As a part of ongoing project on biological screening of about a hundred plant extracts from Iran, the significant inhibitory effect of n-hexane extract of roots of Heracleum persicum on α-glucosidase and its 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity were revealed. The present study was designed to evaluate the antidiabetic and antioxidant activities of various extracts of roots of Heracleum persicum and isolation of ten furanocoumarin and a rare furanocoumarin-dimer type compounds through “bioassay guided fractionation” method. The structures were elucidated by 1D and 2D NMR, EI-MS, and HRESI-MS data as psoralen (1), bergapten (2), xanthotoxin (3), isopimpinellin (4), angelicin (5), isobergapten (6), sphondin (7), pimpinellin (8), heratomin (9), 5-methoxyheratomin (10), moellendorffiline (11), and fraxetin (12). Moellendorffiline (11) with the IC50 value of 17.9 nM showed significant inhibitory activity against α-glucosidase, more potent than acarbose (IC50 = 23.5 nM) and also exhibited high antioxidant activity (IC50 = 0.2 μM), compared with butylated hydroxytoluene (IC50 = 0.1 μM)
