic phen with respectively 3.519 and 3.527 A distances, in a head-to-tail arrangement. Studies of the anticonvulsant properties of this bioligand chelate evidenced its lack of efficacy in preventing MES-induced seizures. Interestingly, complex 4 protected mice against the Minimal Clonic seizures at doses that do not cause Rotorod toxicity, with an ED(50) documenting very potent anticonvulsant activity in this model of seizure, a particularly useful pharmacological profile of activity for the treatment of Petit Mal seizures.

Co-treatment with copper compounds dramatically decreases toxicities observed with cisplatin cancer therapy and the anticancer efficacy of some copper chelates supports the conclusion that copper chelate therapy may be markedly more effective and less toxic than cisplatin therapy

Co-Administration of Cu(II) chelates are reported to decrease life threatening Cisplatin [Pt(II) (NH3)2(CL)2]-induced acute degenerative renal, gastrointestinal, thymic, and bone marrow states consistent with serious necrotizing and immune-mediated inflammatory disease. Initially it was found that copper sulfate treatment completely prevented lethality as well as gastric and nephrotoxicity without compromising Pt(II) (NH3)2(CL) 2 antineoplastic activity, which led to suggestions that prior Cu(II)-treatment be used clinically to prevent serious side effects of Pt(II) (NH3)2(CL)2-treatment. In the course of these studies it was discovered that Cu(II)-treatments alone inhibited neoplastic growth and increased survival of rat and mouse models of cancer. Subsequently it was discovered that a stable non-toxic and non-polar lipophilic chelate, Copper(II)2(3,5-diisopropylsalicylate)4, caused redifferentiation of cultured neuroblastoma and mouse muscle-implanted mammary adenocarcinoma without neoplastic cell killing. Another stable non-toxic and non-polar lipophilic chelate, Copper(II)2(3,5-ditertiarybutylsalicylate)4, was found to prevent Bax-initiated and caspases-3-activation mediated apoptosis. These remarkable observations are concluded to be due to enzyme-mimetic or modulating reactivities of Cu(II) chelates and/or facilitation of Cu(II or I)-dependent enzyme syntheses required to overcome inflammatory-neoplastic disease states. Further, approaches to treating neoplastic diseases by removal of Cu from tissues with ammonium tetrathiomolybdate in an anticopper approach to therapy are not well founded based upon existing scientific literature.

Prevention of cisplatin-induced kidney epithelial cell apoptosis with a Cu superoxide dismutase-mimetic [copper2II(3,5-ditertiarybutylsalicylate)4(ethanol)4]

Copper(2)(II)(3,5-ditertiarybutylsalicylate)(4)(ethanol)(4), Cu(2)(II)(3,5-DTBS)(4)(Eth)(4), was synthesized and characterized for evaluation as an anti-apoptotic superoxide dismutase (SOD)-mimetic in an in vitro 50 microM cis-diamminedichloroplatinum(II), [Pt(II)(NH(3))(2)(Cl)(2)]-treated kidney proximal tubule epithelial cell (LLC-PK) preparation. Synthesized Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) was characterized by elemental analysis, FTIR spectrophotometry, and X-ray crystallography. The IC(50) for SOD-mimetic reactivity of Cu(2)(II)(3,5-DTBS)(4)(Eth)(4), determined with the xanthine/xanthine oxidase/nitroblue tetrazolium (NBT) system, was found to be 2.69 microM for the binuclear chelate. Pretreatment of LLC-PK cells with 20 microM Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) prevented 50 microM Pt(II)(NH(3))(2)(Cl)(2)-induced and superoxide-mediated apoptosis. This SOD-mimetic significantly suppressed Pt(II)(NH(3))(2)(Cl)(2)-induced translocation of pro-apoptotic Bax from the cytosol to the inner mitochondrial membrane, prevented Pt(II)(NH(3))(2)(Cl)(2)-induced release of cytochrome c from the inner mitochondrial membrane and the appearance of cytochrome c in the cytosol, and prevented conversion of procaspase-3 to active caspase-3. Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) treatment inhibited Pt(II)(NH(3))(2)(Cl)(2)-mediated tubular cell injury by preventing activation of cellular mechanisms that lead to proximal tubule kidney cell death. Based on these observations, Pt(II)(NH(3))(2)(Cl)(2)- induced O(2)(-)-mediated apoptosis can be mechanistically overcome with a small molecular mass SOD-mimetic, Cu(2)(II)(3,5-DTBS)(4)(Eth)(4). Prior treatment of patients who are to undergo treatment with Pt(II)(NH(3))(2)(Cl)(2) for their neoplastic disease with Cu(2)(II)(3,5-DTBS)(4)(Eth)(4) may be beneficial to these patients.

