Synthesis and Characterization of 9-(4-[18F]Fluoro-3-(hydroxymethyl)butyl)-2-(phenylthio)-6-oxopurine as a Novel PET Agent for Mutant Herpes Simplex Virus Type 1 Thymidine Kinase Reporter Gene Imaging.
Molecular imaging and biology
PURPOSE: [18F]FHBG has been used as a positron emission tomography (PET) imaging tracer for the monitoring of herpes simplex virus type 1 thymidine kinase (HSV1-tk), a reporter gene for cell and gene therapy in humans. However, this tracer shows inadequate blood-brain barrier (BBB) penetration and, therefore, would be limited for accurate quantification of reporter gene expression in the brain. Here, we report the synthesis and evaluation of 9-(4-[18F]fluoro-3-(hydroxymethyl)butyl)-2(phenylthio)-6-oxopurine ([18F]FHBT) as a new PET tracer for imaging reporter gene expression of HSV1-tk and its mutant HSV1-sr39tk, with the aim of improved BBB penetration.PROCEDURES: [18F]FHBT was prepared by using a tosylate precursor and [18F]KF. The cellular uptake of [18F]FHBT was performed in HSV1-sr39tk-positive (+) or HSV1-sr39tk-negative (-) MDA-MB-231 breast cancer cells. The specificity of [18F]FHBT to assess HSV1-sr39tk expression was evaluated by in vitro blocking studies using 1mM of ganciclovir (GCV). Penetration of [18F]FHBT and [18F]FHBG across the BBB was assessed by dynamic PET imaging studies in normal mice.RESULTS: The tosylate precursor reacted with [18F]KF using Kryptofix2.2.2 followed by deprotection to give [18F]FHBT in 10% radiochemical yield (decay-corrected). The uptake of [18F]FHBT in HSV1-sr39tk (+) cells was significantly higher than that of HSV1-sr39tk (-) cells. In the presence of GCV (1mM), the uptake of [18F]FHBT was significantly decreased, indicating that [18F]FHBT serves as a selective substrate of HSV1-sr39TK. PET images and time-activity curves of [18F]FHBT in the brain regions showed similar initial brain uptakes (~12.75min) as [18F]FHBG (P>0.855). Slower washout of [18F]FHBT was observed at the later time points (17.75 - 57.75 min, P >0.207).CONCLUSIONS: Although [18F]FHBT showed no statistically significant improvement of BBB permeability compared with [18F]FHBG, we have demonstrated that the 2-(phenylthio)-6-oxopurine backbone can serve as a novel scaffold for developing HSV1-tk/HSV1-sr39tk reporter gene imaging agents for additional research in the future.
View details for DOI 10.1007/s11307-020-01517-5
View details for PubMedID 32691392
Synthesis and validation of [F-18]6 ''-fluromaltotriose, a radiotracer for imaging bacterial infections
WILEY. 2019: S315–S316
View details for Web of Science ID 000468965200248
Synthesis and characterization of 9-(4fluoro-3-(hydroxymethyl)butyl)-2-(phenylthio)6-oxopurine ([F-18]FHBT) as a PET tracer for HSV1-tk reporter gene imaging
WILEY. 2019: S537–S538
View details for Web of Science ID 000468965200450
The discovery of quinoline-3-carboxamides as hematopoietic prostaglandin D synthase (H-PGDS) inhibitors.
Bioorganic & medicinal chemistry
With the goal of discovering more selective anti-inflammatory drugs, than COX inhibitors, to attenuate prostaglandin signaling, a fragment-based screen of hematopoietic prostaglandin D synthase was performed. The 76 crystallographic hits were sorted into similar groups, with the 3-cyano-quinoline 1a (FP IC50 = 220,000 nM, LE = 0.43) being a potent member of the 6,6-fused heterocyclic cluster. Employing SAR insights gained from structural comparisons of other H-PGDS fragment binding mode clusters, the initial hit 1a was converted into the 70-fold more potent quinoline 1d (IC50 = 3,100 nM, LE = 0.49). A systematic substitution of the amine moiety of 1d, utilizing structural information and array chemistry, with modifications to improve inhibitor stability, resulted in the identification of the 300-fold more active H-PGDS inhibitor tool compound 1bv (IC50 = 9.9 nM, LE = 0.42). This selective inhibitor exhibited good murine pharmacokinetics, dose-dependently attenuated PGD2 production in a mast cell degranulation assay and should be suitable to further explore H-PGDS biology.
View details for DOI 10.1016/j.bmc.2019.02.017
View details for PubMedID 30858025
Electrochemical [(11)C]CO2 to [(11)C]CO conversion for PET imaging.
Chemical communications (Cambridge, England)
2017; 53 (20): 2982–85
The development of a novel electrochemical methodology to generate carbon-11 carbon monoxide ([(11)C]CO) from cyclotron-produced carbon-11 carbon dioxide ([(11)C]CO2) using Ni(cyclam) and Zn(cyclen) complexes is described. This methodology allows up to 10% yields of [(11)C]CO from [(11)C]CO2. Produced [(11)C]CO was subsequently converted to [(11)C]N-benzylbenzamide under mild conditions with a radiochemical purity (RCP) of >98%.
View details for DOI 10.1039/c7cc00319f
View details for PubMedID 28234400