The conversion of previtamin D2 to vitamin D2 in white button mushrooms and baby bella mushrooms, and in organic solvent

Abstract

Vitamin D is essential for maintaining bone metabolism, calcium homeostasis, the immune system, and much more. Upon exposure to sunlight, 7-dehydrocholestrol in the skin converts to previtamin D3, which undergoes a temperature-dependent isomerization in the plasma membrane to form the more stable vitamin D3. Many species of plants and fungi, including mushrooms, produce vitamin D2 from ergosterol upon exposure to ultraviolet-B radiation. To determine whether the vitamin D formation in mushrooms is more similar to that in human skin or in organic solvent, this study compares the rate of thermal isomerization of previtamin D2 to vitamin D2 in white button mushrooms and baby bella mushrooms with the isomerization in methanol under identical conditions. At 25°C, the rate of isomerization is enhanced by approximately 400% in button mushrooms and in baby bella mushrooms compared to that in methanol. Therefore, the formation of vitamin D2 in mushrooms from previtamin D2 is enhanced, similar to that in lizard and human skin. As a result, it is possible that a membrane enhanced conversion for previtamin D2 to vitamin D2 played an important role in the evolution of mushrooms and still aids in some unknown function in mushrooms.