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Sidi Thabet, Tunisia

Malek-Saied N.,Radiopharmaceutical Unit | Aissi R.E.,Radiopharmaceutical Unit | Aissi R.E.,French National Center for Scientific Research | Aissi R.E.,Toulouse 1 University Capitole | And 3 more authors.
Applied Organometallic Chemistry | Year: 2011

A new cytectrene prototype of general formula RCpTc(CO)3 (R = C6H5NHCO, Cp = cyclopentadienyl moiety) has been synthesized from N-phenylferrocenecarboxamide 2, characterized and evaluated as a potential brain perfusion imaging agent. An improved procedure has been developed to obtain both the ligand 2, characterized by its solid-state structure (orthorhombic, Pccn, a = 10.4443(2) Å, b = 26.1467(6) Å, c = 9.9977(3) Å), and the corresponding metallic Tc- and Re-complexes in good yield. These latter complexes possessed similar HPLC retention times, thereby indicating identity of their molecular structures. The Tc-complex 99mTc-2 is lipophilic enough to cross the blood-brain barrier. This complex exhibits good brain uptake (1.41% injected dose per gram tissue at 5 min) combined with a fairly good retention of radioactivity in brain (0.48% injected dose per gram tissue after 1 h). Then, the distribution of the activity at 5 min post-injection in various rat brain regions showed a higher accumulation in the hippocampus area. The new 99mTc- cyclopentadienyltricarbonyl technetium complex reported here showed promising biological results, making it an interesting base for the development of a new generation of cytectrene as brain perfusion imaging agent. Copyright © 2011 John Wiley & Sons, Ltd. Source

El Aissi R.,Radiopharmaceutical Unit | El Aissi R.,French National Center for Scientific Research | El Aissi R.,Toulouse 1 University Capitole | Malek-Saied N.,Radiopharmaceutical Unit | And 5 more authors.
Radiochimica Acta | Year: 2015

The synthesis, characterization and biological evaluation of five neutral and lipophilic 99mTc-complexes, so-called cytectrenes, obtained from N-substitutedferrocenecarboxamide derivatives are reported. N-substitutedferrocenecarboxamide starting materials were obtained in two steps, with good yield and were fully characterized by classical spectroscopic methods including X-ray diffraction analysis for one of them. Using a microwave strategy for the 99mTc-radiolabelling step, each cytectrene were obtained quickly (radiolabelling time <5 min), from modest to good yield. The 99mTc-complexes, characterized by HPLC comparison with cold rhenium complex analogues, are stable, neutral and lipophilic (log Po/w ranged between 1.8 and 2.9). Unfortunately, despite such suitable features, in vivo studies of two of them gave poor results, in terms of brain uptake. Both radiocompounds exhibited the maximum brain accumulation of 0.31% ID/g and 0.26% ID/g at 5 min post-injection, respectively, followed by a very fast washout from the brain (0.06% ID/g and 0.07% ID/g at 30 min post-injection, respectively). Although our ligand systems exhibited high stability against exchange reactions with blood proteins, the high radioactivity level in stomach, increasing with time, suggests in vivo decomposition of our complex to pertechnetate. © 2014 Walter de Gruyter Berlin/Boston. Source

Essouissi I.,Radiopharmaceutical Unit | Saied N.M.,Radiopharmaceutical Unit | Mejri N.,Radiopharmaceutical Unit | Guizani S.,Radiopharmaceutical Unit | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2014

In this work we propose a technetium-99m-labeled derivative from Ethionamide (ETH), further referred to as 99mTc-ECF for tuberculosis diagnosis. The biological features of this radioactive agent have been studied. The 2-ethylpyridine-4-carbothioamide-ferrocène (ECF) was chemically synthesized and then labeled with technetium-99m. It has been confirmed through this work that 99mTc-ECF is obtained with high radiolabelling yield (>90 %). Radiochemical analysis of 99mTc-ECF revealed that the molecule was efficiently labeled with a little free remaining pertechnetate. Only 1-2 % of the tracer was leached out from the complex at 24 h when incubated in serum at 37°C which confirmed its high stability. The sensitivity test of ECF showed that the group of grafted ferrocenyl does not seem to have largely altered the active site of the molecule. In-vitro investigations were conducted using BCG (Bacille Calmette-Guérin) as analogue of Mycobacterium Tuberculosis and Listeria Monocytogenes as negative control. It was proved that for BCG, ECF has kept the bacteriostatic properties of the parent compound (ETH). In physiological conditions, the measured up-take of the tracer with live bacteria was about 24.1 and 7.1 % for BCG and Listeria Monocytogenese, respectively. The comparison of the 99mTc-ECF accumulation at sites of BCG infected animals, which is expressed as target-to-non-target ratio (found to be equal to 2.15) with other radiotracers was discussed. This allowed us to consider that 99mTc-ECF could be a reasonable radiotracer for mycobacterial infections. Obtained results were good and encourage to undergo a similar labeling for the Mycobacterium tuberculosis as perspective of this work. © 2014 Akadémiai Kiadó. Source

Guizani S.,Radiopharmaceutical Unit | Malek Saied N.,Radiopharmaceutical Unit | Picard C.,CNRS Chemistry Laboratory | Picard C.,Toulouse 1 University Capitole | And 3 more authors.
Journal of Labelled Compounds and Radiopharmaceuticals | Year: 2014

A novel bifunctional chelating agent based on a click chemistry strategy has been synthesized and characterized on the basis of spectroscopic techniques. The metal chelating part of this new class of tridentate N2O ligand combined a triazole unit and an aromatic ring. This latter semi-rigid framework induced a pre-organization of the chelating cavity, improving the stability of the corresponding metallic complexes (M = 99mTc, Re). Thus, the 99mTc(CO)3 complex, obtained with good yield and excellent radiochemical purity (>90%), exhibited a high in vitro serum stability. Tissue biodistribution in normal mice showed a rapid clearance, no long-term retention in organs and no in vivo reoxidation of technetium-99m, making this compound a promising 99mTc-chelating system. Copyright © 2014 John Wiley & Sons, Ltd. Source

Essouissi I.,Radiopharmaceutical Unit | Ghali W.,Radiopharmaceutical Unit | Saied N.M.,Radiopharmaceutical Unit | Saidi M.,Radiopharmaceutical Unit
Nuclear Medicine and Biology | Year: 2010

A technetium-99m-labeled derivative from sulfanilamide, further referred to as 99mTc-N-SFC, targeting infections in experimental animals, has been synthesized. The biological features of this radioactive agent have also been studied. The N-sulfanilamide ferrocene carboxamide (N-SFC) was chemically synthesized and then labeled with technetium-99m. It has been confirmed through this work that it is stable and obtained with radiolabelling yield (>87%). Radiochemical analyses of 99mTc-N-SFC revealed that the molecule was labeled rapidly (within 2 min) and effectively with little free pertechnetate in the preparations containing purified compound. Furthermore, in vitro investigations were conducted and the label's stability in serum was observed up to 24 h of testing. Uptake of the tracer with live and heat/killed bacteria was compared in physiological conditions and was about 69% and 61.9% for the Escherichia coli and Staphylococcus aureus strains, respectively. We concluded that synthesis and labeling of Sulfanilamide derivative with 99m-Tc by this method is rapid, efficient and safe. Biodistribution studies demonstrated that our radiolabeled compound is accumulated rapidly and significantly (P<.05) at infection sites. The comparison of the 99mTc-N-SFC accumulation at sites of S. aureus-infected animals, which is expressed as target-to-non-target ratio, (2.88±0.10) with other radiotracers was discussed. © 2010 Elsevier Inc. Source

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