PHOTOTOXIC COUMARINS IN LIMES

Coumarins in the rind and pulp of Persian and Key limes were quantifie d. In the rind of Persian limes, coumarin concentrations were in the o rder: limettin > bergapten > isopimpinellin > xanthotoxin > psoralen. In the rind of Key limes, psoralen and xanthotoxin were analytically a bsent; limettin was 10 times more concentrated than either bergapten o r isopimpinellin, which were equal in concentration. Coumarin content in Persian lime pulp was in the order: isopimpinellin > limettin > ber gapten > xanthotoxin > psoralen. For Key lime pulp, the concentrations of limettin, isopimpinellin and bergapten were equal; psoralen and xa nthotoxin were not detected. Coumarins in lime pulp were 13 to 182 tim es less concentrated than those in the peel. Based on the amounts and types of coumarins, Persian limes appear to be potentially more photot oxic than Key limes. Although bergapten may be the main component of l imes responsible for phytophotodermatitis, dermatological interaction assays with psoralen. bergapten, xanthotoxin and limettin should be co nducted.