25hydroxylated
25-hydroxylated refers to a chemical modification where a hydroxyl group (-OH) is added to the 25th carbon atom of a molecule. This modification is particularly significant in the metabolism of vitamin D. When vitamin D, whether obtained from sunlight or diet, enters the body, it undergoes hydroxylation in the liver. This process adds a hydroxyl group at the 25th position, converting vitamin D into 25-hydroxyvitamin D, also known as calcidiol. Calcidiol is the major circulating form of vitamin D and serves as a precursor to the biologically active form, 1,25-dihydroxyvitamin D (calcitriol).
The 25-hydroxylation of vitamin D is a crucial step in regulating calcium and phosphate homeostasis, which
Beyond vitamin D, the concept of 25-hydroxylation can apply to other organic molecules in biological systems,