1. Production and manufacture of Medicinal Plants Lecture (7)
Dr Dalia Rasheed

2. Extraction of Medicinal Plants
Aromatic Plants Extracts
Types of Isolates that can be obtained commercially from aromatic plants:
Essential oils:
Essential oils are generally derived from one or more plant parts, such as flowers (e.g. Rose, Jasmine & Lavender), leaves (e.g. Mint, & Lemongrass), leaves and stems (e.g. Geranium), barks (e.g. Cinnamon & Cassia), woods (e.g. Cedar & Pine), roots (e.g. Valerian), fruits & seeds (e.g Fennel, Coriander, Caraway, Dill, Nutmeg & Orange), rhizomes (e.g. Ginger & Curcuma) and gums or oleoresin exudations (e.g. Balsam of Peru, Myrrh &, benzoin).

3. Extraction of Medicinal Plants
Aromatic Plants Extracts
Types of Isolates that can be obtained commercially from aromatic plants:
Essential oils:
They can be extracted by Distillation, Maceration or Percolation with volatile solvents and Enfleurage methods.
They are widely used in a variety of products such as detergents, soaps, toilet products, cosmetics, perfumes, pharmaceuticals, confectionery food products, soft drinks, distilled alcoholic beverages (hard drinks) and insecticides.
Limonene
Menthol
Thymol

4. Extraction of Medicinal Plants
Aromatic Plants Extracts
Types of Isolates that can be obtained commercially from aromatic plants:
Concretes:
They are semi-solid, waxy, dark colored products representing mixtures of volatile constituent, wax, fats, pigments and albuminous materials.
They are prepared by extraction using a volatile solvent followed by removal of the volatile solvent by distillation under reduced pressure.
They are rich in hydrocarbon-soluble material and devoid of water-soluble components.
Concretes when prepared as previously described can’t be widely used in perfumery.

5. Extraction of Medicinal Plants
Aromatic Plants Extracts
Types of Isolates that can be obtained commercially from aromatic plants:
Absolutes:
They are alcohol-soluble volatile concentrates consist mainly of oxygenated constituents which are responsible of fragrance.
Absolutes are prepared by repeated extraction of the concrete using absolute ethyl alcohol and purified by cooling to remove fats, waxes and pigments.

6. Extraction of Medicinal Plants
Aromatic Plants Extracts
Types of Isolates that can be obtained commercially from aromatic plants:
Resinoids:
They are extracts of naturally dry resinous material, made using a hydrocarbon solvent.
The extraction process is same as that of concrete production.
Pomades:
They are the products of extracts of a process known as ENFLEURAGE, which is a cold fat extraction method.

7. Methods of Extraction of Volatile Constituents from Aromatic Plants

8. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.1. Water Distillation (Hydro-distillation):

9. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.1. Water Distillation (Hydro-distillation):
Principle:
The herbal material is soaked with water in the distillation chamber.
The mixture is directly heated to boiling and thus vaporizes → steam carrying volatile constituents.
This steam is then directed to cooling condenser chamber → distillate (water + volatile constituents) to be collected in the collecting flask.
The volatile constituents (essential oils) may be lighter or denser than water and according to this, volatile oils could be isolated.

10. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.1. Water Distillation (Hydro-distillation):
Disadvantages:
Oil components like esters are sensitive to hydrolysis while others like acyclic monoterpene hydrocarbons and aldehydes are susceptible to polymerization.
Oxygenated components like phenols have a tendency to dissolve in the still water, so their complete removal by distillation is not possible.
As water distillation tends to be a small operation (operated by one or two persons), it takes a long time to accumulate much oil and good quality oil is often mixed with bad quality oil.
Water distillation is a slower process than either water and steam distillation or direct steam distillation.

11. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.1. Water Distillation (Hydro-distillation):
Applications:
For air-dried plant material with constituents not degraded by direct heating up to 100 °C.
Ex: water distillation of Turpentine oil from the crude turpentine oleoresin.

12. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.2. Water and Steam Distillation (Wet Steam Distillation):

13. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.2. Water and Steam Distillation (Wet Steam Distillation):
Principle:
Water is directly heated to boiling in a water tank → steam.
The steam is then flowed to the herbal material (packed in another tank and pre-macerated with water for several hours prior to distillation) → vaporized water + volatile constituents.
The vaporized water & volatile constituents are then directed to the cooling tank (cooling condenser) → distillate to be collected in the collecting tank.
The volatile constituents (essential oils) may be lighter or denser than water and according to this, volatile oils could be isolated.

14. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.2. Water and Steam Distillation (Wet Steam Distillation):
Advantages:
Higher oil yield.
Components of the volatile oil are less susceptible to hydrolysis and polymerization (the control of wetness on the bottom of the still affects hydrolysis, whereas the thermal conductivity of the still walls affects polymerization).
If refluxing is controlled, then the loss of polar compounds is minimized.
Oil quality produced is more reproducible.
It is faster than water distillation, so it is more energy efficient.

15. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.2. Water and Steam Distillation (Wet Steam Distillation):
Applications:
For fresh or dried plant material with constituents undergo degradation by direct heating.
Ex: wet steam distillation of Clove oil, Cinnamon oil & Lemongrass oil.

16. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.3. Direct Steam Distillation (Dry Steam Distillation):

17. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.3. Direct Steam Distillation (Dry Steam Distillation):
Principle:
Same as wet steam distillation EXCEPT that the herbal material is not pre-macerated with water.
Advantages:
More rapid and thus the energy consumption is lower and less likely to damage oils which contain reactive compounds such as esters.
Applications:
For fresh plant material that is loaded with sufficient natural moisture and hence requires no maceration with water prior to distillation.
Ex: dry steam distillation of Peppermint oil & Spearmint oil.

