Vasorelaxing effect of coumarins from Cnidium monnieri on rabbit corpus cavernosum

Bioassay-directed fractionation led to the identification of four known cou marins, osthole (1), imperatorin (2), xanthotoxin (3), and isopimpinellin ( 4), from the ethanolic extract of the fruit of Cnidium monnieri (L.) Cusson . In phenylephrine (PE)-precontracted endothelium-intact rabbit corpus cave rnosum, all four coumarins exhibited relaxing effect with the IC50 values f or compounds 1, 2, 3, and 4 determined to be 2.14 +/- 0.73, 0.85 +/- 0.16, 1.24 +/- 0.45, and 18.4 +/- 8.10 muM, respectively. The four compounds were identified by comparision of their physical data (EIMS, H-1- and C-13-NMR) with those from published reports.