Manganese(II) complex of 6,7-dicycanodipyridoquinoxaline with antitumor activities: synthesis, crystal structure and binding with DNA

Structural investigation, DNA interactions and in vitro anticancer studies of transition metal complexes of 3-(2-(2, 4-dihydroxy benzylidene) hydrazinyl) quinoxalin-2(1H) -one

The Schiff base ligand, 3-(2-(2, 4-dihydroxybenzylidene) hydrazinyl) quinoxalin-2(1H)-one (RHQO) has been synthesized and characterized by spectral and single crystal X-ray analysis. The Mn(II), Ni(II) and Cu(II) complexes of RHQO have been synthesized and characterized by FT-IR, UV-VIS, mass, EPR spectra, CHN, thermo gravimetric analysis, magnetic susceptibility and conductivity measurements. The morphology of the ligand and complexes is studied by Scanning Electron Microscopy. The metal complexes formed were found to be polymeric in nature. The abilities of the ligand and its metal complexes to interact and bind with calf thymus DNA (CT-DNA) has been studied by electronic absorption spectroscopy and their quantitative binding strength was evaluated in terms of their intrinsic binding constant (K_b). The cleavage interaction of the ligand and its metal complexes with super coiled pBR 322 DNA has been investigated by agarose gel electrophoresis. Cytotoxicity of the Cu(II) and Ni(II) complexes was evaluated using various cancer cell lines, Human cervical cancer cell line (Hela), B16 melanoma F10(B16-F10), Human ovarian cancer cell (SKOV3) and Breast cancer cell line (MCF7) by MTT assay. The results indicated that the ligand and its metal complexes bind with CT-DNA by groove binding mode and cleaved the supercoiled pBR 322 DNA in to nicked form. The Ni(II) and Cu(II) complexes exhibited anticancer activity without affecting the normal CHO-K1 cell lines. Communicated by Vsevolod Makeev.

Metalo components exhibiting significant anticancer and antibacterial properties: a novel sandwich-type like polymeric structure

Four new dicyanoargentate(I)-based complexes 1-4 were synthesized from certain metal ions with a tetradentate ligand [N, N-bis (2-hydroxyethyl) -ethylenediamine; N-bishydeten] and determined by diverse procedures (elemental, thermal, FT-IR, ESI-MS for 1-3 and, magnetic susceptibility and EPR for 1, and 2) including crystal analysis of 4. The crystal method revealed that complex 4 has a sandwich-type like polymeric chemical structure with layers formed by [Cd(N-bishydeten)2]2+ cations and [Ag(CN)2]- anions. The complexes were further characterized by fluorescence and UV spectroscopy to determine their physicochemical features. The complexes displayed a DNA binding activity within the same range as found for cisplatin, in addition to their strong stability in the presence of the physiological buffer system. The complexes were also investigated for pharmacological properties like interaction with DNA/Bovine serum albumin, anticancer and antibacterial activities. Physicochemical studies of DNA with the complexes suggested that the interaction mode between them are possibly both intercalative and groove binding types. These spectroscopic measurements also show that there may be a binding tendency between BSA and the complexes via hydrogen or Van der Waals bonds. The viability tests demonstrated that all the complexes exhibited antibacterial (1-4) and anticancer effects (2-4) toward ten diverse bacterial strains and three tumor cells (HT-29 colon adenocarcinoma, HeLa cervical cancer, and C6 glioma), respectively.

The comparative study of the DNA binding and biological activities of the quaternized dicnq as a dicationic form and its platinum(II) heteroleptic cationic complex

The square-planar heteroleptic Pt(II) coordination compound [Pt(bpy)(dicnq)](NO₃)₂ (1) and the quaternized dicnq ligand, namely 12,13-dicyano-5,6-dihydrodipyrazino[2,3-f:1',2',3',4'-lmn][1,10]phenanthroline-4,7-diium dibromide (2) (Fig. 1) were synthesized and fully characterized by means of FTIR, NMR, MALDI-TOF MS and the purity was confirmed by CHN analyses. The DNA binding profiles of 1 and 2 were identified in an identical condition. The biological activities of these compounds were investigated by the assays of transcription and replication inhibition, cytotoxic and antimicrobial activity. The result of this study indicates that, both compounds strongly bind to DNA via intercalation but only 1 has a strong nuclease activity. The coordination compound of dicnq (1) binds to the DNA only slightly stronger than the quaternized form of dicnq (2), and is more potent as an inhibitor of transcription and replication and therefore, 1 has more potential as an anticancer agent but the compounds did not show cytotoxic activity against MCF-7 and MDA-MB-231 breast cancer, and DLD-1 colon cancer cell lines it was found that they only had activities against HepG2 liver cancer cell line with following IC₅₀ values; 94.75 and 159.60 µM for 1 and 2, respectively. In addition, tested bacteria are more susceptible to compound 1. These biological activities of 1 may strongly be due to its ability to digest DNA as a chemical nuclease. According to this study, the quaternization of the ligand does not make biologically more active than the coordination compound of the same ligand in this case. The compound (1) is worth further investigation for its antitumor activities.

