When we say Steroids, our mind unconsciously thinks of the Anabolic steroids used by body builders or weight lifters. We also think them to be just Steroidal Contraceptives for prevention of pregnancy. However, steroids have a broader definition that just sex hormones or substances used for sports.
Steriods are a class of biological organic compounds that has 4 rings of carbon atoms ( 3 Cyclohexane rings and 1 cyclopentane ring) in a cyclic pattern.
Nevertheless, The four rings (A,B,C and D) of a steroid is known as the steroidal nucleus or Gonane. It contains 17 carbon atoms and 28 hydrogen atoms. Because of this configuration, they are hardly soluble in water.
Modification of this gonane by addition, replacement or substitution with different functional groups can produce different types of steroids that exists in microorganisms, plants and Animals.
Synthesis of Steriods
The plant and animal steroids ( Lanosterol and Cycloartenol ) are synthised via the Mevalonic acid Pathway (MVA). This pathway starts with Acetyl-coA which is converted to acetoacetyl-coA by the enzyme Acetoacetyl-coA thiolase. Further conjugation with another molecule of Acetyl-coA produces the compound called 3-Hydroxymethylglutaryl-coA ( HMG-coA) by the HMG-coA synthase. This HMG-coA further produces the mevalonic acid by the help of HMG reductase enzyme – Statins ( Lipid-lowering drugs) acts here.
The Mevalonic acid is split to produce the Isopentenyl Pyrophosphate (IPP) and Dimethylallyl pyrophosphate (DMAPP). The fusion of this two compounds forms Farnesyl Pyrophosphate (FPP). FPP is further converted to Squalene and then to Sterols.
The sterols from squalene produces the cycloartenol and the lanosterol. The cycloartenol is the building block of all Phytosterols ( plant sterol) while the lanosterol is the precussor to zoosterol (Animal sterols). Examples of Phytosterols from plants are Carotenoids and Phytoestrogen while examples of Zoosterol are, Sex hormones, Adrenocortical hormoness, Cholesterol and bile acids.
Types of Steroids
Steroids in animals can exist as a Corticosteroid or the Anabolic steroids. These two types of steroids exists as hormones and have variety of life-saving functions.
The corticosteroids are located in the Adrenal cortex of the kidney and are divided into three; the Mineralocorticoids, the Glucorticoids and the sex hormones.
Mineralocorticoids e.g., the Aldosterone is responsible for the balance of the electrolytes in the body especially Sodium and Potassium which helps in the proper functioning of the heart and kidneys. The Aldosterone regulates the volume of the blood through excretion and retention of sodium and, therefore, plays a very important role in Hypertension.
Glucocorticoids e.g., Cortisol focuses on the metabolism of glucose. It is usually known as a stress hormone since it can help an individual withstand Stress. Glucocorticoids also helps to stop inflammation, hence, the synthetics of glucocorticoids such as hydrocortisone is used to manage Arthritis, Asthma, insect bites, Dermatitis and Skin rash.
The synthetic corticosteroids such as Prednisolone, hydrocortisone and cortisone are used in life-threatening issues. They help in treatment of so many allergic reactions and also suppression of the immune system during transplant of organs. However, long term use of corticosteroids can cause infections because of their tendency to suppress the immune system that fights diseases.
Addison disease results from insufficient production of the Glucocorticoids and minerocorticoids. it is a life-threatening disease that can lead to hypertension, low blood sugar, depression, sexual and mood dysfunction e.t.c.
The sex hormones are produced also in small quantity in the adrenal cortex while the bulk of it is from the ovaries and testes. The anabolic are synthetics of the male sex hormone – Testosterone. This hormone regulates so many activities in male. They help in building a strong muscle mass, production of sperm, development of secondary sexual characters and improvement in sports.
The anabolic steroids are usually prescribed in cases of Hypogonadism, in some cancers and muscle wasting syndromes. However, its likely and easily abused when used indiscriminately on a long term without a doctors prescription. Steroid abuse have so many side effects that are very detrimental to health.
Furthermore, another class of steroids known as Steroidal contraceptives are used to prevent unwanted pregnancy. They are the Oestrogen and Progesterone synthetics (sex hormones).
Steroids such as Cardenolides and Bufanolides, also known as Cardiac glycosides are used in medicine to help a failing heart. Carotenoids also found in plants is a rich source of vitamin A for the eye.
The human skin helps manufacture Vitamin D from Ultraviolet rays of the sun using 7-dehydrocholesterol which is converted to Cholecalciferol (vitamin D3). Cholecalciferol helps in Calcium reabsorption in the intenstine and also deposition of calcium to the bones. The disease called Rickets results from deficiency of Vitamin D3 which is characterised by softening of bones.
Cholanic acids from bile form esters with sulphuric acids, with amino acids or as bile alcohols in the intestine and acts as fats emulsifiers. Emulsification of fats helps in the absorption of fats you eat and is the work of bile acids.
Finally, the Phytochemistry of some plants proves the presence of a Phytoestrogen. It is a hormone-like compound in plants that can bind to human estrogen receptors and illicit functions similar to estrogen.