Mark E. Webster

Identification and chemical synthesis of MDL 105,212, a non-peptide tachykinin antagonist with high affinity for NK1 and NK2 receptors

We have synthesized and identified MDL 105,212, a non-peptide tachykinin receptor antagonist that has high affinity for human NK1 (IC50=3.11 nM) and NK2 (IC50=8.40 nM) receptors. The chemical synthesis of MDL 105,212 and the SAR of a series of racemic amide analogs are described.

Synthesis and structure-activity relationships for a series of substituted pyrrolidine NK1/NK2 receptor antagonists

Abstract We recently described the synthesis and characterization of MDL 105,212, a non peptide tachykinin antagonist with high affinity for NK1 and NK2 receptors.1 Here we report the synthesis and structure-activity relationships for a series of analogs of MDL 105,212 with regards to: NK1 and NK2 receptor binding affinity, physical-chemical characterization; in vitro absorption potential; in vitro metabolic stability; and efficacy in a capsaicin-challenge conscious guinea pig model after oral administration.

Discovery of orally bioavailable 1,3,4-trisubstituted 2-oxopiperazine-based melanocortin-4 receptor agonists as potential antiobesity agents.

A study that was designed to identify plausible replacements for highly basic guanidine moiety contained in potent MC4R agonists, as exemplified by 1, led to the discovery of initial nonguanidine lead 5. Propyl analog 23 was subsequently found to be equipotent to 5, whereas analogs bearing smaller and branched alkyl groups at the 3 position of the oxopiperazine template demonstrated reduced binding affinity and agonist potency for MC4R. Acylation of the NH2 group of the 4F-D-Phe residue of 3-propyl analog 23 significantly increased the binding affinity and the functional activity for MC4R. Analogs with neutral and weakly basic capping groups of the D-Phe residue exhibited excellent MC4R selectivity against MC1R whereas those with an amino acid had moderate MC4R/MC1R selectivity. We have also demonstrated that compound 35 showed promising oral bioavailability and a moderate oral half life and induced significant weight loss in a 28-day rat obesity model.

Hydroxyoxazolidines as α-aminoacetaldehyde equivalents: Novel inhibitors of calpain

The synthesis of [1-[(5-hydroxy-4-(phenylmethyl)-3-oxazolidinyl)carbonyl]-2-ethylpropyl]carbamic acid phenylmethyl ester (2; MDL 104,903), a potent inhibitor of calpain, is described. Synthesis of related compounds, which offer insights into the mechanism of action for 2, are also described, as is an O-acetyl prodrug derivative of 2.