Design and Synthesis of Non-Covalent Imidazo[1,2-a]quinoxaline-Based Inhibitors of EGFR and Their Anti-Cancer Assessment

A series of 30 non-covalent imidazo[1,2-a]quinoxaline-based inhibitors of epidermal growth factor receptor (EGFR) were designed and synthesized. EGFR inhibitory assessment (against wild type) data of compounds revealed 6b, 7h, 7j, 9a and 9c as potent EGFR^WT inhibitors with IC₅₀ values of 211.22, 222.21, 193.18, 223.32 and 221.53 nM, respectively, which were comparable to erlotinib (221.03 nM), a positive control. Furthermore, compounds exhibited excellent antiproliferative activity when tested against cancer cell lines harboring EGFR^WT; A549, a non-small cell lung cancer (NSCLC), HCT-116 (colon), MDA-MB-231 (breast) and gefitinib-resistant NSCLC cell line H1975 harboring EGFR^L858R/T790M. In particular, compound 6b demonstrated significant inhibitory potential against gefitinib-resistant H1975 cells (IC₅₀ = 3.65 μM) as compared to gefitinib (IC₅₀ > 20 μM). Moreover, molecular docking disclosed the binding mode of the 6b to the domain of EGFR (wild type and mutant type), indicating the basis of inhibition. Furthermore, its effects on redox modulation, mitochondrial membrane potential, cell cycle analysis and cell death mode in A549 lung cancer cells were also reported.     

Virtual screening of B-Raf kinase inhibitors: A combination of pharmacophore modelling,molecular docking, 3D-QSAR model and binding free energy calculation studies

B-Raf kinase has been identified as an important target in recent cancer treatment. In order to discover structurally diverse and novel B-Raf inhibitors (BRIs), a virtual screening of BRIs against ZINC database was performed by using a combination of pharmacophore modelling, molecular docking, 3D-QSAR model and binding free energy (ΔG_bind) calculation studies in this work. After the virtual screening, six promising hit compounds were obtained, which were then tested for inhibitory activities of A375 cell lines. In the result, five hit compounds show good biological activities (IC₅₀ < 50 μM). The present method of virtual screening can be applied to find structurally diverse inhibitors, and the obtained five structurally diverse compounds are expected to develop novel BRIs.     

Development of a novel class of B-Raf(V600E)-selective inhibitors through virtual screening and hierarchical hit optimization

Oncogenic mutations in critical nodes of cellular signaling pathways have been associated with tumorigenesis and progression. The B-Raf protein kinase, a key hub in the canonical MAPK signaling cascade, is mutated in a broad range of human cancers and especially in malignant melanoma. The most prevalent B-Raf(V600E) mutant exhibits elevated kinase activity and results in constitutive activation of the MAPK pathway, thus making it a promising drug target for cancer therapy. Herein, we describe the development of novel B-Raf(V600E) selective inhibitors via multi-step virtual screening and hierarchical hit optimization. Nine hit compounds with low micromolar IC(50) values were identified as B-Raf(V600E) inhibitors through virtual screening. Subsequent scaffold-based analogue searching and medicinal chemistry efforts significantly improved both the inhibitor potency and oncogene selectivity. In particular, compounds and possess nanomolar IC(50) values with selectivity for B-Raf(V600E)in vitro and exclusive cytotoxicity against B-Raf(V600E) harboring cancer cells.     

3D-QSAR (CoMFA,CoMSIA, HQSAR and topomer CoMFA), MD simulations and molecular docking studies on purinylpyridine derivatives as B-Raf inhibitors for the treatment of melanoma cancer

As per the World Health Organization (WHO), cancer is the second most leading cause of death after cardiovascular diseases in worldwide with around 9.88 million total new cases and 1.08 million were observed due to skin cancer in 2018. Amongst two types of skin cancer, progression of melanoma cancer is increasing day by day due to the environmental changes than non-melanoma cancer. Most of B-Raf mutation, specifically B-RafV600E, is responsible for the progression of the melanoma cancer. Here, various 3D-QSAR techniques like comparative molecular field analysis (CoMFA), comparative molecular similarity indices analysis (CoMSIA), molecular hologram QSAR (HQSAR) and topomer CoMFA were used to design novel B-Raf inhibitors by using 28 synthetic B-Raf inhibitors. Except for topomer CoMFA model, remaining models were generated by three different alignment methods in which distil-based alignment method was found best and gave prominent statistical values. After performing N-fold statistical validation, in CoMFA, q², r² and r²_pred values were found to be 0.638, 0.969 and 0.848, respectively. Similarly, q², r² and r²_pred values were found to be 0.796, 0.978 and 0.891 in CoMSIA (SHD) and 0.761, 0.973 and 0.852 in CoMSIA (SH) by N-fold statistical validation. In HQSAR analysis, statistical values were found for q² as 0.984, r² as 0.999 and r²_pred as 0.634 with 97 as best hologram length (BHL). The results of topomer CoMFA showed the q² value of 0.663 and the r² value of 0.967. Important features of purinylpyridine were identified by contour map analysis of all 3D-QSAR techniques, which could be useful to design the novel molecules as B-Raf inhibitors for the treatment of melanoma cancer.

