Synthesis, structure and biological activity of cobalt(II) and copper(II) complexes of valine-derived schiff bases

Cu(II) complexes with a salicylaldehyde derivative and α-diimines as co-ligands: synthesis, characterization, biological activity. Experimental and theoretical approach

Copper(II) complexes with an α-diimine show a wide variety of biological activities, such as antibacterial, antifungal, antioxidant and anticancer. In this work, we synthesized and structurally characterized two novel Cu(II) complexes with methyl 3-formyl-4-hydroxybenzoate (HL) and α-diimines: 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). Crystal structure analysis shows that the formulas of the compounds are [Cu(bipy)(L)(BF4)] (1) and [Cu(phen)(L)(H2O)](BF4)·H2O (2), with BF4- as a ligand in complex 1, which is rarely coordinated to metals. Both complexes have a square pyramidal geometry, while DFT calculations showed that the most stable structures of complexes 1 and 2 in a water/DMSO mixture are square-planar derivatives [Cu(bipy)(L)]+ and [Cu(phen)(L)]+. The antibacterial activity of compounds was evaluated in vitro on four Gram-negative and four Gram-positive bacterial strains. Complex 2 showed greater antibacterial activity towards all bacterial strains comparable to the control compound Amikacin. Complex 2 exerted a strong cytotoxic effect against the tested cancer cell lines (IC50 values ranging from 0.32 to 0.44 μM). Both complexes caused apoptotic cell death in HeLa cells and a noticeable in vitro antiangiogenic effect. In the concentration range of 5 to 100 μM, the complexes showed the absence of a genotoxic effect and displayed a protective effect against oxidative DNA damage induced by H2O2 in human peripheral blood cells. The interaction between the compounds and calf-thymus DNA was evaluated by diverse techniques suggesting a tight binding, which was also confirmed by molecular docking. In addition, it was found that the complexes bind tightly and reversibly to bovine and human serum albumin.

An overview: metal-based inhibitors of urease

Urease is a kind of nickel-dependent metalloenzyme, which exists in the biological world widely, and can catalyse the hydrolysis of urea into ammonia and carbon dioxide to provide a nitrogen source for organisms. Urease has important uses in agriculture and medicine because it can catalyse the production of ammonia. Therefore, in this review, metal-based inhibitors of urease will be summarised according to different transition metal ions. Including the urease inhibition, structure-activity relationship, and molecular docking. Importantly, among these reviewed effective urease inhibitors, most of copper metal complexes exhibited stronger urease inhibition with IC50 values ranging from 0.46 μM to 41.1 μM. Significantly, the collected comprehensive information looks forward to providing rational guidance and effective strategies for the development of novel, potent, and safe metal-based urease inhibitors, which are better for practical applications in the future.

Green synthesis of nanosized N,N'-bis(1-naphthylidene)-4,4'-diaminodiphenylmethane and its metal (II) complexes and evaluation of their biological activity

Condensation of ecofriendly synthesized 4,4'-methanedianiline with 2-hydroxy-1-naphthaldehyde produced a (1:1) octopus-like Schiff base mixed ligand. Reaction with Co(OAc)2⋅H2O, NiCl2⋅6H2O, Cu(OAc)2⋅H2O and Zn(OAc)2⋅2H2O metals furnished their complexes in high yield and purity. All new structures were fully characterized by various spectroscopic and spectrometric measurements. The complexes exhibited high thermal stability up to 700 °C, leaving nearly 40% of their mass as residues. Antimicrobial screening results exhibited moderate activities towards all studied microbes. Antioxidant screening was concentration dependent, and their activities were in the order Ni(II) > Zn(II) > Cu(II) > Co(II) complexes. The NO inhibitory effect revealed that the nickel complex exhibited the highest activity, whereas the cobalt complex showed the lowest inhibition. All compounds showed a significant lipid peroxidation inhibitory effect against oxidative stress. The complexes significantly diminished the TBARS level, and the nickel complex exhibited the highest inhibition at p < 0.01. Antioxidants stress the oxidative damage induced by iron, indicating that the nickel complex has the highest reducing activity. The inhibitory effect against acetylcholine esterase showed that the copper complex has the highest activity. Membrane stabilization activities clearly indicated that most compounds can improve the integrity of the cells and stability of their membrane, and this result may be related to their antioxidant capacity to protect against cytotoxicity. The nickel complex exhibited a stronger total antioxidant capacity than the other complexes. The biological and antioxidant capacities of these complexes may make them promising candidates in pharmaceutical applications.

