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Classification of Drugs
Chemical classification of drugsChemical constituents Drugs
1. Carbohydrates
a) Monosaccharidase
b) Disaccharide
c) Polysaccharide
Gum
Mucilages
Cellulose
- Dextrose, fructose, galactose
- Sucrose, Lactose, Maltose
- Starch
- Acacia, Tragacanth
- Plantago seed
- Cotton
2. Glycosides
a) Cardiac
b) Anthraquinone
c) Saponins
d) Cyanophore
- Digitalis, strophanthus
- Aloe, Cascara, senna
- Arjuna
- Wild cherry bark
3. Tanins Amla, Bohera, Ashoka bark
4. Volatile oil Clove oil, rose oil, peppermint oil, tulsi etc
5. Lipids
a) Fixed oils & fats
b) Waxes
- Olive oil, castor oil, coconut oil etc
- Bees wax
Carbohydrates are aldehyde or ketone derivatives of higher polyhydric alcohol.
It is a neutral compound made up of Carbon, hydrogen and oxygen (C, H, O) in which H and O are in generally the same ratio as in water (H2O)
General formula of carbohydrate is – (CH2O)n.
The Chlorophil of the plants can easily synthesize carbohydrates from air, CO2 and H2O in the presence of light. The reaction is as follows –
CO2 + H2O Carbohydrate + O2
Carbohydrates
Carbohydrates
Nutrient – good source of energy
Sweetening agent – Tablet, syrup, suspension
Masking bad test – tablet, liquid (iron syrup)
Diluent, binder, disintegrating agent, suspending agent, demulcent.
Antibacterial agent (at 66.6%) and preservative
Antioxidant (it is a reducing sugar)
Uses of Carbohydrates
By considering sweet taste-imparting property CHO are classified as-
1. Sugar: Monosaccharides – glucose, fructose, galactose.
Disaccharides - Sucrose, lactose, maltose.
2. Nonsugar: Polysaccharides – starch, inulin, gums and mucilage, cellulose.
Carbohydrates - Classification
Carbohydrates
Sugar Nonsugar (Polysaccharide)
Monosaccharides Disaccharides
Glucose Fructose Galactose
Sucrose Lactose Maltose
Starch Cellulose Inulin Gums &mucilage
Monosaccharides, the simplest CHO, are aldehydes or ketones that have multiple hydroxyl groups. The general formula of many is (CH2O)n.
It is obtained from hydrolysis of starch.
In nature it is found in grapes and fruits.
Glucose (Monosaccharides)
Structure CH=O | HC-OH | HO-CH | HC-OH | HC-OH | CH2-OH
D-Glucose
Ring Structure of Glucose
Nutrient – oral or intravenous injections.
It is also used in anticoagulant solution to preserve whole blood.
For manufacture of beverage, ice-cream, bakery products and in the caning industry.
Glucose - Use
Liquid glucose
It is obtained from incomplete hydrolysis of starch. It is serupy liquid consist chiefly of dextrose, with maltose and water. It is used as a sweetening agent as a substitute of sucrose in syrup and as a tablet binder and coating agents.
Fructose is a ketone sugar occurs naturally in most sweet fruits and honey.
Use:
1. Nutrient – food for diabetics and may be of particular benefit of diabetic acidosis.
2. Infant formula.
3. When given parenterally it produces less urinary secretion than glucose.
Fructose
Structure of Fructose
Ring structure of fructose
Glucose & fructoseGlucose & fructose
6-membered ring structure
5-membered ring structure
Disaccharide consists of 2 monosaccharides (glucose & fructose) joined by an glycosidic bond.
Sucrose is the only disaccharide abundant in the free state in plants.
It occurs in fruit juice , sugar cane, sugar beet and in many other plants.
Commercially it is obtained from sugar cane and sugar beet.
Sugar (Sucrose, disaccharides)
Structure
glucose Fructose
Sugar (Sucrose, disaccharides)
glycosidic bond
OH H
H
OHH
OH
CH2OH
HOH H
H
OHH
OH
CH2OH
H1
3
14
223
4
6
5
6
5
-linkage
O OO
n
Nutrient – good source of energy
Sweetening agent – Tablet, syrup, suspension
Masking bad test – tablet, liquid (iron syrup)
Antibacterial agent (at 66.6%) and preservative
Antioxidant (it is a reducing sugar)
Uses of Sugar
The saccharides which reduce Fehling’s reagent and Tollen’s
reagent are called reducing sugar.