     

Design and synthesis of some novel pyridothienopyrimidine derivatives and their biological evaluation as antimicrobial and anticancer agents targeting EGFR enzyme

A new series of pyridothienopyrimidine derivatives was designed and evaluated as antimicrobial and anticancer agents. The target compounds were synthesized starting with 3-aminothieno[2,3-b]pyridine-2-carboxamide derivative 1 which underwent cyclocondensation reaction with aromatic aldehydes to give the key intermediates 2a,b. By further treatment of 2a,b with various reagents, the target 2,4-disubstituted-pyrido[3′,2′:4,5]thieno[2,3-d]pyrimidines 3a,b–11a,b were obtained. To evaluate the antimicrobial activity of the new compounds, they were tested against five bacterial and five fungal strains. Compounds 6c, 8b, 9a and 9b revealed the most significant antimicrobial activity against the tested microorganisms with MIC values range (4–16 μg/mL). Also, compounds 2a,b–11a,b were screened for their in vitro cytotoxic activity against HepG-2 and MCF-7 cancer cell lines compared with doxorubicin and cisplatin as references drugs. Moreover, compounds (2b, 4a, 6a, 7b, 7c and 9a) which exhibited the most potent anticancer activity, were further subjected to EGFR^WT enzyme inhibition assay utilizing erlotinib as a standard drug. The compounds 6a, 7b, 7c and 9a which showed the most promising suppression effects were also evaluated as inhibitors against the mutant forms EGFR^L858R and EGFR^T790M. The 4-aminopyrazolone analogue 9a showed superior anticancer activity against both HepG-2 and MCF-7 cell lines (IC50 = 1.27, 10.80 μM, respectively) and more potent enzymatic inhibition activity against EGFR^WT and its mutant forms EGFR^L858R and EGFR^T790M than that obtained by erlotinib (IC₅₀ = 0.021, 0.053, 0.081 µM, respectively, IC_50erlotinib; 0.027, 0.069, 0.550 µM, respectively). Finally, the molecular docking study showed good binding patterns of the most active compounds with the prospective target EGFR^WT.     

Design,synthesis, docking and mechanistic studies of new thiazolyl/thiazolidinylpyrimidine-2,4-dione antiproliferative agents

In this article, we display on the synthesis and biological evaluation of a new series of thiazolylpyrimidine 3a-l and thiazolidinylpyrimidine derivatives 5a-e. The structures of the new compounds were confirmed by using different spectral techniques including NMR, IR, mass spectroscopy in addition to elemental analyses. The cell viability of the new compounds was assessed against normal human mammary gland epithelial (MCF-10A) cell line. Data revealed that none of the compounds examined exhibited cytotoxic effects, and the cell viability for the compounds examined at 50 µM was greater than 87%. The antiproliferative activity of 3a-l and 5a-e was evaluated against four human cancer cell lines where the compounds showed promising activity. The most potent derivatives were compounds 3a, 3c, 3f, 3i, and 5b with GI₅₀ values ranging from 0.90 µM to 1.70 µM against the four cancer cell lines in comparison to doxorubicin (GI₅₀ = 1.10 µM). Compounds 3a, 3c and 3i showed potent antiproliferative activity with dual inhibitory action against EGFR and BRAF^V600E. Compounds 3a, 3c, and 3i demonstrated promising AutoDock scores towards EGFR and BRAF^V600E with values of ? 9.1 and ? 8.6, ?9.0 and ? 8.5, and ? 8.4 and ? 8.0 kcal/mol, respectively. The physicochemical and pharmacokinetic characteristics of 3a, 3c, and 3i were anticipated, demonstrating their oral bioavailability.     

