Synthesis, characterization, in vitro biological evaluation and molecular docking studies of newly synthesized mononuclear lanthanum(III) complexes of N,N'-bis(2-aminoethyl)oxamide and phenanthroline bases

Four lanthanum(III) complexes were newly synthesized using the ligand N,N'-bis(2-aminoethyl)oxamide ( 1 ) and phenanthroline bases [La(oxae)(2)(NO3)(2)](NO3) ( 2 ) [La(oxae)(bpy)](NO3)(3) ( 3 ), [La(oxae)(phen)](NO3)(3) ( 4 ) and [La(oxae)2(dppz)](NO3)(3) ( 5 ) and characterized by H-1-NMR, IR, UV- Visible spectroscopic analyses, ESI-Mass spectrometric measurements, molar conductivities, and cyclic voltammetric measurements. Complex 2 was found to be 1:1 electrolyte and complexes 3, 4 and 5 were 1:3 electrolytes. The redox ehavior of the complexes was confirmed by cyclic voltammetry. The interac-tions of 1 and its complexes ( 2, 3, 4 and 5 ) with calf thymus DNA (CT-DNA) were studied by UV-Visible absorption spectroscopy, cyclic voltammetric studies, viscosity measurements and molecular docking studies. The studies confirmed the highest binding propensity for complex 5 (K-b = 2.26 x 10(-6) +/- 7) in the reduced state through the intercalation method. Molecular docking studies revealed that complex 5 was found to bind strongly with the DNA molecule due to intercalation with a more negative binding energy AG = -8.6 kcal/mol having an association constant (K-a) = 0.892 mu M. The oxidative cleavage of SC pUC19 DNA by La(III) complexes was confirmed by the Agarose gel electrophoresis method. Of all the compounds tested, complex 5 exhibited the highest cleavage ability (94%) in the presence of H2O2 in the major groove region. The MTT assay revealed the highest antiproliferative activity of complex 5 against MCF-7 cell lines at IC50 value is 21.86 mu M. The complexes have been tested for antibacterial activities wherein at 50 mu g mL( -1), complex 5 inhibits the growth of K. pneumonia and at 100 mu g mL (-1), ligand oxae ( 1 ) and its complex 2 were active against E. coli and K. pneumonia ; complex 4 inhibited the growth of E. coli, K. pneumonia and B. subtilis. The antioxidant activities showed that complex 2 had the highest chelation ability towards Fe2+. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, four new lanthanum(III) complexes were synthesized and characterized. The complexes exhibited high binding affinity and oxidative cleavage activity towards DNA. In addition, complex 5 showed strong antiproliferative and antibacterial activities.