Synthesis, crystal structure and biological evaluation of three new Rh(III) complexes incorporating benzimidazole derivatives

Three new non-cisplatin analogs [Rh(BID1)(CH3OH)]center dot CH3OH (Rh-1), [Rh(BID2)(CH3OH)]center dot CH3OH (Rh-2) and [Rh(BID3)(CH3OH)]center dot 2CH(3)OH (Rh-3) bearing benzimidazole derivatives (BID1-BID-3) were first prepared as potential anti-tumor compounds. The Rh-3 complex with 8-fluoro group in BID-3 ligand exhibited potential antiproliferative activity against multidrug-resistant human lung adenocarcinoma A549/DDP and cisplatin-resistant human ovarian cancer SK-OV-3/DDP cells, at most 5.0 fold more potent than Rh-1, Rh-2 and cisplatin under the same conditions. Importantly, Rh-1-Rh-3 are more selective for A549/DDP cells versus human normal liver HL-7702 cells. The Rh-2 and Rh-3 caused mitochondrial dysfunction was in the following order: Rh-3 > Rh-2. The different biological behavior of Rh-1-Rh-3 may correlate with different 8-substituted groups in benzimidazole derivatives.