Photoprotective effect of coumarin and 3-hydroxycoumarin in sea urchin gametes and embryonic cells.

Ultraviolet radiation B (UVB) represents 5% of all solar UV radiation and chronic exposure can induce harmful biological responses, including skin cancer. Prospection of new drugs with photoprotective properties and less toxic effects is constant and natural products have been the main options in this field. Coumarins are a group of natural phenolic compounds that shows several pharmacological activities. The aim of present work was to investigate the effect of coumarin and six derivatives in sea urchin gametes and zygotes exposed to UVB. Embryonic development assay was used to monitor UVB embryotoxicity. Firstly, we demonstrated that coumarin inhibited first embryonic cell division from 5 μM (EC50 = 52.9 μM) and its derivatives showed an embryotoxic effect ten times higher. Then, gametes or zygotes were treated with coumarin compounds before or after UVB exposure (UVB doses ranged from 0.056 to 0.9 kJm(-2)). Pretreatment of gametes or zygotes with coumarin or 3-hydroxycoumarin (1 μM, both) decreased UVB embryotoxic effect. Protective effect of the compounds was observed only when cells were treated previous to UVB exposure. Coumarin derivatives 4-hydroxycoumarin, 6-hydroxycoumarin, 7-hydroxycoumarin, 6,7-dihydroxycoumarin and 6-methoxy-7-hydroxycoumarin did not exhibit photoprotective activity. Our data provides evidences that coumarin and 3-hydroxycoumarin can be a promising class of photoprotective drugs.