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Photocytotoxic Oxidovanadium(IV) Complexes of Polypyridyl Ligands Showing DNA‐Cleavage Activity in Near‐IR Light
Author(s) -
Banerjee Samya,
Hussain Akhtar,
Prasad Puja,
Khan Imran,
Banik Bhabatosh,
Kondaiah Paturu,
Chakravarty Akhil R.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200344
Subject(s) - chemistry , iodide , hela , ligand (biochemistry) , crystallography , propidium iodide , stereochemistry , moiety , dna , bridging ligand , phenazine , crystal structure , inorganic chemistry , apoptosis , programmed cell death , receptor , biochemistry , cell
Oxidovanadium(IV) complexes [VO(pyphen)(L)]Cl 2 ( 1 , 2 ) and [VO(pydppz)(L)]Cl 2 ( 3 , 4 ), where L is 1,10‐phenanthroline (phen in 1 and 3 ) and dipyrido[3,2‐ a :2′,3′‐ c ]phenazine (dppz in 2 and 4 ) are prepared and characterized. The crystal structure of [VO(pyphen)(phen)](ClO 4 ) 2 ( 1a ) shows a six‐coordinate VN 5 O geometry with a VO 2+ moiety in which the polypyridyl ligand binds in a meridional fashion and the phen ligand displays a chelating binding mode with an N‐donor site trans to the oxidovanadyl group. The complexes show a d–d band within 720–750 nm in DMF. The one‐electron paramagnetic complexes are 1:2 electrolytes in DMF. The complexes exhibit an irreversible V IV /V III redox response near –0.85 V vs. SCE in DMF/0.1 M TBAP. The complexes bind to calf thymus (ct) DNA giving K b values within 7.5 × 10 4 to 1.1 × 10 6 M –1 . The complexes show poor chemical nuclease activity in the dark and exhibit significant DNA‐photocleaving activity in near‐IR light of 705 and 785 nm forming · OH radicals. Complexes 2 – 4 show remarkable photocytotoxicity in HeLa cancer cells. FACS analysis of the HeLa cells treated with complex 4 shows cell death as highlighted by the sub G1 peak. Propidium iodide staining data indicate apoptosis as the primary mode of cell death.