Synthesis, structural activity-relationships, and biological evaluation of novel amide-based allosteric binding site antagonists in NR1A/NR2B N-methyl-D-aspartate receptors.

The synthesis and structure-activity relationship analysis of a novel class of amide-based biaryl NR2B-selective NMDA receptor antagonists are presented. Some of the studied compounds are potent, selective, non-competitive, and voltage-independent antagonists of NR2B-containing NMDA receptors. Like the founding member of this class of antagonists (ifenprodil), several interesting compounds of the series bind to the amino terminal domain of the NR2B subunit to inhibit function. Analogue potency is modulated by linker length, flexibility, and hydrogen bonding opportunities. However, unlike previously described classes of NR2B-selective NMDA antagonists that exhibit off-target activity at a variety of monoamine receptors, the compounds described herein show much diminished effects against the hERG channel and alpha(1)-adrenergic receptors. Selections of the compounds discussed have acceptable half-lives in vivo and are predicted to permeate the blood-brain barrier. These data together suggest that masking charged atoms on the linker region of NR2B-selective antagonists can decrease undesirable side effects while still maintaining on-target potency.

Nonpeptide inhibitors of measles virus entry.

Measles virus (MV) is one of the most infectious pathogens known. Despite the existence of a vaccine, over 500,000 deaths/year result from MV or associated complications. Anti-measles compounds could conceivably reverse these statistics. Previously, we described a homology model of the MV fusion protein trimer and a putative binding site near the head-neck region. The resulting model permitted the identification of two nonpeptidic entry inhibitors. Here, we present the design, synthesis, and bioevaluation of several series of fusion inhibitors and describe their structure-activity relationships (SAR). Five simply substituted anilides show low-microM blockade of the MV, one of which (AS-48) exhibits IC50 = 0.6-3.0 microM across a panel of wild-type MV strains found in the field. Molecular field topology analysis (MFTA), a 2D QSAR approach based on local molecular properties (atomic charges, hydrogen-bonding capacity and local lipophilicity), applied to the anilide series suggests structural modifications to improve potency.