A fragment-based drug discovery strategy applied to the identification of NDM-1 β-lactamase inhibitors

Hydrolysis of β-lactam drugs, a major class of antibiotics, by serine or metallo-β-lactamases (SBL or MBL) is one of the main mechanisms for antibiotic resistance. New Delhi Metallo-β-lactamase-1 (NDM-1), an acquired metallo-carbapenemase first reported in 2009, is currently considered one of the most clinically relevant targets for the development of β-lactam-β-lactamase inhibitor combinations active on NDM-producing clinical isolates. Identification of scaffolds that could be further rationally pharmacomodulated to design new and efficient NDM-1 inhibitors is thus urgently needed. Fragment-based drug discovery (FBDD) has become of great interest for the development of new drugs for the past few years and combination of several FBDD strategies, such as virtual and NMR screening, can reduce the drawbacks of each of them independently. Our methodology starting from a high throughput virtual screening on NDM-1 of a large library (more than 700,000 compounds) allowed, after slicing the hit molecules into fragments, to build a targeted library. These hit fragments were included in an in-house untargeted library fragments that was screened by Saturation Transfer Difference (STD) Nuclear Magnetic Resonance (NMR). 37 fragments were finally identified and used to establish a pharmacophore. 10 molecules based on these hit fragments were synthesized to validate our strategy. Indenone 89 that combined two identified fragments shows an inhibitory activity on NDM-1 with a K_i value of 4 μM.

Synthesis, docking studies and biological evaluation of benzo[b]thiophen-2-yl-3-(4-arylpiperazin-1-yl)-propan-1-one derivatives on 5-HT1A serotonin receptors

A series of novel benzo[b]thiophen-2-yl-3-(4-arylpiperazin-1-yl)-propan-1-one derivatives 6a-f, 7a-f and their corresponding alcohols 8a-f were synthesized and evaluated for their affinity towards 5-HT(1A) receptors. The influence of arylpiperazine moiety and benzo[b]thiophene ring substitutions on binding affinity was studied. The most promising analogue, 1-(benzo[b]thiophen-2-yl)-3-(4-(pyridin-2-yl)piperazin-1-yl)propan-1-one (7e) displayed micromolar affinity (K(i) = 2.30 μM) toward 5-HT(1A) sites. Docking studies shed light on the relevant electrostatic interactions which could explain the observed affinity for this compound.

Fluorescent N-Heterocycles via One-Pot Tandem Reactions

Substituted indolizines are very attractive heterocyclic units. On developing efficient methods toward differently substituted indolizines, we were particularly interested in elaborating efficient approaches toward three-component reaction of these compounds which are very interested from the point of view fluorescent properties. The microwave-mediated three component reaction of acyl bromide, bipyridine and dipolarophyl is catalyzed by basic alumina to give corresponding bis-indolizines in excellent yields in a one –pot reaction.