Drugs Containing Carbohydrates and Derived Products

Chapter 14

Drugs Containing Carbohydrates and Derived Products

INTRODUCTION

Carbohydrates, as the name suggest, were defined as a group of compounds composed of carbon, hydrogen and oxygen in which the latter two elements are in the same proportion as in water and were expressed by a formula (CH2 O)n , that is, hydrates of carbon.

The term ‘carbohydrates’ arose from the mistaken belief that substances of this kind were hydrates of carbon, because the molecular formula of many substances could be expressed in the form CX(H2 O)Y , for example, glucose (C6 H12 O6 ), sucrose (C12 H22 O11), etc. In these examples, the hydrogen and oxygen are present in the same ratio as in water. But this definition has certain drawbacks as given below:

It should be kept in mind that all organic compounds containing hydrogen and oxygen in the proportion found in water are not carbohydrates. For example, formaldehyde HCHO for the present purpose written as C(H2 O); acetic acid CH3 COOH written as C3 (H2 O)2 ; and lactic acid CH3 CHOHCOOH written as C3 (H2 O)3 are not carbohydrates.

Also, a large number of carbohydrates such as rhamnose (C6 H12O5 ), cymarose (C7 H14O4 ), digitoxose (C6 H12O4 ), etc., are known which do not contain the usual proportions of hydrogen to oxygen.

Finally, certain carbohydrates are also known which contain nitrogen or sulphur in addition to carbon, hydrogen and oxygen.

From the above discussion, it can be concluded that the definitions described above are not correct; however, carbohydrates are now defined chemically as polyhydroxy aldehyde or polyhydroxy ketones or compound that on hydrolyses produce either of the above.

Carbohydrates are among the first products to arise as a result of photosynthesis. They constitute a large proportion of the plant biomass and are responsible, as cellulose, for the rigid cellular framework and, as starch, for providing an important food reserve. Of special pharmacognostical importance is the fact that sugars unites with a wide variety of other compounds to form glycosides and secondary metabolites. Mucilage, as found in marshmallow root and psyllium seeds, act as water-retaining vehicles, where as gums and mucilage, which are similar in composition and properties, are formed in the plant by injury or stress and usually appear as solidified exudates; both are typically composed of uronic acid and sugar units. The cell walls of the brown seaweeds and the middle lamellae of higher plant tissues contain polysaccharides consisting almost entirely of uronic acid components.

Low molecular weight carbohydrates are crystalline, soluble in water and sweet in taste, for example, glucose, fructose, sucrose, etc. The high molecular weight carbohydrates (polymers) are amorphous, tasteless and relatively less soluble in water, for example, starch, cellulose, inulin, etc.

CLASSIFICATION

Monosaccharides

The term ‘monosaccharides’ is employed for such sugars that on hydrolysis yield no further, lower sugars. The general formula of monosaccharides is Cn H2n On . The monosaccharides are subdivided as bioses, trioses, tetroses, pentoses, hexoses, heptoses, depending upon the number of carbon atoms they possess.

Bioses

They contain two carbon atoms. They do not occur free in nature.

Trioses

They contain three carbon atoms, but in the form of phosphoric esters, for example, glyceraldehydes.

Tetroses

They contain four carbon atoms, for example, erythrose, threose, etc.

Pentoses

They are very common in plants and are the products of hydrolysis of polysaccharides like hamicelluloses, mucilages and gums, for example, ribose, arabinose and xylose.

Hexoses

They are monosaccharides containing six carbon atoms and are abundantly available carbohydrates of plant kingdom. They are further divided into two types: aldoses and ketoses. They may be obtained by hydrolysis of polysaccharides like starch, insulin, etc.

Aldoses : Glucose, mannose, galactose

Ketoses : Fructose and sorbose

Heptoses

They contain seven carbon atoms, vitally important in the photosynthesis of plant and glucose metabolism of animals and are rarely found accumulated in plants, for example, glucoheptose and manoheptose.

Disaccharides

Carbohydrates, which upon hydrolysis yield two molecules of monosaccharides, are called as disaccharides.

Sucrose Hydrolysis Glucose + fructose (sugarcane) Maltose Hydrolysis Glucose + Glucose (malt sugar) Lactose Hydrolysis Glucose + Galactose (cow’s milk)

Trisaccharides

As the name indicates, these liberate three molecules of monosaccharides on hydrolysis. Raffinose Hydrolysis Glucose + fructose + galactose (in beet) (sugarcane) Gentianose Hydrolysis Glucose + Glucose + fructose (gentian roots)

Tetrasaccharides

Stachyose, a tetrasaccharide, yields on hydrolysis, four molecules of monosaccharide, found in manna.