QM/MM based 3D QSAR models for potent B-Raf inhibitors

Three dimensional (3D) quantitative structure-activity relationship studies of 37 B-Raf inhibitors, pyrazole-based derivatives, were performed. Based on the co-crystallized compound (PDB ID: 3D4Q), several alignment methods were utilized to derive reliable comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models. Receptor-guided alignment with quantum mechanics/molecular mechanics (QM/MM) minimization led to the best CoMFA model (q ² = 0.624, r ² = 0.959). With the same alignment, a statistically reliable CoMSIA model with steric, H-bond acceptor, and hydrophobic fields was also derived (q ² = 0.590, r ² = 0.922). Both models were validated with an external test set, which gave satisfactory predictive r ² values of 0.926 and 0.878, respectively. Contour maps from CoMFA and CoMSIA models revealed important structural features responsible for increasing biological activity within the active site and explained the correlation between biological activity and receptor-ligand interactions. New fragments were identified as building blocks which can replace R1-3 groups through combinatorial screening methods. By combining these fragments a compound with a high bioactivity level prediction was found. These results can offer useful information for the design of new B-Raf inhibitors.     

New thieno[2,3-d]pyrimidine derivatives as EGFRWT and EGFRT790M inhibitors: Design,synthesis, antiproliferative activities,docking studies,ADMET, toxicity,MD simulation studies

A series of thieno[2,3-d]pyrimidines were designed and synthesized as epidermal growth factor receptor (EGFR) inhibitors. These compounds were tested for their ability to inhibit MCF-7 and A549 cancer cells. The most active compound, 12c , inhibited the growth of both cell lines, with IC₅₀ values of 15.67 and 12.16 μM, respectively. It was found that 12c had inhibitory effects on both EGFR^WT and EGFR^T790M isoforms, with inhibitory partialities of 37.50 and 148.90 nM, respectively. Additionally, 12c was found to be safer than erlotinib against normal cell lines (IC₅₀ = 38.61 μM). Compound 12c induced early and late apoptosis in A549 cells and arrested cell growth at G1 and G2/M phases. 12c was also found to increase caspases 3 and 8 ratios. Molecular docking indicated the correct binding modes of the synthesized compounds. MD simulations, MM-GBSA, and PLIP studies confirmed the precise binding of 12c to the EGFR protein over 100 ns.     

Synthesis,crystal structures and spectroscopic properties of two new organotin (IV) complexes and their antiproliferative effect against cancerous and non-cancerous cells

Cancer has become a leading cause of death worldwide, which is responsible for 7.6 million cancer deaths according to GLOBOCAN survey conducted in 2008. The exploration of cis-platin analogues (carboplatin, lobaplatin, nedaplatin, oxaliplatin) and their incorporation to the treatment of cancer patients has further led interest in exploring metal-based anticancer drugs. The current study describes the synthesis of two new tetra-coordinated mono- and tetranuclear organotin(IV) carboxylate complexes and their in vitro anticancer studies. Each one of the complexes (1–2) has been characterized by analytical (micro- and gravimetric analysis) and spectroscopic (FTIR, ¹H, ¹³C, ¹¹⁹Sn-NMR) techniques. Furthermore, molecular structures of 1 and 2 were elucidated using X-ray crystallography. The characterization data showed that the coordination took place via oxygen atoms from the carboxylate anions to generate 1 as an organodistannoxane dimer and 2 as a mononuclear complex. Exceptionally, the NMR spectroscopic and X-ray crystallographic study showed that acetone molecules also took part in crystallizing 2. Both complexes were tested against three cancerous (colon cancer HCT 116, breast cancer MCF 7, leukemia K562) and one non-cancerous (3T3-L1) cell lines. Both complexes showed same IC₅₀ value (0.2 μM) against HCT 116, whereas for the other two cancer cell lines (MCF 7 and K562) and a normal cell line (3T3-L₁), 2 showed results better than 1. Importantly, the complexes showed exceptional activity against MCF 7 and K562 cell lines and the IC₅₀ values were calculated in nanomoles (MCF 7, IC_50s = 86.5 and 53.4 nM; K 562, IC_50s = 22.9 and 49.6 nM for 1 and 2, respectively). Both, 1 and 2, showed IC₅₀ values many times better than the standard drugs (5-FU, Tamoxifen, betulinic acid and cis-platin) used. Compared to cancerous cell lines, the complexes showed mild toxicity against normal cells (3T3-L1). Overall, two remained relatively effective.     

