Philippe Uriac

Synthesis and cytotoxic activities of usnic acid derivatives

Nine usnic acid-amine conjugates were evaluated on murine and human cancer cell lines. The polyamine derivatives showed significant cytotoxicity in L1210 cells. Their activities appeared to be independent of the polyamine transport system (PTS). Indeed, their activities were similar in chinese hamster ovary (CHO) and in the PTS deficient CHO-MG cells. In addition, alpha-difluoromethylornithine, an ornithine decarboxylase inhibitor known to indirectly enhance the activity of the PTS and consequently increase the cytotoxicity of cytotoxic drugs entering cells via the PTS, had no effect on the activity of the polyamine derivatives. The more active derivative (1,8-diaminooctane derivative) displayed similar activities on all cancer cell lines studied and induced apoptosis.

Synthesis of substituted pyrrolin-4-ones from amino acids in mild conditions via a gold-catalyzed approach.

The gold-catalyzed cyclization of various alpha-amino-ynone derivatives gave the corresponding pyrrolin-4-ones in high yields. Moreover, the use of gold(III) oxide as catalyst allows a moderate to total stereocontrol during the cyclization. These pyrrolin-4-ones are highly useful intermediates for the synthesis of functionalized pyrrolidines and other natural products.

Solid phase organic synthesis of polyamine derivatives and initial biological evaluation of their antitumoral activity

A series of N1-monosubstituted putrescine and spermine derivatives was synthesised using a solid phase methodology. We evaluated their cytotoxicity, calmodulin antagonism and polyamine uptake inhibition, pharmacological properties shared by some antitumoral agents.

Novel chiral molecular tweezer from (+)-usnic acid.

A new chiral molecular tweezer was synthesized with (1R,2R)-1,2-diaminocyclohexane as spacer and two molecules of (+)-usnic acid as pincers. The ability of this molecular tweezer to bind 2,4,7-trinitrofluorenone was studied. A charge-transfer complex was formed in which TNF was sandwiched between the two usnic acid units with pi-pi-stacked aromatic interactions.

1-Benzazepine derivatives acting as ATP-dependent potassium-channels antagonists

Summary In order to select between various pharmacological activities related to the 1-benzazepine nucleus, a set of 1-benzazepine derivatives bearing different N-1 or C-2 substituents were synthesized and tested in vitro as ATP-dependent K + -channel antagonists on isolated guinea-pig trachea. Cumulative concentration curves to cromakalim were constructed in the absence or presence of the various compounds tested in comparison with glibenclamide. Products bearing N-1 substituents, especially (2-imidazolinyl)methyl showed a non-competitive antagonism towards ATP-dependent K + channels.

Gold-Mediated Synthesis and Functionalization of Chiral Halopyridones

A rapid and efficient one-step halopyridone synthesis has been developed based on gold-catalyzed cyclization of β-amino-ynone intermediates and halodeauration process.

Targeting the Polyamine Transport System with Benzazepine- and Azepine-Polyamine Conjugates†

The polyamine transport system (PTS) whose activity is up-regulated in cancer cells is an attractive target for drug design. Two heterocyclic (azepine and benzazepine) systems were conjugated to various polyamine moieties through an amidine bound to afford 18 compounds which were evaluated for their affinity for the PTS and their ability to use the PTS for cell delivery. Structure-activity relationship studies and lead optimization afforded two attractive PTS targeting compounds. The azepine-spermidine conjugate 14 is a very selective substrate of the PTS that may serve as a vector for radioelements used for diagnoses or therapeutics in nuclear medicine. The nitrobenzazepine-spermine conjugate 28 is a very powerful PTS inhibitor with very low intrinsic cytotoxicity, able to prevent the growth of polyamine depleted cells in presence of exogenous polyamines.

Solid-phase combinatorial synthesis of polyamine derivatives using aminoalcohol building blocks

Abstract A systematic study of nucleophilic displacement of mesyl groups using benzylamine was carried out on Multipin Synphase™ supports. The optimal conditions were applied for the combinatorial synthesis of polyamine derivatives from commercially available aminoalcohols and amines.

Combined approaches for drug design points the way to novel proline racemase inhibitor candidates to fight Chagas' disease.

Chagas’ disease is caused by Trypanosoma cruzi, a protozoan transmitted to humans by blood-feeding insects, blood transfusion or congenitally. Previous research led us to discover a parasite proline racemase (TcPRAC) and to establish its validity as a target for the design of new chemotherapies against the disease, including its chronic form. A known inhibitor of proline racemases, 2-pyrrolecarboxylic acid (PYC), is water-insoluble. We synthesized soluble pyrazole derivatives, but they proved weak or inactive TcPRAC inhibitors. TcPRAC catalytic site is too small and constrained when bound to PYC to allow efficient search for new inhibitors by virtual screening. Forty-nine intermediate conformations between the opened enzyme structure and the closed liganded one were built by calculating a transition path with a method we developed. A wider range of chemical compounds could dock in the partially opened intermediate active site models in silico. Four models were selected for known substrates and weak inhibitors could dock in them and were used to screen chemical libraries. Two identified soluble compounds, (E)-4-oxopent-2-enoic acid (OxoPA) and its derivative (E)-5-bromo-4-oxopent-2-enoic acid (Br-OxoPA), are irreversible competitive inhibitors that presented stronger activity than PYC on TcPRAC. We show here that increasing doses of OxoPA and Br-OxoPA hamper T. cruzi intracellular differentiation and fate in mammalian host cells. Our data confirm that through to their binding mode, these molecules are interesting and promising as lead compounds for the development of chemotherapies against diseases where active proline racemases play essential roles.

Electrochemical oxidation of 2,5-dihydro-1h-1-benzazepines : Synthesis of 5H-1-benzazepines

Abstract Formation of 5H-1-benzazepines was observed after electrochemical oxidation of the title compounds in a flow cell at a graphite felt anode and in acetic buffer. In basic medium, coupling reaction also occurs leading to [2,5-dihydro-1H-1-benzazepin-1-yl]-5H-1-benzazepines. Oxidation mechanisms are discussed.