PREPARATION OF MEDICINAL PLANTS and ESSENTIAL OILS
INTRODUCTION
In this page we recall the basic principles of collecting and preserving medicinal plants, as well as how to prepare traditional herbal remedies in Western medicine.
We discuss the preparation of herbal medicines and make a few stops around the world (Creole, Amerindian, Polynesian, Australian Aboriginal medicines).
It is possible, especially in tropical-equatorial zones, to use, when needed, the medicinal plants that surround us without storing or preserving them.
On the other hand, in countries with very marked seasons (dry or cold), we are led to use medicinal plants during their flowering, but also to try to preserve them in order to be able to use them later during the bad season.
Preparing your own remedies is not a necessity in developed countries, but it is satisfying to treat yourself « naturally », it is cheap and it also avoids consuming synthetic drugs with too powerful or inappropriate effects; conversely, it is often the only way to try to cure yourself in many countries where medical services are disorganized and synthetic drugs inaccessible.
HARVESTING MEDICINAL PLANTS
Traditionally, and preferentially, medicinal plants are harvested in their natural habitat but, increasingly, and in many regions, this is difficult to achieve:
- because of the permanent increase in agricultural areas « treated » with pesticides, including pastures, hedgerows and fallow lands,
- and for some species, because of the worrying disappearance of medicinal plants in the wild, overexploited (to meet the growing global demand of the pharmaceutical industry, traders and merchants in medicinal plants),
- or weakened by changes in the natural environment (pollution, industrial agriculture, agro-forestry, desertification and excessive grazing).
Many highly sought-after medicinal plants are now cultivated in a reasonably organic way, but also sometimes intensively using fertilizers and pesticides.
When harvesting wild plants, in all cases, only the quantity of plants necessary should be collected, if possible away from busy roads and areas of intensive agriculture and finally ensure the correct identification of the medicinal plant (botany guide, pharmacist, traditional practitioner).
If possible, we collect:
Whole plants: at the time of their flowering.
Leaves: after full development and if possible before flowering.
Flowers and flowering branches: immediately before the flowers are fully open.
Roots of annual plants: at the end of the vegetative period (end of growth).
Roots of biennial plants: at the end of the vegetative rest of the first year and before the resumption of the second year.
Roots of perennial plants: during their second or third year, before they become too hard and fibrous (lignification).
Fruits and seeds: when ripe or very slightly before when you plan to dry the fruits
Tree bark: in winter or early spring (or during the dry season); shrub bark: after the hot season (or at the end of the wet season).
If the medicinal plant is not to be used within 24-48 hours (stored in a cool place or with its feet in water), it must be dried (or a mother tincture prepared, see below):
- drying in the shade if possible, in an unconfined and therefore ventilated space: attic, solar oven, shaded rack,
- sometimes oven drying (gentle heat) in regions with high humidity and almost always, for large fleshy roots, after they have been cut into slices or pieces.
- Once well dehydrated, the plants are kept in a bouquet when we think of using them (or selling them) soon,
- Otherwise, they are stored (whole, in fragments or in powder) in airtight and watertight containers for 6 to 12 months.
MAIN PREPARATIONS OF REMEDIES
based on medicinal plants
POWDERED PLANTS
Well dried, the plants are reduced to powder and used as is, without preparation.
They can be mixed with a little water or food, but the taste is often frankly unpleasant especially because of the bitterness which is much too strong for humans; we then prepare pills or capsules of dry powder to swallow and which will dissolve in the stomach or intestine.
INFUSIONS DECOCTIONS MACERATIONS
Water is the easiest way to use to extract the pharmacologically active parts of medicinal plants.
Some components are sensitive to heat, others difficult to dissolve, so we can play on the temperature of the water and the time it is kept in the water to specifically extract the interesting parts.
INFUSION or « tea » or « herbal tea »:
the dry or fresh plant, sometimes in powder or small pieces is covered with very hot or boiling water, after 3 to 6 minutes, it is stirred lightly and filtered.
Consume immediately warm or cold, it can be kept refrigerated for 6 to 12 hours.
THE DECOCTION or concentrated tea:
the dry or fresh plant, sometimes in powder, chopped or bruised form is put in a container with cold water, brought to the boil and simmered for 10 to 20 minutes, filtered.
The decoction can be kept for 2 to 3 days in the cold.
AQUEOUS MACERATION: the fragmented medicinal plant is kept in cold water, in a cool place, for 12 to 24 hours, stirred from time to time, filtered, to be used within 6 hours.
ALCOHOLIC TINCTURE
By definition, MOTHER(HOMEOPATHIC) TINCTURE is “a liquid preparation which results from the dissolving action of an alcoholic vehicle on FRESH plant drugs.”
The mother tincture is obtained by maceration in ethyl alcohol at different degrees, of fresh or « stabilized » medicinal plants; if the plant is DRY we speak of ALCOHOLIC TINCTURE.
