Linear Furocoumarins (Psoralens) from the Seed of Texas Ammi majus L. (Bishop's Weed)

Abstract

Twelve linear furocoumarins (psoralens) were isolated from the ripened seed of a Texas collection of the photosensitizing weed Ammi majus L. Four of the compounds, xanthotoxin, bergapten, isopim-pinellin, and isoimperatorin, have already been reported from this plant, and six of the eight other psoralens isolated are known plant products but have not been previously obtained from A. majus. Two of the A. majus psoralens, 8-[2-(3-methylbutyroxy)-3-hydroxy-3-methylbutoxy]psoralen and 5-[2-(acetoxy)-3-hydroxy-3-methylbutoxy]psoralen, have apparently not been previously isolated from any plant source. Six other synthetic psoralens were not observed in the seed extracts. Most of the major A. majus psoralens are potent photosensitizers, based on bioassays against chick skin, and the presence of these compounds in the seed and other parts of A. majus almost certainly accounts for the high photosensitizing activity of this plant toward cattle and sheep. © 1978, American Chemical Society. All rights reserved.