Cefepime, a fourth-generation cephalosporin, in complex with manganese, inhibits proteasome activity and induces the apoptosis of human breast cancer cells

Cefepime (FEP), which is a member of the fourth-generation cephalosporin class, has been extensively studied as a biochemical and antimicrobial reagent in recent years. Manganese (Mn) is important in the biochemical and physiological processes of many living organisms, and it is also high expressed in some tumor tissues. In the present study, we aimed to investigate the proteasome-inhibitory and anti-proliferative properties of 8 metal complexes (FEP‑Cu, FEP-Zn, FEP-Co, FEP-Ni, FEP-Cd, FEP-Cr, FEP-Fe, FEP-Mn) in MDA-MB‑231 human breast cancer cells. The FEP-Mn complex was found to be more potent in its ability to inhibit cell proliferation and proteasome activity than the other compounds tested. Moreover, the FEP-Mn complex inhibited proteasomal chymotrypsin-like (CT-like) activity and induced the apoptosis of breast cancer cells in a dose-and time-dependent manner. Furthermore, the MCF-10A cells were much less sensitive to the FEP complexes compared with the MDA-MB-231 breast cancer cells. These results demonstrated that the FEP-Mn(II) complex has the potential to act as a proteasome inhibitor and apoptosis inducer and therefore has possible future applications in cancer chemotherapy.

Cu(II) and Mn(II) complexes containing macroacyclic ligand: synthesis, DNA binding, and cleavage studies

The two new metal complexes of Cu(II) and Mn(II) containing macroacyclic ligand of the type [Cu(hpn)](PF(6))(2) (1) and [Mn(hpn)](PF(6))(2) (2) [where hpn = [1-{[2-{[2-hydroxynaphthalen-1-yl)methylidine]amino}phenyl)imino]methyl}naphthalene-2-ol]] have been synthesized and characterized by employing analytical and spectral methods. The DNA binding properties of the complexes with calf thymus-DNA were studied by using absorption spectra and viscosity measurements, as well as thermal denaturation experiments. The absorption spectra indicated that the complexes intercalate tightly between the base pairs of the DNA with intrinsic DNA binding constants of 1.8 × 10(4) M(-1) for (1) and 3.7 × 10(4) M(-1) for (2) in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2, respectively. The enhancement in the relative viscosity of DNA on binding to the ligand supports the proposed DNA binding modes. The oxidative cleavage activity of complexes (1) and (2) were carried out on double-stranded pUC19 circular plasmid DNA using gel electrophoresis. The complexes show significant nuclease activity.

An ortho-rhom-bic polymorph of pyrazino-[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile

The title compound, C₁₆H₆N₆, is a polymorph of the previously reported structure [Kozlov & Goldberg (2008 ▶). Acta Cryst. C64, o498–o501]. Unlike the previously reported monoclinic polymorph (space group P2₁/c, Z = 8), the title compound reveals ortho­rhom­bic symmetry (space group Pnma, Z = 4). The mol­ecule shows crystallographic mirror symmetry, while the previously reported structure exhibits two independent mol­ecules per asymmetric unit. In the title compound, adjacent mol­ecules are essentially parallel along the c axis and tend to be vertical along the b axis with dihedral angles of 72.02 (6)°. However, in the reported polymorph, the entire crystal structure shows an anti­parallel arrangement of adjacent columns related by inversion centers and the two independent mol­ecules are nearly parallel with a dihedral angle of 2.48 (6)°.

