Secosteroid

Secosteroids a group of naturally occurring chemical compounds which are derived from the steroids. They include some important substances from the vitamin D group. The physiologically active form of vitamin D is calcitriol, which acts as Proteininduktor, immune modulator, as well as the absorption of calcium in the intestine.

Structure and examples

Steroids have four combined ring structures are referred to as a ring A to the ring D. In the formation of Seco steroids in organisms of the B ring of 7- dehydrocholesterol is opened by UV radiation mostly. Through this photolysis initially formed previtamin D3, which spontaneously rearranges to cholecalciferol ( isomerized ). Analog arises from ergosterol the ergocalciferol (vitamin D2). From these further seco steroids can be made by UV light irradiation, or other reactions. Since the ring B is opened at the 9 -10 position for most Seco steroids, also called this exact 9,10 -seco steroids.

The best known examples are next to cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2), calcidiol, calcitriol, tachysterol, lumisterol and tacalcitol.