Issue 18, 2011

Impact of metal binding on the antitumor activity and cellular imaging of a metal chelator cationic imidazopyridine derivative

Abstract

A new water soluble cationic imidazopyridine species, viz. (1E)-1-((pyridin-2-yl)methyleneamino)-3-(3-(pyridin-2-yl)imidazo[1,5-a]pyridin-2(3H)-yl)propan-2-ol (1), as a metal chelator is prepared as its PF6 salt and characterized. Compound 1 shows fluorescence at 438 nm on excitation at 342 nm in Tris-HCl buffer giving a fluorescence quantum yield (ϕ) of 0.105 and a life-time of 5.4 ns. Compound 1, as an avid DNA minor groove binder, shows pUC19 DNA cleavage activity in UV-A light of 365 nm forming singlet oxygen species in a type-II pathway. The photonuclease potential of 1 gets enhanced in the presence of Fe2+, Cu2+ or Zn2+. Compound 1 itself displays anticancer activity in HeLa, HepG2 and Jurkat cells with an enhancement on addition of the metal ions. Photodynamic effect of 1 at 365 nm also gets enhanced in the presence of Fe2+ and Zn2+. Fluorescence-based cell cycle analysis shows a significant dead cell population in the sub-G1 phase of the cell cycle suggesting apoptosis via ROS generation. A significant change in the nuclear morphology is observed from Hoechst 33258 and an acridine orange/ethidium bromide (AO/EB) dual nuclear staining suggesting apoptosis in cells when treated with 1 alone or in the presence of the metal ions. Apoptosis is found to be caspase-dependent. Fluorescence imaging to monitor the distribution of 1 in cells shows that 1 in the presence of metal ions accumulates predominantly in the cytoplasm. Enhanced uptake of 1 into the cells within 12 h is observed in the presence of Fe2+ and Zn2+.

Graphical abstract: Impact of metal binding on the antitumor activity and cellular imaging of a metal chelator cationic imidazopyridine derivative

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
07 Dec 2010
Accepted
25 Feb 2011
First published
24 Mar 2011

Dalton Trans., 2011,40, 4855-4864

Impact of metal binding on the antitumor activity and cellular imaging of a metal chelator cationic imidazopyridine derivative

M. Roy, B. V. S. K. Chakravarthi, C. Jayabaskaran, A. A. Karande and A. R. Chakravarty, Dalton Trans., 2011, 40, 4855 DOI: 10.1039/C0DT01717E

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