Physicochemical, in vitro therapeutic activity, DNA-binding, and in silico molecular docking studies of samarium(III) complexes bearing N,O-chelated Schiff base ligands

Abstract

Two new Sm(III) complexes, [Sm(L1)2Cl(H2O)]·3H2O and [Sm(L2)2Cl(H2O)]·2H2O, where HL1 is (E)-4-bromo-2-(((4-(2-hydroxyethyl)phenyl)imino)methyl)phenol and HL2 is (E)-2-(((4-(2-hydroxyethyl)phenyl)imino)methyl)-4-methoxyphenol, are reported. From the spectral data, it was deduced that the two Schiff base ligands existed as monobasic bidentate ON bonded to samarium(III) through deprotonated hydroxyl oxygen and azomethine nitrogen adopting an octahedral environment around Sm(III). The optimized structures, molecular electrostatic potential, and the energies HOMO and LUMO were calculated using DFT/B3LYP calculations employing the Gaussian 09 program. The antimicrobial efficacy of complexes and their parent ligands have been tested in vitro against various strains of bacteria and fungus. The antimicrobial activity of the new complexes has been enhanced compared to their parent free ligands. MTT assay was used to assess the in vitro cytotoxicity of the ligands and their Sm(III) complexes against the human breast cancer cell line (MCF-7) and human liver carcinoma cell line (Hep-G2). The CT-DNA binding constants of the interaction have been calculated and follow the order SmL1 > SmL2.