Low-temperature (180 K) crystal structures of tetrakis-μ-(niflumato)di(aqua)dicopper(II) N,N-dimethylformamide and N,N-dimethylacetamide solvates, their EPR properties, and anticonvulsant activities of these and other ternary binuclear Copper(II)niflumate complexes

Two pseudopolymorphs, solvates, of [Cu(2)(II)(niflumate)(4)(H(2)O)(2)] of unknown structure were obtained following solution of [Cu(2)(II)(niflumate)(4)(H(2)O)(2)] in N,N-dimethylacetamide (DMA) or N,N-dimethylformamide (DMF). Low-temperature crystal structures obtained for these solvates revealed that they were ternary aqua DMA and DMF solvates: [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMA and [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMF. Intermolecular hydrogen bonding interactions account for the formation of these stable DMA and DMF solvates. These pseudopolymorphs contain a centrosymmetric binuclear center with Cu-Cu bond distances ranging from 2.6439(7) to 2.6452(9) A; the coordination sphere of Cu(II) is characterized by one long Cu-O (water) bond length of 2.128(3)-2.135(3) A and four short Cu-O (carboxylate) bonds of 1.949(3)-1.977(3) A. Crystal parameters for the DMA pseudopolymorph: a=10.372(1), b=19.625(2), c=17.967(2) A, beta=97.40(1) degrees , V=3626.8(6) A(3); monoclinic system; space group: P2(1)/a and for the DMF pseudopolymorph: a=10.125(2), b=18.647(3), c=19.616(4) A, alpha=74.38(2)(o), beta=88.18(2)(o), gamma=79.28(2)(o), V=3504(1) A(3); triclinic system; space group: P1. EPR spectra of these solids are identical and show strong antiferromagnetic coupling between the copper atoms, similar to the spectrum obtained for [Cu(2)(II)(niflumate)(4)(DMSO)(2)]. The [Cu(2)(II)(niflumate)(4)(H(2)O)(2)], [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMA, [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMF, [Cu(2)(II)(niflumate)(4)(DMF)(2)], and[Cu(2)(II)(niflumate)(4)(DMSO)(2)] evidenced protection against maximal electroshock-induced seizures and Psychomotor seizures at various times after treatment, consistent with the well known antiinflammatory activities of Cu chelates, but failed to protect against Metrazol-induced seizures while evidencing some Rotorod Toxicity consistent with a mechanism of action involving sedative activity.

Pharmacological and haematological results of rat skin burn injury treatment with Cu(II)2(3,5-diisopropylsalicylate)4

This research was performed to determine whether or not treatment of burn-injured rats with Cu(II)2(3,5-diisopropylsalicylate)4(Cu(II)2(3,5-DIPS)4) facilitated recovery from burn-injury. Four groups of adult male rats received a standard skin burn 1 h before an initial subcutaneous treatment which was continued daily for three days with either 0, 5, 10 or 20micromol Cu(II)2(3,5-DIPS)4/kg body mass. A fifth group was given no treatment. A sixth group served as a non-burn-injured non-treated normal control group. At 3 h and on days 1, 2, 3, 7 and 14 post-burn-injury blood samples were obtained from rats in all groups for the determination of leukocyte, platelet and erythrocyte counts, clotting times, hemoglobin and hematocrit values. Total protein and middle mass peptides in plasma, as well as plasma lipid and erythrocyte membrane peroxidation products were determined on days 7 and 14. Burn wound healing and body mass were determined daily from day 0 to 6 with a notation of crust rejection by day 14. Treatment with Cu(II)2(3,5-DIPS)4 produced effects consistent with a facilitation of Cu-dependent immune-mediated physiological inflammatory responses to burn injury. It is concluded that treatment of burn injury with Cu(II)2(3,5-DIPS)4 supports Cu-dependent physiological responses involved in overcoming burn injury, which may have been further optimized by continued treatment beyond day 2, the last day of treatment.

