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Photorelease and Cellular Delivery of Mitocurcumin from Its Cytotoxic Cobalt(III) Complex in Visible Light

Garai, Aditya and Pant, Ila and Banerjee, Samya and Banik, Bhabatosh and Kondaiah, Paturu and Chakravarty, Akhil R (2016) Photorelease and Cellular Delivery of Mitocurcumin from Its Cytotoxic Cobalt(III) Complex in Visible Light. In: INORGANIC CHEMISTRY, 55 (12). pp. 6027-6035.

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Official URL: http://dx.doi.org/10.1021/acs.inorgchem.6b00554

Abstract

Ternary cobalt(III) complexes of curcumin (Hcur) and mitocurcumin Hmitocur, a dicationic bis(triphenylphosphonium) derivative of curcumin] having a tetradentate phenolate-based ligand (H2L), namely, Co(cur)(L)] (1) and Co(mitocur)(L)] Cl-2 (2), were prepared and structurally characterized, and their photoinduced cytotoxicity was studied. The diamagnetic cobalt(III) complexes show an irreversible Co(III)-Co(II) redox response and a quasireversible curcuminoid-based reduction near -1.45 and -1.74 V SCE, respectively, in DMF/0.1 M (Bu4N)-Bu-n](ClO4). The complexes exhibit a curcuminimitocurcumin-based absorption band near 420 nm. Complex 1 was structurally characterized by X-ray crystallography. The structure contains the metal in a CoN2O4 distorted octahedral coordination arrangement with curcumin binding to the metal in its enolic form. Binding to cobalt(III) increases the hydrolytic stability of curcumin. Complex 2, having a dicationic curcuminoid, shows significant cellular uptake and photoinduced cytotoxicity compared to its curcumin analogue 1. The dicationic cobalt(III) complex 2 has significantly better cellular uptake and bioactivity than the neutral species 1. Complex 2 with mitochondrial localization releases the mitocurcumin dye upon exposure to visible light (400-700 nm) in human breast cancer MCF-7 cells through photoreduction of cobalt(III) to cobalt(II). Complex 2 displays a remarkable photodynamic therapy (PDT) effect, giving an IC50 value of similar to 3.9 mu M in visible light (400-700 nm) in MCF-7 cells while being much less toxic in the dark (>50 mu M). The released mitocurcumin acts as a phototoxin, generating intracellular reactive oxygen species (ROSS). The overall process leads to light-controlled delivery of a curcuminoid (mitocur) into the tumor cells while the dye alone suffers from hydrolytic instability and poor bioavailability.

Item Type: Journal Article
Additional Information: Copy rights of this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre: Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Division of Chemical Sciences > Inorganic & Physical Chemistry
Depositing User: Id for Latest eprints
Date Deposited: 17 Aug 2016 04:18
Last Modified: 17 Aug 2016 04:18
URI: http://eprints.iisc.ac.in/id/eprint/54265

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