Novel Meroterpenoids from Hypericum patulum: Highly Potent Late Nav1.5 Sodium Current Inhibitors.

Hypulatones A and B (1 and 2), two racemic meroterpenoids possessing an unprecedented spiro[benzofuran-2,1'-cycloundecan]-4'-ene-4,6(5H)-dione core, were characterized from Hypericum patulum. Compound 2 was found to significantly inhibit the late current of Nav1.5 (late INa, IC50 = 0.2 μM). Importantly, 2 exhibited remarkable separation (>100-fold) of late INa relative to peak INa and notable selectivity over Cav3.1, Kv1.5, and hERG. 1 showed comparable inhibition on late INa compared to that of 2 with poorer selectivity.