Extraction Techniques of Medicinal Plants PDF

13. EXTRACTION TECHNIQUES OF MEDICINAL PLANTS Maceration is a technique widely used in medicinal plants extraction. Maceration involves soaking plant materials (coarse or powdered) in a stoppered container with a ………………….. and allowed to stand at room temperature for a period of minimum t...

13. EXTRACTION TECHNIQUES OF MEDICINAL PLANTS Maceration is a technique widely used in medicinal plants extraction. Maceration involves soaking plant materials (coarse or powdered) in a stoppered container with a ………………….. and allowed to stand at room temperature for a period of minimum three days with frequent agitation. The processed intended to soften and break the plant’s cell wall to release the soluble phytochemicals. After three days, the mixture is pressed or strained by filtration. In this conventional method, heat is transferred through convection and conduction and the choice of solvents will determine the type of compound extracted from the samples. Infusion uses the same principle as maceration; Plant materials are soaked in …………………............................ However, the maceration period for infusion is shorter and the sample is boiled in specified volume of water (eg. 1:4 or 1:16) for a defined time. Decoction also uses the same principle as maceration. It is only suitable for extracting ………………………. compounds, hard plants materials (e.g. roots and barks) and usually resulted in more oil-soluble compounds compared to maceration and infusion. In this process, the crude drug is …………………. in a specified volume of ……………….. for a defined time; it is then cooled and strained or filtered. The starting ratio of crude drug to water is fixed, e.g. 1:4 or 1:16; the volume is then brought down to one-fourth its original volume by boiling during the extraction procedure. Then, the concentrated extract is filtered and used as such or processed further. Percolation: This is the procedure used most frequently to extract active ingredients in the preparation of …………………… and ……………………. A percolator (a narrow, cone-shaped vessel open at both ends) is generally used. The solid ingredients are moistened with an appropriate amount of the specified ……………………… and allowed to stand for approximately four hour in a well closed container, after which the mass is packed and the top of the percolator is closed. Additional menstruum is added to form a shallow layer above the mass, and the mixture is allowed to macerate in the closed percolator for 24 hours. The outlet of the percolator then is opened and the liquid contained therein is allowed to drip slowly. Additional menstrum is added as required, until the percolate measures about three-quarters of the required volume of the finished product. The marc is then pressed and the expressed liquid is added to the percolate. Sufficient menstrum is added to produce the required volume, and the mixed liquid is clarified by filtration or by standing followed by decanting.  14. MORPHOLOGICAL FEATURES OF AROMATIC PLANTS 1. Grass aromatics- Lemon grass., Citronella, Palmarosa, Vetiver Lemon grass C. flexuosus var. flexuosus grows to height of about 3 m. The leaves of the plant are linear, lanceolate, 125 cm long and 1.7 cm broad. Panicles are very large, drooping lax, greyish or greyish green, rarely have a purple tinge, with the raceme pairs in dense masses, spreading, 100-135 cm tall, slightly hairy, lower glumes of the sessile spikelets 3-4, rarely 4-5 mm long, 1 mm wide, having 1-3 definite or obscure introcrainal nerves, shallowly concave with one or two depressions. Types of the lemongrass 1. ……………………………………………………………………………………………... 2. ……………………………………………………………………………………………… ……………………………………………………………………………………………… 3. ……………………………………………………………………………………………… …………………………………………………………………………………………….. 4. