Generation of potentially bioactive ergosterol-derived products following pulsed ultraviolet light exposure of mushrooms (Agaricus bisporus)

The production of vitamin D₂ from ergosterol in mushrooms upon exposure to ultraviolet (UV) irradiation has been well established in recent years. However, the effect of this treatment on the generation of non-vitamin D₂ products of ergosterol in mushrooms has not been reported. In this study, the ergosterol-derived photoproducts previtamin D₂, lumisterol₂ and tachysterol₂ were, for the first time, identified and quantified in white button mushrooms (Agaricus bisporus) following treatment with pulsed UV (PUV) light. Mushrooms were treated with up to 60 pulses of PUV irradiation and the formation of major photoproducts was observed to increase as a function of dose. Vitamin D₂ was the most abundant product, followed by previtamin D₂, lumisterol₂ and tachysterol₂ in order of decreasing abundance. Untreated mushroom samples were not observed to contain detectable levels of any photoproduct. This study shows for the first time the production of these photoproducts in UV irradiated mushrooms. A complete understanding of the potential biological significance of these products remains to be seen.