Active Principles Of Drugs & Pharmacopeias

DR. GHULAM SAQULAINM.B.B.S., D.L.O., F.C.P.SHEAD OF DEPARTMENT OF ENTCAPITAL HOSPITAL, ISLAMABAD

Active Principle Definition

The chemical constituents present in crude animal/vegetable preparations, responsible for

their biological activity are called active principles.

Important active principles

Alkaloids Glycosides Saponins Fixed oils Volatile oils Fats Waxes

GumsResinsOleoresinsGum resinsBalsamsTannins Neutral principles

Alkaloids:

Nitrogenous compounds of complex structure. Found in plants, more than one alkaloids may be present in one plant.

Intensely bitter. Insoluble in water, soluble in alcohol. Very active biologically, alkaline in reaction. Form salts with acids which are water soluble. Mostly solids, only a few are liquids. English names end in ----“INE”.

Solid Alkaloids: Morphine, Papavarine Atropine , Hyoscine Quinine Ephedrine Strychnine

Liquid Alkaloids: Nicotine , Pilocarpine , Lobeline

Glycosides:

1. Non nitrogenous, containing carbon, hydrogen & oxygen

2. Complex structure & very active biologically

3. Found in plants

4. Hydrolyzed by acid / enzymes into:• Sugar component or Glycone ---- Mainly determines pharmacokinetics• Non-Sugar component or Aglycone/Genin - --Pharmacologically active

5. When sugar component is glucose, it is called glucoside

6. English names end in letter “IN”

Cardiac Glycosides:

Digoxin Digitoxin Gitoxin Gitalin Strophanthin

Saponins:

These resemble glycosidesNeutral in reactionFound in plantsAct as emulsifying agentsForm clear solution with water which forms froths

on shaking They are toxic May cause haemolysis of RBCSExamples: Senegin, Quillia sapotoxin

Fixed Oils:

Obtained from various plants or animals. Esters of higher fatty acid (Oleic/Palmitic/Stearic acids) . Insoluble in water , soluble in ether, chloroform, alcohol. Non irritating . Leave greasy mark on paper. Decompose on distillation . Form soaps with alkalies. Used as: Nutrient , Emollient , Purgative.Examples: Castor oil , Cod liver oil , Olive oil.

Volatile Oils: (Essential Oils / Ethereal Oil)

Obtained from various parts of plants by distillation processes & are highly aromatic.

Mostly contain liquid hydrocarbons

In addition most contain oxidised hydrocarbons. They are usually crystalline solids, called stearoptenes Highly aromatic, slightly water soluble – impart smell & taste. Used as: Carminative e.g. cardamon oil Diuretic e.g. oil of sandal wood Antiseptic e.g. clove oil

Fats:

Fixed oils solid at room temperature Natural ester of glycerol & fatty acids. All the three OH groups of glycerol are esterified, so called Triglycerides

Examples: Theobroma (cocoabutter)

Waxes: Esters of fatty acids with monohydric alcohols Complex mixtures Used in ointments & other topical preparations used on skin.

Examples: White bee’s wax (cera alba)

Gums:

Plant exudations Carbohydrate in nature Amorphous, Transparent Form viscous solution with water – Mucilage Used as suspending/emulsifying agents in preparation of suspensions & emulsions.

Examples: Gum Acacia, Gum Tragacanth

Resins:

Solid & brittle substances, produced by oxidation of volatile oils

Form soap with alkali Soluble in alcohol Examples: Colophony.

Oleo Resins: Resins dissolved in volatile oils e.g CopaibaGum Resins: ◦ Combination of gum + resin e.g. Myrrh, Asafetida ◦ Used in dentistry

Balsams:

Combination of resins with benzoic acid / cinnamic acid or both.

Examples: BenzoinBenzoin is used as Tincture Benzoin Co ---- applied on small superficial wounds & abrasions.

Tannins: Non-Nitrogenous compounds . Precipitated by metallic salts or alkaloids. Astringent action on mucosa. Produce blue inky color with iron. Some are hydrolyzed to tannic acid.Neutral Principles:

Do not conform to any special group . Examples: Santonin, Bitter principles .