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………... Citronella Citronella oil is classified in trade into two types i.e. …………………………….. oil obtained from Cymbopgon nardus Rendle is rather inferior type, while ………………………. oil obtained from Cymbopogon winterianus is considered superior. Java citronella oil has higher alcohol content (90-95%) as compared to Ceylon type (60-71%). A tufted aromatic perennial herb with fibrous roots, clumps stout, erect, over 2 m tall, smooth and shining, leafy, glabrous at the nodes, leaf blades linear, gradually tapering to a long membranous acuminate tip, upto 1 m long, 1.5 cm wide, drooping 2/3 length. Leaf sheaths smooth and glabrous, yellow or purplish red. Inflorescence is very large decompound panicle, spreading loose, over 30 cm long, erect, finally drooping, consisting of a branched and rebranched axis, giving rise to branches of the third and fourth degree which finally end in racemose pairs supported by proper sheaths. Spathes-12 mm long, narrow, dull reddish, membranous on margins. Racemes - 20 mm long one sessile or short the other longer pedicelled with two lower spikelets, Ovary with one carpel, unilocular, stigma bifid, lateral and leathery, superior, ovule single erect. Palmarosa Palmarosa is an aromatic perennial grass. It attains a height up to 300 cm. Leaves linear- lanceolate to lanceolate, cordate or amplexicaul, 8-50 cm long, 1-3 cm broad, finely caudate; panicles 10-30 cm long, turning reddish, often very bright, when mature; glumes 3.3-4 mm long, awns 11.4-14 mm long; lower glume of fertile spikelets deeply channeled; Channel of glume in lower half, very narrow, corresponding to a rib on the inner side, lowest pedicel of sessile, racemes slightly swollen and connate to the base of the rachis. Vetiver It is a perennial grass. Clumps are erect, growing to a height of 1 to 1.8 m. The underground stem is branching with spongy, aromatic root system having fine rootlets 10.56 cm long and 1-3 mm in diameter. The aerial stem is tall, smooth, glabrous, leaf polished. The leaves are long with leaf blade 30 cm to 40 cm long, erect, rigid, firm, narrow, 0.7 cm or less wide and somewhat spongy, usually glabrous pale green, and rough on edges. Panicle is oblong of many rayed whorls of slender simple racemes (and is terminal) 5 cm long with pairs of dissimilar spikelets, pediceled male and sessile hermaphrodite, the spikelets are pale or reddish brown or purplish. The anthers are 2 mm in size and stigma is purple in colour. Grain is oblong and oblique at top. Pedicelled spikelets which are male are smooth, upper floral glume entire, acute, 3 mm long. Vetiver is an autogamous plant. Selfing does not occur and it is an obligatory cross pollinated crop. 2. Herbal aromatics –Ocimum, Patchouli, Mint, Geranium Ocimum tenuiflorum Family: Lamiaceae An erect, herbaceous, much-branched, soft hairy biennial or triennial, 30-75 cm high. Leaves elliptic oblong, acute or obtuse, entire or serrate, pubescent on both sides, minutely gland- dotted; flowers purplish or crimson, in racemes, close whorled; nut-lets sub-globose or broadly ellipsoid, slightly compressed, nearly smooth, pale brown or reddish with small black markings. In India two types of O. sanctum are under cultivation; the green type (……………); the second type (…………………….) bears purple leaves and is preferred in the trade for its higher potency of drug. O. basilicum Linn. It is a large herbaceous erect strongly aromatic annual herb, about 30- 90 cm high. Leaves opposite, ovate-lanceolate, 3cm long; entire or deviate, surfaces glabrous, petioles very slender usually slightly hairy; flowers 0.72-1.25 cm long, borne in long terminal racemose inflorescences, simple or much branched; calyx 5-toothed, upper tooth rounded, shorter than others, 2-lower teeth ovate, lanceolate with brittle point, 2 lateral shorter than the lower; corolla 0.72 - 1.25 cm long, white, pink or pale purplish 2-lipped tube, short, upper lip equally 4- lobed, stamens 4, protruding; ovary bicarpellary, syncarpous, bilocular, stigma bifid, fruits nutlets, mucilagenous when wet. Patchouli: ………………………………; Family: ………………………….. Patchouli is an erect, branched, pubescent herb, 0.5 to 1.0 m high and aromatic when crushed. Leaves ovate to oblong-ovate, coarse; simple or doubly crenate-serrate, on both surfaces more or less densely tomentose, gland dotted beneath, up to 12 cm by 10 cm; petiole 6-8 cm; stem densely tomentose swollen on the nodes; spikes terminal and axillary, panicled, dense, sometime interrupted, 2.5-14 cm long; Calyx 5-6.5 mm; corolla lobes obtuse 6-9 mm, pink purple or white violet blotched on all segments; filaments violet, bracts