Application of Supercritical Fluid Extraction to Components of Crude Drugs and Plants. II. Extraction of Coumarins, Lignans and Prenylflavonoids

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Abstract
The supercritical fluid extraction was applied to coumarins, lignans and prenylflavonoids of crude drugs. Scoparone (1) and capillarisin (2), main components of Artemisia capillaris, were easily extracted with supercritical carbon dioxide. Scopoletin (3), fraxidin (6), isofraxidin (7) and fraxinol (8), which have a hydroxyl group on the coumarin skeleton, were also extracted from Fraxinus japonica and F. mandshurica var japonica, and when ethanol was used as an entrainer, the amounts of these coumarins were comparable to those obtained with boiling methanol. However, esculetin (4) and fraxetin (5) possessing two hydroxyl groups on the coumarin ring, were not extracted even in the presence of ethanol or water as an entrainer. Between two lignans, (+)-fraxiresinol (9) and (+)-1-hydroxypinoresinol (10), only the latter was extracted from F. japonica and F. mandshurica var. japonica, with supercritical earbon dioxide by using water or ethanol as an entrainer. Water was more efficient than ethanol as an entrainer for the supercritical extraction of 10, although ethanol was better than water for the extraction of the other compounds in this paper. Extractabilities of the lignans of Forsythia suspensa and F. viridissima, by the supercritical carbon dioxide were similar to those by boiling n-hexane, and similar to those by boiling methanol in the presence of the entrainers. Among the prenylflavonoids in the barks of Morus species, morusin (15) and sanggenon A (19) having less than three hydroxyl groups were extracted without using the entrainers, while those having more than four hydroxyl groups were not extracted even in the presence of entrainers.

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