(NH4)2[Co(H2O)6]2V10O28·4H2O Vs. (NH4)2[Ni(H2O)6]2V10O28·4H2O: Structural, Spectral and Thermal Analyses and Evaluation of Their Antibacterial Activities

This paper presents the synthesis of two cluster compounds {(NH4)2[Co(H2O)6]2V10O28·4H2O (C1) and (NH4)2[Ni(H2O)6]2V10O28·4H2O (C2)} which were obtained as single crystals suitable for XRD analysis that revealed their crystallization in the monoclinic (C2/c) and triclinic (P-1) space groups, respectively. Additionally, C1 and C2 were characterized using CHN analysis and FT-IR spectroscopy and their thermal decomposition mechanisms were investigated. The antibacterial activities of both compounds were determined against three human pathogenic bacterial strains {Bacillus cereus ATCC 33,018, Escherichia coli O157:H7 and Pseudomonas aeruginosa ATCC 9027} and one phytopathogenic bacterial strain {Ralstonia solanacearum}, while drug standards {chloramphenicol and streptomycin} were used as control. The inhibitory activity and the minimum inhibitory concentration (MIC) values of the tested compounds clearly indicated higher antibacterial activities of the nickel compound against B. cereus ATCC 33,018, E. coli O157 and R. solanacearum with MIC values of 3.150, 3.150 and 6.300 mg/ml, respectively. On the other hand, (NH4)2[Co(H2O)6]2V10O28·4H2O exhibited higher antibacterial activity against P. aeruginosa ATCC 9027 (MIC value of 6.300 mg/ml) in comparison to the nickel analog. In general, the measured activities are lower than that obtained for the standards except for the higher activity given by C2 in comparison to streptomycin against the R. solanacearum strain.

Antibacterial Activity of Co(III) Complexes with Diamine Chelate Ligands against a Broad Spectrum of Bacteria with a DNA Interaction Mechanism

Cobalt coordination complexes are very attractive compounds for their therapeutic uses as antiviral, antibacterial, antifungal, antiparasitic, or antitumor agents. Two Co(III) complexes with diamine chelate ligands ([CoCl₂(dap)₂]Cl (1) and [CoCl₂(en)₂]Cl (2)) (where dap = 1,3-diaminopropane, en = ethylenediamine) were synthesized and characterized by elemental analysis, an ATR technique, and a scan method and sequentially tested against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration results revealed that anaerobic and microaerophilic bacteria were found to be the most sensitive; the serial passages assay presented insignificant increases in bacterial resistance to both compounds after 20 passages. The synergy assay showed a significant reduction in the MIC values of nalidixic acid when combined with Compounds (1) or (2). The assessment of cell damage by the complexes was performed using scanning electron microscopy, transmission electron microscopy, and confocal microscopy, which indicated cell membrane permeability, deformation, and altered cell morphology. DNA interaction studies of the Co(III) complexes with plasmid pBR322 using spectrophotometric titration methods revealed that the interaction between Complex (1) or (2) and DNA suggested an electrostatic and intercalative mode of binding, respectively. Furthermore, the DNA cleavage ability of compounds by agarose gel electrophoresis showed nuclease activity for both complexes. The results suggest that the effect of the tested compounds against bacteria can be complex.

