white to off-white
156-158 °C (lit.)
Looking for similar products? Visit Product Comparison Guide
Vitamin D2 (ergocalciferol) is naturally synthesized from ergosterol by invertebrates, fungi, and plants in response to ultraviolet B irradiation, while vitamin D3 synthesis (cholecalciferol) is uniquely initiated in the skin of vertebrates. During sun exposure, ultraviolet B photons are absorbed by 7-dehydrocholesterol, which is found within the plasma membranes of epidermal and dermal skin layers. This reaction yields an unstable derivative of 7-dehydrocholesterol, named precholecalcitrol, which rapidly rearranges to vitamin D3. Vitamin D binding protein (DBP) is a carrier protein responsible for drawing vitamin D3 from the plasma membrane into the dermal capillaries within the extracellular space.