25-Hydroxyvitamin D3 monohydrate (CAS 63283-36-3)

25-Hydroxyvitamin D3 monohydrate (Calcifediol) is the major circulating metabolite of Vitamin D and precursor for 1alpha,25-Dihydroxycholecalciferol. It is converted to 1alpha,25-Dihydroxycholecalciferol by 5-Hydroxyvitamin D3 1-alpha-hydroxylase. When 25-Hydroxyvitamin D3 monohydrate is converted to the active form calcitriol, it increases and normalizes vitamin D plasma levels, which, in turn, regulates calcium plasma levels, and normalizes elevated parathyroid hormone (PTH) levels by suppressing both PTH synthesis, and secretion. Vitamin D modulates and enhances the innate and adaptive immune responses. This may improve unregulated inflammation and prevents the production of pro-inflammatory cytokines. Specifically, vitamin D binds to its receptor vitamin D receptor (VDR) which is widely expressed on immune cells and epithelial cells. This stimulates neutrophils, macrophages, and natural killer (NK) cells, and activates epithelial cells to produce antimicrobial peptides (AMPs). In addition, upon infection, vitamin D promotes the migration of myeloid dendritic cells (mDCs) to lymphoid organs where they activate B- and T-lymphocytes.