What is "secosteroid"

n. (context organic chemistry English) Sec·o·ster·oid, sek'ō-stēr'oyd (L. ''seco'', "to cut"), any of the subclass of many terpenoid compounds of the tetracyclic steroid class that are structural relatives bearing a cleavage of one of the four rings of that parent class. The prototypical secosteroid is cholecalciferol, vitamin D.

A secosteroid (sec·o·ster·oid, sek'ō-stēr'oyd) is a type of steroid with a "broken" ring. The word ''secosteroid ''derives from the verb meaning "to cut", and of steroid, meaning "solid, three-dimensional". Secosteroids are alternatively described as a subclass of steroids or derived from steroids.

Types or subclasses of secosteroids are defined by the carbon atoms of the parent steroid skeleton where the ring cleavage has taken place. For example, 9,10-secosteroids derived from cleavage of the bond between carbon atoms C9 and C10 of the steroid B-ring (similarly 5,6-secosteroids, 13,14-steroids, etc.).

The prototypical secosteroid is cholecalciferol (vitamin D).