Get access

99mTc-DTPA-Amino Acids Conjugate as Specific SPECT Pharmaceuticals for Tumor Imaging

Authors

  • Deepa Sinha,

    1. Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi 110054, India
    2. Department of Chemistry, University of Delhi, Delhi 110007, India
    Search for more papers by this author
  • Gauri Shukla,

    1. Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi 110054, India
    2. Department of Chemistry, University of Delhi, Delhi 110007, India
    Search for more papers by this author
  • Anjani K. Tiwari,

    1. Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi 110054, India
    Search for more papers by this author
  • Shubhra Chaturvedi,

    1. Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi 110054, India
    Search for more papers by this author
  • Krishna Chuttani,

    1. Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi 110054, India
    Search for more papers by this author
  • Harish Chandra,

    1. Department of Chemistry, University of Delhi, Delhi 110007, India
    Search for more papers by this author
  • Anil K. Mishra

    1. Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi 110054, India
    Search for more papers by this author

Abstract

99mTc-Diethylene triamine pentaacetic acid-bis (amide) conjugates have been synthesized and evaluated as a potential radiopharmaceutical for tumor imaging. The compounds were synthesized by the condensation reaction of DTPA bis(anhydride) with different l-amino acids (methyl tryptophan, and 5-hydroxy tryptophan) and were characterized on the basis of IR, NMR, and Mass spectroscopy. 99mTc-labeled compounds were found stable for about 24 h under physiological conditions with more than 95% radiolabeling yield. Blood kinetic studies of all these complexes showed a bi-exponential pattern as well as quick wash out from the blood circulation. The biological t1/2(F) and t1/2(S) were found to be 20 ± 0.001 min for DTPA-(Me-Trp)2 and 18 ± 0.001 min for DTPA-(5HT)2 and t1/2 (slow) 5 h 45 min ± 0.001, 5 h 30 ± 0.001 min for DTPA-(Me-Trp)2, and DTPA-(5HT)2, respectively. Imaging and biodistribution studies were performed in mice bearing Ehrlich ascites tumor (EAT) tumors in right thigh. Radioconjugate derived from l-5-hydroxytryptophan exhibited remarkable localization at tumor site; whereas radiotracer derived from l-methyl tryptophan shows relatively less accumulation at the tumor site. Tumor-to-muscles ratios were 5.07 ± 0.001, and 4.2 ± 0.001 at 1 and 4 h for 99mTc-DTPA-(Me trp)2 and 4.97 ± 0.001 and 5.8 ± 0.001 at 1 and 4 h after postinjection for 99mTc-DTPA-(5HT)2, respectively. The preliminary results with these amino acid based ligands are encouraging to carrying out further in vivo experiments for targeted tumor imaging.

Ancillary