Abdominal and midback skin were more photosensitive than skin of the lateral aspects of the underarms and legs. 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 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. Kavli G Midelfart GV Haugsbo S Prytz JO Phototoxicity of Heracleum laciniatum.
Case reports and experimental studies.
Experimental phytophotodermatitis was produced using homogenates from leaves of the plant and long-wave ultraviolet light. The homogenates of leaves produced strong phototoxic reactions. The minimal phototoxic erythema dose was determined to be lowest for abdominal and midback skin. Camm E Buck HW Mitchell JC Phytophotodermatitis from Heracleum mantegazzianum. Photopatch testing confirmed phototoxicity from the plant.