Effect of Zinc(II)-2,4,5-triphenyl-1H-imidazole Complex Against Replication DENV-2 in Vero Cell

Dengue virus (DENV) is a significant pathogen emerging worldwide as a cause of infectious disease. DENVs are transmitted to humans through female mosquitoes from Aedes aegypti and Aedes albopictus species. Indonesia is one of the largest countries in the world in dengue endemic regions worldwide. Dengue fever was occurred for the first time as an outbreak in Surabaya and Jakarta in 1968. Many efforts have been made to prevent and treat DENV infections, and clinical trials of a number of vaccines are currently underway. Antiviral testing of DENV is an important alternative for drug characterization and development. Complex compounds are formed as a result of metal and organic complex reactions. Complex compounds can be used as an anti-inflammatory, antimicrobial antifungal, antibacterial, antivirus. The Zn2+ ion can be used as an antiviral candidate. The purpose of this project was investigated Zinc(II)-2,4,5-triphenyl-1H-imidazole antiviral compound to be further tested for inhibitory effect on the replication of DENV-2 in cell culture. DENV replication was measured by antiviral activity assay and cytotoxicity assay. The inhibitory activity of Zinc(II)-2,4,5-triphenyl-1H-imidazole complex compound was determined by Viral ToxGloTM Assay. The cytotoxicity of Zinc(II)-2,4,5-triphenyl-1H-imidazole complex compound was determined by CellTiter96® AQuoeus assay. The inhibitory concentration (IC50) of Zinc(II)-2,4,5-triphenyl- 1H-imidazole against dengue virus type-2 was 34.42 μg/ml. The cytotoxic concentration (CC50) of compound against Vero cell was <100 μg/ml. The results of this study demonstrate the antidengue serotype 2 inhibitory activity of investigated Zinc(II)-2,4,5-triphenyl-1H-imidazole complex and its high toxicity in Vero cells. Further studies are not required before investigated Zinc(II)-2,4,5-triphenylimidazole can be applied in the treatment of DENV-2 infections

Antitumor effect of a pyrazolone-based-complex [Cu(PMPP-SAL)(EtOH)] against murine melanoma B16 cell in vitro and in vivo

Pyrazolone-based derivative metal complexes were reported to have cytotoxicity in some tumor cells. In this study, the antitumor effect of [Cu(PMPP-SAL)(EtOH)] (PMPP-SAL = N-(1-phenyl-3-methyl-4-propenylidene-5-pyrazolone)- salicylidene hydrazide anion) in murine melanoma B16 cells in vitro and in vivo was investigated. The results showed that [Cu(PMPP-SAL)(EtOH)] inhibited the survival of B16 cells in vitro, and the IC50 value was superior to cisplatin (DDP) (p < 0.001). B16 cell apoptosis was significantly higher in comparison to the control group (DMSO) (p < 0.01), and cell cycle arrest occurred at the G0/G1 phase. When challenged C57 BL/6J mice were treated with [Cu(PMPPSAL)(EtOH)], a smaller volume of B16 solid tumors were reported than the control group (p < 0.01), with lower positive expression indices of CD 34, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) (p < 0.01). Moreover, the tumor growth was suppressed in mice due to the induction of apoptosis, as detected by the TUNEL assay (p < 0.001). In summary, [Cu(PMPP-SAL)(EtOH)] effectively inhibited the growth of B16 cells in vitro and in vivo due to the induction of apoptosis and the inhibition of intra-tumoral angiogenesis, demonstrating its therapeutic potential in melanoma treatment.

Single Molecule Magnets of Co2 and Co2La MOFs Synthesized by New Schiff Base Ligand N,N'-bis(o-Vanillinidene) Ethylenediamine (o-VEDH2)

Schiff base ligand N,N'-bis(o-vanillinidene) ethylenediamine (o-VEDH2) has been employed to synthesize new [CoIICoIV(o-VED)(OAc)2(μ2-OAc)(OMe)]•MeOH (1) and [Co 2 IV (o-VED)2(en)2(NCCH3)(OCH3)][La(NO3)6](NO 3 - )•2MeOH•MeCN•H2O (2) metal-organic frameworks (MOFs) that have interesting single molecule magnets (SMMs) property. The synthesized complexes are characterized by single crystal X-ray diffraction, fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, and squid magnetic measurement. Single crystal X-ray data show that both complexes crystallize in the monoclinic crystal system with P21/c(14) and P21/n(14) space groups and generate unique MOF-like structures. Overall, both the metal centers of 1 form octahedral geometry with a butterfly core structure. Variable temperature (T) and field (H) solid-state direct-current (dc) and alternative current (ac) magnetic susceptibility measurements were performed on both the complexes over 1.8 to 300 K, which exhibited a ground state spins (S) of 4 and 5 of complexes 1 and 2, respectively. The AC out-phase and in-phase properties of complexes show SMMs. Other properties such as optical, sensing, and DNA-binding interactions were also investigated by the complexes. Complexes 1 and 2 have energy band gaps of 3.7 and 3.03 eV indicating semiconductor properties. Simultaneously, complex 1 was found to sense H2O2 with a rate constant (k) = 1.59 × 10-4 s-1, whereas complex 2 was found to bind with calf-thymus-DNA by intercalation mode with binding constant (K b ) of 1.22 × 105 M-1.