18. Methods of Extraction of Volatile Constituents from Aromatic Plants

19. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.4. Cohobation:
Herbal distillates:
These are aqueous products of hydro-distillation or steam-distillation, which are colloidal suspensions (hydrosol) of essential oils as well as water soluble components.
They have been used as flavoring agents & in skin care.
Herbal distillates go by many other names including floral water, hydrosol, hydrolate, herbal water and essential water.

20. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.4. Cohobation:
Principle of Cohobation:
It is a process of repeated distillation of the same matter with the liquid drawn from it, usually an aqueous distillate.
Applications of Cohobation:

21. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
1.4. Cohobation:
Applications of Cohobation:
When rose oil is extracted by water distillation, one main constituent - phenyl ethyl alcohol - dissolves into the water of the distillation.
The oil so extracted is therefore not whole (incomplete), and is deficient in one main rose-smelling ingredient.
In order to produce a "complete" rose oil, the phenyl ethyl alcohol needs to be distilled from the water in which it dissolved and added back to the "incomplete oil".
When this phenyl ethyl alcohol is so distilled, it is added back to the original distillate, in the correct proportion, to form a complete and whole rose oil.

22. Extraction of Medicinal Plants
Aromatic Plants Extracts
Distillation:
Preparation of herbal material to be distillated:
Plant material should be comminuted before distillation to facilitate hydro-diffusion (penetration of the steam + H2O through plant cell membranes).
The comminuted materials should be distilled immediately to avoid any loss of the oil.
Purification of the distillated oil:
De-colorization and removal of any bad smelling compounds of the distilled oil by re-distillation under reduced pressure.
Dehydration: water is removed from distilled oil by filtration over anhydrous sodium sulphate to prevent hydrolysis of esters if present.

23. Extraction of Medicinal Plants
Aromatic Plants Extracts
Extraction:
2.1. Extraction by Volatile Organic Solvents:
Volatile Organic Solvents used:
Petroleum Ether - Diethyl Ether - n-Hexane.
Principle:
First: herbal material is percolated or macerated with the organic solvent at room temperature.
Then: volatile solvent is removed by distillation under reduced pressure.
The product is a semi-solid residue known as concrete, If the herbal material is flowers the product is known as floral concrete.

24. Extraction of Medicinal Plants
Aromatic Plants Extracts
Extraction:
2.2. Extraction by Non-Volatile Solvents (Enfleurage):
Principle:
Fat is spread out on glass plates contained in wooden frames, leaving a clear margin near the edges. The absorptive surface of the fat is increased by surface grooves made with a wooden spatula.
Fresh flowers are spread out on the surface of the fat and the frames are stacked in piles. After the perfume oils have been absorbed from the flowers, the spent flowers are removed by hand. Fresh flowers are again spread on the fat surface. This is repeated until the fat surface is completely enriched with perfume oils.
The product so obtained, called pomade, is ready for cold alcoholic extraction.

25. Extraction of Medicinal Plants
Aromatic Plants Extracts
Extraction:
2.2. Extraction by Non-Volatile Solvents (Enfleurage):

26. Extraction of Medicinal Plants
Aromatic Plants Extracts
Extraction:
2.2. Extraction by Non-Volatile Solvents (Enfleurage):
Extract with fat (grease)
Flowers
Enfleurage product (Pomade)
“fat saturated with volatile constituent”
Extract three times using ethyl alcohol absolute
Purify by cooling to remove the greasy material
Triple extract

27. Extraction of Medicinal Plants
Aromatic Plants Extracts
Extraction:
2.2. Extraction by Non-Volatile Solvents (Enfleurage):
Triple extract
(consisting of alcoholic solution of volatile constituents – pigments – traces of fats)
Evaporation
Distillation under reduced pressure
Absolute enfleurage
A semi-solid product consisting of volatile oil, pigments and traces of fats prepared from triple extract by evaporation.
Pure volatile oil

28. Extraction of Medicinal Plants
Aromatic Plants Extracts
Scarification and Expression الخدش و العصر :
Applications:
Heat sensitive oils.
Volatile oils present in large amount in glands in the outer rind of fruits.
Used for preparation of volatile oils occurring in the rind or peel of citrus fruit.
Pelatrice machine:
In the pelatrice process, citrus fruits are fed from a hopper into the abrasive shell of the machine. The fruits are rotated against the abrasive shell

29. Extraction of Medicinal Plants
Aromatic Plants Extracts
Enzymatic Hydrolysis:
Applications:
This method is a necessity when the volatile oil is present in a combination with sugars i.e. in the form of glycosides.
Sinigrin glycoside + H2O + Myrosinase → Mustard oil (allyl isothiocyanate).
Gaultherin + H2O + Gaultherase → methyl salicylate (Winter green oil) + glucose
S-Allyl-L-cysteine → Alliin + H2O + Alliinase → Allicin
Amygdalin + H2O + Amygdalin hydrolyase → Prunasin + H2O + Prunasin hydrolyase → Mandelonitril + H2O + Manelonitril lyase→ Benzaldehyde +HCN (V. oil of bitter almond)

30. General Methods of Extraction of Medicinal Plants
Maceration
Infusion
Digestion
Decoction
Percolation
Sonication
Soxhlet
Super critical fluid
Phytosols
Aromatic cpds
Distillation
Extraction
( by volatile solvent or enfleurge method)
Scarification and expression
enzymatic hydrolysis