Synthesis and 5-lipoxygenase inhibitory activities of some novel 2-substituted 5-benzofuran hydroxamic acids

A series of 2-substituted benzofuran hydroxyamic acids were synthesized as rigid analogs of simple (benzyloxy)phenyl hydroxamates, evaluated for their in vitro and in vivo 5-lipoxygenase activity and found to be potent inhibitors of the enzyme. Substituents which enhanced lipophilicity near the 2-position of the benzofuran nucleus increased inhibitor potency but reduced oral activity. Incorporation of small polar substituents such as methoxymethylene, hydroxymethylene, and amino (urea) on the acyl group led to more consistent oral activity. The most potent inhibitors of this series in vitro were N-hydroxy-N-[1-(2-phenyl-5-benzofuranyl)-ethyl]furancarboxamide (12) and methyl 5-[N-hydroxy-N-[1-(2-(3,4,5-trimethoxyphenyl)-5-benzofuranyl]ethyl]-5- oxopentanoate (17), both with IC50 values of 40 nM, and in vivo the most potent compound was N-hydroxy-N-[1-(2-phenyl-5-benzofuranyl)ethyl]urea, 20, with an ED50 = 10.3 mg/kg.