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

作者：Lahiri Debojyoti; Majumdar Ritankar; Patra Ashis K; Chakravarty Akhil R^*

来源：Journal of Chemical Sciences, 2010, 122(3): 321-333.

DOI：10.1007/s12039-010-0037-4

• icopper(II) complexes
• anaerobic DNA photo-cleavage
• crystal structure
• disulphide bond activation
• D-penicillamine disulphide

Binuclear complexes [Cu(mu-RSSR)](2) (1) and [M(2)(mu-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 center dot center dot center dot Cu, 6.420 angstrom). 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 ((center dot)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.

• 出版日期2010-5