as long as calyx. Mint M. arvensis (…………………………………..) is a downy perennial herb spreading by root-stocks which creep along the ground or just under the surface and root at the nodes. There are three horticultural varieties; one with reddish purple stem and broad obtuse leaves and other two having green stem, broad or narrow leaves and with purplish green stem and narrow leaves, respectively. They have rigid branches, pubescent, 60-90 cm tall. The leaves are lanceolate to oblong, 3.7-10 cm long, sharply toothed, or shortly petiolated and hariy. Flowers arranged in cyme which are usually sessile or rarely pedunculate. Flowers are purplish, minute. Calyx 2.5-3.0 mm long deltoid acuminate, corolla white to purple, 4-5 mm long. M. piperata (…………………….) spreads by a system of branching, underground root- stocks and grows to a height of 45 to 90 cm (1 1/2 to 3 feet). The square, branching stems are of dark-green (var officinalis sole sub var. pallescens camus) to deep purple colour (var officinalis sole sub var. rubescens camus) and bear opposite, broadly lance-shaped, slightly toothed leaves of deep-green colour, 2.5 to 5 cm (1 to 2 inches) long. Small purplish flowers are borne in terminal spikes on the main stem and branches. M. citrata grows up to 30-60 cm height, with decumbent branches and erect ends. Leaves are 1.25-5.0 cm long, thin, bronzy green, petiolate, smooth, broadly ovate to elliptical and apex obtuse. Flowers are purple, appearing in upper axils on short dense terminal spikes. Calyx is glabrous with subulaste teeth while corolla is glabrous and about 0.5 cm long. M. spicata (2n=41) propagating by stolons from which 30-60 cm erect, ascending branches arise. Leaves are sessile, smooth, lanceolate or ovate-lanceolate, sharply serrate, smooth above and glandular below, acute apex and upto 6.5 cm long. Flowers are sharply pointed, long and narrow and hence the name spear mint is attributed to the plant. Calyx tooth are hirsute or glabrous and corolla about 3 mm long. Geranium Geranium is a bushy aromatic plant. Stem is cylindrical, woody at base, pubescent, green when young, turning brown with age. Leaves alternate, stipulate, simple, with 5 primary lobes and secondary lobes and densely pubescent. Leaves are highly aromatic in nature. Inflorescence is umbellate and hairy. Flower is bisexual, hypogynous, with pink corolla, two posterior petals larger, with reddish purple markings. Stamens 10, filaments sub-equal, united at base; anthers 7, dithecous, shed easily; ovary hairy, superior, pentacarpellary, syncarpous; style hairy breaking up distally into five stigma. 3. Floral aromatics –Jasmine, rose, tuberose Jasmine Jasmines are climbing, trailing and erect shrubs; there are both evergreen and deciduous species. Leaves are opposite or alternate, simple, trifoliate or pinnate, leaflets entire. Flowers white, yellow or rarely reddish, sometimes solitary, more often in cymose clusters of three to many, usually fragrant, corolla tubular with four to nine lobes. Stamens 2; ovary 2-loculed with 1-4 erect ovules. Fruit is a berry and black in colour. Important jasmines 1. J. auriculatum Vahl. It is a turning shrub having small leaves which are shiny with auricles. Flowers are white, sweet-scented, borne in pubescent compound many flowered flat cymes and they open early (6-7 PM). 2. J. grandiflorum Linn. (Syn. J. officinale forma grandiflorum) It is a semi-creeper having pinnate leaves with 3 to 5 leaflets of equal size. Flowers large, white, reddish beneath, delightfully fragrant and are borne in lax, axillary or terminal cymes and they open early (6-7 AM). 