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To explore the therapeutic potential of copper-based benzimidazole complexes, tetranuclear Cu(II) complex 1 and dinuclear ternary amino acid complexes 2 and 3 {L-trp and L-val, respectively} were synthesized and thoroughly characterized. In vitro DNA binding studies of complexes 1-3 were carried out employing UV-vis titrations, fluorescence, circular dichroic and viscosity measurements which revealed that the complexes 1-3 bind to CT DNA preferably via groove binding. Complex 1 cleaved pBR322 DNA via hydrolytic pathway (validated by T4 DNA ligase assay), accessible to major groove while 2 followed oxidative mechanism, binding to minor groove of DNA double helix; binding events were further validated by molecular docking studies. Additionally, the complexes 1 and 2 exhibit high Topo-I inhibitory activity at different concentrations. The complexes 1-3 were evaluated for antibacterial activity against Escherichia coli and Staphylococcus aureus, and 2 was found to be most effective against Gram-positive bacteria., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Novel ternary dizinc(II) complexes 1-3, derived from 1,2-bis(1H-benzimidazol-2-yl)ethane-1,2-diol and l-form of amino acids (viz., tryptophan, leucine and valine) were synthesized and characterized by spectroscopic (IR, (1)H NMR, UV-vis, ESI-MS) and other analytical methods. To evaluate the biological preference of chiral drugs for inherently chiral target DNA, interaction of 1-3 with calf thymus DNA in Tris-HCl buffer was studied by various biophysical techniques which reveal that all these complexes bind to CT DNA non-covalently via electrostatic interaction. The higher K(b) value of L-tryptophan complex 1 suggested greater DNA binding propensity. Further, to evaluate the mode of action at the molecular level, interaction studies of complexes 1 and 2 with nucleotides (5'-GMP and 5'-TMP) were carried out by UV-vis titrations, (1)H and (31)P NMR which implicates the preferential selectivity of these complexes to N3 of thymine rather than N7 of guanine. Furthermore, complex 1 exhibits efficient DNA cleavage with supercoiled pBR322. The complex 1 cleaves DNA efficiently involving hydrolytic cleavage pathway. Such chiral synthetic hydrolytic nucleases with asymmetric centers are gaining considerable attention owing to their importance in biotechnology and drug design, in particular to cleave DNA with sequence selectivity different from that of the natural enzymes., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A series of benzimidazole‐derived–furanones (4a–l) were synthesized, characterized, and explored for their in vitro anticancer activities. The pharmacokinetic parameters assessed revealed that all the compounds followed the Lipinski's rule of five, making them potential drug candidates. Further, the results of anticancer activity revealed that (E)‐5‐(1H‐benzo[d]imidazol‐2‐yl)‐3‐(3,4,5‐trimethoxybenzylidene)furan‐2(3H)‐one (4a), was active against A549, MCF7, and DU145 with an IC50 values of 10.4 ± 0.39, 11.1 ± 0.43, and 10.7 ± 0.19 μM, respectively. While another compound (E)‐5‐(1H‐benzo[d]imidazol‐2‐yl)‐3‐([5‐phenyl]furan‐2‐yl)furan‐2(3H)‐one (4k) also exhibited good activity against A549, MCF7, and DU145 with IC50 values of 11.4 ± 0.39, 9.1 ± 0.43, and 12.7 ± 0.19 μM, respectively. Doxorubicin was used as the standard drug. Further, molecular docking studies were carried out to provide binding mode into the binding sites of vascular endothelial growth factor receptor (VEGFR). Docking scores and binding energies corroborated well with the results of experimental anticancer activity. Pharmacokinetic (ADME) parameters of the potent derivatives were also found to be in an acceptable range. The benzimidazole‐furanonone conjugates seem to be a potential source for the further development of potent cytotoxic agents. [ABSTRACT FROM AUTHOR]

Abstract: The chiral benzimidazole ligand, 1,2-Bis(1H-benzimidazol-2-yl)ethane-1,2-diol, L, exhibiting coordination mode with an oxygen atom of alcohol group directed towards the metal ion and another –OH group with different molecular axis directed away from the metal center was utilized as a building block for organotin complexes [C18H19N4O2SnCl], [C28H23N4O2SnCl] and [C52H42N4O2Sn2] (1–3). Complexes 1 and 3 exhibit a pentacoordinate geometry while the complex 2 reveals hexacoordinated environment around the Sn(IV) metal ions as evidenced by 119Sn NMR studies. The DNA binding ability of benzimidazole ligand and their organotin(IV) complexes 1–3 were examined by employing different biophysical methods. The absorption titration of the complexes with CT-DNA reveal significant hyperchromic effect together with strong bathochromic shift of 4–5 nm which infer substantial binding of the complexes with CT-DNA. The intrinsic binding constant K b values of the complexes 1–3 were found to be 2.16 ± 0.04 × 104, 3.47 ± 0.04 × 104 and 4.60 ± 0.04 × 103 M−1, respectively, suggesting pronounced binding of complex 2 with DNA double helix. The mechanism of binding of the complexes was further ascertained by the interaction studies of these complexes with nucleotides (5′-GMP and 5′-TMP) using absorption spectroscopy suggesting a clear preference for 5′-GMP binding which was further authenticated by NMR (1H and 31P NMR) studies. [Copyright &y& Elsevier]