Thermodynamic study of perfluorohexane + ether mixtures: VLE, LLE, and H

Vapour–liquid equilibria (VLE), liquid–liquid equilibria (LLE), and excess enthalpies (H^E) of binary mixtures of perfluoro-n-hexane plus an ether (diethyl, dipropyl, dibutyl, butyl methyl, and butyl ethyl ether), have been determined using a head-space gas-chromatographic technique, a turbidimetric apparatus, and a heat-flow calorimeter, respectively. A recently designed titration technique and calculation procedure have been used to obtain H^E from heats of solution. The observed liquid–liquid coexistence curves have been compared with those predicted by the activity coefficients γ_i and their temperature dependence. All mixtures are strongly endothermic (H^E > 0) and show large positive deviations from ideality (G^E > 0), which increase with the size of the ether. Molecular interactions have been examined by calculating and discussing solvation functions and Kirkwood–Buff (KB) integrals. Perfluorohexane proved to be an inert molecule that interacts with ethers more weakly than hexane.     

Novel Substituted Purine Isosteres: Synthesis,Structure-Activity Relationships and Cytotoxic Activity Evaluation

A number of pyrrolo[2,3-c]pyridines, pyrrolo[3,2-d]pyrimidines and pyrazolo[4,3-d]pyrimidines were designed and synthesized as antiproliferative agents. The target compounds possessed selected substituents in analogous positions on the central scaffold that allowed the extraction of interesting SARs. The cytotoxic activity of the new derivatives was evaluated against prostatic (PC-3) and colon (HCT116) cell lines, and the most potent analogues showed IC₅₀ values in the nM to low µM range, while they were found to be non-toxic against normal human fibroblasts (WI-38). Flow cytometric analysis of DNA content revealed that the most promising derivative 14b caused a statistically significant accumulation of PC-3 cells at G₂/M phase and induced apoptosis in PC-3 cells.     

Novel structures of Zn(II) biometal cation with the biologically active substituted acetic acid and nitrogen donor ligands: Synthesis,spectral, phosphate diester catalytic hydrolysis and anti‐microbial studies

The complexes [Zn(methoxyacetate)₂1,10‐phenanthroline] 1 and [Zn₂(phenylacetate)₄(quinoline)₂] 2 , were prepared and characterized by IR‐spectroscopy, UV–Visible spectroscopy, ¹H and ¹³C NMR spectroscopy, single crystal X‐ray diffraction. BNPP hydrolysis of the complexes and their parent nitrogen ligands were scanned, the results indicated that the hydrolysis rates of BNPP were 4.5 × 10⁴ and 6.2 × 10⁵ for ( 1 ) and ( 2 ), respectively. In addition, anti‐bacterial activities were scanned to investigate the effect of complexation on their activity against Gram‐positive (S. epidermidis , S. aureus , E. faecalis , M. luteus and B. Subtilis ) and Gram‐negative (K. pneumonia , E. coli , P. Mirabilis and P. Aeruginosa ) bacteria using agar well‐diffusion method. Complex 1 showed high activity against G⁻and G ⁺ bacteria except against E. faecalis and P. Aeruginosa . Complex 2 did not show any activity against G⁻ or G ⁺ bacteria.     

Lysosome‐targeted potent half‐sandwich iridium(III) α‐diimine antitumor complexes

Fifteen organometallic Ir(III) half‐sandwich complexes ( 1A – 5C ) having the general formula [(η⁵‐Cp^x)Ir(N^N)Cl]PF₆ (Cp^x = Cp*, tetramethyl(phenyl)cyclopentadienyl (Cp^xph) or tetramethyl(biphenyl)cyclopentadienyl (Cp^xbiph); N^N = diamine) have been synthesized and characterized. The molecular structure of 1A was determined using single‐crystal X‐ray diffraction analysis. The hydrolysis of 1A – 5C was monitored using UV–visible spectra. Complexes 3A – 3C showed catalytic activity for the oxidation of NADH to NAD⁺, where 3C showed the highest turnover number of 29.9 within 450 min. Cytotoxicity examination by MTT assay was carried out against two human cancer cell lines (HeLa and A549) after 24 or 48 h drug treatment. The complexes showed high potency, where the most potent complex ( 3C ; IC₅₀ = 3.4 μM) was six times more active than cisplatin against A549 cells after 24 h drug exposure. Cytotoxic potency towards A549 cells increased with phenyl substitution on Cp ring: Cp^xbiph > Cp^xph > Cp*. In addition, the biological studies showed that 3C caused cell apoptosis and cell cycle arrest at G₁ phase in A549 cancer cells. Moreover, 3C increased the level of reactive oxygen species markedly after 24 h, which may provide an important basis for killing cancer cells. Confocal laser scanning microscopy was used to track 3C in A549 cells. The cellular localization experiment showed that 3C targeted lysosomes and caused lysosomal damage.     