Apart from the fact of using alcohol which can be prohibitive for some, the alcoholic (or mother) tincture is very interesting because it is easy to implement, the result is fairly regular, the concentration of active substance controllable (allowing an easy prescription) and its conservation is quite good.
Here is how we should proceed:
Sorting and pruning of medicinal plants (previously carefully determined) or their fragments.
Crushing and immediate maceration in 95° alcohol (ethanol), the quantity of distilled water necessary to obtain an alcoholic strength of 60 to 70 is added to the mixture.
At the same time, a part of the fresh medicinal plant is set aside and, after being weighed, is left to dry in an autoclave at 50°C for 12 to 24 hours; it is then weighed again to obtain its « dry weight » which generally corresponds to 20 or 30% of the fresh weight.
The macerate is kept cool, in an airtight container and away from light for 3 weeks, shaking it from time to time.
After three weeks, it is filtered and the liquid obtained by pressing the residue of the macerated plant is also collected, and everything is mixed.
The liquid obtained is measured and the alcohol content (60°) and the volume of tincture are adjusted to obtain the required strength (in relation to the theoretical weight of the dry matter):
in a 1/10 tincture (the most common in France), 1 litre of tincture corresponds to 100 grams of dehydrated medicinal plant or 250 to 300 grams of fresh plant.
Other fairly common strengths are 1/5, 1/20.
At a family level (domestic) and for non-commercial use, we can act more simply, for example:
100 grams of dried plant in 1 liter of 60° alcohol or 250 grams of fresh plant in 1 liter of 70° alcohol give, after maceration for a few weeks, filtration and expression of the residue, an alcoholic tincture approximately 1/10 in alcohol between 50° and 60°; for good conservation, it should not go below 45°.
If an alcoholic tincture is concentrated by evaporation, a « fluid extract » is obtained, strength 1/1 which corresponds to 100 g of dry plant in 100 g of fluid extract (much more concentrated in active ingredients).
If the evaporation is continued, the « soft extract » with a syrupy consistency of honey is obtained.
Alcoholic tincture is very convenient to use (internal and external use) and can be stored for several years in a cool place away from light (colored or opaque glass), in a well-sealed non-metallic container.
It can be incorporated into a lotion, an ointment, a poultice, an enema and mixtures can be made, i.e., tinctures of medicinal plants can be combined with each other.
ESSENTIAL OILS
By definition, essential oils are “products containing the volatile principles contained in plants”.
To obtain these volatile substances and condense them:
- they are carried along by hot water vapor which will then condense; the essential oil then separates by difference in gravity;
- the contents of the secretory pockets are expressed by pressure when they are present (for example in Citrus)
- Other methods exist: extraction by volatile solvents, extraction by supercritical carbon dioxide (very compressed and very cold), extraction by a fatty solvent;
all this requires very specialized equipment and is a matter for professionals.
However, the volatile principles of the essential oil can be recovered using alcoholic maceration (alcoholic tincture).
Furthermore, the components of the essential oil become volatile when heated, so we can:
- heat the leafy branches, aromatic woods and barks, aromatic seeds, resins (incense) and thus breathe in the components of the essential oil which are absorbed through the respiratory tract;
- Soak the aromatic leaves in very hot water and obtain an aromatic bath, remembering that the components of essential oils easily pass through the skin during bathing.
- The components of the essential oil are soluble in fatty substances: melted fatty substances can be used but it is easier with vegetable oils (coconut, olive, sweet almond, etc.). This gives an aromatic oil that contains a good part of the essential oil but also other fat-soluble components (which is not always interesting).
PREPARATION of an OILY MACERATE or AROMATIC OIL:
- fill a container halfway with the well-dried and coarsely crushed aromatic medicinal plant and top up with the oil;
- let it macerate for 2 to 4 weeks at room temperature, stirring from time to time. The oil settles, otherwise it is filtered through a clean cloth;
- This aromatic oil is stored in tinted glass away from light and heat: examples: monoi based on coconut oil, aromatic oil (or infused) with flowers (rose, St. John’s wort), with labiatae (thyme, rosemary, sage, etc.).
These aromatic oils can be used as massage oil, or in localized skin application (St. John’s wort) or quite simply in cooking (thyme, rosemary).
COMMERCIAL PHYTOMEDICAMENTS
The pharmaceutical industry mainly offers:
preparations which correspond more or less to the whole plant:
- Fresh plant “juice” packaged for preservation
- dried plants split or pulverized
- micronized dry powder
- dry powder of the plant after “cryocrushing”
i- s an integral suspension of fresh crushed and stabilized plant
Extracts:
- hydro-alcoholic, analogous to tincture, fluid extract or soft extract;
- aqueous, similar to infusions, decoctions, syrups;
- dry and sometimes atomized, in very fine powder, we then speak of nebulization;
- the glycero-alcoholic macerate, somewhat similar to the mother tincture but with the addition of glycerin to better extract certain active ingredients from the buds and very small branches; this macerate is the basis of gemmotherapy;
- essential oil that allows aromatherapy (see above).
