Ensulizole
Ensulizole, also known as 2-phenylbenzimidazole-5-sulfonic acid, is a water-soluble sunscreen agent that absorbs strongly at UV-B wavelengths. It is commonly found in cosmetic products and sunscreen formulas in combination with other UV filter compounds due to its minimal protection against UV-A wavelengths. Due to its water solubility, ensulizole is commonly used in products formulated to feel light and less oily. It was demonstrated by studies that ensulizole treatment provided protection against cyclobutane pyrimidine dimers and photosensitized the formation of oxidized guanine bases after UV-A or UV-B exposure. According to the FDA, the maximal approved concentration of ensulizole is 148 mM although concentrations ranging between 74 and 148mM can be found in commercial sunscreen products.