Design, Synthesis and Pharmacological Evaluation of Rutaecarpine Derivatives toward Topoisomerase I

The DNA topoisomerases (Top) is a crucial enzyme for replication, transcription, and various nuclear processes. Top cleaves and religates the phosphodiester backbone of the double strand DNA to relive strand stress of super coil DNA during various nuclear processes. Therefore, Top have been the target of interest for development of agents such as, antitumor, antiviral, antibacterial, anti-protozoa, and immunomodulation agents to suppress overexpression of nuclear processes. Evodiamine (EVO) and its structure analogue, rutaecarpine, are alkaloidal compounds which possess many physiological functions including vasorelaxation, antiobesity, anticancer, and anti-inflammatory effects. Previously, we discovered that EVO and rutaecarpine are potent agents to inhibit TopI activities thus stopping various DNA related nuclear process in cells. From our results, we envision that the chemical structures of rutaecarpine will serve as a drug designing template for novel anticancer agents. Our structure-activities relationship analysis of EVO and rutaecarpine toward TopI inhibition reveals several possible structural modifications on the A- and E-rings of rutaecarpine which would expect to enhance a stable formation of DNA-TopI complexes and stop the regeneration of TopI. To confirm our analysis, we propose to prepare 12 rutaecarpine derivatives which various functional groups are substituted on the A- and E-rings of rutaecarpine. Those substitutions are various halides substituted on A-ring, and the nitro or amino functional groups substituted on the E-rings. A concise synthetic scheme toward these 12 derivatives will be described in the proposal. The in vitro TopI inhibition activities evaluation by the derivatives prepared herein will be assessed using computer-aid molecular modeling, surface plasmon resonance, and DNA relaxation assay. The cytotoxic effects of these derivatives will be examined in high TopI-expression cells. The most potent derivatives discovered herein will be further assessed in an in vivo experiment by cancer cell-implanted mice. Currently many TopI inhibitors have been applied in clinical cancer therapy; however, those TopI inhibitors exhibits multiple drug resistance upon treatment thus hampers their feasibility. This proposal will provide the insights on the targeted action of rutaecarpine derivatives and establish new structure templates for anticancer drug discovery.