INTRODUCTION

1. INTRODUCTION • Crude drugs(herbs) &galenical products or phytomedicinals are widely used in "complementarymedicine " [about 50% of the total drug market]. • "Pharmacognosy" = "knowledge of drugs" gives "a scientific description of natural materials used in medicine(herbs, animal products & inorganic materials)". • "Phytochemistry"studies "thechemistry, distribution, isolation, identification, quantitative determination, biosynthesis, metabolism & biological activity of plant constituents."

2. Role of natural products in modern medicine • Useful drugs which cannot be commercially produced by synthesis e.g. opium, ergot & cinchona alkaloids, digitalis glycosides & most antibiotics. • Basic compounds, which could be modified to be more effective or less toxic e.g. morphine molecule. • Modelsfor production of synthetic analogues with similar physiological activities, e.g. procaine. • Starting materialsfor production of potent drugs e.g. hydrocortisone & steroidal hormones from stigmasterol & saponins.

3. Different forms of plant products Different formsare supplied based on: • Aim of use • Nature of active ingredients • Economic factors • Fresh plant materials[especially in perfume industry]. • Dried plant materials: [flavoring agents, spices & drugs where dosage is not critical]. • Acellular products :materials derived directly from plants [gums, resins, & fixed & volatile oils]. • Galenical preparations: [plant extracts & tinctures] • Processed extracts :standardized to contain a certainconcentration of the active principle. • Pure compounds :most required in pharmaceutical formulations as they facilitate proper standardization of biological activity & quality control

4. Primary & secondary plant metabolites Plant metabolites : organic substances formed & accumulated by plants. • Primary metabolites : essential for life & present in all organisms e.g. carbohydrates, proteins, fats, & nucleic acids • Secondary metabolites: formed as a defense against predators, attractants (volatile or colored) or detoxifying agents. Mostly pharmacologically active & found in specific organisms or group of organisms. Some metabolites could be included in both divisions e.g. certain fatty acids & sugars.

5. Nomenclature of plant constituents Systematic nomenclatureis difficult due to complexityof structure. Naming is based on trivial nomenclature. Root names are derived from: • Name of the discoverer e.g. Pelletierine alkaloid after Pelletier • Common name of the plant e.g. vinca alkaloids, (vincristine & vinblastine), ergot alkaloids (ergometrine & ergotamine) • Latin name of the plant e.g. visnagin from Ammi visnaga &digitoxin from Digitalis lanata • Biological action e.g. emetine alkaloid which produces emesis

6. Classification of plant constituents Plant constituents occur as: • Single chemicalse.g. glycosides & alkaloids …….. • Mixtures of compoundse.g. gums, fixed oils, fats, waxes, volatile oils, resins & resin combinations.

7. Classification of plant constituents may be according to: Pharmacological activity[analgesics, laxatives, cardiotonics etc……..] Biosynthetic origin, solubility properties & key functional groups Chemistry & common physical properties

8. According to biosynthetic origin, solubility properties & key functional groups: • Phenolics:e.g. flavonoids & their glycosides, phenyl propanoids, anthocyanins, xanthones, tannins & quinones • Terpenoids: e.g. carotenoids, steroids & the major constituents of volatile oils • Organic acids & lipids:e.g. simple organic acids (citric, oxalic & ascorbic), fatty acids (in the form of esters in fixed oils, fats & waxes) • Nitrogenous compounds:e.g. alkaloids &cyanogenic glycosides • Water-soluble carbohydrates & their derivatives:e.g. monosaccharides, oligosaccharides & water-soluble glycosides • Macromolecules:e.g. proteins & polysaccharides

9. According to chemistry & common physical properties This classification will be adopted for convenience, the major groups are: • Volatile oils, Resins & Resin combinations • Carbohydrates • Bitter Principles • Tannins • Alkaloids • Glycosides

10. VOLATILE, ETHEREAL or ESSENTIAL OILS • "Volatile" or "ethereal":as they easily evaporate on exposure to air at room temperature (volatile, from the Latin "volare" i.e. to fly & ethereal = ether-like in their volatility) • "Essential":as they mostly represent the "essences" or principal active principles of the plants in which they occur. They differ entirely from "fixed oils“ in both chemical & physical properties.

