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Prostaglandins (PG) are a class of physiologically active lipid compounds known as eicosanoids that have a variety of hormone-like effects in animals.
- Prostaglandins are present in almost every tissue in humans and other animals.
- They are enzymatically produced from the fatty acid and arachidonic acid.
- Each prostaglandin consists of 20 carbon atoms, including a 5-carbon ring.
- They are a category of eicosanoids and fatty acid derivatives classified as prostanoids.
- During pregnancy and labor, uterine cells create prostaglandins, which help widen the cervix and cause uterine contractions.
- These contractions help the baby pass through the delivery canal.
| Table of Content |
Key Terms: Prostaglandin, Lipids, Fatty acid, Eicosanoids, Prostanoids, Receptors, Tissue, Cells, Endocrine hormones, Arachidonic acid. Enzymes, Jasmonic acid.
What is Prostaglandin?
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Prostaglandins are a group of physiologically active compounds that have a variety of hormone-like effects on animals.
- Ulf von Euler, a Swedish scientist, discovered prostaglandins in human semen in 1935 and called them after believing they were released by the prostate gland.
- In the 1960s and 1970s, Swedish biochemists Sune K. Bergström and Bengt Ingemar Samuelsson, as well as British biochemist Sir John Robert Vane, conducted pioneering research on prostaglandins.
- In 1982, the threesome shared the Nobel Prize in Physiology or Medicine for their work isolating, identifying, and analyzing many prostaglandins.
The structural variations of prostaglandins are responsible for their diverse biological functions.
- In some situations, a given prostaglandin might have different and opposite effects on various tissues.
- The type of receptor to which a prostaglandin binds determines its ability to stimulate one tissue while inhibiting another.
- They function as autocrine or paracrine factors, interacting with target cells located near the site of secretion.
- Prostaglandins vary from endocrine hormones in that they are synthesized in many places throughout the human body.
Prostaglandin
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Synthesis of Prostaglandin
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The prostaglandins are composed of unsaturated fatty acids with a cyclopentane (5-carbon) ring, produced from the 20-carbon, straight-chain, polyunsaturated fatty acid precursor arachidonic acid.
- Arachidonic acid is a major component of phospholipids, which are also essential components of cell membranes.
- In response to a variety of stimuli, including hormonal, chemical, and physical agents, a sequence of events occurs, resulting in prostaglandin production and release.
- These stimuli, whether directly or indirectly, stimulate an enzyme known as phospholipase A2.
- This enzyme catalyzes the release of arachidonic acid from phospholipid molecules.
- Depending on the type of stimuli and enzymes available, arachidonic acid may follow one of several different paths.
- One enzyme, lipoxygenase, converts arachidonic acid to one of many leukotrienes, which are essential inflammatory mediators.
- Another enzyme, cyclooxygenase, converts arachidonic acid to one of many endoperoxides.
- The endoperoxides are further modified to produce prostaglandins, prostacyclin, and thromboxanes.
- The thromboxanes and prostacyclin play significant roles in blood coagulation.
Biological Activities of Prostaglandins
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Prostaglandins are present in almost every tissue in humans and other animals.
- Plants synthesize molecules with similar structures to prostaglandins, such as jasmonic acid (jasmonate), which controls plant reproduction, fruit ripening, and flowering.
- Prostaglandins are extremely potent; for example, in humans, they can impact blood pressure in quantities as low as 0.1 micrograms per kilogram of body weight.
- The structural differences of prostaglandins are responsible for their diverse biological functions.
- Some prostaglandins work in an autocrine manner, stimulating reactions in the same tissue in which they are generated.
- Whereas others act in a paracrine manner, stimulating responses in local tissues near the place of synthesis.
- Furthermore, a given prostaglandin might have diverse and opposite effects in various tissues.
- The type of receptor to which a prostaglandin binds determines its ability to stimulate one tissue while inhibiting another.
Functions of Prostaglandins
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There are now 10 prostaglandin receptors found in different cell types.
- The prostaglandins bind to a subfamily of seven transmembrane receptors on the cell surface, called G-protein-coupled receptors.
- These receptors have names such as DP1-2, EP1-4, FP, IP1-2, and TP, depending on which receptor ligates the corresponding prostaglandin (DP1-2 receptors bind to PGD2).
Due to the diverse receptors on prostaglandins, they can act on a variety of cells and have a wide range of effects, including:
- Produce eicosanoid hormones.
- Increases mating behaviors in goldfish by acting on the thermoregulatory center of the hypothalamus.
