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Platinum(II) Complexes of Curcumin Showing Photocytotoxicity in Visible Light
Author(s) -
Mitra Koushambi,
Gautam Srishti,
Kondaiah Paturu,
Chakravarty Akhil R.
Publication year - 2017
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.201601078
Subject(s) - chemistry , curcumin , platinum , visible spectrum , acetylacetone , photochemistry , adduct , ethylenediamine , covalent bond , absorption (acoustics) , nuclear chemistry , medicinal chemistry , stereochemistry , inorganic chemistry , organic chemistry , catalysis , optoelectronics , biochemistry , physics , acoustics
Three platinum(II) complexes of curcumin, [Pt(NH 3 ) 2 (cur)](NO 3 ) ( 1 ), [Pt(en)(cur)](NO 3 ) ( 2 ) and [Pt(dach)(cur)](NO 3 ) ( 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(NH 3 ) 2 (acac)]NO 3 ( 4 ), was prepared to investigate the role of photoactive curcumin. The crystal structure of [Pt(NH 3 ) 2 (acac)]CF 3 SO 3 ( 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 IC 50 values of 15–45 µ m (400–700 nm, 10 J cm –2 ) with no apparent activity in the dark (IC 50 > 200 µ m ). Cytoplasmic localization and reactive oxygen species (ROS)‐mediated apoptotic cell death in visible light was observed for the curcumin complexes.