Organometallic [Re(CO)3]+and [Re(CO)2(NO)]2+Labeled Substrates for Human Thymidine Kinase 1
摘要:
Thymidine was functionalized at position N3 with a tridentate iminodiacetic acid chelating system and a potentially tetradentate mercaptoethyliminodiacetic acid chelating system. Spacers of different lengths (ethyl and butyl) were introduced between the chelators and thymidine, The derivatives were labeled with the [Re(CO)(2)(NO)](2+) and [Re(CO)(3)](+) cores to give isostructural complexes with different overall charges. All complexes were analyzed by NMR, MS, and IR, and in addition, the X-ray structure of a [Re(CO)(2)(NO)](2+) labeled thymidine derivative functionalized at the N3 position was solved. The ligands incorporating the potentially tetradentate mercaptoethyliminodiacetic acid chelating system coordinated tridentately through iminodiacetic acid to both the [Re(CO)(2)(NO)](2+) core and the [Re(CO)(3)](+) core. This was surprising given that the reaction of [NEt4][Re(CO)(2)(NO)Br-3] with the model ligand ethylmercaptoethyliminodiacetic acid led to dissociation of a carbonyl ligand and formation of a monocarbonyl-mononitrosyl complex, as confirmed by X-ray structure analysis. All of the organometallic thymidine derivatives were substrates for human thymidine kinase 1, a key enzyme in (cancer) cell proliferation. Neutral [Re(CO)(2)(NO)](2+) labeled thymidine derivatives revealed substrate activity ranging from 24 to 40%, and the structurally analogous anionic [Re(CO)(3)](+) labeled thymidine derivatives from 20 to 38% compared with the natural substrate thymidine.
Synthesis, In Vitro, and In Silico Evaluation of Organometallic Technetium and Rhenium Thymidine Complexes with Retained Substrate Activity toward Human Thymidine Kinase Type 1
摘要:
Human cytosolic thymidine kinase (hTK1) has proven to be a suitable target for noninvasive imaging of cancer cell proliferation using radiolabeled substrates such as [F-18]fluorothymidine ([F-18]FLT). However, a thymidine tracer useful for single photon emission tomography (SPECT) based off the inexpensive radionuclide technetium-99m would be of significant interest. In this work, a series of thymidine derivatives labeled with the organometallic [M(CO)(3)](+) core (M = Tc-99m, Re) were synthesized. Neutral, cationic, and anionic complexes were readily formed in aqueous media. and all were substrates of recombinant hTK1 when incubated with ATP. The neutral complexes were phosphorylated to a greater extent than the charged complexes. The extent of phosphorylation was further improved by increasing the spacer length separating thymidine and the organometallic core. A molecular dynamics Simulation Study performed with a modified hTK1 structure Supported the experimental findings. In vitro cell internalization experiments performed if) a human neuroblastoma cell line (SKNMC) showed low uptake of the charged complexes but significant uptake for the neutral, lipophilic complexes with a log P value > 1.
Synthesis, In Vitro, and In Silico Evaluation of Organometallic Technetium and Rhenium Thymidine Complexes with Retained Substrate Activity toward Human Thymidine Kinase Type 1
Human cytosolic thymidine kinase (hTK1) has proven to be a suitable target for noninvasive imaging of cancer cell proliferation using radiolabeled substrates such as [F-18]fluorothymidine ([F-18]FLT). However, a thymidine tracer useful for single photon emission tomography (SPECT) based off the inexpensive radionuclide technetium-99m would be of significant interest. In this work, a series of thymidine derivatives labeled with the organometallic [M(CO)(3)](+) core (M = Tc-99m, Re) were synthesized. Neutral, cationic, and anionic complexes were readily formed in aqueous media. and all were substrates of recombinant hTK1 when incubated with ATP. The neutral complexes were phosphorylated to a greater extent than the charged complexes. The extent of phosphorylation was further improved by increasing the spacer length separating thymidine and the organometallic core. A molecular dynamics Simulation Study performed with a modified hTK1 structure Supported the experimental findings. In vitro cell internalization experiments performed if) a human neuroblastoma cell line (SKNMC) showed low uptake of the charged complexes but significant uptake for the neutral, lipophilic complexes with a log P value > 1.
Organometallic [Re(CO)<sub>3</sub>]<sup>+</sup>and [Re(CO)<sub>2</sub>(NO)]<sup>2+</sup>Labeled Substrates for Human Thymidine Kinase 1
Thymidine was functionalized at position N3 with a tridentate iminodiacetic acid chelating system and a potentially tetradentate mercaptoethyliminodiacetic acid chelating system. Spacers of different lengths (ethyl and butyl) were introduced between the chelators and thymidine, The derivatives were labeled with the [Re(CO)(2)(NO)](2+) and [Re(CO)(3)](+) cores to give isostructural complexes with different overall charges. All complexes were analyzed by NMR, MS, and IR, and in addition, the X-ray structure of a [Re(CO)(2)(NO)](2+) labeled thymidine derivative functionalized at the N3 position was solved. The ligands incorporating the potentially tetradentate mercaptoethyliminodiacetic acid chelating system coordinated tridentately through iminodiacetic acid to both the [Re(CO)(2)(NO)](2+) core and the [Re(CO)(3)](+) core. This was surprising given that the reaction of [NEt4][Re(CO)(2)(NO)Br-3] with the model ligand ethylmercaptoethyliminodiacetic acid led to dissociation of a carbonyl ligand and formation of a monocarbonyl-mononitrosyl complex, as confirmed by X-ray structure analysis. All of the organometallic thymidine derivatives were substrates for human thymidine kinase 1, a key enzyme in (cancer) cell proliferation. Neutral [Re(CO)(2)(NO)](2+) labeled thymidine derivatives revealed substrate activity ranging from 24 to 40%, and the structurally analogous anionic [Re(CO)(3)](+) labeled thymidine derivatives from 20 to 38% compared with the natural substrate thymidine.