Synthesis, Characterization, Cyclic Voltammetry, and Biological Studies of Co(II), Ni(II), and Cu(II) Complexes of a Tridentate Schiff Base, 1-((E)-(2-Mercaptophenylimino) Methyl) Naphthalen-2-ol (H2L1)

A novel tridentate Schiff base, 1-((E)-(2-mercaptophenylimino) methyl) naphthalen-2-ol (H2L1), was synthesized by the condensation reaction of 2-hydroxy-1-naphthaldehyde with 2-aminothiophenol in absolute ethanol. The resulting ligand was reacted with Co(II), Ni(II), and Cu(II) ions to obtain tetrahedral CoL1, NiL1, and square planar CuL1 complexes. The Schiff base and its metal complexes were characterized using 1H-NMR, microanalysis, FT-IR, UV-visible, and mass spectroscopy (ESI-MS). All the compounds are soluble in DMSO and DMF. Spectroscopic studies show that the ligand coordinates to the metal center through the azomethine nitrogen, naphthoxide oxygen, and thiophenoxide sulfur to form a tridentate chelate system. Conductance measurements show that these compounds are molecular in solution. Cyclic voltammetry studies show Co(III)/Co(II) and Cu(II)/Cu(I) redox systems to be quasi-reversible involving a monoelectronic transfer while Ni(III)/Ni(II) was irreversible. In vitro antibacterial and antifungal activity against five bacterial strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, and Proteus mirabilis) and five fungal strains (Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, and Candida parapsilosis) showed no antifungal activity but moderate antibacterial activity on E. coli, S. aureus, P. aeruginosa, and P. mirabilis bacterial strains. Antioxidant studies reveal that the ligand and its Cu(II) complex are more potent than Co(II) and Ni(II) complexes to eliminate free radicals.

Synthesis and Characterization of Cobalt(II) and Manganese(II) Schiff Base Complexes: Metal Effect on the Binding Affinity with β-Casein

In this study, two metal Schiff base complexes (cobalt(II) and manganese(II), were synthesized and characterized by ¹H-NMR and FT-IR analyses. The in vitro binding behavior of this complexes with β-Casein (β-CN) was investigated by using biophysical techniques. For evaluation the thermodynamics parameters of interaction between Schiff base complexes and β-CN,the fluorescence data at different temperatures were done. The results showed that the intrinsic fluorescence of the β-CN was quenched by increasing the complexes through the dynamic quenching mechanism. Also, these complexes demonstrated a considrable binding affinity to β-CN and the process is mainly entropy driven. Fluorescence resonance energy transfer was used in order to estimating the distance between donor (β-CN) and acceptor (complex). Results demonstrated that the sequence of tendency of the complexes to β-CN was as follows: Mn-Schiff base complex > Co-Schiff base complex. All these experimental results propose that β-CN might act as carrier protein for Co(II) and Mn (II) complexes to deliver it to the target molecules.

