Isoxazole analogues bind the System xc- transporter: Structure–activity relationship and pharmacophore model

Analogues of amino methylisoxazole propionic acid (AMPA), were prepared from a common intermediate 12, including lipophilic analogues using lateral metalation and electrophilic quenching, and were evaluated at System xc-. Both the 5-naphthylethyl-(16) and 5-naphthylmethoxymethyl-(17) analogues adopt an E  -conformation in the solid state, yet while the former has robust binding at System xc-, the latter is virtually devoid of activity. The most potent analogues were amino acid naphthyl-ACPA 7g, and hydrazone carboxylic acid, 11e Y = Y′ = 3,5-(CF3)2, which both inhibited glutamate uptake by the System xc- transporter with comparable potency to the endogenous substrate cystine, whereas in contrast the closed isoxazolo[3,4-d] pyridazinones 13 have significantly lower activity. A preliminary pharmacophore model has been constructed to provide insight into the analogue structure–activity relationships.

Isoxazole amino acid 7g and hydrazone 11e were found to possess System xc- binding affinity comparable to the endogenous substrate cystine, and using these observations a pharmacophore model had been developed.Figure optionsDownload as PowerPoint slide