Vasorelaxing effect of coumarins from Cnidium monnieri on rabbit corpus cavernosum.

Bioassay-directed fractionation led to the identification of four known coumarins, 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 cavernosum, all four coumarins exhibited relaxing effect with the IC50 values for 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 microM, respectively. The four compounds were identified by comparison of their physical data (EIMS, 1H- and 13C-NMR) with those from published reports.