Absence of phototoxicity/photoirritation potential of bergamottin determined In Vitro using OECD TG 432

The phototoxic potential of a number of furocoumarins is well established. On the other hand, studies have shown that bergamottin, a furocoumarin containing a bulky, hydrophobic side chain, has significantly less or is even absent of phototoxicity potential. The OECD Test Guideline 432 3T3/Neutral Red Uptake (NRU) in vitro phototoxicity test has shown to be a highly predictive test for identifying compounds that exhibit no phototoxicological potential. In this study using OECD 432, the established phototoxic furocoumarin 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP) and psoralen were phototoxic, whereas bergamottin showed no phototoxic potential. When compared to 5-MOP, 8-MOP and psoralen, bergamottin was clearly negative at molar-adjusted concentrations that were more than 9 times higher than those that produced phototoxicity in 8-MOP; nearly 16 times than those for psoralen and more than 36 times higher than those for 5-MOP. These data using in vitro 3T3 NRU Phototoxicity Test (OECD 432) are supportive of earlier studies showing bergamottin does not exhibit phototoxicological properties. The detection and quantification of bergamottin should therefore not contribute to the potential marker furocoumarins for risk management interventions intended to reduce the phototoxicity of natural furocoumarin containing preparations.