11. Major Differences between volatile & fixed oils

12. Historical • In ancient Egypt:embalming process (antibacterial properties of essential oils & resins). • In the Roman culture:aromatic essences in massage & baths. • Incenses:[in temples, churches & mosques] consist of resins rich in volatile oils • In folk medicine:inhalation of aromatics as tranquilizers (e.g. incenses in case of irritability) or stimulants (e.g. onions in case of fainting)

13. Animal sources: Musk, musk-like products (civet, castoreum) & ambergris Secretions produced for attraction or protection Botanical sources: Mainly in higher plants Especially in Pinaceae, Lauraceae, Rutaceae, Myrtaceae, Labiateae, Zingiberaceae, Umbellifereae, & Compositeae. Distribution & Occurrence

14. Free & Combined Forms of Volatile Oils They may be present : • Free aromatic characteristic odor, or • Combined with: • Sugars glycosides • Gums, resins or both oleo-gums, oleoresins or oleo-gum-resins.

15. Location in the plant They may be: • Diffused in all plant tissues(e.g. Pinaceae, Conifers) • Accumulated inspecialized secretory structuresusuallyon or near the surface of the plante.g.: • Modified parenchyma or oil cells: (Lauraceae & Zingiberaceae) • Glandular hairs: (Labiateae) • Oil tubes or Vittae: (Umbellifereae) • Oil glands: (Rutaceae & Pinaceae)

16. Distribution in plant organs V. O. may accumulate in all types of plant organs: • Flowerse.g. rose • Leavese.g. eucalyptus & peppermint • Barks e.g. cinnamon • Woodse.g. sandalwood • Rootse.g. vetiver • Rhizomese.g. ginger • Fruitse.g. umbelliferous & citrus • Seeds e.g. cardamon

17. Variation in composition of v. oils from different organs of the same plant • Cinnamon tree: bark oil rich in cinnamaldehyde leaf oil rich in eugenol root oil rich in camphor • Bitter orange tree: "Bitter orange oil": from the fresh pericarp of the fruit (rind or zest), "Neroli oil": from the flowers  "Petit grain oil": from the leaves,twigs & unripe fruits. These oils are different in composition & aroma

18. Physiological role of V.O. in the plant • Waste products of metabolism(detoxifying agents) • Energy producersin case of deficiency from CO2 assimilation • H+ donorsin certain metabolic reactions • Protectantsagainst predators: e.g. insect repellents & antifungals (i.e. for defense). • Pollinators: attracting insects during cross-pollination (due to their nice odors).

19. Common Physical Characters • Colorless, pleasant smelling liquids, volatile at room temperature • Steam distillable • High refractive index • Mostly optically active • Density < water (i.e. lighter than water) except for few ones • Immiscible with water, but sufficiently soluble to impart a fragrance to water  aromatic waters [hydrosols] • Soluble in alcohol & common organic solvents • Darken in color if exposed to air & light (resinification)

20. Exceptions • Oils of cinnamon, clove & winter green are heavier than water • Oils of anise & rose solidify just below room temperature (15 & 18oC, respectively) • Oils containing azulenes are colored (e.g. oil of chamomile is blue).

