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Updated: Jun 21, 2026
Real-time Cytotoxicity Assays in Human Whole Blood
Published on: November 7, 2014
Live cell cytotoxicity studies: documentation of the interactions of antitumor active dirhodium compounds with
J Dafhne Aguirre1, Alfredo M Angeles-Boza, Abdellatif Chouai
1Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
Abstract:
The promising antitumor activity of dirhodium complexes has been known for over 30 years. There remains, however, a general lack of understanding of their activity in cellulo. In this study, we report the DNA interactions and activity in living cells of six monosubstituted dirhodium(II,II) complexes of general formula [Rh(2)(mu-O(2)CCH(3))(2)(eta(1)-O(2)CCH(3))(L)(CH(3)OH)](+), where L = bpy (2,2'-bipyridine) (1), phen (1,10-phenanthroline) (2), dpq (dipyrido[3,2-f:2',3'-h]quinoxaline) (3), dppz (dipyrido[3,2-a:2',3'-c]phenazine) (4), dppn (benzo[i]dipyrido[3,2-a:2',3'-c]phenazine) (5), and dap (4,7-dihydrodibenzo[de,gh][1,10]phenanthroline) (6). DNA interactions were investigated by UV/visible spectroscopy, relative viscosity measurements, and electrophoretic mobility shift assay. These measurements indicate that compound 5 exhibits the strongest interaction with DNA. Compound 5 also causes the most damage to DNA after cellular internalization, as evaluated by the alkaline comet assay. Compound 5, however, is not the most effective at inhibiting cell viability of the human cancer cells HeLa and COLO-316. The greater hydrophobicity of 5 as compared to that of 4, which is the most effective compound in the series, hinders its ability to reach its cellular target(s). Data from modulation studies of glutathione using N-acetylcysteine and L-buthionine-sulfoximine indicate that changes in glutathione levels do not affect the activity of these particular dirhodium complexes. These results suggest that glutathione is not the only agent involved in the deactivation of these dirhodium complexes.
Insights
Dirhodium complexes show antitumor potential, but their in-cell activity is unclear. Compound 5 strongly interacts with DNA, yet compound 4 is more effective at inhibiting cancer cell growth due to hydrophobicity differences.
Area of Science:
- Inorganic Chemistry
- Medicinal Chemistry
- Chemical Biology
Background:
- Dirhodium complexes have demonstrated significant antitumor activity for decades.
- Understanding the in-cellulo mechanisms of these complexes remains a challenge.
- This study investigates six specific monosubstituted dirhodium(II,II) complexes.
Purpose of the Study:
- To elucidate the DNA interactions and in-cellulo activity of novel dirhodium(II,II) complexes.
- To correlate structural properties with DNA binding and cellular effects.
- To explore the role of glutathione in the deactivation of these complexes.
Main Methods:
- Synthesis and characterization of six dirhodium(II,II) complexes with varying ligands (L).
- DNA interaction studies using UV/visible spectroscopy, viscosity, and electrophoretic mobility shift assays.
- Cellular activity assessment via alkaline comet assay and cell viability assays (HeLa, COLO-316).
- Glutathione modulation studies using N-acetylcysteine and L-buthionine-sulfoximine.
Main Results:
- Compound 5 (L=dppn) showed the strongest DNA interaction and caused the most DNA damage post-cellular uptake.
- Compound 4 (L=dppz) was the most effective in inhibiting cancer cell viability.
- Increased hydrophobicity of compound 5 compared to 4 limited its cellular efficacy.
- Glutathione levels did not significantly impact the activity of these dirhodium complexes.
Conclusions:
- The study highlights the complex relationship between DNA interaction, cellular uptake, and overall efficacy of dirhodium complexes.
- Ligand hydrophobicity plays a critical role in determining the in-cellulo antitumor activity.
- Glutathione is likely not the sole factor responsible for the deactivation of these dirhodium complexes in cells.