Polysaccharides

On hydrolysis they give an indefinite number of monosaccharides. By condensation, with the elimination of water, polysaccharides are produced from monosaccharides. Depending upon the type of product of hydrolysis these are further classified as Pentosans and Hexosans. Xylan is pentosan, whereas starch, insulin and cellulose are the examples of hexosans.

Cellulose is composed of glucose units joined by β-1, 4 linkages, whereas starch contains glucose units connected with α- 1, 4 and α- 1, 6 units. Polyuronides, gums and mucilages are the other pharmaceutically important polysaccharide derivatives.

TESTS FOR CARBOHYDRATES

The following are some of the more useful tests for sugars and other carbohydrates.

Reduction of Fehling’s Solution

To the solution of carbohydrate, equal quantity of Fehling’s solutions A and B is added. After heating, brick red precipitate is obtained.

Molisch Test

The test is positive with soluble as well as insoluble carbohydrates. It consists of treating the compounds with α-naphthol and concentrated sulphuric acid which gives purple colour. With a soluble carbohydrate this appears as a ring if the sulphuric acid is gently poured in to form a layer below the aqueous solution. With an insoluble, carbohydrate such as cotton wool (cellulose), the colour will not appear until the acid layer is shaken to bring it in contact with the material.

Osazone Formation

Osazones are sugar derivatives formed by heating a sugar solution with phenylhydrazine hydrochloride, sodium acetate and acetic acid. If the yellow crystals which form are examined under the microscope they are sufficiently characteristic for certain sugars to be identified. It should be noted that glucose and fructose form the same osazone (glucosazone, m.p. 205°C). Before melting points are taken, osazones should be purified by recrystalization from alcohol. Sucrose does not form an osazone, but under the conditions of the above test sufficient hydrolysis takes place for the production of glucosazone.

Resorcinol Test for Ketones (Selivanoff’s Test)

A crystal of resorcinol is added to the solution and warmed on a water bath with an equal volume of concentrated hydrochloric acid. A rose colour is produced if a ketone is present (e.g. fructose, honey or hydrolysed inulin).

Test for Pentoses

Heat a solution of the substance in a test tube with an equal volume of hydrochloric acid containing a little phloroglucinol. Formation of a red colour indicates pentoses.

Keller-Kiliani Test for Deoxysugars

A Deoxysugar (found in cardiac glycosides) is dissolved in acetic acid containing a trace of ferric chloride and transferred to the surface of concentrated sulphuric acid. At the junction of the liquids a reddish-brown colour is produced which gradually becomes blue.

Furfural Test

A carbohydrate sample is heated in a test tube with a drop of syrupy phosphoric acid to convert it into furfural. A disk of filter paper moistened with a drop of 10% solution of aniline in 10% acetic acid is placed over the mouth of the test tube. The bottom of the test tube is heated for 30–60s. A pink or red stain appears on the reagent paper.

BIOSYNTHESIS OF CARBOHYDRATES

Production of Monosaccharides by Photosynthesis

Carbohydrates are products of photosynthesis, a biologic process that converts electromagnetic energy into chemical energy. In the green plant, photosynthesis consists of two classes of reactions. One class comprises the so-called light reactions that actually convert electromagnetic energy into chemical potential. The other class consists of the enzymatic reactions that utilize the en ergy from the light reactions to fix carbon dioxide into sugar. These are referred to as the dark reactions. The results of both of these types of reactions are most simply summarized in the following equation:

2H2 O + CO2 + light chlorophyll (CH2 O) + H2 O + O2

Although this equation summarizes the overall relationships of the reactants and products, it gives no clue as to the nature of the chemical intermediates involved in the process. The elucidation of the reactions by which carbon dioxide is accepted into an organic compound and ultimately into sugars with regeneration of the carbon dioxide acceptor was a major achievement in biosynthetic research. The pathway of carbon in photosynthesis, as worked out primarily by Calvin and coworkers, is presented in Figure 14.1.

Production of sucrose

Sucrose is of considerable metabolic importance in higher plants. Studies have shown that sucrose is not only the first sugar formed in photosynthesis but also the main transport material. Newly formed sucrose is, therefore, probably the usual precursor for polysaccharide synthesis. Although an alternative pathway consisting of a reaction between glucose 1-phosphate and fructose is responsible for sucrose production in certain microorganisms, the biosynthesis of this important metabolite in higher plants apparently occurs as shown in Figure 14.2.

