Steroids are organic compounds with four carbon rings that have important biological functions. They are synthesized in glands and delivered through the bloodstream to target tissues. There are several types of steroids including sex steroids that influence reproduction, anabolic steroids that increase muscle and bone synthesis, and corticosteroids that have anti-inflammatory effects. Steroids can be synthesized chemically or biologically from cholesterol in the body. Their metabolism involves breakdown by cytochrome enzymes and excretion of metabolites from the liver. Deficiencies can result in symptoms like weakness, dizziness, and gastrointestinal issues.

1. Steroids
Presentation by Mungwariri Hope
Hope.Mungwariri.jnr@gmail.com

2. What are steroids?
• They are defined as any of a large class of non polar organic compounds with a
characteristic molecular structure containing four rings of carbon atoms (three six-
membered and one five).
• They are synthesized in glands and delivered by the blood stream to target tissues to
stimulate or inhibit some processes.
• Steroids have two principal biological functions which are :
i. Activating the steroid hormone receptors
ii. Altering membrane fluidity in cells

3. Steroid core structure
The core structure consists of 17 carbon
atoms bonded in combined rings containing
4 rings which are 3 cyclohexane and one
cyclopentane rings.
The steroids then differ from each other by
the functional groups that are attached at the
four rings.

4. Types of steroids
• Sex steroids – influence sexual differences and reproduction e.g
progesterone, testosterone, estrogens
• Anabolic steroids – increase muscle and bone synthesis
• Corticosteroids – anti inflammatory

5. Synthesis of Steroids
• Steroids can either be synthesized chemically or biologically
• Synthesis of all hormones in the body start with the conversion of
cholesterol to pregnenolone by an enzyme called CYP11A which can then be
converted to other hormones.
• The natural steroid hormones are generally synthesized from cholesterol in
the gonads and adrenal glands in the form of lipids.

6. Chemical synthesis of steroids
• Bechmann’s Synthesis (1940) of Equilenin
• Woodward’s synthesis of Cholesterol
• Synthesis of Estrone by Torgov (1950, 63), Hughes (1960)
• Synthesis of Cortisone by Sarrett (1952), Y. Horiguchi (1986))

7. Metabolism and Excretion
• Steroids are oxidized by enzymes called cytochrome oxidase enzymes(e.g
CYP3A4 introducing oxygen into the steroid rings breaking them down to
smaller molecules for example when cholesterol is broken down by enzymes
to bile acids.
• These acids can then be eliminated by secretion from the liver in bile.

8. Deficiency of Steroids
• The deficiency of steroid hormones is as a direct result of adrenal insufficiency and this may
be as a result of certain diseases such as tuberculosis, AIDS, Addison's disease etc.
• The effects of steroid deficiency include:
i. Weakness
ii. Dizziness
iii. Low blood pressure
iv. Vomiting
v. Diarrhoea