Steroids are a family of important chemicals involved in the control of
biological processes.
They are a terpene system based on a common polycyclic framework with "named"
rings:
Steroid ring system with the
A, B, C, D rings identified.
The unique numbering scheme used for steroids
The most important steroid is cholesterol : other steroids are derived
from it biologically and it is the most common steroid in the human body.
When you look at the 3D CHIME image, notice how flat the structure looks
from a side view.
Variations of the functional groups and the nature of the ring junctions
(most are steroids have trans ring junctions) give the steroids
their different biological functions. A selection of steroids including
the sex hormones and a corticosteroid are shown below. Norethindrone
is a synthetic steroid that is used as a oral contraceptive. Note its similarity
to progesterone.
Chemically, the functional groups in the steroids undergo the chemical
reactions typical of those functional groups (see appropriate Chapters)