Design and Synthesis of Hsp90 Inhibitors with B-Raf and PDHK1 Multi-Target Activity

The design of multi-target ligands has become an innovative approach for the identification of effective therapeutic treatments against complex diseases, such as cancer. Recent studies have demonstrated that the combined inhibition of Hsp90 and B-Raf provides synergistic effects against several types of cancers. Moreover, it has been reported that PDHK1, which presents an ATP-binding pocket similar to that of Hsp90, plays an important role in tumor initiation, maintenance and progression, participating also to the senescence process induced by B-Raf oncogenic proteins. Based on these premises, the simultaneous inhibition of these targets may provide several benefits for the treatment of cancer. In this work, we set up a design strategy including the assembly and integration of molecular fragments known to be important for binding to the Hsp90, PDHK1 and B-Raf targets, aided by molecular docking for the selection of a set of compounds potentially able to exert Hsp90-B-Raf-PDHK1 multi-target activities. The designed compounds were synthesized and experimentally validated in vitro. According to the in vitro assays, compounds 4 a , 4 d and 4 e potently inhibited Hsp90 and moderately inhibited the PDHK1 kinase. Finally, molecular dynamics simulations were performed to provide further insights into the structural basis of their multi-target activity.     

(Vapour + liquid) equilibria and excess molar enthalpies for mixtures with strong complex formation. Trichloromethane or 1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) with tetrahydropyran or piperidine

Isothermal (vapour  +  liquid) equilibria were measured for (trichloromethane  +  tetrahydropyran or piperidine) at T =  333.15 K and {1-bromo-1-chloro-2,2,2-trifluoroethane (halothane)  +  tetrahydropyran or piperidine} atT =  323.15 K with a circulation still. The results were verified by effective statistical procedures and used to calculate activity coefficients and excess molar Gibbs free energiesG_m^E . Excess molar enthalpiesH_m^E for these mixtures were determined at T =  298.15 K by means of an isothermal CSC microcalorimeter equipped with recently reconstructed flow mixing cells. Reliable performance of the calorimetric setup was proved by the good agreement of H_m^Efor (hexane  +  cyclohexane), (2-propanone  +  water), and (methanol  +  water), with the best literature results. The trichloromethane- or halothane-containing mixtures exhibit strong negative deviations from Raoult’s law and are highly exothermic, thus indicating that complex formation via hydrogen bonding is a governing nonideality effect. A close similarity in the behaviour of corresponding mixtures with trichloromethane and halothane is observed, but for halothane-containing mixtures,G_m^E and H_m^Eare consistently more negative, confirming that halothane is a more powerful proton donor than chloroform.     

Design,Synthesis, and Antipoliferative Activities of Novel Substituted Imidazole-Thione Linked Benzotriazole Derivatives

A new series of benzotriazole moiety bearing substituted imidazol-2-thiones at N1 has been designed, synthesized and evaluated for in vitro anticancer activity against the different cancer cell lines MCF-7(breast cancer), HL-60 (Human promyelocytic leukemia), and HCT-116 (colon cancer). Most of the benzotriazole analogues exhibited promising antiproliferative activity against tested cancer cell lines. Among all the synthesized compounds, BI9 showed potent activity against the cancer cell lines such as MCF-7, HL-60 and HCT-116 with IC₅₀ 3.57, 0.40 and 2.63 µM, respectively. Compound BI9 was taken up for elaborate biological studies and the HL-60 cells in the cell cycle were arrested in G₂/M phase. Compound BI9 showed remarkable inhibition of tubulin polymerization with the colchicine binding site of tubulin. In addition, compound BI9 promoted apoptosis by regulating the expression of pro-apoptotic protein BAX and anti-apoptotic proteins Bcl-2. These results provide guidance for further rational development of potent tubulin polymerization inhibitors for the treatment of cancer.     

Excess properties and vapour pressure of (3-diethylaminopropylamine + n-alkanes)

The vapour pressures of liquid (3-diethylaminopropylamine (3-DEPA) + n-heptane) mixtures were measured by a static method between T = (303.15 and 343.15) K at 10 K intervals. The molar excess enthalpies H^E at T = 303.15 K were measured for the systems {3-DEPA + C_nH_2n+2 (n = 6, 7, 12)}. The molar excess Gibbs free energies G^E were obtained with Barker’s method and fitted to the Redlich–Kister equation. The Wilson equation was also used. Deviations between experimental and predicted G^E and H^E, by using group contribution UNIFAC (Gmehling version) model, were evaluated.     