Fructose 6-phosphate, derived from the photosynthetic cycle, is converted to glucose 1-phosphate, which, in turn, reacts with UTP to form UDP-glucose. UDP-glucose either reacts with fructose 6-phosphate to form first sucrose phosphate and ultimately sucrose, or with fructose to form sucrose directly. Once formed, the free sucrose may either remain in situ or may be translocated via the sieve tubes to various parts of the plants. A number of reactions, for example, hydrolysis by invertase or reversal of the synthetic sequence, convert sucrose to monosaccharides from which other oligosaccharides or polysaccharides may be derived.

ACACIA GUM

Synonyms

Acacia gum, Acacia vera, Egyptian thorn, Gummi africanum, Gum Senegal, Gummae mimosae, Kher, Sudan gum arabic, Somali gum, Yellow thorn, Indian Gum and Gum Arabic.

Biological Source

According to the USP, acacia is the dried gummy exudation obtained from the stems and branches of Acacia senegal (L.) Willd or other African species of Acacia. In India, it is found as dried gummy exudation obtained from the stems and branches of Acacia arabica Willd, belonging to family Leguminosae.

Geographical Source

Acacia senegal is the characteristic species in the drier parts of Anglo-Egyptian Sudan and the northern Sahara, and is to be found throughout the vast area from Senegal to the Red Sea and to eastern India. It extends southwards to northern Nigeria, Uganda, Kenya, Tanzania and southern Africa. The plant is extensively found in Arabia, Kordofan (North-East Africa), Sri Lanka and Morocco. In India it is found chiefly in Punjab, Rajasthan and Western Ghats. Sudan is the major producer of this gum and caters for about 85% of the world supply.
Cultivation and Collection

Acacia is a thorny tree up to 6 m in height. In Sudan, gum is tapped from specially cultivated trees while in Senegambia, because of extremes of climate; cracks are produced on the tree and the gum exudes and is collected from the wild plants. Acacia trees can be cultivated by sowing the seeds in the poor, exhausted soil containing no minerals. The trees also grow as such by seed-dispersal.

Gum is collected by natives from 6 to 8 years old trees, twice a year in dry weather in November or in February— March. Natives cut the lower thorny branches to facilitate the working and by means of an axe make 2–3 ft long and 2–3 inches broad incision on the stem and branches, loosen the bark by axe and remove it, taking care not to injure the cambium and xylem. Usually they leave a thin layer of bark on xylem. If xylem is exposed, white ant enters the plant and gum is not produced. After injury in winter gum exudes after 6–8 weeks while in summer after 3–4 weeks. It is believed that bacteria finding their way through the incision are more active in summer and gum is produced quickly. The exuded gum is scraped off, collected in leather bags and then is cleaned by separating debris of bark and wood and separating sand, etc., by sieving

Gum is dried in the sun by keeping it in trays in thin layers for about 3 weeks when bleaching takes place and it becomes whiter. This result in uneven contraction and cracks and fissures are formed on its outer surface and as a result original transparent gum becomes opaque. This process is called ripening of the gum.

Morphology

History

Gum was brought from the Gulf of Aden to Egypt in the 17th B.C., and in the works of Theophrastus it is spoken of as a product of Upper Egypt. The West African product was imported by the Portuguese in the fifteenth century. Until quite recently, commerce in the Sudan was in the hands of a number of local merchants, but it is now entirely controlled by the Gum Arabic Company Ltd., a concessional company set up by the Sudanese Government. This Company alone produces about 40,000 tonnes per annum.

Chemical constituents

Acacia consists principally of arabin, which is a complex mixture of calcium, magnesium and potassium salts of arabic acid. Arabic acid is a branched polysaccharide that yields L-arabinose, D-galactose, D-glucuronic acid and L-rhamnose on hydrolysis. 1, 3-Linked D-galactopyranose units form the backbone chain of the molecule and the terminal residues of the 1, 6-linked side chains are primarily uronic acids. Acacia contains 12–15% of water and several occluded enzymes such as oxidases, peroxidases and pectinases. The total ash content should be in the range of 2.7–4.0%

Chemical Tests

Lead acetate test: An aqueous solution of acacia when treated with lead acetate solution yields a heavy white precipitate

Reducing sugars test: Hydrolysis of an aqueous solution of acacia with dilute HC1 yields reducing sugars whose presence are ascertained by boiling with Fehling’s solution to give a brick-red precipitate of cuprous oxide.

