Anovel photoprotectivemycosporinewas isolated fromthe lichenized ascomyceteCollema cristatum. Biological activity was measured in terms of protection against UV-B induced membrane destruction and pyrimidine dimer formation in cultured human keratinocytes, and prevention of UV-B induced erythema. It was found that the pure isolated compound prevented UV-B induced cell destruction in a dose-dependent manner, that the compound partially pre-vented pyrimidine dimer formation and completely preven-ted UV-B induced erythema when applied to the skin prior to irradiation