Thermodynamics of the cell Pt | H2(p)| HCl (m)| AgCl| Ag and primary medium effects upon HCl in (glycerol + water) solvents

The electromotive force (e.m.f.)E of the cellPt|H₂(p)|HCl(m) in Z|AgCl|Ag in {glycerol (G)  +  water (W)} solvents, Z  =  (G  +  W), up to glycerol mass fraction w_G =  0.7 has been measured within the temperature range from 273.15 K to 313.15 K at HCl molalities up to 0.1mol · kg ^− 1. On this basis, the standard molar e.m.f. E_m ^∘ values pertaining to such solvent mixtures have been obtained, and have been combined with sparse literature data for optimization. At glycerol mass fractions up tow_G ≈  0.5, at constant temperature,E_m ^∘  shows a linear dependence on the glycerol mole fractionx_G and, in parallel, E_c ^∘ (on the amount-of-substance concentration scale) shows linear dependence on the glycerol volume fractionϕ_G . The primary medium effect upon HCl, defined as the difference (E_c ^∘ )_W −  (E_c ^∘ )_Z, has been considered as a function of the water volume fraction ϕ_Win terms of Feakins and French’s theory: this would lead to a primary hydration number n(hydr)  =  2.4 for HCl, in good agreement with previous results obtained with solvents other than (glycerol  +  water). In this connection, some basic methodological aspects are discussed. Ancillary values of the densities ρ_Zof the relevant solvent mixtures, which were hitherto unavailable and are necessary for the data processing leading toE_m ^∘  , have also been measured.     

Investigation of the isothermal (vapour + liquid) equilibria of aqueous 2-amino-2-methyl-1-propanol (AMP), N-benzylethanolamine,or 3-dimethylamino-1-propanol solutions at several temperatures

The vapour pressures of (2-amino-2-methyl-1-propanol (AMP) + water), (N-benzylethanolamine + water), or (3-dimethylamino-1-propanol + water) binary mixtures, and of pure AMP and 3-dimethylamino-1-propanol components were measured by means of two static devices at temperatures between 283 K and 363 K. The data were correlated with the Antoine equation. From these data, excess Gibbs functions (G^E) were calculated for several constant temperatures and fitted to a fourth-order Redlich–Kister equation using the Barker’s method. The {2-amino-2-methyl-1-propanol (AMP) + water} binary mixture exhibits negative deviations in G^E (at T < 353.15 K) and a sinusoidal shape for G^E for the higher temperatures over the whole composition range. For the aqueous N-benzylethanolamine solution, a S shape is observed for the G^E for all investigated temperatures over the whole composition range. The (3-dimethylamino-1-propanol + water) binary mixture exhibits negative deviations in G^E (at T < 293.15 K), positive deviations in G^E (for 293.15 K < T < 353.15 K) and a sinusoidal shape for G^E for the higher temperatures over the whole composition range.     

Synthesis,spectroscopic, thermal and biological aspect of mixed ligand copper(II) complexes

Derivative of 8-hydroxyquinoline i.e. Clioquinol is well known for its antibiotic properties, drug design and coordinating ability towards metal ion such as Copper(II). The structure of mixed ligand complexes has been investigated using spectral, elemental and thermal analysis. In vitro anti microbial activity against four bacterial species were performed i.e. Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Bacillus substilis and found that synthesized complexes (15–37 mm) were found to be significant potent compared to standard drugs (clioquinol i.e. 10–26 mm), parental ligands and metal salts employed for complexation. The kinetic parameters such as order of reaction (n = 0.96–1.49), and the energy of activation (E _a = 3.065–142.9 kJ mol⁻¹), have been calculated using Freeman–Carroll method. The range found for the pre-exponential factor (A), the activation entropy (S* = −91.03 to−102.6 JK⁻¹ mol⁻¹), the activation enthalpy (H* = 0.380–135.15 kJ mol⁻¹), and the free energy (G* = 33.52–222.4 kJ mol⁻¹) of activation reveals that the complexes are more stable. Order of stability of complexes were found to be [Cu(A⁴)(CQ)OH] · 4H₂O > [Cu(A³)(CQ)OH] · 5H₂O > [Cu(A¹)(CQ)OH] · H₂O > [Cu(A²)(CQ)OH] · 3H₂O