Jean d'Angelo

Design of Folic Acid‐Conjugated Nanoparticles for Drug Targeting

The new concept developed in this study is the design of poly(ethylene glycol) (PEG)-coated biodegradable nanoparticles coupled to folic acid to target the folate-binding protein; this molecule is the soluble form of the folate receptor that is overexpressed on the surface of many tumoral cells. For this purpose, a novel copolymer, the poly[aminopoly(ethylene glycol)cyanoacrylate-co-hexadecyl cyanoacrylate] [poly(H(2)NPEGCA-co-HDCA)] was synthesized and characterized. Then nanoparticles were prepared by nanoprecipitation of the obtained copolymer, and their size, zeta potential, and surface hydrophobicity were investigated. Nanoparticles were then conjugated to the activated folic acid via PEG terminal amino groups and purified from unreacted products. Finally, the specific interaction between the conjugate folate-nanoparticles and the folate-binding protein was evaluated by surface plasmon resonance. This analysis confirmed a specific binding of the folate-nanoparticles to the folate-binding protein. This interaction did not occur with nonconjugated nanoparticles used as control. Thus, folate-linked nanoparticles represent a potential new drug carrier for tumor cell-selective targeting.

Styrylquinolines, Integrase Inhibitors Acting Prior to Integration: a New Mechanism of Action for Anti-Integrase Agents

ABSTRACT We have previously shown that styrylquinolines (SQLs) are integrase inhibitors in vitro. They compete with the long terminal repeat substrate for integrase. Here, we describe the cellular mode of action of these molecules. We show that SQLs do not interfere with virus entry. In fact, concentrations of up to 20 times the 50% inhibitory concentration did not inhibit cell-to-cell fusion or affect the interaction between GP120 and CD4 in vitro. Moreover, the pseudotype of the retrovirus envelope did not affect drug activity. Quantitative reverse transcription PCR experiments showed that SQLs do not inhibit the entry of the genomic RNA. In contrast, the treatment of human immunodeficiency virus type 1-infected cells with SQLs reduced the amount of the late cDNA, suggesting for the first time that integrase targeting molecules may affect the accumulation of DNA during reverse transcription. The cellular target of SQLs was confirmed by the appearance of mutations in the integrase gene when viruses were grown in the presence of increasing concentrations of SQLs. Finally, these mutations led to SQL-resistant viruses when introduced into the wild-type sequence. In contrast, SQLs were fully active against reverse transcriptase inhibitor- and diketo acid-resistant viruses, positioning SQLs as a second group of anti-integrase compounds.

HIV-1 integrase: the next target for AIDS therapy?

HIV-1 is the aetiological agent of AIDS. Present treatment of AIDS uses a combination therapy with reverse transcriptase and protease inhibitors. Recently, the integrase (IN), the third enzyme of HIV-1 which is necessary for the integration process of proviral DNA into the host genome, has reached as a legitimate new drug target. Several families of inhibitors of the catalytic core domain of HIV-1 IN exhibiting submicromolar activities have now been identified. Our contribution in this field was related to the development of new polyhydroxylated styrylquinolines. The latter compounds have proved to be potent HIV-1 IN inhibitors, that block the replication of HIV-1 in cell culture, and are devoid of cytotoxicity. The crystal structure of the catalytically active core domain of a HIV-1 IN mutant has been determined. The active site region is identified by the position of two of the conserved carboxylate residues essential for catalysis, Asp64 and Asp116, which coordinate a Mg2+ ion, whereas the third catalytic residue, Glu152 does not participate in metal binding. However, a recent molecular dynamics simulation of the HIV-1 IN catalytic domain provides support to the hypothesis that a second metal ion is likely to be carried into the HIV-1 IN active site by the DNA substrate. The structure of a complex of the HIV-1 IN core domain with the inhibitor 5-CITEP has been recently reported. The inhibitor binds centrally in the active site of the IN and makes a number of close contacts with the protein, particularly with Lys156, Lys159 and Gln148, amino acids which were identified to be near the active site of the enzyme, through site-directed mutagenis and photo-crosslinking experiments. The exact mechanism by which HIV-1 IN inhibitors block the catalytic activity of the protein remains unknown. However, several putative pharmacophore components have been characterized. All these groups lie in a possible coordination to a divalent ion, supporting thus the hypothesis that the interaction causing the inhibition is mediated by one or two cations. Finally, among the HIV-1 IN inhibitors, three classes have proved to exhibit significant antiviral activities. Thus, it seems likely that the efficient use of HIV-1 IN as a target for rational design will become possible in the next future, possibly through the use of combination regimens including IN inhibitors.

Enantioselective synthesis of oxa-spiro compounds

Abstract Optically active compound 10b, efficiently prepared from imine 8b, was transformed into oxa-spiro derivatives 15 and 16 .

The asymmetric michael addition process involving chiral imines : stereochemical data in support of a cyclic-like transition state

Abstract Additions of imine 4 to Michael acceptors 5 and 8 are both highly selective processes. The observed stereocontrol of the newly created asymmetric centers in the resulting adducts strongly supports cyclic-like transition states.

Enantioselective synthesis of ring-C aromatic steroids by asymmetric Michael-type alkylation of chiral imines.

Abstract Optically active phenanthrones 7 and 12 were prepared, using the asymmetric process involving Michael-type alkylation of chiral imines. Compound 12 was then transformed into the ring-C aromatic steroid 16 .

HIV-1 replication inhibitors of the styrylquinoline class: incorporation of a masked diketo acid pharmacophore

Abstract A novel variant of HIV-1 replication inhibitors of the styrylquinoline class, bearing an α-keto acid appendage at C-7, has been synthesized. Though completely inactive in in vitro experiments against HIV-1 integrase, this compound exhibited a significant antiviral activity (IC 50 =10 μM).

Racemization processes at a quaternary carbon center in the context of the asymmetric Michael reaction

Abstract Several examples of racemization process at a quaternary carbon center affecting Michael adducts were reported. A brief statement to prevent the occurrence of the interfering retro-Michael reaction was also presented.

A new strategy for the enantioselective synthesis of aspidosperma alkaloids: I - Construction of the [ABC]-type tricyclic intermediates.

Abstract Carbazolone 19 has been prepared in eight steps from cyclohexanone 11 (36% overall yield).

The asymmetric Michael process involving chiral imines: the diastereofacial differentiation aspect

Abstract A mechanism for the diastereofacial differentiation in the title reaction is proposed on the basis of the variation of the chiral auxiliary amines and of the examination of the crystal structure of enamino-ester 15 .