Reactivity trends of cobalt(III) complexes towards various amino acids based on the properties of the amino acid alkyl chains

The reactivity of the cobalt(III) complexes dichlorido[tris(2-aminoethyl)amine]cobalt(III) chloride, [CoCl₂(tren)]Cl, and dichlorido(triethylenetetramine)cobalt(III) chloride, [CoCl₂(trien)]Cl, towards different amino acids (L-proline, L-asparagine, L-histidine and L-aspartic acid) was explored in detail. This study presents the crystal structures of three amino acidate cobalt(III) complexes, namely, (L-prolinato-κ²N,O)[tris(2-aminoethyl)amine-κ⁴N,N',N'',N''']cobalt(III) diiodide monohydrate, [Co(C₅H₈NO₂)(C₆H₁₈N₄)]I₂·H₂O, I, (L-asparaginato-κ²N,O)[tris(2-aminoethyl)amine-κ⁴N,N',N'',N''']cobalt(III) chloride perchlorate, [Co(C₄H₇N₂O₃)(C₆H₁₈N₄)](Cl)(ClO₄), II, and (L-prolinato-κ²N,O)(triethylenetetramine-κ⁴N,N',N'',N''')cobalt(III) chloride perchlorate, [Co(C₄H₇N₂O₃)(C₆H₁₈N₄)](Cl)(ClO₄), V. The syntheses of the complexes were followed by characterization using UV-Vis spectroscopy of the reaction mixtures and the initial rates of reaction were obtained by calculating the slopes of absorbance versus time plots. The initial rates suggest a stronger reactivity and hence greater affinity of the cobalt(III) complexes towards basic amino acids. The biocompatibility of the complexes was also assessed by evaluating the cytotoxicity of the complexes on cultured normal human fibroblast cells (WS1) in vitro. The compounds were found to be nontoxic after 24 h of incubation at concentrations up to 25 mM.

An Overview on Conventional and Non-Conventional Therapeutic Approaches for the Treatment of Candidiasis and Underlying Resistance Mechanisms in Clinical Strains

Fungal infections and, in particular, those caused by species of the Candida genus, are growing at an alarming rate and have high associated rates of mortality and morbidity. These infections, generally referred as candidiasis, range from common superficial rushes caused by an overgrowth of the yeasts in mucosal surfaces to life-threatening disseminated mycoses. The success of currently used antifungal drugs to treat candidiasis is being endangered by the continuous emergence of resistant strains, specially among non-albicans Candida species. In this review article, the mechanisms of action of currently used antifungals, with emphasis on the mechanisms of resistance reported in clinical isolates, are reviewed. Novel approaches being taken to successfully inhibit growth of pathogenic Candida species, in particular those based on the exploration of natural or synthetic chemicals or on the activity of live probiotics, are also reviewed. It is expected that these novel approaches, either used alone or in combination with traditional antifungals, may contribute to foster the identification of novel anti-Candida therapies.

Eighteen 5,7-Dihalo-8-quinolinol and 2,2'-Bipyridine Co(II) Complexes as a New Class of Promising Anticancer Agents

Here we first report the design of a series of bis-chelate Co(II) 5,7-dihalo-8-quinolinol-phenanthroline derivative complexes, [Co(py)(QL1)₂] (Co1), [Co(py)(QL2)₂] (Co2), [Co(Phen)(QL1)₂] (Co3), [Co(Phen)(QL2)₂] (Co4), [Co(DPQ)(QL1)₂]·(CH₃OH)₄ (Co5), [Co(DPQ)(QL2)₂] (Co6), [Co(DPPZ)(QL1)₂]·CH₃OH (Co7), [Co(MDP)(QL1)₂]·3H₂O (Co8), [Co(ODP)(QL1)₂]·CH₃OH (Co9), [Co(PPT)(QL1)₂]·CH₃OH (Co10), [Co(ClPT)(QL1)₂] (Co11), [Co(dpy)(QL3)₂] (Co12), [Co(mpy)(QL1)₂] (Co13), [Co(Phen)(QL4)₂] (Co14), [Co(ODP)(QL4)₂] (Co15), [Co(mpy)(QL4)₂]I (Co16), [Co(ClPT)(QL4)₂] (Co17), and [Co(ClPT)(QL5)₂] (Co18), with 5,7-dihalo-8-quinolinol and 2,2′-bipyridine mixed ligands. The antitumor activity of Co1–Co18 has been evaluated against human HeLa (cervical) cancer cells in vitro (IC₅₀ values = 0.8 nM–11.88 μM), as well as in vivo against HeLa xenograft tumor growth (TIR = 43.7%, p < 0.05). Importantly, Co7 exhibited high safety in vivo and was more effective in inhibiting HeLa tumor xenograft growth (43.7%) than cisplatin (35.2%) under the same conditions (2.0 mg/kg). In contrast, the H-QL1 and DPPZ ligands greatly enhanced the activity and selectivity of Co7 in comparison to Co1–Co6, Co8–Co18, and previously reported cobalt(II) compounds. In addition, Co7 (0.8 nM) inhibited telomerase activity, caused G2/M phase arrest, and induced mitochondrial dysfunction at a concentration 5662.5 times lower than Co1 (4.53 μM) in related assays. Taken together, Co7 showed low toxicity, and the combination could be a novel Co(II) antitumor compound candidate.

