Chemistry in Everyday Life
Chemistry in everyday life Introduction: Chemistry plays an important role in our everyday life. We start our day by brushing our teeth’s the toothpaste we use is a chemical substance. Such as soap, detergent, fuel, LPG gas, clothes, food medicines etc. all are the chemicals which come across our daily life. In short we can say that our every moment is related to chemistry.
In this unit we shall study the use of chemicals in three different areas i.e. medicines, food materials and cleansing agents. Before going to this topic we have to familiar with classification of drugs and their action of target.
Chemistry in everyday life drugs
In medicine the word ‘drug’ is derived from French word ‘drogue’ meaning a dry herb.
Drug is defined as a chemical substance which is used for the purpose of diagnosis, prevention, cure or relief of a disease.
An ideal drug is one which should not disturb psychological processes, harmless to host but should destroy harmful organisms, localized to affected site and the most important is that it should have minimum side effects.
Classification of drugs
In chemistry in everyday life, types of drugs or classification of drugs is necessary. So, Drugs can be classified by different ways as given below
- Classification based on molecular target.
- Classification based on chemical structure.
- Classification based an action of drugs on a particular biochemical process.
- Classification based on pharmacological effects of the drug.
- Classification based on lay public.
Here we will study the classification based on molecular targets that is on drug target interaction.
Action of drugs on target
Those substrates which are crucial to communication system are called receptors.
The receptors are highly specialized macromolecules present in the tissues that combine chemically with drug.
1. Enzyme as a drug target
Enzymes hold the substrate at its active site in a suitable and right position for performing various biochemical reactions through variety of interactions such as ionic bonding, hydrogen bonding and van-der Waals interaction.
2. Action of drugs
The drugs and substrate complete each other to attach on active site of enzymes. The drug binds with the enzyme and prevents to substrate to bind with enzyme such drugs are called competitive inhibitor. Sometimes drug binds with enzymes at different site called allosteric site and changes the shape of enzymes so that the substrate do not recognize the active site of enzymes.
3. Receptor act as drug target
Biological receptors are composed of macromolecules in the cell membrane. In cell membrane of a cell the receptor are situated in a such a way that their active site remains open outside the cell membrane. The chemicals which carry different massages in the body between neuron and muscles are called chemical messengers. Chemical messengers or drug interact with receptors and deliver the message into cell. There are two types of drug i.e. antagonists and agonists.
The drugs which bind the receptors and disturb their functions such drugs are called antagonists. The drugs which activate the receptors are called agonists.
CHEMICAL IN MEDICINE
A] Antacids and Antihistamines
During digestion of food, stomach secretes hydrochloric acid. Sometimes there is excessive secretion of hydrochloric acid in stomach leads to acidity to overcome this hyperacidity we use antacids which are basic in nature such as sodium bicarbonate and aluminium or magnesium hydroxide. These chemicals controls the symptoms but not the cause hence the chemicals such as antihistamines are synthesized.
The chemical histamine is responsible for production of hydrochloric acid and pepsin in stomach. Antihistamines are drugs which prevent the interaction between histamines and receptors present in stomach wall, thus releasing less amount of hydrochloric acid. Ranitidine, cimetidine, terfenadine and bromopheniramine are antihistamines.
Drugs which relieve the pain by acting on central nervous system without loss of consciousness or without much disturbing the nervous system are called analgesics.
There are two types of analgesics.
1. Narcotic analgesics
Morphine, codeine, heroin etc. are narcotic analgesics. These drugs are used to reduce the pain due to fracture of bones, pain during child birth, post operative pain, pain due to burns, cardiac pain and pain of terminal cancer etc. These are addictive drugs having adverse effects like mental confusion, coma, vomiting, fatigue, dysphoria and ultimately death. These drugs produce depression of central nervous system.
2. Non – Narcotic analgesics
Non – Narcotic analgesics do not produce depression of central nervous system. These drugs reduce the cause of inflammation i.e. anti inflammatory and antipyretic (reduce fever). They are used in headache, cold, tissue swelling, arthritis etc. e.g. aspirin, paracetamol, methyl salicylate etc.
The chemical substances used to relieve or reduce the stress and anxiety lead to calmness are called tranquilizers.
They affect the mechanism for the transfer of message from nerve to receptors. If the level of noradrenalin (neurotransmitter) is low then person suffers from depression. In such situation tranquilizers such as equanil, valium, veronal, iproniazide and phenelzine are used to inhibit the enzymes which catalyzes the degradation of nor adrenaline.
The drugs used to kill or stop the growth of micro – organisms like fungi, bacteria and virus are called antimicrobial drugs.
The antimicrobial drugs include antibiotics, antiseptics and disinfectants.
Antibiotics is a drug derived from living matter or micro – organisms used to kill or prevent the growth of other micro – organisms.
Antibiotics are chemical which are prepared in laboratories by using living cells. In 1908 Paul Ehrlich got Nobel prize for discovering salvarsan to kill syphills bacteria. The first successful antibiotic produced was penicillin from penicillium fungus.
