A ruthenium(III) complex formulated as [Ru(pyc)3]H2O (where pyc is pyridine-2-carboxylate) was prepared through a one-pot reaction of pyridine-2,6-dicarboxylic acid and anhydrous ruthenium(III) chloride. Here, hydrothermal conditions led to decarboxylation from pyridine-2,6-dicarboxylic acid into pyridine-2-carboxylate. The compound was identified by spectroscopic methods and its crystal structure was determined by single-crystal X-ray diffraction. The cytotoxicity of the compounds was evaluated by MTT(3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay against three cancer cell lines containing a human melanoma (A375), a human non-small cell lung carcinoma (H1299), a human colon adenocarcinoma (HT29), and also one normal cell human foreskin fibroblast (HFF). A strong and selective inhibitory effect of the complex (IC50 ¼ 6.50 lM, viability inhibition ¼ 67.12%) was exhibited toward A375 cells. The apoptosis through a mitochondrial pathway was suggested via reactive oxygen species (ROS) production and mitochondria membrane potential (MMP) collapse. The cytostatic effect of the complex in the A375 3D spheroid model was depicted
