1. DIFFERENT METHODS OF EXTRACTION OF CRUDE DRUGS NAME:MIMONA AKTER ID:11715019 DEPARTMENT OF PHARMACY

2. INTRODUCTION  Extraction may be defined as the removal of soluble constituents from a solid or liquid or semi-solid with means of suitable solvent.  It may be also be defined as the treatment of the plant or animal tissues with appropriate solvent which would dissolve medicinally active constituents.

3. Necessary terms to know  Menstrum:Solvent used for extraction.  Marc:The inert fibrous and other insoluble materials remaining after extraction.  Crude drugs:The crude drugs are plant and animal durgs that contain natural drugs containing natural substance that have undergone only the processes of collection and drying.  Extracts:It can be defined us preparation of crude drugs.

4. Types of extract 1. Dry extract 2. Soft extract 3. Aqueous extract 4. Hydro-alcoholic extract

5. Classification of extraction 1. Solid-liquid extraction 2. Liquid-liquid extraction

6. Theory of extraction 1. Suitable size reduction 2. Penetration of drug by the solvent 3. Solution of the soluble matter 4. Escape of dissolve material through the boundary layer surrounding the particles 5. Separation of the solution and exhausted drug

7. Method of extraction  Infusion  Decoction  digestion  Maceration  Percolation  Decoction  Super-continuous hot extraction  Critical fluid extraction  Aqueous alcoholic extraction  Ultrasound extraction

8. Infusion  In this method, the plant material (herbal tea) is placed in a pot and wetted with cold water. Immediately afterwards, boiling water is poured over it, then left to stand, covered with a lid, for about fifteen minutes after which the tea is poured off.

9. Maceration  This method is used frequently for water soluble active constituents. It consists of macerating the plant material in cold water (15-20°) for several hours.

10. Percolation  In this method, the ground plant material is subjected to a slow flow of fresh solvent.  There are two processes of percolation: Reserve percolation processes Modified percolation processes

11. Digestion  This method is suitable for hard barks or woods which are difficult for water to penetrate. Digestion is also considered as maceration but, at a relatively elevated temperature. As a general rule the temperature of the extracting medium should be in the range from 35-40° but not exceeding 50°.

12. Decoction  If the plant material is boiled for ten minutes or if boiling water is poured over it and allowed to stand for thirty minutes, the result is called decoction.  For example: Cinchona bark

13. Continuous hot extraction method  This procedure is considered as the most common method used for the extraction of organic constituents from dried plant tissue. It can be used both on laboratory and industrial scales. In the lab, the powdered material is continuously extracted in a Soxhlet apparatus with a range of solvents of increasing polarity.

14. Aqueous alcoholic extraction  It involves soaking the crude drugs in the form of either of powder or a decoction for a specified period of time during which it undergoes fermentation and generates alcohol in situ;this facilitates the extraction of the active constituents

15. Ultra-sound extraction(sonication)  The procedure involves the use of ultrasound with requencies ranging from 20 KHz to 2000 KHz;this increases the permeability of cell walls and procedures cavitation.The process is useful in some csases like extraction of raulfia roots.