Novel molecular imaging ligands targeting matrix metalloproteinases 2 and 9 for imaging of unstable atherosclerotic plaques

Molecular imaging of matrix metalloproteinases (MMPs) may allow detection of atherosclerotic lesions vulnerable to rupture. In this study, we develop a novel radiolabelled compound that can target gelatinase MMP subtypes (MMP2/9) with high selectivity and inhibitory potency. Inhibitory potencies of several halogenated analogues of MMP subtype-selective inhibitors (N-benzenesulfonyliminodiacetyl monohydroxamates and N-halophenoxy-benzenesulfonyl iminodiacetyl monohydroxamates) were in the nanomolar range for MMP2/9. The analogue with highest inhibitory potency and selectivity was radiolabelled with [I-123], resulting in moderate radiochemical yield, and high radiochemical purity. Biodistribution studies in mice, revealed stabilization in blood 1 hour after intravenous bolus injection. Intravenous infusion of the radioligand and subsequent autoradiography of excised aortas showed tracer uptake in atheroprone mice. Distribution of the radioligand showed co-localization with MMP2/9 immunohistochemical staining. In conclusion, we have developed a novel selective radiolabeled MMP2/9 inhibitor, suitable for single photon emission computed tomography (SPECT) imaging that effectively targets atherosclerotic lesions in mice

GTP analogue inhibits polymerization and GTPase activity of the bacterial protein FtsZ without affecting its eukaryotic homologue tubulin

The prokaryotic tubulin homologue FtsZ plays a key role in bacterial cell division. Selective inhibitors of the GTP-dependent polymerization of FtsZ are expected to result in a new class of antibacterial agents. One of the challenges is to identify compounds which do not affect the function of tubulin and various other GTPases in eukaryotic cells. We have designed a novel inhibitor of FtsZ polymerization based on the structure of the natural substrate GTP. The inhibitory activity of 8-bromoguanosine 5'-triphosphate (BrGTP) was characterized by a coupled assay, which allows simultaneous detection of the extent of polymerization (via light scattering) and GTPase activity (via release of inorganic phosphate). We found that BrGTP acts as a competitive inhibitor of both FtsZ polymerization and GTPase activity with a Ki for GTPase activity of 31.8 +/- 4.1 microM. The observation that BrGTP seems not to inhibit tubulin assembly suggests a structural difference of the GTP-binding pockets of FtsZ and tubuli

Solid phase synthesis and antiprotozoal evaluation of di- and trisubstituted 5'-carboxamidoadenosine analogues

The rapid increase of resistance to drugs commonly used in the treatment of tropical diseases such as malaria and African sleeping sickness calls for the prompt development of new safe and efficacious drugs. The pathogenic protozoan parasites lack the capability of synthesising purines de novo and they take up preformed purines from their host through various transmembrane transporters. Adenosine derivatives constitute a class of potential therapeutics due to their selective internalisation by these transporters. Automated solid-phase synthesis can speed up the process of lead finding and we pursued the solid-phase synthesis of di- and trisubstituted 5'-carboxamidoadenosine derivatives by using a safety-catch approach. While efforts with Kenner's sulfonamide linker remained fruitless, successful application of the hydrazide safety-catch linker allowed the construction of two representative combinatorial libraries. Their antiprotozoal evaluation identified two compounds with promising activity: N(6)-benzyl-5'-N-phenylcarboxamidoadenosine with an IC(50) value of 0.91 microM against Trypanosoma brucei rhodesiense and N(6)-diphenylethyl-5'-phenylcarboxamidoadenosine with an IC(50) value of 1.8 microM against chloroquine resistant Plasmodium falciparu

Probing FtsZ and tubulin with C-8-substituted GTP analogs reveals differences in their nucleotide binding sites