Three new Cu(II) and Cd(II) complexes with 3-(2-pyridyl)pyrazole-based ligand: Syntheses, crystal structures, and evaluations for bioactivities

Three new complexes [Cu(L)(2)(NO(3))](NO(3))(H(2)O)(1/2)(CH(3)OH)(1/2) (1), [Cd(L)(2)(NO(3))(2)](H(2)O)(3) (2) and [Cd(L)(2)(ClO(4))(CH(3)OH)](ClO(4))(H(2)O)(1/4)(CH(3)OH) (3) (L=1-[3-(2-pyridyl)pyrazol-1-ylmethyl]naphthalene) were synthesized and characterized by elemental analyses, IR and X-ray diffraction analysis. Among them, the Cu(II) and Cd(II) ions were both coordinated by four N donors from two distinct L ligands via N,N-bidentate chelating coordination mode. Additional weak interactions, such as the face-to-face pi-pi stacking and C-Hcdots, three dots, centeredO H-bonding interactions, linked the mononuclear unit into 1D chain and further into 2D network. Complexes 1-3 were subjected to biological assays in vitro against six different cancer cell lines. All of them exhibited cytotoxic specificity and notable cancer cell inhibitory rate. The interactions of 1-3 with calf thymus DNA were investigated by thermal denaturation, viscosity measurements, spectrophotometric and electrophoresis methods. The results indicate that these complexes bound to DNA by intercalation mode via the ligand L and had different nuclease activities, which were in good agreement with their DNA-binding strength. Moreover, the central metal ions of 1-3 played a vital role in DNA-binding behaviors, DNA-cleavage activities and cytotoxicities, whereas the contribution of the different counter anions to their bioactivities also should not be ignored.

Two New Co(II) and Ni(II) Complexes with 3-(2-Pyridyl)pyrazole-Based Ligand: Synthesis, Crystal Structures, and Bioactivities

Two new Co(II) and Ni(II) complexes exhibiting DNA cytotoxic activities with 3-(2-pyridyl)pyrazole-based ligand, [Co(L)(3)](ClO(4))(2) (1) and [Ni(L)(3)](ClO(4))(2) (2) (L=1-[3-(2-pyridyl)-pyrazol-1-ylmethyl]-naphthalene) were synthesized and structurally characterized. Both 1 and 2 crystallized in the monoclinic system, space group P2(1)/c, for 1, a=12.8324(8), b=12.1205(8), c=33.27(2) A, beta=93.92(3) degrees and Z=4; for 2, a=12.8764(3), b=12.1015(3), c=33.2415(9) A, beta=93.998(1) degrees and Z=4. Among them, the Co(II) and Ni(II) ions were all coordinated by six N donors from three distinct L ligands. In addition, the cytotoxic activities of 1, 2 and L in vitro were evaluated against three different cancer cell lines HL-60 (human leukemia), BGC-823 (stomach cancer) and MDA-MB-435 (mammary cancer), respectively. The results showed that 1 exhibited significantly high cytotoxic activities against HL-60 and moderate activities against BGC-823 and MDA-MB-435. In order to further investigate the relationships between structures and DNA-binding behaviors of these complexes, the interactions of 1, 2 and L with calf thymus DNA (CT-DNA) were then subjected to thermal denaturation, viscosity measurements and spectrophotometric methods. The results indicated that 1 and 2 intercalated with DNA via L ligand. The intrinsic binding constants of 1, 2 and L with DNA were 1.6x10(4), 5.6x10(3) and 2.76x10(3) M(-1), respectively.

New homodi-and heterotrinuclear metal complexes of Schiff base compartmental ligand: interaction studies of copper complexes with calf thymus DNA

The new homodinuclear complexes 1–4 of the type [LMII 2Cl2], heterotrinuclear complexes 5 and 6 of the type [LMII 2SnIVCl6] where M = CuII, MnII, CoII, NiII and CuII and NiII, respectively have been synthesized and characterized by elemental analysis and various spectroscopic techniques. The homodinuclear complexes possess two different environments (N2 and N2O2donor sets) for holding the metal ions. The metal ion in N2 set exhibits square planar geometry with two chloride ions in the inner sphere but rhombic structure is found in tetradentate N2O2 Schiff base cavity while in heterotrinuclear complexes SnIV atom is in the octahedral environment. The interaction of complexes 1 and 5 with calf thymus DNA was carried out by absorption spectroscopy and cyclic voltammetry. The intrinsic binding constants (K b) of complex 1 and 5 were determined as 3.2 × 103 M−1 and 9.6 × 103 M−1, respectively suggesting that complex 5 binds more strongly to CT-DNA than complex 1. Fluorescence studies along with viscosity measurements have also been checked to authenticate the binding of metal complexes with DNA.

