Computer Modeling of Ruthenium and Ruthenium-Nitrosyl Complexes to Identify Chemotherapeutic Agents

1. Computer Modeling of Ruthenium and Ruthenium-Nitrosyl Complexes to Identify Chemotherapeutic Agents Eric M. Majchrzak, Stephanie V. Harding, and Matthew S. Ward Daemen College Natural Sciences Department Photodynamic Therapy and Chemotherapy Simulating the Blood Stream Examining Bond Angles and Bond Distances According to the American Cancer Society, nearly half of the 1.5 million cases of cancer diagnosed in 2005 will result in death. The development of new chemotherapeutic agents with increased in vivo selectivity and less severe side effects is essential. This study focuses on computational chemistry to identify potential new chemotherapeutic agents and examines the reliability of computer based molecular modeling. Chemotherapy is the treatment of cancer cells utilizing specific chemical agents to destroy malignant cells and tissue. Chemotherapy destroys malignant cells by interrupting and inhibiting the growth and reproduction of cancer cells. Ruthenium complexes were chosen for this study because of the potential they have shown as chemotherapeutic agents. Ruthenium coordinated ligands will mimic iron in vivo and possess a much higher selectivity than currently available products. Photodynamic therapy (PDT) is a potential treatment for cancer that utilizes a photo-chemically active complex that can be altered in vivo to destroy malignant cells. Ruthenium nitrosyl complexes can be utilized as PDT photo-sensitizers because of their ability to release a photo-labile nitric oxide unit. Comparisons of bond length, bond angle, and energy were made between computation data and results reported in literature. These comparisons were used to determine the relevance of molecular modeling to ruthenium nitrosyls and to examine potential new nitrosyl complexes. Table of Spartan calculated values using PM3 semi-empirical calculations for ruthenium nitrosyl complexes. Literature values were obtained by X-ray diffraction. (1) Patra, A.K.; Rose, M.J.; Murphy, K.A.; Olmstead, M.M.; Mascharak, P.K. Inorg. Chem.2004, 43, 4487-4495. (2) Patra, A. K.; Mascharak, P. K. Inorg. Chem.2003, 42, 7363-7365. Table of Spartan calculated values using MMFF calculations for ruthenium nitrosyl complexes. Literature values were obtained by X-ray diffraction. (1) Patra, A.K.; Rose, M.J.; Murphy, K.A.; Olmstead, M.M.; Mascharak, P.K. Inorg. Chem.2004, 43, 4487-4495. (2) Patra, A. K.; Mascharak, P. K. Inorg. Chem.2003, 42, 7363-7365. [(Me2bpb)Ru(NO)(Cl)] [(Me2bpb)Ru(NO)(py)](BF4) Ru(PaPy3)(NO)](BF4)2 [Ru(tpen)]2+ + 30H2O [Ru(edta)]2- [Ru(edampda)] + 5H2O Chemotherapy Ru(edta)-G(N-3) Conclusions Ru(edta)-G(N-7) • PM3 calculationsyield Ru(rap) with the lowest calculated energy. • The complex Ru(im)2 yielded the lowest MMFF calculated energy. • RuII/III edta, edampda, and tpen complexes show a similar trend in increasing energy difference (PM3) to the reported E1/2 values of the corresponding iron complexes 0.14V (edta), 0.44V (edampda) and 0.84V (tpen) vs. NHE (Inorg. Chim. Acta1999, 286, 197-206). • Both MMFF and PM3 calculations yield linear relationships for the calculated energies to the addition of waters. • Comparative studies show that the PM3 calculated bond distances and bond angles are in closer agreement to the reported x-ray diffraction data for the ruthenium-nitrosyl complexes. Electrochemistry [Ru(edampda)]+ 100H2O [RuII(edampda)]→ [RuIII(edampda)]1+ +1e- [RuII(edta)]2- → [RuIII(edta)]1- +1e- Acknowledgements Daemen College Natural Sciences Department Daemen College Faculty Research Fund Daemen College Think Tank [RuII(tpen)]2+ → [RuIII(tpen)]3+ +1e-