NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2013.

Cover of Molecular Imaging and Contrast Agent Database (MICAD)

Molecular Imaging and Contrast Agent Database (MICAD) [Internet].

Show details


, PhD
National Center for Biotechnology Information, NLM, NIH, Bethesda, MD, vog.hin.mln.ibcn@dacim

Created: ; Last Update: October 29, 2007.

Chemical name:3'-Deoxy-3'-[18F]fluoro-1-β-D-xylofuranosyl-adenineimage 26740882 in the ncbi pubchem database
Abbreviated name:[18F]FXA
Agent Category:Compound
Target Category:Non-catabolized trapping inside cells
Method of detection:PET
Source of signal:18F
  • Checkbox Rodents
Click on the above structure for additional information in PubChem.



Adenylates are important in cellular metabolism and functions (1). Adenosine is converted intracellularly to adenosine triphosphate (ATP), which is an important source of energy as well as a regulator of cellular functions. Adenosine stimulates the acetylcholine-sensitive K+ current in the heart. Many fluorinated analogs of adenosine nucleoside have been investigated as potential antitumor and antiviral agents (2-5). 3'-Deoxy-3'-fluoro-9-β-D-xylofuranosyl-adenine (FXA) was found to have antiviral activity (3, 6). [18F]FXA has been synthesized and studied in tumor-bearing mice with positron emission tomography (PET) imaging. [18F]FXA was not visualized in the tumor but in the heart (7).



Alauddin et al. (7) synthesized [18F]FXA by reaction of the respective triflate (N3,2’,5’-tri-methoxytrityl-3’-trifluoromethanesulfonyl-9-β-D-arabinofuranosyl-adenine with tetrabutylammonium [18F]fluoride, followed by acid hydrolysis to remove the methoxytrityl protecting groups. The desired product, [18F]FXA, was purified with high-performance liquid chromatography with a radiochemical yield of 30%–35% (decay-corrected) and a radiochemical purity >99%. The average specific activity for [18F]FXA was >74 GBq/µmol (2,000 mCi/µmol) at the end of the synthesis. Total synthesis time was 90–95 min from the end of bombardment.

In Vitro Studies: Testing in Cells and Tissues


No publication is currently available.

Animal Studies



Alauddin et al. (7) performed biodistribution studies of [18F]FXA in nude mice (n = 5) bearing an HT-29 tumor in the left flank and a herpes simplex virus thymidine kinase (HSV-tk)–transduced HT-29 tumor in the right flank. [18F]FXA cleared rapidly from the blood within 20 min after injection with a plasma half-life of ~8 min. The heart had the highest accumulation at 120 min (the only time point studied) with 8.4% injected dose (ID)/g, followed by the liver (6.9% ID/g) and kidney (6.4% ID/g). The accumulation in the two tumors was 0.67% ID/g in the wild-type tumor and 0.49% ID/g in the HSV-tk–transduced tumor, which suggests that [18F]FXA is not a substrate for HSV-tk gene. Radioactivity levels in the blood and muscle were 1.03% ID/g and 2.43% ID/g, respectively. The heart/blood ratio was 8.15. The tumor/blood ratio was <1, which suggests that [18F]FXA is not suitable for tumor imaging. PET images were obtained at 30, 60, and 120 min after injection. The heart exhibited the highest radioactivity, followed by the liver and kidney. Neither tumor was clearly visualized. No significant differences in images were observed at the three time points. No blocking experiment was performed. The authors suggested that further studies are necessary to understand the mechanism of heart accumulation.

Other Non-Primate Mammals


No publication is currently available.

Non-Human Primates


No publication is currently available.

Human Studies


No publication is currently available.

NIH Support



Dzeja P.P. , Terzic A. Phosphotransfer networks and cellular energetics. J Exp Biol. 2003;206(Pt 12):2039–47. [PubMed: 12756286]
Kim C.G. , Yang D.J. , Kim E.E. , Cherif A. , Kuang L.R. , Li C. , Tansey W. , Liu C.W. , Li S.C. , Wallace S. , Podoloff D.A. Assessment of tumor cell proliferation using [18F]fluorodeoxyadenosine and[18F]fluoroethyluracil. J Pharm Sci. 1996;85(3):339–44. [PubMed: 8699341]
Mikhailopulo I.A. , Poopeiko N.E. , Pricota T.I. , Sivets G.G. , Kvasyuk E.I. , Balzarini J. , De Clercq E. Synthesis and antiviral and cytostatic properties of 3'-deoxy-3'-fluoro- and 2'-azido-3'-fluoro-2',3'-dideoxy-D-ribofuranosides of natural heterocyclic bases. J Med Chem. 1991;34(7):2195–202. [PubMed: 2066992]
Pittillo R.F. , Moncrief C. , Brockman R.W. , Chambers P. Antimicrobial Activity of 2-Fluoroadenosine and 2-Fluoroadenine. Antimicrobial Agents Chemother (Bethesda) 1964;10:474–84. [PubMed: 14287979]
Secrist J.A. , Shortnacy A.T. , Montgomery J.A. Synthesis and biological evaluations of certain 2-halo-2'-substituted derivatives of 9-beta-D-arabinofuranosyladenine. J Med Chem. 1988;31(2):405–10. [PubMed: 3339610]
Van Aerschot A. , Herdewijn P. , Janssen G. , Cools M. , De Clercq E. Synthesis and antiviral activity evaluation of 3'-fluoro-3'-deoxyribonucleosides: broad-spectrum antiviral activity of 3'-fluoro-3'-deoxyadenosine. Antiviral Res. 1989;12(3):133–50. [PubMed: 2624455]
Alauddin M.M. , Shahinian A. , Park R. , Tohme M. , Fissekis J.D. , Conti P.S. Biodistribution and PET imaging of [(18)F]-fluoroadenosine derivatives. Nucl Med Biol. 2007;34(3):267–72. [PMC free article: PMC1905838] [PubMed: 17383576]


Search MICAD

Limit my Search:

Related information

Similar articles in PubMed

See reviews...See all...

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...