Dear Readers,
The qualitative and quantitative presence of the active ingredients contained in drugs and their preparations can be determined with specific, even sophisticated, analyzes (gas chromatography).
The plant hosts several active ingredients (molecules endowed with pharmacological and therapeutic activity) which interact harmoniously with each other, in a game of synergies and antagonisms, and which are capable of producing a pharmacological effect different from that of the single active ingredient.
The set of active principles contained in the single plant takes the name of phytocomplex which acts globally on several organic dysfunctions. Frequently the pharmacological action of the phytocomplex (the set of active ingredients contained in the drug as a whole) can be superior to that of the active ingredient extracted and administered individually or synthesized.
The extraction of the phytocomplex takes place with different techniques, according to the part of the plant to be subjected to the procedure and according to the type of preparation to be obtained. Generally the plants are first dried and finely ground, then subjected to the action of a solvent – often alcohol – in order to extract the active ingredients. Sometimes shredding can be followed by simple pulverization: this process is used when the final product is a herbal tablet, whose active ingredients are "extracted" from the digestive processes of those who have taken it. The oldest and most immediate way to use is represented by herbal tea or decoction. If boiling water is poured over the herbs as is done with tea, an herbal tea or infusion is obtained; if, on the other hand, the herbs are boiled in water for a certain period, a decoction is obtained.
Phytotherapy has long used industrial systems for the extraction of active ingredients capable of altering the therapeutic value of the phytocomplex as little as possible and offering final preparations that are easy to use, whose titre in active ingredients is sufficiently high.
Herbal preparations
Extracts
To make the best use of the active ingredients, it is possible to free them from the plant cells that contain them using suitable solvents: water, ethyl alcohol, oils, glycols.
Aqueous extracts
Infusion: obtained by pouring boiling water over the fresh or dried and chopped drug, mix, cover and leave to macerate, stirring occasionally for an average of 10 minutes. It is filtered and consumed. This type of preparation is normally used for aromatic drugs rich in volatile components (essential oils) and/or which easily transfer the active ingredients to the solvent (flowers, leaves, flowering tops, etc.).
Decoction: obtained by placing the fresh or dried and chopped drug in the prescribed amount of boiling water; it is covered and the boiling continues for the time necessary for an optimal extraction. It is filtered and consumed. This type of preparation is indicated for non-aromatic, non-thermolabile, woody and poorly permeable drugs (stem, roots, bark, rhizomes, etc.).
Hydroalcoholic extracts
These extracts are obtained by macerating for the indicated time cold or hot, statically or dynamically (percolation; turboextraction), the dried or fresh drug, but always chopped or powdered in a solution of water and 95° "good taste" ethyl alcohol (hydroalcoholic solution). The water/alcohol ratio and the consequent alcoholic degree of the solution changes with respect to the drug used and generally varies between 30° and 70°.
In principle, non-coriaceous, mucilaginous drugs require a low alcohol content for optimal extraction, which instead would not be obtained with a higher alcohol content. On the other hand, active ingredients that are poorly soluble in water or tough drugs require a higher alcohol content.
In the case of extraction from fresh drugs, the amount of water already naturally present in the plant must be considered for the alcohol content of the finished product.
To obtain the required strength for one liter of hydroalcoholic solution, dilute the ethyl alcohol at 95° in drinking water with the following proportion: Alcohol at 95° x alcohol content to obtain / 95. The resulting quantity of alcohol at 95° is poured into a graduated container and a lot of water is added until the exact volume of one liter is obtained.
Tincture or Alcoholic: a maceration in alcohol is required, after having minced or pulverized the drug, both in a closed vessel at 40 degrees of temperature, and cold. The operation is performed in two times; first with half of the alcohol used, then with the other half, prolonging each of the two macerations for 4 or 5 days. Then the residue is squeezed out, the two liquids that have been kept separate are combined and filtered. Tinctures of not very active substances are prepared in the drug / solvent ratio of 1 to 5, tinctures of particularly active substances in the ratio of 1 to 10.
Mother tincture: usually means a hydroalcoholic extract from a fresh plant with a drug-solvent ratio of 1 to 5. The term "mother" is used because these are starting products for the production, by means of successive dynamizations (dilutions and agitations), of homeopathic extracts. However, these preparations are also used in phytotherapy.
Fluid extract: usually hydroalcoholic solutions whose solvent is evaporated under vacuum to obtain a preparation which contains 1 gram of soluble drug principles for each gram, i.e. a drug-solvent ratio of 1/1.
Soft extracts: with the same procedure carried out for the production of fluid extracts, the evaporation of the solvent continues until the residue wets the paper and has a pasty consistency.
Dry extracts : with the same procedure carried out for the production of fluid extracts, the evaporation under vacuum of the solvent is continued until the finished product can be reduced to powder. These are particularly active and unstable products because they are hygroscopic.
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