3. J. sambac (Linn) Ait: The plant is a sub-erect shrub. The leaves are simple, opposite, cordate to oblong, almost sessile and dark green in colour. Flowers white, very fragrant borne in solitary or three flowered terminal cymes and they open late (8-9 PM). Rose R. damascena is a perennial shrub with a long life span of 20 to 30 years under cultivation. It grows to a height of 2.5-3 m. The stem possesses numerous moderately hooked falcate prickles of unequal size, intermixed with glandular bristles. Leaf is stipulate compound and imparipinnate having 5-7 leaflets, the stipules are adnate. The leaflets are moderately large, ovate to oblong and serrate. Flowers are borne in group of 5 to 7 and axillary terminal in corymbose. The flowers are sweet scented, pink, red or sometimes white striped. The pedicle possesses densely packed acicular and hispid glands. The sepals leafy pinnate, reflexed, after flowering persistant. Petals over seventy, light pink, fading to white. Fruit is pseudo-bractate made of several hard achenes enclosed within a succulent calyx tube. The fruits (hip) are ovoid, bright red, plumb and rich in vitamin C. Tube rose:………………………………………..; Family: ……………………………….. P. tuberosa Linn. has tuberous rootstock and a mass of basal foliage. The leaves are pale green, long, narrow and very dense. The leaves at the base are 30 to 40 cm long, 1.2 to 1.5 cm in width, sometimes, reddish near the base. The flowering stems are long and can reach a height up to 100 cm, although 60 to 75 cm is normal. It is approximately top third of the stem which bears pure white waxy textured raceme of blooms. The flowers are borne in pairs on a lax spike and are 3 to 6 cm length. The segments 1 to 2 cm long, tube long, narrow, funnel shaped slightly bent near the base. Filaments are attached to upper part of corolla. Ovary is three celled, stigma three, ovate falcate. Fruit is crowned by the persistent perianth, seeds are flat. 4. Tree aromatics- Sandal wood, camphor Sandal wood:…………………………………., Family: ………………………….. A small erect glabrous evergreen tree occuring in fairly large groups. They are semiparasitic on the roots of other kinds of trees, is known as obligatory root parasite. It can reach upto 16-18 m in height 2.4 m in girth with slender drooping branches. The leaves are opposite, 3.5-4 cm elliptic to ovate, dark green and estipulate. Flowers are hermaphrodite, regular, small, axillary or terminal compound cymes. Bracts usually small, stamens four to five, filaments short, ovary semi-inferior, ovules 2-3 pendulous. Style elongate and stigma 2-3 lobed. Fruit is a drupe, globose, 1.25 cm in diameter black when ripe, seeds keep viability for about a year. Camphor:…………………………………….. Family: ……………………………. It is a tree that grows up to 20–30 m (66–98 feet) tall. The leaves have a glossy, waxy appearance and smell of camphor when crushed. Each leaf has three distinct yellowish veins. The outer margins of the leaves tend to be somewhat wavy and turn upward. The new foliage starts out a rusty burgundy color, but the leaves soon turn dark green on the upper sides and paler green underneath. In spring, it produces bright green foliage with masses of small white flowers. It produces clusters of black, berry-like fruit around 1 cm (0.39 inches) in diameter. Its pale bark is very rough and fissured vertically.  15. PROPAGATION TECHNIQUES OF AROMATIC PLANTS Aromatic plants Propagation and nursery management Lemon grass Palmarosa Citronella Vetiver Mint Patchouli Geranium Ocimum Jasmine Rose Tuberose Sandal wood Camphor Eucalyptus  16. ESSENTIAL OIL EXTRACTION TECHNIQUES – DISTILLATION METHODS Distillation, the most important process for obtaining essential oils may be defined as the "…………………………………………………………………………………………………… ……………………………………………….…". The three methods of hydro distillation used in the production of essential oils are: (i) ………….. distillation (ii) ……………… distillation (iii) ………………… distillation. (i) Water distillation: When this method is employed the material to be distilled comes in direct contact with the boiling water. It may float on the water or be completely immersed depending on specific gravity. The water is boiled by application of heat by any of the usual methods i.e., direct fire, steam jacket, closed steam coil etc. Through this method, powdered materials like almond and others like rose petals, orange blossoms etc. are distilled. Disadvantages of water distillation i) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ii) …………………………………………………………………………………………………... iii) ………………………………………………………………………………………………….. b) Water and steam distillation: In this case, the plant material is supported on a perforated gird or screen inserted at some distance above the bottom of the still and the lower part of the still is filled with water, to a level below the grid. The water is heated. The typical features