Synthesis, characterization and in vitro DNA binding studies of tin(IV) complexes of tert-butyl 1-(2-hydroxy-1-phenylethylamino)-3-methyl-1-oxobutan-2-yl carbamate

In vitro DNA binding, pBR322 cleavage and molecular docking studies of 1,2-diaminobenzene, dichloro glycyl glycinate tin(IV) and zirconium(IV) complexes

De novo design and synthesis of complexes 1,2-diaminobenzene, dichloro glycyl glycinate tin(IV) and zirconium(IV), 1 and 2 as molecular drug entities were carried out. The structure elucidation of 1 and 2 was done by analytical techniques and spectroscopic methods viz. IR, UV-vis, ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-Mass and XRD techniques. In vitro DNA binding studies of 1 and 2 by various biophysical techniques viz electronic absorption, emission spectroscopy and circular dichroism measurements were carried out to evaluate their potential to act as chemotherapeutic candidates; furthermore, cleavage studies with pBR322plasmid DNA and computer-aided molecular docking studies were also done to study the mechanistic pathway and mode of binding at the molecular level. The observed results revealed that complex 1 exhibited greater DNA binding propensity in contrast to complex 2 primarily via electrostatic binding mode. The pBR322 DNA cleavage studies of both the complexes revealed the hydrolytic cleavage mechanism and DNA minor groove binding, which was ascertained by molecular docking studies of the drug candidate. Communicated by Ramaswamy H. Sarma.

Synthesis and characterization of Co(ii) and Fe(ii) peptide conjugates as hydrolytic cleaving agents and their preferential enantiomeric disposition for CT-DNA: structural investigation of l-enantiomers by DFT and molecular docking studies

Molecular docked model of Co(ii) peptide conjugate with DNA and the mechanism of hydrolytic cleavage of pBR322 DNA.

In vitro DNA binding, pBR322 plasmid cleavage and molecular modeling study of chiral benzothiazole Schiff-base-valine Cu(II) and Zn(II) complexes to evaluate their enantiomeric biological disposition for molecular target DNA

Bicyclic heterocyclic compounds viz. benzothiazoles are key components of deoxyribonucleic acid (DNA) molecules and participate directly in the encoding of genetic information. Benzothiazoles, therefore, represent a potent and selective class of antitumor compounds. The design and synthesis of chiral antitumor chemotherapeutic agents of Cu(II) and Zn(II), L- and -D benzothiazole Schiff base-valine complexes 1a &b and 2a &b, respectively were carried out and thoroughly characterized by spectroscopic and analytical techniques. Interaction of 1a and b and 2a and b with CT DNA by employing UV-vis, florescence, circular dichroic methods and cleavage studies of 1a with pBR322 plasmid, molecular docking were done in order to demonstrate their enantiomeric disposition toward the molecular drug target DNA. Interestingly, these studies unambiguously demonstrated the greater potency of L-enantiomer in comparison to D-enantiomer.

Spectral, electrochemical, thermal, DNA binding ability, antioxidant and antibacterial studies of novel Ru(III) Schiff base complexes

Four new air stable low spin Ru(III) complexes of the type [Ru(L(1-4))(H2O)2]Cl have been synthesized, where L=dianion of the tetradentate Schiff base ligands namely N,N'bis(salicylaldehyde)4,5-dimethy-l,2-phenylendiammine (L(1)H2), N,N'bis(salicylaldehyde)4,5-dichloro 1,2-phenylendiammine (L(2)H2), N,N'bis(o-vanillin)4,5-dimethy-1,2-phenylendiammine (L(3)H2) and N,N'bis(o-vanillin)4,5-dichloro-1,2-phenylendiammine (L(4)H2). The complexes have been fully characterized by elemental analysis, infrared spectroscopy, electronic spectroscopy, magnetic susceptibility and electron spin resonance spectroscopy. Elemental analyses and spectroscopic data have been showed that, the stoichiometries of complexes were 1:1 with an octahedral geometry for all the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. The redox behavior of the complexes has been investigated by the cyclic voltammetric technique. The interaction of these complexes with calf thymus DNA (CT-DNA) was explored by different techniques which revealed that the complexes could bind to CT-DNA through an intercalative mode. Furthermore, the antioxidant activity of the Ru(III) complexes against superoxide and hydroxyl radicals was evaluated by using spectrophotometer methods in vitro. The experiments on antioxidant activity show that the complexes were found to possess potent antioxidant activity. Additionally, as a potential application the antibacterial activity of the complexes was assessed by testing their effect on the growth of various strains of bacteria.

Enantiomeric specificity of biologically significant Cu(II) and Zn(II) chromone complexes towards DNA

Novel chiral Schiff base ligands (R)/(S)-2-amino-3-(((1-hydroxypropan-2-yl)imino)methyl)-4H-chromen-4-one (L(1) and L(2)) derived from 2-amino-3-formylchromone and (R/S)-2-amino-1-propanol and their Cu(II)/Zn(II) complexes (R1, S1, R2, and S2) were synthesized. The complexes were characterized by elemental analysis, infrared (IR), hydrogen ((1) H) and carbon ((13)C) nuclear magnetic resonance (NMR), electrospray ionization-mass spectra (ESI-MS), and molar conductance measurements. The DNA binding studies of the complexes with calf thymus were carried out by employing different biophysical methods and molecular docking studies that revealed that complexes R1 and S1 prefers the guanine-cytosine-rich region, whereas R2 and prefers the adenine-thymine residues in the major groove of DNA. The relative trend in K(b) values followed the order R1>S1>R2>S2. This observation together with the findings of circular dichroic and fluorescence studies revealed maximal potential of (R)-enantiomeric form of complexes to bind DNA. Furthermore, the absorption studies with mononucleotides were also monitored to examine the base-specific interactions of the complexes that revealed a higher propensity of Cu(II) complexes for guanosine-5'-monophosphate disodium salt, whereas Zn(II) complexes preferentially bind to thymidine-5'-monophosphate disodium salt. The cleavage activity of R1 and R2 with pBR322 plasmid DNA was examined by gel electrophoresis that revealed that they are good DNA cleavage agents; nevertheless, R1 proved to show better DNA cleavage ability. Topoisomerase II inhibitory activity of complex R1 revealed that the complex inhibits topoisomerase II catalytic activity at a very low concentration (25 μM). Furthermore, in vitro antitumor activity of complexes R1 and S1 were screened against human carcinoma cell lines of different histological origin.