Synthesis, crystal structures, and anti-convulsant activities of ternary [ZnII(3,5-diisopropylsalicylate)2], [ZnII(salicylate)2] and [ZnII(aspirinate)2] complexes

Following observations that bis(3,5-diisopropylsalicylato)diaquazinc(II), [Zn(II)(3,5-DIPS)(2)(H(2)O)(2)], had anti-convulsant activity, bis(acetylsalicylate)diaquazinc(II), [Zn(II)(aspirinate)(2)(H(2)O)(2)], and the Zn(II) ternary 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neocuproine, NC) or dimethyl sulfoxide (DMSO) complexes of Zn(II)3,5-diisopropylsalicylate, salicylate, and acetylsalicylate were synthesized and spectroscopically characterized. Anti-convulsant and Rotorod toxicity activities of these complexes were determined to examine their anti-convulsant and undesirable central nervous stimulant or depressant activities of these Zn(II) non-steroidal anti-inflammatory agent complexes. Bis(3,5-diisopropylsalicylato)-1,10-phenanthorlinezinc(II), [Zn(II)(3,5-DIPS)(2)(phen)], (1) has one bidentate phen ligand and two mono-deprotonated 3,5-DIPS ligands. One of the carboxylates bonds in an asymmetric chelating mode. The Zn(II) atom exhibits a distorted bicapped rectangular pyramidal environment N(2)O(2)OO (4+1+1 *). In the neocuproine complex, bis(3,5-diisopropylsalicylato)-2,9-dimethyl-1,10-phenanthorlinezinc(II), [Zn(II)(3,5-DIPS)(2)(NC)] (2), the Zn(II) atom has a much more distorted bicapped rectangular pyramidal environment, N(2)O(2)O(2) (4+2 *), compared to 1. The two carboxylate ligands exhibit the same asymmetric coordinating mode with longer metalloelement-oxygen bond distances compared to 1. The space group of [Zn(II)(aspirinate)(2)(H(2)O)(2)] (3), which has been reported as Cc is corrected to C2/c. The zinc atom exhibits a (4+2 *) bicapped square pyramidal environment. While the two ternary phenanthroline-containing complexes, 1 and 2, evidenced weak protection against maximal electroshock (MES)- and subcutaneous Metrazol (scMET) induced seizures, [Zn(II)(3,5-DIPS)(2)(DMSO)(2)], [Zn(II)(aspirinate)(2)(H(2)O)(2)], and bis(salicylato)-1,10-phenanthorlinezinc(II), [Zn(II)(salicylate)(2)(phen)], were found to be particularly useful in protecting against MES and scMET seizures and [Zn(II)(aspirinate)(2)(H(2)O)(2)] and [Zn(II)(salicylate)(2)(phen)] were found to have activity in protecting against Psychomotor seizures, without causing Rotorod toxicity. Activities of these and other Zn(II) complexes of non-steroidal anti-inflammatory agents are consistent with the well-known anti-inflammatory responses of Zn(II)-dependent enzymes. There was also some evidence of Rotorod toxicity consistent with a mechanism of action involving sedative-hypnotic activity of recognized anti-epilepticdrugs.

Low-temperature (180 K) crystal structure, electron paramagnetic resonance spectroscopy, and propitious anticonvulsant activities of CuII2(aspirinate)4(DMF)2 and other CuII2(aspirinate)4 chelates