Preparation, Diagnosis, Biological Activity, and Theoretical Studies of Some Mixed Drug Complexes

This paper includes synthesis and characterization of mixed ligand complexes derived from mefenamic acid and metformin using transition metal ions such as Co(II) and Cu(II). These complexes have been characterized by magnetic susceptibility, molar conductance, TG analyses, and spectral techniques such as FTIR and UV spectra. The theoretical study of the ligands and their complexes using semiempirical (PM6) method was used to measure IR and UV spectroscopy, HOMO-LUMO categories of the ligands. These synthesized complexes are also studied for their biological activities. The studies made on these complexes proposed a six octahedral geometry.

Antifungal Activity and Mechanism of Action of the Co(III) Coordination Complexes With Diamine Chelate Ligands Against Reference and Clinical Strains of Candida spp

Although many antifungal agents are available in clinical treatment, increasing resistance of fungi, especially Candida species, to the available drugs requires the development of new safe and non-toxic compounds with novel modes of action as effective treatment against resistant microorganisms. Cobalt complexes are very interesting and attractive as potential candidates with antimicrobial activity. Their therapeutic uses as antiviral, antibacterial antifungal, antiparasitic, antitumour, transferrin transporters, and anti-inflammatory agents are being intensively investigated. In this study we examined the antifungal activity of Co(III) complexes with diamine chelate ligands against a broad spectrum of Candida species. Minimum inhibitory concentration was determined by the microbroth dilution method and with serial passaging assay; the synergistic antimicrobial activity of the tested complexes combined with two antifungal drugs (ketoconazole and amphotericin B) was made by checkerboard assay. The effects of Co(III) complexes on yeast cell morphology were studied by optical and transmission electron microscopy. The mode of action of Co(III) complexes on the yeast cell wall (sorbitol assay) and cell membrane (ergosterol assay) were investigated. The cytotoxic effects of the tested compounds on red blood cells and the human keratinocyte (HaCaT) cell line were also evaluated. The analyzed compounds revealed significant antifungal activity for selected strains of Candida species; [CoCl₂(dap)₂]Cl (1) and [CoCl₂(en)₂]Cl (2) were more effective than ketoconazole. Its probable mechanism of action did not involve the cell wall or ergosterol binding. However, the checkerboard assay showed, that the antifungal activity of ketoconazole increased in combination with the tested complexes of Co(III). Our results suggest that both diamine complexes with Co(III) analogs caused damage to mitochondrial membrane or the membrane of the endoplasmic reticulum. The effect was observed by transmission electron microscope. Co(III) complexes with diamine chelate ligands are non-toxic at concentrations active against Candida species. This study provides new data on potential antifungal drugs, especially against Candida species.

Schiff bases and their metal complexes as urease inhibitors - A brief review

Schiff bases, an aldehyde- or ketone-like compounds in which the carbonyl group is replaced by an imine or azomethine, are some of the most widely used organic compounds. Indeed, they are widely used for industrial purposes and also exhibit a broad range of biological activities, including anti-urease activity. Ureases, enzymes that catalyze urea hydrolysis, have received considerable attention for their impact on living organisms’ health, since the persistence of urease activity in human and animal cells can be the cause of some diseases and pathogen infections. This short review compiles examples of the most antiurease Schiff bases (0.23 μM < IC₅₀ < 37.00 μM) and their metal complexes (0.03 μM < IC₅₀ < 100 μM). Emphasis is given to ureases of Helicobacter pylori and Canavalia ensiformis, although the active site of this class of hydrolases is conserved among living organisms.

