Preparation of 99mTc-labelled conjugates of ouabagenin and their biological evaluation in animal models.
BACKGROUND
Ouabagenin and its 1,19-acetonide were conjugated with nitrilotriacetic acid (NTA) and diethylenetriaminepentaacetic acid (DTPA) through their respective anhydrides.


METHODS
The reaction mixtures were exhaustively purified by silica gel column chromatography and preparative high-performance liquid chromatography to furnish the ligands in good purity and moderate yield. These ligands were labelled with 99mTc to produce four chelates in 90-95% yield. Of these chelates the 99mTc-oubagenin-NTA conjugate and the corresponding acetonide exhibited appreciable myocardial uptake with respect to that of other vicinal organs in a guinea-pig model. However, all these 99mTc chelates exhibited poor heart-to-blood ratios, which could be attributed to the absence of a 3beta sugar residue in this molecule.


CONCLUSIONS
The result is in agreement with that previously reported in connection with radioiodinated digoxin and digoxigenin derivatives.
Debnath
Mita C
MC
Department of Nuclear Medicine, Indian Institute of Chemical Biology, Kolkata, India. mita_chdebnath@yahoo.com
Sarkar
Bharat R
BR
Ganguly
Shantanu
S
Banerjee
Somenath
S
D000818:Animals; D006168:Guinea Pigs; D006321:Heart / Q000000981:diagnostic imaging; D007553:Isotope Labeling / Q000379:methods; D008657:Metabolic Clearance Rate; D023421:Models, Animal; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity; D010042:Ouabain / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D011817:Rabbits; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics; D051381:Rats; D013045:Species Specificity; D013667:Technetium / Q000737:chemistry* / Q000493:pharmacokinetics*; D014018:Tissue Distribution
D019275:Radiopharmaceuticals; D010042:Ouabain; D013667:Technetium; C008721:ouabagenin