STRUCTURE-ACTIVITY-RELATIONSHIPS OF UNSATURATED ANALOGS OF VALPROIC ACID

The principal metabolite of valproic acid (VPA), 2-ene VPA, appears to share most of VPA's pharmacological and therapeutic properties while lacking its hepatotoxicity and teratogenicity, thus making it a useful lead compound for the development of safer antiepileptic drugs. Analogues of 2-ene VPA were evaluated for anticonvulsant activity in mice using the subcutaneous pentylenetetrazole test. Cyclooctylideneacetic acid exhibited a potency markedly exceeding that of VPA itself with only modest levels of sedation. Potency, as either ED(50) or brain concentration, was highly correlated (r > 0.85) with volume and lipophilicity rather than with one of the shape parameters calculated by molecular modeling techniques, arguing against the existence of a specific receptor site. Instead, a role for the plasma membrane in mediating the anticonvulsant effect is suggested.