Extraction is the process in which the plant tissues are treated with specific solvents whereby the medicinally active constituents are dissolved out, cell tissues and most of inactive or inert components remain undissolved. The plant material used for extraction should be properly identified. The choice of the plant material for extraction depends on its nature and the components required to be isolated. The solvents used for extraction purposes is known as "Menstruum" and residue left after extracting the desired constituents is known as "Marc".
The medicinal value of natural herb of the plant is due to the active constituents. It is generally advantages to extract the active constituents to formulate a control doses form of that active constituents rather than using the bulk quantity.
Solvents Used for the Extraction of Herbs
From the stand point of pharmacy, the purpose of a solvent is to remove from a solid, either in part or in its entirety such substances that may be rendered to a liquid.
When the material has extracted, the "Menstruum" is known as "Vehicle" or "Carrier" of the extracted materials. Solvents differ widely from each other, not only in differing boiling points, but how they act or react with substances in which they come in contact.
An Ideal Solvent for the Extraction of the Herbs should meet the Following Criteria:-
- It should be non-toxic and selective, i.e. it should dissolve only the required constituent with minimum amount of the inert materials.