For example: all monosaccharides (glucose, fructose, lactose).
Reducing sugar
The saccharides which do not reduce Fehling’s
reagent and Tollen’s reagent are called non-reducing
sugar.
For example: disaccharide (sucrose) and
polysaccharide.
Non-reducing sugar
It is a reducing sugar. Upon hydrolysis lactose yields d-
glucose and d-galactose. It is obtained from fresh,
unpasturized or pasturized cow’s milk. It is also known
as milk sugar. The sugar is crystallized from the whey
obtained in cheese manufacture. The manufacturing
scheme is shown below –
Lactose
Milk Keep stand for few hour Separation
of cream (Skimmed milk) Treated with rennin
Cheese Separation of liquid (Whey)
Crystallization of Lactose Redissolved in water
Decolorized with Charcoal Recrystallized
Lactose
Uses: Diluent – TabletNutrient – Infant food
Caramel or Burn Sugar:
It is a concentrated solution of the product obtained by
heating sugar or glucose until the sweet taste is destroyed and
a uniform dark brown mass result. A small amount of alkali,
added during heating of the sugar.
Uses:Coloring agent – Food and Pharmaceuticals
• It is originally obtained from the ripe berries, Sorbus sp.
(Fam – Rosaceae). • It also occurs in many fruits but is generally prepared
from glucose by hydrogenation or by electric reduction.
Uses:• Humectants: (act as moisturizers by attracting water.
They are often used to prevent creams from drying out). • Sweetner• Diluent/Vehicle• Food – Diabetic food (substitute of glucose)• Diuretic
D-Sorbitol:D-Sorbitol:
Polysaccharide
The complex CHOs are generally called polysaccharide as they are formed by the linkage of a large number of monsaccharide units.
The polysaccharides yield the component monosaccharide units on enzymetic or acid hydrolysis.
Starch
starch is most widely distributed organic compound in plants.
It is produced in large quantities in green leaves as the temporary storage form of potosynthetic products.
It stored in seed, stems and roots. It is lacking in animal.
Commercially it is obtained from corn, cereal (rice, wheat, maize), potato tubers etc.
Polysaccharide - Starch
Starch generally is a mixture of two structurally different polysaccharides which are –
Amylose (-amylose):It is a linear molecule composed of 250 – 300 d-glucose units uniformly linked by -1,4 glucosidic bond.
Starch - Chemistry
Amylopectin (a-amylose):It consists of 1000 or more d-glucose units of which most are connected with -1,4 linkage but there are also a number of -1,6 linkage occurring (4%) at branch points.
Structure of Amylopectin
Structure of amylose:
Amylose vs Amylopectin
Property Amylose Amylopectin
Water solubility More soluble Less soluble
Reaction with I2 Blue color complex purple color
Composition 25% of total starch 75% of total starch
Unit composition D-glucose D-glucose
Type of linkage -1,4 glucosidic bond -1,4 & -1,6 glucosidic bond
Shape of the molecule Linear Branched
Enzymetic hydrolysis -amylase, Split -1,4 -amylase, Split -1,4 & -1,6
Acid hydrolysis (HCl or H2SO4)
D-glucose D-glucose
Diluent
Binder
Disintegrating agent
Uses of Starch
Cellulose is the main structural material of
trees and other plants.
Wood is 50% cellulose, while cotton wood is
almost pure cellulose.
The general formula of cellulose is:
(C6H10O5)n.
Cellulose
Chemical structure:
Cellulose is made of about 5,000 glucose units joined
to each other by -1,4-glycosidic bonds.
Properties:
It decomposes on strong heating.
It is insoluble in water and most organic solvent.
It is hydrolysed by heating with dilute HCl or H2SO4, give d-glucose.
Cellulose
Methyl cellulose
Ethyl cellulose
Hydroxyethyl cellulose
Hydroxypropyl methylcellulose
Sodium carboxymethyl cellulose (Na-CMC)
Derivatives of Cellulose
Derivatives of Cellulose
Methyl celluloseMethyl cellulose
It is a methyl ether of cellulose containing not less than 26% and not more than 33% of methoxy (-OCH3) groups.
Preparation:
It is obtained by reaction of cellulose with caustic soda (NaOH) and an organic solvent (CH3Cl).
Properties:
It swells in water to produce a clear viscous solution.
