Platinum(II) Complexes of Curcumin Showing Photocytotoxicity in Visible Light.

Mitra, Koushambi; Gautam, Srishti; Kondaiah, Paturu; Chakravarty, Akhil R.

Three platinum(II) complexes of curcumin, [Pt(NH3)2(cur)](NO3) ( 1), [Pt(en)(cur)](NO3) ( 2) and [Pt(dach)(cur)](NO3) ( 3), where Hcur is curcumin, en is ethylenediamine and dach is 1 R,2 R-(-)-1,2-diaminocyclohexane, were synthesized, characterized and their photocytotoxic properties were explored. The acetylacetone (Hacac) analogue of 1, [Pt(NH3)2(acac)]NO3 ( 4), was prepared to investigate the role of photoactive curcumin. The crystal structure of [Pt(NH3)2(acac)]CF3SO3 ( 4a) revealed square-planar geometry of the platinum(II) centre. Complexes 1- 3 displayed an intense absorption band at 450 nm ( ε = 22500 m-1 cm-1). The curcumin in metal-bound form showed improved stability in 10 % DMSO/buffer solution at 37 °C. The complexes released curcumin upon irradiation with visible light (400-700 nm) as evident from the increment in emission intensity. The complexes formed Pt-DNA covalent adducts when treated with calf thymus (ct)-DNA and exposed to light. The platinum-curcumin conjugates demonstrated photocytotoxicity in cancer cells giving IC50 values of 15-45 µ m (400-700 nm, 10 J cm-2) with no apparent activity in the dark (IC50 > 200 µ m). Cytoplasmic localization and reactive oxygen species (ROS)-mediated apoptotic cell death in visible light was observed for the curcumin complexes.

CURCUMIN; METAL complexes; PHOTOSENSITIVITY; VISIBLE spectra; CANCER chemotherapy

European Journal of Inorganic Chemistry, 2017, Vol 2017, Issue 12, p1753

1434-1948

Academic Journal

10.1002/ejic.201601078