Biocatalytic production of MRI contrast agents

Executive Summary

Herpes simplex virus type-1 thymidine kinase (HSV1-TK) is an enzyme that phosphorylates a wide range of nucleoside analogs, and has been used as a reporter gene with a variety of radiolabeled nucleotide analogs for positron emission tomography (PET). However, the complexity of synthesizing radiolabel probes and their short lifetime, limits the accessibility of investigating the therapeutic use of HSV1-TK as a reporter gene. MSU researchers have developed new enzymatic methods to produce 5-MDHT, an excellent CEST-MRI probe for imaging the activity of (HSV1-TK). These new methods are eco-friendly, and allow the efficient production of 5-MDHT in a single or two step reactions.

 

Description of Technology

The technology involves both single and two step reaction methods for making 5-methyl-5,6-dihydrothymidine (5-MDHT). In the single-step method, 5-MDHT is synthesized via a catalyzed base-exchange reaction between 5,5-dimethyl-1,3-diazinane-2,4-dione and 2'-deoxyinosine or thymidine. The two step reaction process involves a base-exchange catalyzed reaction between 5-methyl-5,6-dihydrouracil and 2'-deoxyinosine or thymidine, followed by a methylation step using a S-adenosylmethionine (SAM) yielding 5-MDHT. Reactions take place at slightly higher than room temperature for 6 hours, yielding ≥95% pure 5-MDHT.

 

Benefits

  • Simplified non chemical production method for imaging probes
  • Skips many traditional chemical synthesis steps
  • Eco friendly method reduces the generation of hazardous by-products and uses of solvents
  • High specificity and good yield (55% isolated yield, and ≥95% NMR yield)
  • Superior chemical exchange saturation transfer contrast compared to thymidine (distinct exchangeable imino proton signal at 5.3 ppm)

 

Applications

  • Production of 5-methyl-5,6-dihydrothymidine (5-MDHT)
  • General approach can be used to develop many novel imaging probes for specific medical conditions

 

Patent Status

Patent pending

 

Publications

Biocatalytic Construction of a CEST MRI Nucleoside Probe: Synthesis and Evaluation of 5-Methyl-5,6-dihydrothymidine”, BioRxiv, June 25, 2025

 

Licensing Rights

Full licensing rights available

 

Inventors

Dr. Assaf Gilad, Dr. Aimen Al-Hilfi

 

TECH ID

TEC2025-0068

Patent Information: