Studies on the constituents of umbelliferae plants. XV Constituents of Cnidium officinale : Occurrence of pregnenolone, coniferylferulate and hydroxyphthalides.

Pregnenolone (1), coniferylferulate (2) and nine mono-and dihydroxyphthalide derivatives (5-13) were isolated from the commercial C. officinale rhizome. Their structures were determined from the spectroscopic data and the dihydroxyphthalides senkyunolide-H (11) and-I (12) and senkyunolide-J (13) were synthesized from the major components ligustilide (14) and senkyunolide-A (16), respectively. These oxygenated phthalides were absent in the fresh C. officinale rhizome and they were shown to be derived from the major volatile phthalides during storage of the crude drug. Coniferylferulate (2) also decomposes partly during storage, giving ferulic acid.