The range of bacteria or other micro-organisms that are affected by certain antibiotic is expressed as its spectrum of action.
Narrow spectrum antibiotics are effective against either gram-positive or gram-negative bacteria.
Limited spectrum antibiotics are effective against a single organism or disease.
Broad spectrum antibiotics are effective against a wide range of gram-positive or gram-negative bacteria.
Types of Antibiotics
Antibiotics are of two types
i. Bactericidal: The antibiotics that killed bacteria are called bactericidal.
e.g. penicillin and aminoglycosides.
ii. Bacteriostatic : the antibiotics that inhibit the growth of bacteria are called bacteriostatic.
e.g. frythromycin, tetracycline and chloramphenicol.
Drugs which are applied to the living tissue to kill the bacteria and to stop their growth in wound, thus preventing its infection are called antiseptics.
Dettol is mixture of terpeniol and chloroxylenol which is used as antiseptics. Bithionol is as an antiseptic in soaps. Other antiseptics are iodoform, boric acid,phenol, H2O2 etc.
Disinfectant are applied to non-living objects to kill the micro-organism, used in public health sanitation, drainage system, floors, to sterilize instruments etc.
e.g. chlorine, phenol (concentrated), sulphur dioxide etc.
E] Antifertility drugs
Chemical substances which are used to prevent pregnancy in women are called antifertility drugs.
Various drugs like analgesics, antibiotics and antiseptics increased the life span of human beings. This has increased the population and has also causes many social problems like shortage of food resources, environmental pollution, unemployment etc. to control this population antifertility drugs used which are mixture of synthetic estrogen and progesterone derivatieves.
e.g. novestrol and northindrone.
CHEMICAL IN FOOD
Variety of chemicals are added to the food like preservatives, colours, flavours, stabilizing agents, antioxidents, artificial sweeteners etc. to make the food palatable, attractive and to increase its shelf life.
A] Chemical in food preservatives
Food preservatives means a substance, which when added to food is capable of inhibiting, retarding or arresting the process of fermentation acidification or other decomposition of food by growth of microbes.
e.g. sodium benzoate, sodium metabisulphite, etc.
The methods of food preservation are classified as follows
1. Physical methods
i. By removal of heat
ii. By additional of heat
iii. By removal of water
iv. by irradiation
2. Chemical methods
i. Addition of sugar
ii. Addition of salt
iii. Addition of vinegar
iv. Addition of other chemicals like sodium benzoate, salt of sorbic acid and propionic acid.
B] Artificial sweetening agents
Certain chemical which do not occur in nature are synthesized in the laboratory, have sweet taste but have no food value are known as artificial sweetners.
These sweetening agent impart sweetness to food without increasing the colorific intake and enhances its odour and flavor.
Saccharin is the first popular artificial sweetener which is 550 times more sweet than cane sugar. It is used to increase sweetness of products like medicine, toothpaste, low calorie sweets, soft drinks, cold drinks etc.
Aspartame is about 100 times sweeter than cane sugar. It isused in cold foods only because it is unstable of high temperature.
Sucrulose is 600 times sweet than the cane sugar. It is also unstable at high temperature.
Alitame is 2000 times sweeter than the cane sugar. It is very sweet and stable at high temperature.
Antioxidant is a substance which when added to food, retards or prevents oxidative deterioration of food.
Addition of antioxidant to the food prevent its oxidation and prevent them from becoming rancid.
e.g. 1. BHT – Butylated hydroxy toluene (C15H24O)
2. BHA – Butylated hydroxy anisole (C11H16O2)
3. Sulphur dioxide (SO2) and Sulphite
Soaps are sodium or potassium salt of higher fatty acid which contain more than 12 carbon atoms. Potassium soaps are softer than sodium soap.
Soaps are prepared in two different ways.
1. By hydrolysis of fat using sodium or potassium hydroxide solution
When oils and fats are heated with solution of sodium hydroxide or potassium hydroxide, they are hydrolysed to glycerol and sodium or potassium salt of fatty acid known as soap, this process is called as saponification.
2. Direct neutralization of fatty acids
Soaps are prepared by direct neutralization of fatty acids by using sodium hydroxide or sodium carbonate.
Soaps are insoluble in hard water because it contain calcium and magnesium ions. Soap reacts with this ions to form calcium and magnesium salt which are insoluble in water.
Synthetic detergents are formulated products containing either sodium salt of alkyl hydrogen sulphates or sodium salt of long chain alkyl benzene sulphonic acid.
There are three types of detergents.
1. Anionic detergents
Anionic detergents are salt of sulphonated long chain of hydrocarbons or alcohols, they have anions. The anionic parts of detergents take part in cleansing action. They are used in toothpaste and house for cleansing purposes.
2. Cationic detergents
Cationic detergents are quaternary ammonium salt of amines with chlorides, acetates or bromides. They have cations at the soluble ends of chain. They are used as germicides and are expensive.
3. Non ionic detergents
They have hydrogen bonding group at the soluble ends of the chain. These detergents are either monoester of polyhydric alcohols or polyethers derived from ethylene oxide.