The purpose of this research was to characterize by X-ray crystallography the ternary dimethylformamide (DMF) Cu(II) complex of acetylsalicylic acid (aspirin), in an effort to compare the structure-activity relationships for the anticonvulsant activity of this and other Cu(II)aspirinate chelates. The ternary DMF Cu(II) complex of aspirin was synthesized and crystals grown from a DMF solution were characterized by single crystal X-ray diffraction. This crystalline material was analyzed for anticonvulsant activity in the Maximal Electroshock (MES) Grand Mal and subcutaneous Metrazol (scMET) Petit Mal models of seizure used to detect anticonvulsant activity. The ternary DMF complex was found to be a monomolecular binuclear complex, tetrakis-mu-(acetylsalicylato)bis(dimethylformamido)dicopper(II) [Cu(II)(2)(aspirinate)(4)(DMF)(2)] with the following parameters: monoclinic, space group P2(1)/n, a=12.259 (1), b=10.228 (1), c=16.987 (1) A, beta=92.07 (1) degrees; V=2128.5 (3) A(3); Z=2. The structure was determined at 180 K from 2903 unique reflections (I>1sigma(I)) to the final values of R=0.030 and wR=0.033 using F. This binuclear complex contains four acetylsalicylate bridging ligands which are related to each other in a two by two symmetry center. The four nearest O atoms around each Cu atom form a closely square planar arrangement with the square pyramidal coordination completed by the dimethylformamide oxygen atom occupying an apical position at a distance of 2.154 (1) A. Each Cu atom is displaced towards the DMF ligand by 0.187 A from the plane of the four O atoms. Electron paramagnetic resonance (EPR) spectra of [Cu(II)(2)(aspirinate)(4)(DMF)(2)] crystals show a strong antiferromagnetic coupling of the copper atoms, similar to that observed with other binuclear copper(II)salicylate compounds. Studies used to detect anticonvulsant activity revealed that [Cu(II)(2)(aspirinate)(4)(DMF)(2)] was an effective anticonvulsant in the MES model of seizure but ineffective against scMET-induced seizures. The monomolecular ternary binuclear [Cu(II)(2)(aspirinate)(4)(DMF)(2)] complex is more effective in inhibiting MES-induced seizures than other binuclear or mononuclear Cu(II) chelates of aspirin including: binuclear polymeric [Cu(II)(2)(aspirinate)(4)], [Cu(II)(2)(aspirinate)(4)(H(2)O)], which is anticipated to be less polymeric, and monomolecular ternary [Cu(II)(2)(aspirinate)(4)(DMSO)(2)] and [Cu(II)(aspirinate)(2)(Pyr)(2)]. These and other chelates appear to be more effective in the scMET model of seizure than [Cu(II)(2)(aspirinate)(4)(DMF)(2)]. These structure-activity relationships support the potential efficacy of Cu chelates of aspirin in treating epilepsies.

Activation of calcium-dependent calmodulin by calcium(II)3(3,5-diisopropylsalicylate)6(H2O)6 decreases thrombin receptor activating peptide-induced P-selectin expression

We examined the influence of 3,5-diisopropylsalicylic acid (3,5-DIPS) and calcium(II)3 (3,5-diisopropylsalicylate)6 (H2 O)6 [Ca(II)3 (3,5-DIPS)6 ], a new activator of calcium-dependent calmodulin-triggered nitric oxide synthase, on thrombin-induced platelet P-selectin expression. Citrated whole blood samples were incubated with either ethanol vehicle, 3,5-DIPS, or Ca(II)3 (3,5-DIPS)6. These whole blood samples were also co-incubated with thrombin receptor activating peptide (TRAP) or adenosine diphosphate (ADP), to up-regulate P-selectin (CD62P) on platelets. Both TRAP and ADP up-regulated P-selectin on platelets compared with platelets in whole blood samples that were not incubated with either platelet activator. Co-incubation of whole blood samples with TRAP, ADP together with 3,5-DIPS, or Ca(II)3 (3,5-DIPS)6 revealed that Ca(II)3 (3,5-DIPS)6 caused a decrease in platelet P-selectin expression for TRAP, ADP, and no-activator co-incubated samples of whole blood. Incubation of platelets with 3,5-DIPS also caused a decrease in ADP-induced up-regulation of P-selectin but failed to affect TRAP or no-activator-treated platelets. Incubation of whole blood with Ca(II)3 (3,5-DIPS)6 induced some hemolysis. We found that hemolysis increases basal P-selectin expression on platelets. We therefore conclude that Ca(II)3 (3,5-DIPS)6 decreased not only basal, but also hemolysis-induced P-selectin expression on platelets. In contrast, incubation of haemolysed whole blood with SIN-1 (standard nitric oxide-releasing drug) had no effect on P-selectin expression. In summary, Ca(II)3 (3,5-DIPS)6, a new calmodulin-dependent nitric oxide synthase activator, decreases P-selectin expression of human platelets in response to thrombin receptor activation. Improved calcium-dependent calmodulin activators may become useful drugs for the treatment of disorders associated with platelet activation, and P-selectin may decrease expression due to hemolysis.

