Ficus carica; isolation and quantification of the photoactive components.
The presence and levels of furocoumarins in several parts of Ficus carica including the milky sap, were investigated. The results show that psoralen and bergapten are the only significant photoactive compounds, and are present in appreciable quantities in the leaf and shoot sap but are not detected in the fruit or its sap. These compounds are more concentrated in the leaf sap compared to the shoot sap. The psoralen levels are several times higher than those of bergapten. Lower concentrations of both compounds are present in autumn compared to spring and summer. These findings suggest that the reaction is induced primarily by psoralen. The response can follow contact with the leaf and shoot sap but not with the fruit sap, and is expected to occur more frequently from exposure to the leaf sap. The higher content of both photoactive compounds in spring and summer is partly responsible for the increased incidence of fig dermatitis during these seasons. Ingestion of the fruit does not cause photosensitization and the absence of photoactive furocoumarins in the fruit and its sap remains unexplained.