21. Chemical Composition • V. O. arecomplex mixtures of hydrocarbons & oxygenated compounds[alcohols, phenols, ethers, aldehydes, ketones, oxides, peroxides & esters]. All of these contribute to the odor & physiological activity of the oil. • Few oilsconsist ofone main componente.g. • Oil of mustard (93% allylisothiocyanate) • Oil of clove (85% eugenol) • Most V. O. constituents belong to 2 main groups: • Terpenoids [derived from acetate] & • Phenylpropanoids [aromatic compounds, derived from phenylpropane]

22. Variation in Physico-Chemical Characteristics Most important influencing factors are: • The environmental conditionsunder which the plant is grown • Themethod used forpreparationof the oil

23. Medicinal & Commercial Uses of V.O. • Therapeutic & medicinal uses: local stimulants, carminatives, diuretics, mild antiseptics, local irritants, anthelmintics, parasiticides … • Spices & condiments: in food seasoning (to impart aroma & flavor) or as preservatives • Flavoring agents: in food (e.g. beverages, soups, bakery products, confectionery) & pharmaceutical industries • Aromatic agents: in all types of perfume industries (cosmetics, soaps, deodorizers, household cleaners, polishes & insecticides)

26. Selection of the suitable method is done according to : • The condition of the plant material (moisture content, degree of comminution) • The localization of the oil in the plant (superficial or deep) • The amount of the oil • The nature of the oil constituents

27. Distillation methods Principle • Most volatile oil constituents boil between 150-300ºC. In order to reduce decomposition, volatile oils are distilled in the presence of water. • The mixture will boil below 100ºC [Dalton’s law of partial pressure : “When 2 immiscible liquids are heated together, they will boil at a temperature below the boiling point of either one”]. • The oil is carried over with steam in the form of vapor

28. Distillation methods Application: preparation of thermostable oils, present in large amounts & not rich in esters (e.g. oils of turpentine, peppermint, cardamon, anise, eucalyptus) Types of distillation: • Water-distillation • Steam distillation • Water-and-steam distillation • Direct-steam distillation

29. Distillation: Terminology • Hydrodiffusion = process by which water or steam penetrates the plant tissues to take over the oil • Aromatic water = Hydrosols = distilled aqueous layer saturated with oil e.g. rose, orange flower & peppermint waters • Cohobation = return of aromatic water to the distillation chamber, in water distillation, in order to recover the dissolved oil.

30. Distillation methods

31. Distillation apparatus Consists of3 parts: • The distillation chamber made of stainless steel free from any Fe+++ ions to avoid degradation of the oil constituents  darker oils. • The condensing system • The receiver e.g. Florentine receivers which allow separation of the oily layer from water in the distillate (oils lighter or heavier than water)

33. Florentine Receivers Purification (Rectification) of distilled oils Bad smelling or dark colored oils are purified by: • Redistillation or dry distillation under reduced pressure • Dehydrationby passing over anhydrous sodium sulphate

34. Remarks • Distillation should be done just after comminution [ i.e. reduction in size, crushing, powdering)  prevent loss by evaporation or deterioration of the oil. • Coarse comminutionincrease "Hydrodiffusion"  oils with better yield & quality. • High temperature & water distilled oils differing in composition from natural oils [artifacts]. • Insufficient distillation time (shorter)  fractionation of the oil. • Hydrolytic products (e.g. lower alcohols & acids) are water-soluble & remain in the distillation chamber. • Steam volatile impurities e.g. amines & furfural (degradation product of carbohydrates) contaminate the final product. • Sensitive constituents could be affected by boiling water e.g. • Esters hydrolyzed. • Tertiary alcohols  dehydratedhydrocarbons. • Unsaturated hydrocarbonspolymerized.

35. Scarification & Expression Methods Principle Mechanical procedures carried at room temperature & based on puncturing & squeezing of the plant material to liberate the oil, which is collected. Applications Preparation of heat sensitive oils, present in large amounts in outer peels of fruits e.g. Citrus fruits (Rutaceae) as orange, lemon & bergamot.

36. Scarification & Expression Methods The peel of Citrus fruits consists of 2 distinct layers: • Outer colored zone (waxes + pigments + oil glands) • Inner white zone (pectin + cellulose).

