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.
Department of Nuclear Medicine, Indian Institute of Chemical Biology, Kolkata, India. mita_chdebnath@yahoo.com
Mita C
MC
Debnath
Bharat R
BR
Sarkar
Shantanu
S
Ganguly
Somenath
S
Banerjee
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