of this method are, first, that the steam is always fully saturated, wet and never super-heated, second, that the plant material is in contact with steam only and not with the boiling water. This method gives best results with the materials like seeds, roots etc. Disadvantages of water and steam distillation i) …………………………………………………………………………………………………. ii) ……………………………………………………………………………………………….... iii) ………………………………………………………………………………………………... c) Steam distillation: In this method of distillation, no water is kept in the bottom of the stills, but saturated or superheated steam is introduced through open or perforated steam coils below the charge or above the grid. This method is commonly employed in the extraction of essential oils from herb and leaf materials. Disadvantages of steam distillation i) ………………………………………………………………………………………………….... ii) …………………………………………………………………………………………………...  17. ESSENTIAL OIL EXTRACTION TECHNIQUES – SOLVENT EXTRACTION, SUPER CRITICAL FLUID EXTRACTION (SCFE) 1. Solvent Extraction Principle: Fresh flowers are charged into especially constructed extractors at room temperature and treated carefully with purified solvent usually petroleum ether. The solvent penetrates the flowers and dissolves the natural flower perfume together with some waxes and other albuminous and colouring matters. This solution is subsequently pumped into an evaporator and concentrated at a low temperature. After the solvent is completely driven off in vacuum, the flower oil is obtained. Since no heat is applied in the method at any stage, the oil is saved from harmful effects of higher temperatures and therefore more truely represent the natural perfume as originally present in the flowers. Quality of solvent: Ideally the solvent used for the extraction should possess the following properties. i)…………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ii)…………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… iii)………………………………………………………………………………………………....... ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… iv)…………………………………………………………………………………………………... ……………………………………………………………………………………………………… v) …………………………………………………………………………………………………... vi)…………………………………………………………………………………………………... There is no solvent yet discovered which satisfies all the requirements. Highly purified petroleum ether appears to be the most suitable one followed by benzene Extraction Process: The extractors to be used for solvent extraction may be stationary or rotary, commonly with a capacity of about 1200 L and holding up to 200 kg of flowers per charge. Three to four washings with solvent are usually required. About five hours are required for processing a batch of flowers, including final steam distillation of the spent material to recover solvent. The concentrated washings are filtered, then evaporated in a water bath type of still in which temperature never reaches 60OC. Final purification of the oil in order to obtain the concentrated oil and to get rid of waxes or albumin impurities may be done under vacuum to precipitate out the impurities. 2. Supercitical Fluid Extraction (SCFE) Supercritical carbon dioxide has the density of a liquid, low viscosity and diffuses like a gas. It is an excellent solvent for a wide range of natural substrates. Advantages 1.…………………………………………………………………………………………………… …………………………………………………………………………………………………….. 2. ………………………………………………………………………………………………….. 3.…………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… 4. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… Extraction process: For extraction, the raw material is enclosed in a cylindrical container with porous ends which is located in the extraction chamber. Temperature and pressure are selected (above its critical temperature at 31OC and pressure 73.8 bar) according to the material and desired end product. Super critical CO2 circulates through the material, dissolving the essential oil. Solvent and solute then circulate into a separator where the pressure is maintained below super critical point. The CO2 becomes gaseous and its solute precipitates before collection. Further the gaseous CO2 is taken to a heat exchanges where it is again cooled and liquified. The liquid CO2 goes back into the extraction unit for further use.