In addition, pharmaceutical laboratories extract pharmacologically active substances, purify them, sometimes modify them or use them to synthesize new molecules that are more active or less toxic to the body.
Thus, we find in pharmacies many varied preparations sometimes combining several plants, several preparatory methods.
AROUND THE WORLD: SOME STOPOVERS
CREOLE MEDICINE OF THE WEST INDIES
Creole medicine in the Antilles makes great use of infusion and decoction, several plants can be mixed together; we distinguish between « herbal teas » which refresh and « teas » (less abundant in quantity) which warm. The opposition of hot and cold (cooling and inflammation) balances health in Creole thought (we find this notion in other populations and also in Europe).
If infusion-decoction is common, « looch » is less so, it is an aqueous extract concentrated by evaporation.
Alcoholic maceration (in rum of course but also « cognac » or brandy and cooked wines) is common, we can mix leaves and roots, fragments of wood or bark and sometimes animals (snake heads).
The sap of the plants is collected by expression or after rapid passage through a flame.
The use of plant ashes on skin lesions, traditional in Africa, is taken up in the Antilles-Guyana.
Children are easily bathed or sprayed with a herbal bath.
Fresh plant plasters or poultices are frequently used, more rarely now, the mixture of dried plant and animal fat.
AMONG THE AMERINDIANS OF THE GUYANAS
Among the Amerindians of the Guianas, the harvest, preparation and use of plants are generally done during the day; the forest is omnipresent around the village.
All plant parts are usable: leaf, bud, fruit and seed, flower, bark and wood, root, sap and latex, exudate.
The plants are macerated in cold water or prepared as a decoction.
Sometimes the leaves are « cooked » slowly over low heat over embers to then be reduced to powder or to produce a « medicinal smoke ».
The juice of the leaves and buds is collected, the bark is softened by passing it more or less quickly over a flame.
Among the Amerindians, the healer’s preparations are absorbed by mouth, but external « washings » are quite often carried out using a gourd of preparation that is poured over the head and shoulders, and the mouth is also rinsed without swallowing.
Steam baths with plants are rather reserved for shamans or healers to promote their « vision ».
Body friction with leaves or bark sometimes passed through a flame to soften them or make them « sweat », plant or sap plasters are common.
IN POLYNESIA
In Polynesia, no infusion or decoction is used.
Medicinal plants (whole plants, leaves, flowers, fruits, roots, wood, bark) are generally crushed with a stone pestle and mixed with the water of the green coconut (at degrees of maturation that depend on the recipe) or in coconut milk (also prepared in a special way, sometimes with immature nuts) or in coconut oil. Brown sugar is sometimes added to reduce the bitterness; the preparation is carefully filtered with plant fibers.
In some cases, the crushed plant or its pure juice is applied directly to the sick or painful part.
The plaster that is left in place and the liniment are well known to Polynesians.
The recipes most often combine different plants.
THE ABORIGINES OF AUSTRALIA
The Australian Aborigines were considered by the first settlers to be healthy people despite living in very harsh conditions; they used plants from the Australian bush to help heal wounds and ulcers, to fight against diarrhea, muscle pain, eye infections and the fairly frequent « inflammatory ophthalmia », wounds due to venomous bites, etc.
As is often the case in traditional medicine, plants also have a symbolic, clan value, a healing capacity expected by the Aborigine but which baffles the modern pharmacologist.
Unlike the Polynesians, they often used aqueous infusion-decoction.
Like many populations living very close to nature, they made extensive use of fresh plants: sap, latex, leaves as well as young shoots, and crushed bark as a plaster or temporary application. The leaves were chewed but the juice was spat out for mouth ailments and toothache.
The Australian Aborigines had discovered the powerful physiological effect of nicotine.
In the Australian bush, there are indeed Solanaceae of the genera Duboisia and Nicotiana; the leaves of the small tree Duboisia hopwoodii were the most sought after (to be distinguished from D. myoporoides and D. leichardtii which contain other alkaloids, scopolamine or hyoscyamine, (see Datura)). These leaves were chewed and later smoked, copying the Europeans.
The leaves and flowering branches were dried, ground into powder and carefully preserved in a small purse (because the « good » Duboisia is not found everywhere), or dried over a fire, then moistened and rolled like a cigar but after having been mixed with plant ash from particular trees and sometimes plant wax to better stick them together.
During chewing, the basic compounds in the ash released the nicotine from the quid, thus increasing the effect felt (the lime from the betel quid in Asia or the coca quid in South America is also there to promote the release of alkaloids).
Copyright 2024: Dr Jean-Michel Hurtel
site dedicated to medicinal plants and essential oils
PHYTOTHERAPY, MEDICINAL PLANTS, AROMATHERAPY, ESSENTIAL OILS