- During menstruation, prostaglandins are produced as endometrial cells are destroyed and their contents are released.
- The release of prostaglandins and other inflammatory mediators in the uterus causes it to contract.
- These substances are regarded to play an essential part in primary dysmenorrhea.
Prostaglandins Examples
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Different types of prostaglandins are
- Prostaglandin I2 (prostacyclin; PGI2)
- Prostaglandin D2 (PGD2)
- Prostaglandin E2 (PGE2), and
- Prostaglandin F2α (PGF2α).
Prostaglandin I2
They act as vasodilators, decrease platelet aggregation, and cause bronchodilation.
Prostaglandin D2
They are primarily generated by mast cells, attract Th2 cells, eosinophils, and basophils, and play a vital role in the development of allergic disorders such as asthma.
Prostaglandin E2
They cause smooth muscle contractions in the gastrointestinal system.
Prostaglandin F2α
Their secretion helps uterine contraction and urine bladder contraction.
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| Types of White Blood Cells | Centriole | Cytoskeleton |
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Things to Remember
- Prostaglandins are a group of physiologically active compounds that have a variety of hormone-like effects on animals.
- Prostaglandins vary from endocrine hormones in that they are synthesized in many places throughout the human body.
- Each prostaglandin consists of 20 carbon atoms, including a 5-carbon ring.
- The type of receptor to which a prostaglandin binds determines its ability to stimulate one tissue while inhibiting another.
- Arachidonic acid is a major component of phospholipids.
- The structural differences of prostaglandins are responsible for their diverse biological functions.
- There are now 10 prostaglandin receptors found in different cell types.
Previous Year Questions
- Which of the following is an antihistamine drug…
- Which of the following is incorrectly matched…
- Which of the following is not an antibiotic…
- Which of the following is a natural dye…
- Which one of the following is not used as a filler…
- Insulin a hormone chemically is…
- Chloropicrin is obtained by the reaction of…
- Which of the following is a natural dye…
- Which one is a broad-spectrum antibiotic…
- which one of the following types of drugs…
- which of the following drugs is an analgesic…
Sample Questions
Ques. What are Prostaglandins? (1 Mark)
Ans. Prostaglandins are a group of physiologically active substances that have various hormone-like effects in animals.
Ques. Explain the biosynthesis of Prostaglandins. (2 Marks)
Ans. They are present in almost all tissues and organs and are generated by almost all nucleated cells. Lipid mediators, whether autocrine or paracrine, act on platelets, endothelium, uterus, and mast cells. Their production occurs within the cell from the fatty acid arachidonic acid.
Ques. Describe how medicinal chemistry uses the terms "target molecules" and "drug targets." (2 Marks)
Ans. The primary molecule that several metabolic pathways that can result in particular diseases are driven by is what the medicine targets. Proteins, nucleic acids, carbohydrates, and lipids are what the medication targets.
Drugs are chemical substances that interact with the active sites of important molecules to stop those target molecules.
Ques. Why do antacids and antiallergic medications not also affect how histamines work, despite the fact that they do so? (2 Marks)
Ans. Only certain receptors are impacted by some medications. Antiallergic medications and antacids do not interact since they target separate receptors. Because of this, antacids and antiallergic medications don't affect each other's ability to affect histamine function.
Ques. Why is it necessary to categorize medications in various ways? (3 Marks)
Ans. The following justify the drug's classification:
- The pharmacological effect is determined by that it offers a wide variety of medications to categorize medications for various conditions.
- Based on how the medications work: This is based on how a medicine affects a certain biochemical procedure.
- Expanding on chemical composition: The group of medications with similar pharmacological activity and common structural traits.
- Advancing molecular targets: The action function on targets of many drugs is the same. This distinction is helpful in certain circumstances.
Ques. What distinguishes antiseptics from disinfectants? Give one illustration of each. (3 Marks)
Ans. Antiseptics and disinfectants are very effective against microorganisms.
- While disinfectants are used for objects like floors, drainage systems, instruments, etc., antiseptics are used to treat living tissues like cuttings, wounds, diseased skin surfaces, and ulcers.
- Living tissues are harmed by disinfectants.
- Iodine works well as an antiseptic.
- Injuries are treated with iodine tincture.
- As a disinfectant, phenol solution at 1% is employed.
