Ortho-substituted benzofused macrocyclic lactams as zinc metalloprotease inhibitors

The design and preparation of ortho-substituted benzofused macrocyclic lactams are described. The benzofused macrocyclic lactams were designed as neutral endopeptidase 24.11 (NEP) inhibitors. Docking studies were carried out in a model of thermolysin (TLN) using the MACROMODEL and QXP modeling programs to select suitable ring sizes. These studies predicted that the 11-, 12-, and 13-membered ring macrocyclic lactams would be active in both enzymes TLN and NEP. Good predictability of experimental results, within this series, of binding to thermolysin and to a lesser extent to NEP was observed. A visual comparison, docked at the active site of TLN, is presented for thiorphan, a 10-membered ring macrocycle and an 11-membered ring benzofused macrocyclic lactam. Potent inhibition of both NEP and thermolysin was obtained. The 11-membered ring macrocycle 25a is the most potent inhibitor from this series of compounds (TLN IC50 = 68 nM; NEP IC50 = 0.9 nM). The effects of prodrug 44b administered at 10 mg/kg po on plasma atrial natriuretic peptide (ANP) levels in conscious rats was greater than 200% over a 4 h period.