The rhizome of Angelica sinensis (Oliv.) Diels (Umbelliferae) is known as "Danggui" in China, has been used widely in traditional Chinese medicine to treat irregular menstruation, anaemia, headache, hypertension, chronic asthma and rheumatism. From the ethyl acetate extract of its roots four phthalides have been isolated. Their structures were identified by MS and NMR spectroscopic methods to be (Z)-3-butylidenphthalide, senkyunolide H, senkyunolide I and dihydroxyligustilide.
