Photochemotherapeutic Properties of Cu(II) Complexes of L-Lysine and L-Arginine Appended to Anthracene

Cu(II) complexes of positively charged amino acids L-Lysine and L-Arginine appended to an anthracene unit and phenanthroline bases, namely [Cu(Anth-Lys)(L)(ClO4)] (1, 2) and [Cu(Anth-Arg)(L)(ClO4)] (3, 4) where L is 1,10-phenanthroline (phen, 1 and 3), dipyrido[3,2-a : 2 ',3 '-c]phenazine (dppz, 2 and 4) were synthesized and fully characterized by various spectral and analytical methods. Cu(II) centered broad and weak d-d band in the visible region along with phenanthroline based pi ->pi* and n ->pi* bands in the UV region were observed in the electronic spectra of the complexes recorded in DMF-Tris-HCl buffer (1 : 4 v/v) (pH 7.2). The complexes 1-4 show efficient DNA binding propensity. They also demonstrated strong binding affinity for human serum albumin (HSA). The complexes showed efficient visible light-induced cytotoxicity against A549 (human lung carcinoma), HaCaT (human epidermal keratinocytes) and MDA-MB-231(human breast cancer cells) cells with low dark toxicity. They generate both singlet oxygen (1O2) and hydroxyl radical (& sdot;OH) as reactive oxygen species (ROS) upon excitation with visible light which is believed to be responsible for killing cancer cells. Significant changes in the nuclear morphology of the HaCaT cells were observed when treated with complexes 2 and 4 in visible light compared to the non-irradiated cells. Cu(II) complexes of positively charged amino acids L-Lysine and L-Arginine appended to an anthracene moiety and phenanthroline bases show significant binding propensity towards calf thymus DNA and human serum albumin along with significant photo-enhanced cytotoxicity in A549, HaCaT and MDB-MB-231 cells in visible light with low toxicity.image