What Are Steroids?

Lucy Bell-Young

by Lucy Bell-Young

19th August 2020

As biologically active organic compounds, steroids are artificial hormones that are derived from naturally-occurring hormones in the body. These compounds are structurally composed of four cycloalkane rings found in multicellular organisms. Steroids mainly function as vital biocomponents that affect a huge range of physiological processes. 

Types Of Steroids

There are hundreds of different natural steroid hormones that can be artificially synthesised. Their types are divided into various classes, depending on function or structure.

The following are the classes of steroids that are classified by their function:

  1. Corticosteroids are mainly used to suppress the immune system and reduce inflammation in the body. They are often prescribed to those who have asthma, arthritis, allergies, and even lupus. The steroid hormones originate in the adrenal cortex of vertebrates.
  2. Gonadocorticoids, a.k.a. sex steroids, are crucial in regulating sexual behaviour patterns as well as sexual differentiation. They are considered crucial hormones to the body’s development, and they function by interacting with vertebrate steroid hormone receptors.
  3. Neurosteroids have a huge impact on the excitability of our brains, i.e. neuronal excitability. Because they are synthesised in the brain, neurosteroids work by interacting with neuronal membrane receptors.
  4. Aminosteroids are neuromuscular blocking agents (NMBAs) that are commonly used during anaesthesia. In a nutshell, this is because they are able to stop acetylcholine, an important neurotransmitter, from reaching the brain.
  5. Secosteroids are also called open-ring steroids because they literally have a broken ring. They are considered crucial in regulating calcium and phosphorus homeostasis, which works to build bones. This makes secosteroids crucial to bone metabolism. Vitamin D is a secosteroid, for example.
Chemical diagram of testosterone hormone

Testosterone is a sex hormone and gonadocorticoid that is commonly used in anabolic steroids. Other sex steroids include androgens, estrogens, and progestogens

The following are classes of steroids that are classified by their chemical structure:

  1. Cholestane (C27H48) is produced by the diagenesis of cholesterol. It is a saturated tetracyclic triterpene and one of the most prominent biomarkers in rocks.
  2. Cholane (C24H42) is also a triterpene. While it does not have any direct uses, its derivatives can be used to treat some mediated diseases.
  3. Pregnane (C21H36) is an indirect parent of the hormone progesterone . It is used in the formulation of a huge variety of drugs, from topical corticosteroid creams to medicines that help to regulate periods when there is a progesterone deficiency.
  4. Androstanes (C19H32) are also from the steroid family that androgens are derived from, the most famous androgen being testosterone.
  5. Estranes (C18H30) are critical in the formation of estrogens, which are hormones that all have an estrane steroid nucleus. Estrane is, therefore, used in many estrogen-derived drugs.

Steroids are also available in a variety of forms. The common steroid types are tablets and liquids, but steroids can also be found in nasal sprays, inhalers, creams, and even injections. 

How Do Steroids Work?

Since steroids are man-made versions of hormones, they work by interacting with their respective hormone receptors. This happens because as molecules, steroids are small and hydrophobic, allowing them to easily travel across plasma membranes and into cells, where they are able to bind to their receptors. 

In humans and animals, man-made steroids resemble the hormones normally produced by endocrine glands, commonly known as the adrenal glands. This is done in order to boost hormone production in individuals who are either deficient in a given hormone, or want increased levels of a specific hormone for, say, athletic reasons, or to improve physical appearance.

Even though they are often highly concentrated energy compounds, steroids are usually metabolised and excreted by mammals, and are not used as sources of energy, unlike phospholipids.

Diagram showing how steroids bind with hormone receptors

Steroids work by binding with hormone receptors in cells

What Are Steroids Used For?

Ranging from medical to non-medical uses, steroids have been utilised in many applications – although their exact uses will, of course, depend on what type of steroid is being used. In general, steroids regulate a range of important physiological mechanisms, including but limited to:

  • Metabolic processes
  • Immune system reactions
  • Electrolyte balance
  • Stress-adaptive capabilities
  • Sexual development

When taken in certain doses, steroids have anti-inflammatory properties that reduce excessive swelling. Corticosteroids are most commonly used in this context. There are two main classes of corticosteroids that are naturally produced by the adrenal cortex:

  • Glucocorticoids: used for decreasing inflammation and assisting in metabolising fats, proteins, and carbohydrates
  • Mineralocorticoids: used to help with salt retention and management of salt-water balance in the body 

These effects can thus be mimicked by synthetic corticosteroids that are pharmacologically processed and used to supplement an individual’s deficiency in this hormone. 