Ques. Why are cimetidine and ranitidine superior to magnesium, sodium hydrogen carbonate, or aluminum hydroxide as antacids? (3 Marks)
Ans. The antacids magnesium hydroxide, sodium hydrogen carbonate, and aluminum hydroxide are used to neutralize excess hydrochloric acid in the stomach. However, the cause of the acid release has not been addressed.
Because they reduce the cause of acidity, cimetidine and ranitidine are effective antacids.
These medications stop histamine from connecting with the receptors found in the stomach's walls, which can lessen the amount of acid the stomach secretes.
Ques. What does the phrase "wide spectrum antibiotics" mean? Explain. (3 Marks)
Ans. Antibiotics are referred to as broad-spectrum antibiotics because they work well against both gram-positive and gram-negative bacteria, such as chloramphenicol.
Acute fever, typhoid, meningitis, dysentery, TB, and certain UTIs are all treated with this. Vancomycin and ofloxacin are the other 2 antibiotics with a broad spectrum. Broad-spectrum antibiotics that are synthetically produced from penicillin include amoxicillin and ampicillin.
Chloramphenicol
Ques. How do enzymes in a biological system catalyze a chemical reaction? Giving the target of an enzyme as an example, describe drug-target interaction. (5 Marks)
Ans. Since they are catalysts, enzymes are crucial in biological reactions.
The process that the enzyme catalyzes is:
- The substrate is captured by the enzyme's active site and held there so that it can react with the substrate in an efficient manner. Ionic, hydrogen, Van der Waals, and dipole-dipole interactions are some of the forces that bind the substrate to the active site. The substrates should be held by these binding forces long enough for the enzymes to catalyze the reaction, but they should be weak enough to let the products escape after they have formed.
- By offering functional groups to attack the substrate and finish the chemical processes, enzymes also operate as catalysts. Protein amino acid residues present on the enzyme's active site play this role. They enact chemical reactions by attacking the substrate. The active site attachment of the substrate is prevented by the enzyme inhibitor medications, which obstruct this process.
Ques. In terms of cleaning power, synthetic detergents have an edge over traditional soaps. However, long-term usage of synthetic detergents pollutes the ecosystem. What steps may be taken to reduce the pollution that synthetic detergents cause? Sort the detergents into groups based on their chemical composition. (5 Marks)
Ans. Straight, unbranched chains are more vulnerable to bacterial attack. Therefore, branching is kept to a minimum in most detergents used today. Branching is kept to a minimum in detergents to facilitate easy biodegradation and reduce pollution.
Cleaning solutions known as synthetic detergents possess all the qualities of soaps but do not actually contain any soap. Both soft and hard water can be utilized with these.
They are primarily divided into three groups.
- Anionic Detergents: Sulfonated long-chain alcohols or hydrocarbons are salts of sodium that form anionic detergents. In order to create alkyl hydrogen sulfates, long-chain alcohols are treated with conc. Alkali neutralizes H2SO4 to produce anionic detergents. Similar to how alkyl benzene sulphonates are produced, alkyl benzene sulphonic acids are neutralized with alkali.
The cleaning activity in these detergents is carried out by the anionic portion of the molecule. They are mainly employed for domestic tasks. Toothpaste also contains them.
- Cationic Detergents: Acetates, chlorides, and bromides act as anions in cationic detergents, which are quaternary ammonium salts of amines. The cationic component has a lengthy hydrocarbon chain and a nitrogen atom with a positive charge. The common cationic detergent cetyltrimethylammonium bromide is used to treat hair.
- Non-ionic Detergents: Non-ionic detergents are those that don't have any ions in them. When polyethylene glycol and stearic acid combine, one such detergent is created.
Ques. What are enzyme inhibitors? Sort them into groups depending on how they connect to enzyme active sites. Use illustrations that demonstrate how inhibitors reduce enzyme activity. (5 Marks)
Ans. Enzymes retain the substrate molecule during a chemical reaction and supply functional groups that will force the substrate for the reaction to occur. Enzyme inhibitors are medications that stop any enzyme activity.
The catalytic activity of the enzyme can be inhibited by enzyme inhibitors by preventing the substrate from interacting with the active site.
Drugs block in two distinct ways based on the attachment of a neutral substrate to the active site of enzymes, as described below.
(i) Competitive inhibitors are medications that fight the natural substrate for the right to connect to enzyme active sites.
(ii) Some medications attach to an enzyme's allosteric site, which is a separate site from the active site. The effects of the enzymes' activity are altered by the drug's binding at the allosteric site in a way that the natural substrate is unable to recognize. We refer to these enzymes as non-competitive inhibitors.
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