Vitamin

Vitamins and vitamin analogs cover essential micronutrients and their synthetic derivatives for metabolic research. Fat-soluble vitamins A, D, E and K act through nuclear receptors, membranes or enzyme cofactor roles, whereas the water-soluble B vitamins and vitamin C mainly serve as cofactors. Vitamin D analogs include calcipotriol monohydrate, doxercalciferol and MC-976, a vitamin D3 derivative. Hydroxocobalamin is a form of vitamin B12, and leucovorin calcium salt is a reduced folate that supplies one-carbon units. Beta carotene is a provitamin A carotenoid, while L-ascorbyl 6-palmitate is a fat-soluble ester of vitamin C. The vitamin K antagonists phenindione and phenprocoumon inhibit vitamin K epoxide reductase and so block the carboxylation of clotting factors.