Metal complexes with α-picolinic acid frameworks and their antitumor activity

•Pyridine (carboxylate) metal complexes exhibit moderate anticancer activity.•Ir(III) pyridine based compounds are promising anticancer agents.•Increased anticancer activity directed by different mode of ligand coordination, N, N,O or N,N.•Polynuclear Ru and Pt pyridine based complexes are opening new area in design of anticancer agents.