6. Example - Steroids

Steroid hormones are naturally produced in the human body and are important in many physiological processes such as the stress response, inflammation and immune responses, and reproduction. Naturally occurring hormones can be modified to create medicines for pharmaceutical use. For example, glucocorticoids are semi-synthetically created from the natural hormone cortisol. Glucocorticoids are prescribed as medicines to treat a range of inflammatory conditions including joint pain and arthritis , asthma and allergic reactions.

Another example is ethinyl estradiol, which is made by semi-synthetic processing of the naturally occurring hormone estrone (an estrogen hormone) and is commonly used in contraceptive pills.

Cortisol and oestrone were originally isolated from animals (cortisol was extracted from the adrenal glands of pigs and cows, and oestrone was purified from the urine of pregnant horses), but they are now both produced in the laboratory by genetically modified microorganisms, such as yeast.