In an attempt to develop potent antitumor agents, new rhodacyanine analogues containing the pyridinium ring (5a–5h), the isoquinolinium ring (6a–6c) and the quinolinium ring (7a– 7e) linked to the rhodanine ring via N–N covalent bond were designed, synthesized and evaluated for antitumor activity against human lung cancer cell line (H460) by MTT assay in vitro. Most of the tested compounds showed enhanced antitumor activity with IC50 values ...