New Naphthoquinone‐Based Manganese (II) Complexes: Synthesis, Characterization, and Cytotoxicity

Abstract We have synthesized and characterized two new complexes of stilbenes‐quinone hybrids with a manganese(II) center, Mn1 [Mn(NQ1) 2 (EtOH) 2 ] and Mn2 ([Mn(NQ2) 2 (EtOH) 2 ], where NQ1 and NQ2 are the 2‐hydroxy‐3‐styryl‐1,4‐naphthoquinone and 2‐hydroxy‐3‐(4‐chlorostyryl)‐1,4‐naphthoquinone in their deprotonated forms. FTIR and UV–vis spectroscopy analyses were used to verify changes in characteristic bands upon the coordination to a manganese center. Single‐crystal X‐ray diffraction analysis allowed the structural elucidation of Mn1 as cis ‐[Mn(NQ1) 2 (EtOH) 2 ] and Mn2 as cis ‐[Mn(NQ2) 2 (EtOH) 2 ] isomers. The charge distribution, dipole moments, and Gibbs free energy of the complexes were also calculated. The in vitro cytotoxicity results revealed that the coordination of quinone nucleus into a metal center improved their cytotoxicity, highlighting the effect of the manganese complexes on ovarian cancer cells. Mn1 , the promising candidate, was able to change the morphology and inhibit the colony formation in A2780 cells. Further, based on circular dichroism and fluorescence results, this manganese complex interacts with DNA via minor groove binding. In light of these results, Mn1 displays a promising skeleton for the development of more cytotoxic and selective manganese‐based compounds against ovarian cancer.