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Organometallic 99mTc-technetium(I)- and Re-rhenium(I)-folate derivatives for potential use in nuclear medicine
- Source :
-
Journal of Organometallic Chemistry . Dec2004, Vol. 689 Issue 25, p4712-4721. 10p. - Publication Year :
- 2004
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Abstract
- Abstract: The folate receptor (FR) is a high affinity membrane protein which is overexpressed on a wide variety of tumor cells, but highly restricted in normal tissues. Therefore folate derivatives labeled with short living isotopes such as 99mTc (γ, t1/2=6 h) or 188Re (β−, t1/2=17 h) could be used for tumor diagnosis and therapy. In this respect there is a great interest to develop organometallic technetium(I) and rhenium(I) modified folate radiopharmaceuticals. For this purpose folic acid was functionalized with a tridentate picolylamine monoacetic acid chelating system. The chelating system was selectively coupled via an aminohexane spacer to the γ- or α-carboxyl group of the glutamate moiety of folic acid to obtain the corresponding γ- or α-folate derivative or – if directly attached to pteroic acid – the pteroate derivative. The derivatives were reacted with the precursor [M(OH2)3(CO)3]+ (M=99mTc, Re) to form uniform organometallic folate complexes under mild reaction conditions. All compounds were chemically characterized by means of NMR, MS, IR and HPLC. The determination of the IC50-values for the PAMA-γ-folate derivative (100 nM) and the corresponding organometallic rhenium complex (110 nM) proved retained receptor binding properties. The radiolabeling with [99mTc(OH2)3(CO)3]+ was achieved in excellent yield (>95%) at low ligand concentration (10−4 M). The cell binding (>45% of total activity) and internalization (>15% of total activity) of all 99mTc-complexes was very high and specificity for the FR was proved by their complete displacement with excess folic acid. The 99mTc-complexes were positively tested for their plasma stability and for the absence of binding to plasma proteins. [Copyright &y& Elsevier]
- Subjects :
- *RADIOACTIVE substances
*FOLIC acid
*VITAMIN B complex
*CANCER cells
Subjects
Details
- Language :
- English
- ISSN :
- 0022328X
- Volume :
- 689
- Issue :
- 25
- Database :
- Academic Search Index
- Journal :
- Journal of Organometallic Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 19266309
- Full Text :
- https://doi.org/10.1016/j.jorganchem.2004.08.045