Use:Suspending agent –suspension dosage form.Binder- tablet dosage form
Derivatives of Cellulose
Ethyl cellulose
It is an ethyl ether of cellulose containing not less than 45% and not more than 50% of ethoxy (-OC2H5) groups.
Use:• Suspending agent –suspension dosage form.• Binder- tablet dosage form
Derivatives of Cellulose
Hydroxyethyl cellulose
• It is modified cellulose in which the H of –OH groups
is substituted by hydroxyethyl (-OC2H5) groups.
• It is soluble in water.
Use:• Suspending agent –suspension dosage form.• Binder- tablet dosage form• Thickener
Derivatives of Cellulose
Sodium Carboxymethyl cellulose (CMC)
• It is the sodium salt of polycarboxymethyl cellulose in which the H of –OH groups is substituted by
carboxymethyl (-OCH2COOH) groups.
Use:
• Suspending agent –suspension dosage form.
• Binder- tablet dosage form
• Thickener
Gums & Mucilages• Both gums and mucilages are generally considered as
decomposition products of cellulose. They are translucent, amorphous substances usually produced by plants as a protective after injury.
• Gums when hydrolysed, yield large proportion of sugars and also contain a complex organic acid nucleus, by means of which they form salt with calcium, magnesium, etc.
• Gums are precipitated from solution by alcohol and lead acetate solution.
• Gums readily dissolve in water.
• Mucilages are generally sulfuric acid esters, the ester group being a complex polysaccharide.
• Mucilages do not dissolve in water but form slimy masses.
Sources of Natural Gum and Mucilage
1. Acacia:
2. Tragacanth
3. Agar:
Acacia
It is the dried gummy exudate from the stems and
branches of Acacia senegal (Fam. Leguminosae). It
is commonly known as gum Arabic.
Uses:
• Suspending agent• Demulcent• Granulating agent• Binder
Tragacanth
Source: • It is gummy exudate from Astragalus gummifer (Fam
– Leguminosae). • It is commonly known as Gum Trgacanth.
Uses: • Suspending agent• Emollient• Binder
Agar
Source: It is the dried, hydrophilic polysaccharide complex
extracted from the algae known as Gelidium cartilagineum
(Fam – Gelidiaceae); Gracilaria cofervoides and other
species.
Uses: •Suspending agent•Thickening agent•Laxative•Bacterial media
Tests for Carbohydrates
1. Fehling’s test
2. Molisch’s test
3. Osazone formation
4. Resorcinol test
5. Test of pentoses
10% solution of a-naphthol in alcohol is known as Molisch’s reagent
Tests for Carbohydrates
1. Molisch test:
A solution of CHO is prepared with -napthol and taken in test tube.
Concentrated sulphuric acid is added along the side of test tube
This test is standard test for identification of CHO.
A purple ring is formed on the junction below the aqueous layer which indicates the presence of CHO. [With insoluble CHO eg. Cellulose, the color will produce on shaking the reaction mixture].
Tests for Carbohydrates
1. Molisch test:
a negative test (left) and a positive test (right)
Fehling’s solution is an alkaline solution of cupric ion complex with tartrate ion.
Tests for Carbohydrates
1. Fehling’s solution test:
To a heated solution of the CHO containing substance add drop by drop a Fehling’s solution (equal parts of Fehling’s solution 1 & 2).
Red precipitate of cuprous oxide is produced
This test is used for reducing sugar such as all monsaccharides and many disaccharides like lactose, maltose. For nonreducing sugar like disaccharide (sucrose) and polysaccharides boils with acid for hydrolysis before testing with Fehling’s solution, or cuprous oxide will fail to precipitate.
The cupric ion (complexed with tartrate ion) is reduced to cuprous ion by the aldehyde (which is oxidized) and precipitates as cuprous oxide (Cu2O); for this reason, sugars that react with Fehling's solution are called reducing sugars.
Fehling’s solution test:Fehling I consists of 7 g of hydrated copper(II) sulfate dissolved in 100 mL of dist. water. Fehling II is made by dissolving 35 g of potassium sodium tartrate and 10 g of sodium hydroxide in 100 mL of dist. water Fehling's reagent: Equal volumes of Fehling I and Fehling II are mixed to form a deep blue
solution.
conical measure 1 glucose solution brick red precipitate
conical measure 2 fructose solution brick red precipitate
conical measure 3 sucrose solution no change