Synthesis, HPLC enantioresolution and X-ray analysis of a new series of C5-methyl pyridazines as N-formyl peptide receptor (FPR) agonists

The synthesis of three racemates and the corresponding non chiral analogues of a C5-methyl pyridazine series is described here, as well as the isolation of pure enantiomers and their absolute configuration assignment. In order to obtain optically active compounds, direct chromatographic methods of separation by HPLC-UV were investigated using four chiral stationary phases (CSPs: Lux Amylose-2(®), Lux Cellulose-1(®), Lux Cellulose-2(®) and Lux Cellulose-3(®)). The best resolution was achieved using amylose tris(5-chloro-2-methylphenylcarbamate) (Lux Amylose-2(®)), and single enantiomers were isolated on a semipreparative scale with high enantiomeric excess, suitable for biological assays. The absolute configuration of optically active compounds was unequivocally established by X-ray crystallographic analysis and comparative chiral HPLC-UV profile. All compounds of the series were tested for formyl peptide receptor (FPR) agonist activity, and four were found to be active, with EC(50) values in the micromolar range

Synthesis and pharmacological evaluation of indole derivatives as deaza analogues of potent human neutrophil elastase inhibitors

A number of N-benzoylindoles were designed and synthesized as deaza analogues of our previously reported potent and selective HNE inhibitors with an indazole scaffold. The new compounds containing substituents and functions that were most active in the previous series were active in the micromolar range (the most potent had IC(50)=3.8 µM) or inactive. These results demonstrated the importance of N-2 in the indazole nucleus. Docking studies performed on several compounds containing the same substituents but with an indole or an indazole scaffold, respectively, highlight interesting aspects concerning the molecule orientation and H-bonding interactions, which could help to explain the lower activity of this new series

Synthesis, enantioresolution and activity profile of chiral 6-methyl-2,4-disubstituted pyridazin-3(2H)-ones as potent N-formyl peptide receptor agonists.

A series of chiral pyridazin-3(2H)-ones was synthesized, separated as pure enantiomers, and evaluated for N-formyl peptide receptor (FPR) agonist activity. Characterization of the purified enantiomers using combined chiral HPLC and chiroptical studies (circular dichroism, allowed unambiguous assignment of the absolute configuration for each pair of enantiomers). Evaluation of the ability of racemic mixtures and purified enantiomers to stimulate intracellular Ca(2+) flux in FPR-transfected HL-60 cells and human neutrophils and to induce β-arrestin recruitment in FPR-transfected CHO-K1 cells showed that many enantiomers were potent agonists, inducing responses in the sub-micromolar to nanomolar range. Furthermore, FPRs exhibited enantiomer selectivity, generally preferring the R-(−)-forms over the S-(+)-enantiomers. Finally, we found that elongation of the carbon chain in the chiral center of the active compounds generally increased biological activity. Thus, these studies provide important new information regarding molecular features involved in FPR ligand preference and report the identification of a novel series of FPR agonists