Furocoumarins of three species of the genus Dorstenia

Phytochemical studies of the roots of Dorstenia excentrica afforded a diastereoisomer of prandiol having the 2?S,1?S configuration, 4-[3-(4,5-dihydro-5,5-dimethyl-4-oxo-2-furanyl)-butoxy]-7H-furo[3,2-g][1]1benzopyran-7-one, psoralen and 7-hydroxycoumarin. The furocoumarins 5-[3-(4,5-dihydro-5,5-dimethyl-4-oxo-2-furanyl)-butoxyl]-7H-[3,2-[1]benzopyran-7-one and bergapten were also present in the roots of D. drakena, while 7-hydroxycoumarin, psoralen and the psoralen dimer were isolated from D. lindeniana. The structure of the psoralen dimer was established by X-ray diffraction analysis.