INHIBITORY ACTIVITY OF COBALT(II)–MORIN COMPLEX AGAINST THE REPLICATION OF DENGUE VIRUS TYPE 2

Dengue virus (DENV) is a significant pathogen emerging worldwide as a cause of infectious disease. Antidengue treatments are urgently required to control the emergence of dengue. DENV is a mosquito-borne disease responsible for acute systemic diseases and serious health conditions. DENVs were distributed in the tropical and sub-tropical areas and transmitted to humans by Aedes agypty and Aedes albopictus. Dengue vaccine or antiviral has not yet been clinically approved for humans, even though there have been great efforts toward this end. Antiviral activity against DENV is an important alternative for the characterization and development of drugs. Metal–organic compounds were reported to exhibit fungicidal, bactericidal, and antiviral activities its inhibitory activity was not significant, at high concentration it was more toxic to replicating cells than to stationary cell monolayers of Vero cells. The aim of this study is to investigate the antiviral effects of Cobalt(II)–Morin complex. This compound was further investigated for its inhibitory effect on the replication of DENV-2 in Vero cells. The replication of DENV was measured by enzyme-linked immunosorbent assay and the value of selectivity index (SI). SI was determined as the ratio of the 50% cytotoxic concentration (CC50) to the 50% inhibitory concentration (IC50). The IC50 value of the Cobalt(II)–Morin complex for DENV-2 was 3.08 µg/ml, and the CC50 value of the complex for Vero cells was 3.36 µg/ml; thus, the SI value was 1.09. The results of this study demonstrate the antidengue serotype 2 inhibitory activity of Cobalt(II)–Morin complex and its high toxicity in Vero cells. Further studies are not required before Co(II)–Morin can be applied in the treatment of DENV-2 infections.

Synthesis, crystallographic, spectroscopic studies and biological activity of new cobalt(II) complexes with bioactive mixed sulindac and nitrogen-donor ligands

Four novel complexes [Co(H2O)4(sul)2] 1, [Co(2-ampy)2(sul)2] 2, [Co(H2O)2(1,10-phen) (sul)2] 3 and [Co(2,9-dimephen)(sul)2] 4 (sul = sulindac, 2-ampy = 2-amino pyridine, 1,10-phen = 1,10-phenanthroline and 2,9-dimeph = 2,9-dimethyl-1,10-phenanthroline) were prepared and characterized by IR, UV-Visible spectroscopy and magnetic properties. The crystal structures of complexes 1 and 4 were determined by single-crystal X-ray diffraction. In-vitro anti-bacterial activity for the prepared complexes against Gram-positive (Staphylococcus epidermidis, Staphylococcus aureus) and Gram-negative (Bordetella, Escherichia coli) bacteria and Yeast species (Saccharomyces and Candida) were performed using agar well-diffusion method. Only complex 4 showed reasonable activity against yeast. All compounds showed more anti-bacterial activity against Gram-positive bacteria than Gram-negative. Graphical abstract This work reports synthesis, crystallographic, spectroscopic studies and biological activity of new cobalt(II) complexes with bioactive mixed sulindac and nitrogen-donor ligands. The crystal structures of complexes 1 and 4 were determined using single-crystal X-ray diffraction. In-vitro anti-bacterial activity of the prepared complexes and their parent ligands were investigated against different Gram-positive and Gram-negative bacteria using agar diffusion method.

Crystal structure of (E)-3-((naphthalen-1-ylimino)methyl)-4-nitrophenol, C17H12N2O3

C17H12N2O3, monoclinic, P21/c (no. 14), a = 7.2641(5) Å, b = 12.3968(6) Å, c = 16.1786(13) Å, β = 108.200(6)°, V = 1384.02(16) Å3, Z = 4, Rgt(F) = 0.0905, wRref(F2) = 0.1928, T = 293(2) K.