Chiral and Achiral Macrocyclic Copper(II) Complexes: Synthesis, Characterization, and Comparative Binding Studies with Calf-Thymus DNA

The new chiral macrocyclic complexes [1,2-bis(1H-benzimidazol-2-yl)-1-(1,8-dihydro-1,3,5,8,10,12-hexaazacyclotetradecane)-2-hydroxyethanolate] copper(II) and -nickel(II) perchlorate, 3 and 4, respectively, were synthesized by the reaction of 1,2-bis(1H-benzimidazol-2-yl)ethane-1,2-diol (L) and (1,8-dihydro-1,3,5,8,10,12-hexaazacyclotetradecane)copper(II) and -nickel(II) diperchlorate complexes, 1 and 2, respectively. All complexes were characterized by various spectroscopic techniques. Molar-conductance measurements showed that all of the complexes are ionic in nature. In complexes 3 and 4, the metal center is encapsulated by the ligand L in a pentacoordinated environment. The optical-rotation values ([alpha](D)) of 3 and 4 at 25 degrees indicate that the complexes are chiral. Absorption- and fluorescence-spectral studies, cyclic voltammetry, and viscosity measurements have been carried out to assess the comparative binding of complexes 1 and 3 with calf thymus (CT)-DNA. Analysis of the results suggests that the new chiral complex 3 binds to CT-DNA through a partial intercalation mode that is different from the binding mode of parent achiral complex 1. The complexes 1 and 3 bind to CT-DNA with binding constants K(b) of 2.7 x 10(4) and 6.6 x 10(4) M(-1), respectively. Circular-dichroism (CD) studies have been further employed to ascertain the binding mode of complex 3, which is consistent with the other spectral studies.

Synthesis and characterization of a new macrocyclic copper(II) complex with an N-glycosidic pendant arm: in vitro cytotoxicity and binding studies with calf-thymus DNA

The new macrocyclic complex 2-amino-2-deoxy-N-[2-(1,3,5,8,11-pentaazacyclotridecan-3-yl)ethyl]-beta-D-glucopyranosylamine copper(II) dichloride (1a) was prepared and thoroughly characterized by various techniques. Molar-conductance measurements showed that 1a (and its Ni analogue 1b) are ionic in nature. On the basis of spectroscopic data, both complexes were assigned a square-planar geometry, and found to be highly stabile and hydrolytically robust in H2O over a wide range of pH, as confirmed by cyclic voltammetry (CV). The Cu(II) complex 1a was found to bind to CT-DNA, with a binding constant Kb of 2.4x10(3) M(-1), as derived by UV/VIS titration, and confirmed by CV, circular dichroism (CD), and viscosity measurements. DNA binding seems to occur mostly via H-bonding. In an in vitro antitumor MTT assay, 1a exhibited significant anticancer activity against the SY5Y and PC-12 cell lines, with an estimated IC50 value in the micromolar range for SYSY, similar to the standard drug 5-fluorouracil.

Novel peptide derivatives of bleomycin A5: Synthesis, antitumor activity and interaction with DNA

A series of novel amino acid and peptide derivatives of bleomycin (BLM) A(5) were synthesized. All the compounds possessed significant antitumor activities in vitro against HL-60, BGC-823, PC-3MIE8, and MDA-MB-435 cell lines. Their antitumor activities against MDA-MB-435 were 10-fold higher than BLM A5. The DNA cleavage studies indicated that the hydrophobic amino acid or peptide derivatives of BLM A5 could induce higher cleavage ratio of double to single strand DNA than BLM A5. From the DNA binding studies, we found that the derivatives containing either D-conformation amino acid or basic amino acid could facilitate DNA binding of BLM.

Synthesis, biological evaluation and DNA binding properties of novel bleomycin analogues

A series of bleomycin analogues was prepared with a facile synthetic method. All the compounds were shown to display significant antitumor activity against HeLa and BGC-823 cell lines in vitro. The binding properties with CT-DNA and cleavage efficiency to pBR322 DNA were investigated, the results indicate that there is a positive relationship between DNA cleavage efficiency and the binding affinity to DNA, and the antitumor activity of the bleomycin analogues is enhanced as the hydrophobicity of the C-terminus substituent side chain increased.