Syntheses of trans-3′-substituted-CCG-IV analogs and their characterization to ionotropic glutamate receptors

Uncatalysed diaryldiazo cyclopropanations on bicyclic lactams: access to annulated prolines

The uncatalysed cycloaddition of substituted diaryldiazo compounds onto bicyclic unsaturated lactams derived from pyroglutamic acid efficiently leads to highly functionalised azatricyclononanes.

Synthesis and pharmacology of new enantiopure delta(3)-4-arylkainoids

Seven delta(3)-4-arylkainoids possessing various 4-position aromatic and heteroaromatic groups were synthesized and their apparent affinities were measured in order to explore the influences of 4-position electron density and stereochemistry on receptor affinity and specificity. Kainoids 1a-f were shown to be selective agonists at the NMDA receptor and the electron rich furanyl and thienyl analogues exhibited the highest affinities. Naphthylkainoid 1g proved to be a nonselective antagonist at the iGluRs.

Structure of kainic acid totally elucidated by NMR and molecular modelling

One class of glutamate receptors is characterized by the binding of the neuroexcitant and toxin kainic acid (KA), which contains an embedded L-glutamate moiety in a partially restricted (about the 2,3-bond) conformation. While there are a number of compounds that exhibit high specificity and selectivity at the ionotropic N-methyl-D-aspartate receptor, there has been a lack of selective and high-affinity ligands for the ionotropic KA subclass of excitatory amino acid receptors. This substance has received some attention recently being the least understood of the ionotropic type of glutamate receptor. The spatial orientation of the perceived functional groups of KA has been elucidated by a conformational analysis of an aqueous solution of KA using a combination of nuclear magnetic resonance (NMR) experimental results, mechanics and dynamics calculations, and theoretical simulation of NMR spectra. The weak pH-dependent effects on overall conformation and the structure of the principal '4E-envelope' KA conformer are established in aqueous solution. This study clearly shows the structural 'down' position of the double bond and the preferred 'g(-)-c' conformation of the C(3) carboxymethyl side-chain. The complex structure of this compound is thus definitively resolved. The conformation of the envelope ring such as C(3) carboxymethyl and C(4)-isopropenyl groups may strongly influence the potencies of KA interactions with the KA receptor.