Copper(II), cobalt(II) and nickel(II) complexes of lapachol: synthesis, DNA interaction, and cytotoxicity

Three novel copper(II), cobalt(II), and nickel(II) complexes of lapachol (Lap) containing 110-phenanthroline (phen) ligand, [M(Lap)₂(phen)] (M=Cu(II), 1, Co(II), 2, and Ni(II), 3), have been synthesized and characterized using, elemental analysis and spectroscopic studies. Their interactions with calf thymus DNA (CT DNA) were investigated using viscosity, thermal denaturation, circular dichorism, fluorescence quenching, and electronic absorption spectroscopy. The DNA cleavage abilities of 1-3 have been studied, where cleavage activity of copper complex 1 is more than the complexes 2 and 3. The in vitro cytotoxic potential of the complexes 1-3 against human cervical carcinoma (HeLa), human liver hepatocellular carcinoma (HepG-2), and human colorectal adenocarcinoma (HT-29) cells indicated their promising antitumor activity with quite low IC₅₀ values in the range of .15-2.41 μM, which are lower than those of cisplatin.

Phenolate based metallomacrocyclic xanthate complexes of Co(II)/Cu(II) and their exclusive deployment in [2 : 2] binuclear N,O-Schiff base macrocycle formation and in vitro anticancer studies

Potassium salts of phenolate based polydentate xanthate ligands 4,4'-bis(2-dithiocarbonatobenzylideneamino)diphenyl ether () and 4,4'-bis(2-dithiocarbonatonaphthylmethylideneamino)diphenyl ether () have been synthesized and characterized, prior to use. The reaction of or with M(OAc)2 in Et3N affords access to a rare series of binuclear metallomacrocyclic xanthate complexes of the type [M2-μ(2)-bis-(κ(2)S,S-xan(1)/xan(2))] () which quickly forms [2 : 2] binuclear N,O-bidentate Schiff base macrocyclic complexes of the type [M2-μ(2)-bis-(κ(2)N,O-L(1)/L(2))] ( = 4,4'-bis(2-hydroxybenzylideneamino)diphenyl ether, = 4,4'-bis(2-hydroxynaphthylmethylidene-amino)diphenyl ether) via evolution of CS2 in solution. The compounds were characterized by microanalysis, relevant spectroscopy (FT-IR, UV-visible), mass spectrometry (ESI-MS), and powder and single crystal XRD techniques. In vitro anticancer activity of all the compounds was evaluated against HEP 3B (hepatoma) and IMR 32 (neuroblastoma) by the MTT assay. Remarkably, the binuclear copper(ii) xanthate complexes were found to be extremely active against both the cell lines (IC50: 8.1 ± 0.8 μM (), 8.8 ± 1.7 μM () against HEP 3B and 1.9 ± 0.3 μM () and 7.3 ± 0.6 μM () against IMR 32) and this projects them as good candidates for potent antitumor agents and the IC50 values confirm their better potency than the reference drug cisplatin. The flow-cytometric density plot illustrates the induction of apoptosis in HEP 3B and IMR 32 cells after treatment with , , , and .

Synthesis and crystal structures of cobalt(II), cadmium(II), and zinc(II) complexes of 4-nitro phenylcyanamide: enhancing the biological properties through bound to human serum albumin

Metal complexes of the type [Co(phen)₂(4-NO₂pcyd)₂].CH₃OH, 1, [Zn(phen)₂(4-NO₂pcyd)₂].CH₃OH, 2, [Cd(phen)₂(4-NO₂pcyd)₂], and 3, (phen = 1,10-phenanthroline, 4-NO₂pcyd = 4-nitro phenylcyanamide) have been studied. The synthesis, characterization, and the biological activities of complexes 1-3 have been investigated. The geometries of complexes 1-3 were confirmed by single-crystal X-ray crystallography. The interactions of complexes 1-3 with human serum albumin (HSA) were studied using fluorescence and circular dichroism spectroscopy. The thermodynamic studies have showed the reaction for the binding of complexes 1-3 with HSA is hydrophobic (ΔH₀˂ 0 and ΔS₀ > 0). The in vitro cytotoxic potential of complexes 1-3 and their complexes with HSA were examined. The complexes 1-3 with HSA enhance about 3-fold cytotoxicity in cancer cells lines.