37. Scarification & Expression Methods The process involves 3 steps: • Squeezing of the peel under a stream of water emulsion (volatile oil + water + pectin + cellulose + pigments + traces of waxes). • Centrifugation (to remove water + pectin + cellulose) • Strong cooling (to remove waxes)

38. Scarification & Expression Methods A- Sponge Method Based on squeezing the removed peels e.g. orange • Fruits washed, cut into halves & fleshy parts removed. • Peels soaked in water, turned inside out then pressed between a convex projection & a sponge. • Sponge (saturated with oil emulsion) periodically squeezed in a vessel The tissue of the sponge serves for: • Collection of the oil • Filtration of the product from any particles of the inner white zone of the peel.

39. Scarification & Expression Methods B- Ecuelle-à-piquer method • Based on puncturing (scarifying) the surface of whole fruits (lemon), the oil exudes from the outer zone of the peels in the form of emulsion. • The instrument is funnel-shaped, formed of a shallow bowl with a tubular projection at the center. The bowl bears numerous pins which scarify the oil glands to release the oil. • The tubular part serves as: • Handle to rotate the instrument. • Receiver to collect the oil.

40. Scarification & Expression Methods C- Expression of rasping process • Based on removal of the outer layer of the peel with a grater, collecting the rasping in special bags then strong pressing. • The oil emulsion is collected in large vessels D- Machine processes • Based on the same principles as the above 3 traditional methods A, B & C but carried out by machines.

41. Solvent extraction methods Principle Based on extraction of the volatile oil from the plant material with a suitable solvent According to thenature of the solventused,three typesare distinguished: • Volatile solvent extraction • Non-volatile solvent extraction • Supercritical fluid extraction

42. Solvent extraction methods-Application Preparation ofdelicate floweroilse.g. jasmine, violet, tuberose & narcissus which are: • Present invery smallamounts, not easily obtained by distillation or expression • Oils formed ofthermolabile constituents(i.e. easily decomposed by heat)

43. Volatile solvent-extraction Preparation of "floral concretes" • Solvents used:petroleum ether & n-hexane • Extraction(“percolation” or “maceration” at room temperature, “continuous hot extraction” in a Soxhlet apparatus at constant temperature) • Solvent removal(distillation under reduced pressure) Percolator Soxhlet apparatus

44. Volatile solvent-extraction Floral concrete =Fragrant constituents + Fats + Waxes + Albuminous matter + Fat soluble pigments e.g."floral concrete" of jasmineis semi-solid & yellowish-orange in color. Floral absolute = consists mostly of theoxygenated constituents of the oil. • More expensive&purifiedthan the corresponding concrete. • Preparation:repeated extraction with absolute alcohol • Impurities:removed by strong cooling & filtration • Solvent removal : by distillation.

45. Non-volatile solvent extraction Application:Preparation of natural flower oils producing the finest perfumes. Solvents: Lipids of high degree of purity e.g. • Fats (lard : tallowin a mixture 2:1) • Fixed (olive oil) Techniques: • Enfleurage (hot & cold) • Pneumatic method • Maceration (in fixed oils) Principle:based on the liposolubility of volatile oils

46. Enfleurage Process- Preparation of jasmine oil • Equipment: Great number of glass plates closely arranged in wooden frames (or chassis). • Procedure: • Spread the mixture of fat (lard / tallow 2: 1) on both surfaces of each glass plate. • Cover the top of each plate with flowers or petals, so that each layer of flowers is enclosed between 2 layers of fat. • Replace old flowers by fresh ones every 2-3 days • Repeat the process until the fat is saturated with the oil • Remove the last charge of flowers from the fat("Defleurage") • Scrap & collect the fat layers, warm, filter through gauze & cool “Enfleurage product” or “Floral pomade”

47. Jasmine flowers

48. “Enfleurage” Process Cold Enfleurage Hot Enfleurage

49. Super critical fluid extraction Principle:based on usingliquefied gasese.g.CO2 under specific temperatures& pressures as extracting solvents. Under these conditions these gases are liquids but maintain the penetrating properties of gases & allow more efficient extraction. The oils obtained are of closest composition to the natural oils.