In our continuing search for novel
cancer chemopreventive compounds of natural and synthetic origin, we have evaluated 14 commonly used ultraviolet (UV)
sunscreen agents (designated UV-1 to UV-14) for their
skin cancer chemoprevention potential. They belong to 8 different chemical categories: aminobenzoate (UV-5, UV-7, UV-8 and UV-14),
benzophenone (UV-1, UV-2, UV-3 and UV-13),
benzotriazole (UV-10), benzyloxyphenol (UV-9),
cinnamate (UV-6),
quinolone (UV-4),
salicylate (UV-11) and
xanthone (UV-12). In the in vitro assay employed, the
sunscreens were assessed by their inhibition of the
Epstein-Barr virus early antigen (
EBV-EA) activation induced by the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in human lymphoblastoid Raji cells. All
sunscreens tested were found to exhibit anti-tumour promoting activity: listed in decreasing order, moderate (UV-11, UV-2, UV-7, UV-12, UV-3, UV-9 and UV-14) to weak (UV-1, UV-6, UV-8, UV-16, UV-5, UV-4 and UV-10) with octyl
salicylate (UV-11) as the most potent and
drometrizole (UV-10) as the least potent among the compounds evaluated. A plausible relationship between the
antioxidant property of
sunscreens and their ability to promote anti-tumour activity was noted. The results call for a comprehensive analysis of
skin cancer chemoprevention potential of currently used UV
sunscreen agents around the globe to identify those with the best clinical profile.