11 páginas, 4 figuras, 2 tablas -- PAGS nros. 189-199The cytoskeletal proteins, FtsZ and tubulin, play a pivotal role in prokaryotic cell division and eukaryotic chromosome segregation, respectively. Selective inhibitors of the GTP-dependent polymerization of FtsZ could constitute a new class of antibiotics, while several inhibitors of tubulin are widely used in antiproliferative therapy. In this work, we set out to identify selective inhibitors of FtsZ based on the structure of its natural ligand, GTP. We found that GTP analogs with small hydrophobic substituents at C8 of the nucleobase efficiently inhibit FtsZ polymerization, whereas they have an opposite effect on the polymerization of tubulin. The inhibitory activity of the GTP analogs on FtsZ polymerization allowed us to crystallize FtsZ in complex with C8-morpholino-GTP, revealing the binding mode of a GTP derivative containing a nonmodified triphosphate chainThis work was supported in part by a Netherlands Organization for Scientific Research “Vernieuwingsimpuls” grant (016.001.024, T.d.B.) and grants MEC BFU 2005-00505/BMC and CAM S-BIO-0214-2006 (J.M.A.). A.V.P. acknowledges support by the Avenir grant of Inserm, ACI BCMS of the French Research Ministry (project BCM0210), and equipment grants of the “La Ligue contre le Cancer” (Comité de l'Isère) and the “Association pour la Recherche sur le Cancer” (project 7833). A.J. was funded by the program “Emergence 2004” of the Department de Rhône-AlpesPeer reviewe

Novel molecular imaging ligands targeting matrix metalloproteinases 2 and 9 for imaging of unstable atherosclerotic plaques

Molecular imaging of matrix metalloproteinases (MMPs) may allow detection of atherosclerotic lesions vulnerable to rupture. In this study, we develop a novel radiolabelled compound that can target gelatinase MMP subtypes (MMP2/9) with high selectivity and inhibitory potency. Inhibitory potencies of several halogenated analogues of MMP subtype-selective inhibitors (N-benzenesulfonyliminodiacetyl monohydroxamates and N-halophenoxy-benzenesulfonyl iminodiacetyl monohydroxamates) were in the nanomolar range for MMP2/9. The analogue with highest inhibitory potency and selectivity was radiolabelled with [123I], resulting in moderate radiochemical yield, and high radiochemical purity. Biodistribution studies in mice, revealed stabilization in blood 1 hour after intravenous bolus injection. Intravenous infusion of the radioligand and subsequent autoradiography of excised aortas showed tracer uptake in atheroprone mice. Distribution of the radioligand showed co-localization with MMP2/9 immunohistochemical staining. In conclusion, we have developed a novel selective radiolabeled MMP2/9 inhibitor, suitable for single photon emission computed tomography (SPECT) imaging that effectively targets atherosclerotic lesions in mice

Novel molecular imaging ligands targeting matrix metalloproteinases 2 and 9 for imaging of unstable atherosclerotic plaques - Fig 3

<p><b>Synthesis of 10 a-d.</b> (i): HN(CH₂COOH, THF/H₂O, rt, o/n, yield 3–35%; (ii): HN(CH₂CO₂<i>t</i>bu)₂, TEA, DCM, rt, o/n, 78–99%; (iii): HCOOH, rt, o/n, yield 75–94%; (iv): ECF, NMM, THF, NH₂OH x HCl, MeOH, 0°C, 2 h, yield 52–91%.</p

Synthesis of hydroxamate target compound 4a-e from 1a-e.

<p>(i): HN(CH₂CO₂<i>t</i>bu)₂,TEA, DCM, rt, o/n, yield 39–75%; (ii): HCOOH, rt, o/n, yield 30–93%; (iii): ECF, NMM, THF, NH₂OH x HCl, MeOH, 0°C, 2 h, yield 63–97%.</p

Radiosynthesis of [¹²³I]10c from 10d by nucleophilic radioiodination.

<p>(i): Na[¹²³I]I, ethanol, citric acid, 2,5 dihydroxybenzoic acid, CuSO₄, SnSO_4, 130°C, 40 min, yield 51%.</p

List of halogenated forms of two sulfonamide hydroxamate based compounds examined.

<p>List of halogenated forms of two sulfonamide hydroxamate based compounds examined.</p