Synthesis, crystal structure, EPR properties, and anti-convulsant activities of binuclear and mononuclear 1,10-phenanthroline and salicylate ternary copper(II) complexes

Two ternary Cu(II) complexes of 1,10-phenanthroline (phen) and singly (Hsal(-)) or dideprotonated (sal(2-)) salicylate ligands were synthesized, their X-ray crystal structure and electron paramagnetic resonance spectral characteristics determined, and evaluated for anti-convulsant activities in the maximal electroshock (MES) and Metrazol models of seizure and Rotorod toxicity. The X-ray crystal structure of [bis(1,10-phenanthroline)-mu-bis(salicylato-O,O')dicopper(II)] dihydrate, 1, ([Cu(II)(2)(phen)(2)(sal)(2)].2[H(2)O]), shows it to be binuclear. This dimer consists of two centrosymmetrically related pseudo-five coordinate Cu(II) atoms 3.242(2) A apart and bridged by two dideprotonated salicylate ligands. The X-ray crystal structure of [bis(1,10-phenanthroline)(salicylato)copper(II)][salicylate] monohydrate, 2, ([Cu(II)(phen)(2)(Hsal)](+)[Hsal](-)[H(2)O]), shows it to be mononuclear. This complex cation exhibits a highly irregular distorted square pyramidal geometry about the Cu(II) atom, (4+1+1*). Each salicylate is singly deprotonated and one of them is ligand bonded in an asymmetric chelating mode. EPR results for 2 indicate that in concentrated DMF solution phen remains bonded to copper but salicylate is likely monodentate in contrast to the situation for 1. However, in dilute DMF solution, both 1 and 2 form the same species, which accounts for the similarity in anti-convulsant activity of the two compounds. Both 1 and 2 were found to be effective in preventing MES-induced seizures and ineffective in preventing Metrazol-induced seizures. Rotorod toxicity, consistent with central nervous system depression, paralleled the observed anti-convulsant activity. It is suggested that the observed anti-convulsant activity is consistent with central nervous system depression as a physiological mechanism in overcoming MES-induced seizures due to MES-induced brain inflammatory disease.

Cu, Fe, Mn, and Zn chelates offer a medicinal chemistry approach to overcoming radiation injury

This review points out that treatment with essential metalloelement (Cu, Fe, Mn, and Zn) chelates facilitate tissue repair processes required for recovery from radiation injury including survival of lethally irradiated mice and rats. Results of studies pertaining to successful uses of bioavailable essential metalloelement chelates and combinations of them as well as aminothiols, Ca-channel blockers, acyl Melatonin homologs, substituted anilines, and curcumin radioprotectants are included in this review to suggest their use as chelates in overcoming radiation injury. Additional reports document that non-toxic doses of essential metalloelement chelates are effective in increasing survival and repairing radiation injury when administered before irradiation, in the radiation protection paradigm, and effective in increasing survival when used to treat after irradiation, in the radiorecovery paradigm. There are no other agents known to be effective in increasing survival when they are used to treat after irradiation. These approaches to radioprotection and radiorecovery offer promising approaches to facilitating recovery from radiation-induced injury experienced by patients undergoing radiation therapy for their neoplastic disease and by individuals who experience environmental, occupational, or accidental exposure to ionizing radiation. These individuals include those exposed to radiation resulting from nuclear accidents, the use of depleted uranium missiles, and astronauts undertaking space travel. Since there are no existing safe and effective treatments of radiation injury, studies of essential metalloelement chelates and combinations of them, as well as combinations of them with existing radioprotectant aminothiols, Ca-channel blockers, acyl Melatonin homologs, substituted anilines, and curcumin as radioprotectants seem worthwhile.

[Crystallochemistry of copper (II) and zinc (II) chelates by nonsteroidal antiinflammatory drugs]

Copper(II) and zinc(II) chelates by some non-steroidal antiinflammatory drugs NSAIDs (niflumic acid, indomethacin) and 3,5-diisopropylsalicylic acid (DIPS) were characterized by single X-ray diffraction methods. Copper(II) complexes by these two types of chelates are binuclear compounds, with Cu(2)(DIPS)(4)L(2) or Cu(2)(AINS)(4)L(2) formula (L=axial non-NSAID ligand such as diethylether, dimethylsulfoxide DMSO). In zinc(II) complex by DIPS, the metal ion is tetrahedrally coordinated and the corresponding compound is mononuclear with Zn(DIPS)(2)(DMSO)(2) formula. These copper(II) and zinc(II) complexes were found to be more active than their parent drugs from the antiinflammatory and anticonvulsant properties. It was pointed out that the Cu(2)(DIPS)(4)L(2) complexes (L=diethylether, N,N-dimethylformamide) exhibited no rotorod toxicity when examined for anticonvulsant activity using the seizure produced by maximal electroshock, following oral administration to rats.