Chapter 26: Lipids

Steroids

• 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 JMOL image, notice how flat the structure looks from a side view.

Jmol._Canvas2D (Jmol) "window0"[x]

Highlight steriod ring system

• 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)

© Dr. Ian Hunt, Department of Chemistry