In clinical settings, steroids have a variety of applications that have been scientifically recognised. You may remember that aminosteroids, for example, are commonly used in anaesthesia because of how effective they are as blocking agents. Corticosteroids are also commonly used in ESI, a.k.a. Epidural Steroid Injections. This is a procedure that eases spinal nerves that have become inflamed, and it can help to reduce pain felt around the body. 

But there are also many non-medical applications that steroids are used for. When used in this way, they are referred to anabolic steroids:

  • Athletes use anabolic steroids to build muscle mass and improve stamina 
  • Anabolic steroids are often used as a way of enhancing certain physical features
  • These types of steroids can also help individuals to recover quickly from injuries 
  • People also use anabolic steroids as a way of reducing fat in the body

However, there are more risks associated with this type of steroid. When overused, anabolic steroids have been proven to cause high blood pressure, kidney failure and heart disease. They can also affect menstrual cycles, sperm production, and your overall mood, so it is important to proceed with caution when taking anabolic steroids. 

Diagram showing how a corticosteroid ESI works

Corticosteroids are commonly used in Epidural Steroid Injections (ESI)

The Chemistry Behind Steroids

As a major class of lipids, steroids have distinct chemical structures from other lipids. This distinction is in the four fused molecular rings, three of which are cyclohexanes (six-sided carbon rings) and one a cyclopentane (a five-sided carbon ring). This is the common structure of steroids because all steroids have the same nucleus: gonane.

Gonane is the fundamental steroid nucleus, with 17 carbon atoms that are fused in four rings. The first three rings, cyclohexane, are fused to form a perhydro-derived skeleton of phenanthrene, while the last ring is a cyclopentane structure.

This system has a high number of non-polar hydrocarbon compositions. This is present in largely studied compounds such as cholesterol, sex-related hormones, cortisone, and anabolics – although many more notable compounds are included.

Common examples of steroids with similar structures are:

  • Dexamethasone (C22H29FO5): a synthetic corticosteroid
  • Testosterone (C19H28O2): a male sex hormone acting as an anabolic steroid
  • Lanosterol (C30H50O): a triterpenoid, or 30-carbon-based biosynthetic compound
  • Progesterone (C21H30O2): a female sex hormone that regulates menstruation and gestation
  • Cholic acid (C24H40O5): an acid in the bile which often has carbolic acid and hydroxyl groups

These structures have a varied carbon-carbon bond framework that differs depending on the steroid. This framework is determined through (a) bond order; (b) the number of methyl compounds attached to the four-ring system; (c) the functional groups; and (d) molecular configuration. For instance, sterols differ from sex hormones as the latter have a double carbon bond in a different numbered-chain, and have a carbonyl group attachment, instead of hydroxyl.

These subtle chemical differences already imply a huge difference in some steroids. However, it should be noted that unique chemical structures do not always mean different functions, as shown by synthetic steroids mimicking the functions of hormones.

A diagram of the gonane molecule

Gonane is the fundamental steroid nucleus, with 17 carbon atoms that are fused in four rings

What Is The Chemical Formula Of Steroids?

Steroids have various chemical formulae depending on the specific compounds that they represent. Regardless, there is a similarity in their chemical structure. This similarity stems from the fact that their chemical structures share a common four-ring system of carbon-carbon bonds. They only differ in terms of additional molecular attachments and order of configuration.

Despite their distinctions, steroid compounds generally consist of, at the very least, 17 carbon atoms and 28 hydrogen atoms in a stable four-ring system. In addition to this chemical information, there are a number of crucial points to remember about steroids:

  • Steroids belong to a major class of lipids, cholesterol being a common example. This means that steroids are generally fat-soluble, not-water soluble. 
  • Some common steroids, like cholesterol, are part of precursor chains, from which a compound is further chemically processed to turn into another.
  • Steroids can directly affect brain activity and behaviours. This is especially the case with neurosteroids, which regulate neuronal excitability, and aminosteroids, which block neurotransmitters.

It’s important to know that it is not advisable to administer any form of steroid without the guidance of experts, like doctors and other licensed professionals. The associated health risks of steroids are well documented, and taking these drugs incorrectly could mean life-changing consequences.


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