Anaerobic DNA cleavage in red light by dicopper(II) complexes on disulphide bond activation

Abstract

Binuclear complexes [Cu(μ-RSSR)] 2 (1) and [M 2 (μ-PDS)(H 2 O)] 2 (M = Cu(II), 2; Fe(II), 3),where H 2 RSSR is a reduced Schiff base derived from 2-(thioethyl)salicylaldimine having a disulphide moiety and H 2 PDS is derived from dimerization of D-penicillamine, have been prepared, structurally characterized, and their photo-induced DNA cleavage activity studied. The crystal structure of 1 shows the complex as a discrete binuclear species with each metal in a CuN 2 O 2 square-planar geometry (Cu…Cu, 6⋅420 Å). The tetradentate RSSR 2-acts as a bridging ligand. The sulphur atoms in the disulphide unit do not interact with the metal ions. Complexes 1-3 do not show any DNA cleavage activity in darkness. The copper(II) complexes exhibit chemical nuclease activity in the presence of 3-mercaptopropionic acid. Cleavage of supercoiled DNA has been observed in UV-A light of 365 nm for 1 and red light of 647⋅1 nm for both 1 and 2 in air. Mechanistic data reveal the involvement of the disulphide unit as photosensitizer generating hydroxyl radicals ( • OH) as the reactive species. Photo-induced DNA cleavage in red light seems to involve sulphide radicals in a type-I process and hydroxyl radicals. The dicopper(II) complexes show significant anaerobic photo-induced DNA cleavage activity in red light under argon following type-I pathway without involving any reactive oxygen species.

Synthesis, Spectroscopic, Coordination, DNA cleavage and Antibacterial activities of Mn(II) complex derived from 1H-Indole-2, 3-dione

“…Schiff base metal complexes have ability to reversibly bind oxygen in epoxidation reactions [3], biological activity [4,5], catalytic activity in hydrogenation of olefins [6,7] photochromic properties [8] and nonlinear optical materials [9]. The Schiff base complexes was also used as drugs and they possess a wide variety of antimicrobial activity against bacteria, fungi and it also inhibits the growth of certain type of tumors [10][11][12][13].…”

Synthesis, structural characterization and biological properties of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II) complexes of tetradentate Schiff bases

“…The factors such as planarity of ligands, coordination geometry and flexible valence are the root causes of binding modes of DNA and in antimicrobial activity, nature of metal ion, hydrophilicity, lipophilicity and coordination sites also have considerable influence on activity. The design and development of potential therapeutic agents, particularly those designed to target nucleic acids site can lead to new approaches to novel therapeutic agents for cancer and antimicrobial activities [13][14][15][16].…”