In vitro anticancer activities of Schiff base and its lanthanum complex

•Green protocols are used to synthesize biologically potent Schiff bases and their La(III) complexes.•The Schiff bases are derived from the condensation between heteroaryl ketone and 2–aminobenzothiazole in 1:1 molar ratio.•Ligands and complexes are characterized by different spectroscopic techniques.•In vitro anticancer activities are studied.

Schiff base metal complexes are well-known to intercalate DNA. The La(III) complexes have been synthesized such that they hinder with the role of the topoisomerases, which control the topology of DNA during the cell-division cycle. Although several promising chemotherapeutics have been developed, on the basis of Schiff base metal complex DNA intercalating system they did not proceed past clinical trials due to their dose-limiting toxicity. Herein, we discuss an alternative compound, the La(III) complex, [La(L1)2Cl3]·7H2O based on a Schiff base ligand 2,3-dihydro-1H-indolo-[2,3-b]-phenazin-4(5H)-ylidene)benzothiazole–2-amine (L1), and report in vitro cell studies. Results of antitumor activity using cell viability assay, reactive oxygen species (ROS) generation and nuclear condensation in PC-3 (Human, prostate carcinoma) cells show that the metal complex is more potent than ligand. La(III) complexes have been synthesized by reaction of lanthanum(III) salt in 1:2 M ratio with ligands L1 and 3-(ethoxymethylene)-2,3-dihydro-1H-indolo[2,3-b]-phenazin-4(5H)-ylidene)benzathiazole-2-amine (L2) in methanol. The ligands and their La(III) complexes were characterized by molar conductance, magnetic susceptibility, elemental analyses, FT–IR, UV–Vis, 1H/13C NMR, thermogravimetric, XRD, and SEM analysis.

Graphical abstractSynthesis, spectroscopic, coordination and biological activities lanthanum complex derived from bidentate Schiff base ligand.Figure optionsDownload full-size imageDownload as PowerPoint slide