Furocoumarins of Heracleum Laciniatum: isolation, phototoxicity, absorption and action spectra studies

Abstract

Isolation of the furocoumarins (psoralens) bergapten, isobergapten, sphondin, isopimpinellin and pimpinellin from the Umbilliferous plant H. laciniatum was carried out by column chromatography, and the structure and absorption spectra for the 5 furocoumarins isolated are described. Photoepicutaneous testing showed the strongest phototoxic effects from bergapten, marked effects from pimpinellin, weak effects from sphondin and none from the others. These in vivo findings [with humans] were confirmed by the in vitro Candida test. Action spectrum studies demonstrated peak photosensitivity in the range 330-335 nm, bergapten being more than twice as phototoxic as pimpinellin.