Studies on the chemical components of Rutaceae plants-VI

A new coumarin, C20H22O4, named poncitrin, was isolated from the root of Poncirus trifoliata Rafinisque. The structures of poncitrin (III) and tetrahydroponcitrin (XV) have been elucidated, mainly by means of NMR spectroscopy including intramolecular nuclear Overhauser effect measurements.