No abstract

A monomeric complex of ZnII with ornidazole [Zn(Onz)2Cl2] decreases formation of the nitro-radical anion (R–NO2˙−), and this is realized by recording it in an enzyme assay using xanthine oxidase, which is a model nitro-reductase.

No abstract

The current-voltage characteristics of bilayer lipid membranes of oxidized cholesterol separating two bathing solutions have already been extensively studied under a DC electric field. The observed deviation from linearity at high field has been explained by field-induced pore formation, which then act as ion channels in the membrane. Using thin films of oxidized cholesterol and of dipalmitoyl phosphatidylcholine, we have reported for the first time similar deviation from nonlinearity in the DC I-V characteristics when the applied field is above 40 V/cm. Upon application of an AC field, the conductivity increases as square of frequency, while the nonlinear nature of the I-V characteristic curve is still retained at all frequencies up to 5,000 Hz. Our results indicate that besides pore formation, the intrinsic electrical properties of the constituent lipid molecules are also responsible for the observed nonlinearity.

A family of three water-soluble half-sandwich arene–ruthenium complexes, depicted as C 1 –C 3 , having the general formula [Ru­(p-cymene)­(L)­Cl]Cl has been synthesized, where L represents (1H-benzo­[d]­imidazol-2-yl)­guanidine (L 1 ) or (benzo­[d]­oxazol-2-yl)­guanidine (L 2 ) or (benzo­[d]­thiazol-2-yl)­guanidine (L 3 ). The crystal structure of complex C 3 has been determined. The complexes show several absorption bands in the visible and ultraviolet regions, and they also show prominent emission in the visible region while excited near 400 nm. Studies on the interaction of ligands L 1 –L 3 and complexes C 1 –C 3 with calf thymus DNA reveal that the complexes are better DNA binders than the ligands, which is attributable to the imposed planarity of the ruthenium-bound guanidine-based ligand, enabling it to serve as a better intercalator. Molecular docking studies show that the complexes effectively bind with DNA through electrostatic and H-bonding interactions and partial intercalation of the guanidine-based ligands. Cytotoxicity studies carried out on two carcinoma cell lines (PC3 and A549) and on two non-cancer cell lines (BPH1 and WI-38) show a marked improvement in antitumor activity owing to complex formation, which is attributed to improvement in cellular uptake on complex formation. The C 1 complex is found to exhibit the most prominent activity against the PC3 cell line. Inclusion of the guanidine-based ligands in the half-sandwich ruthenium–arene complexes is found to be effective for displaying selective cytotoxicity to cancer cells and also for convenient tracing of the complexes in cells due to their prominent emissive nature.