Blue colouration due to enzyme: When the aqueous solution of acacia is treated with benzidine in alcohol together with a few drops of hydrogen peroxide (H2 O2 ), it gives rise to a distinct blue colour due to the presence of oxidases enzyme.

Borax test: An aqueous solution of acacia affords a stiff translucent mass on treatment with borax.

Specific test: A 10% aqueous solution of acacia fails to produce any precipitate with dilute solution of lead acetate (a clear distinction from Agar and Tragacanth); it does not give any colour change with Iodine solution (a marked distinction from starch and dextrin); and it never produces a bluish-black colour with FeCl3 solution (an apparent distinction from tannins).

Uses

The mucilage of acacia is employed as a demulcent. It is used extensively as a vital pharmaceutical aid for emulsification and to serve as a thickening agent. It finds its enormous application as a binding agent for tablets, for example, cough lozenges. It is used in the process of ‘granulation’ for the manufacturing of tablets. It is considered to be the gum of choice by virtue of the fact that it is quite compatible with other plant hydrocolloids as well as starches, carbohydrates and proteins. It is used in combination with gelatin to form conservates for micro-encapsulation of drugs. It is employed as colloidal stabilizer. It is used extensively in making of candy and other food products. Gum acacia solution has consistency similar to blood and is administered intravenously in haemodialysis. It is used in the manufacture of adhesives and ink, and as a binding medium for marbling colours.

Allied Drugs

Talka gum is usually much broken and of very variable composition, some of the tears being almost colourless and others brown.

Ghatti or Indian gum is derived from Anogeissus latifolia (Combretaceae). It is produced in much the same localities as sterculia gum, and is harvested and prepared in a similar manner. It resembles talka in possessing tears of various colours. Some of the tears are vermiform in shape and their surface shows fewer cracks than even the natural acacia. Aqueous dispersions of the gum have a viscosity intermediate between those of acacia and sterculia gums.

West African Gum Combretum, obtained from Combretum nigricans, is not permitted as a food additive but is exploited as an adulterant of gum arabic. Unlike the latter in which the rhamnose and uronic acid units are chain terminal, in gum combretum these moieties are located within the polysaccharides chain.

Many other gums of the acacia type are occasionally met with in commerce, and many gum exudates of the large genus Acacia have been given chemotaxonomic consideration.

Toxicology

Acacia is essentially nontoxic when ingested. Allergic reactions to the gum and powdered forms of acacia have been reported and include respiratory problems and skin lesions.

Acacia contains a peroxidase enzyme, which is typically destroyed by brief exposure to heat. If not inactivated, this enzyme forms coloured complexes with certain amines and phenols and enhances the destruction of many pharmaceutical products including alkaloids and readily oxidizable compounds, such as some vitamins. Acacia gum reduces the antibacterial effectiveness of the preservative methyl-phydroxybenzoate against Pseudomonas aeruginosa presumably by offering physical barrier protection to the microbial cells from the action of the preservative. A trypsin inhibitor also has been identified, but the clinical significance of the presence of this enzyme is not known.

Marketed Product

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GUAR GUM

Synonyms

Guar gum, Jaguar gum, Guar flour and Decorpa.

Biological Source

Guar gum is a seed gum produced from the powdered endosperm of the seeds of Cyamopsis tetragonolobus Linn belonging to family Leguminosae.

Geographical Source

Guar or cluster bean is a drought-tolerant annual legume that was introduced into the United States from India in 1903. Commercial production of guar in the United States began in the early 1950s and has been concentrated in northern Texas and south-western Oklahoma. The major world suppliers are India, Pakistan and the United States, Australia and Africa. Rajasthan in western India is the major guar-producing state, accounting for 70% of the production. Guar is also grown in Gujarat, Haryana, Punjab and in some parts of Uttar Pradesh and Madhya Pradesh. India grows over 850,000 tons, or 80% of the total guar produced all over the world. 75% of the guar gum or derivatives produced in India are exported, mainly to the United States and to European countries.

Cultivation, Collection and Preparation

The plant of gaur gum is draught resistance and quite hardy in its constitutions. It is generally shown in May– June and harvested in September–October. At the stage of full maturity, the plant yields 600–800 lb of seeds per acre under un-irrigated conditions but the production nearly doubles under irrigated conditions.

The cotyledons, having a distinct bitter taste are separated from the endosperm by the process called ‘winnowing’. The crude guar gum, that is, the endosperms is subsequently pulverized by means a ‘micro-pulverizer’ followed by grinding. The relatively softer cotyledons sticking to the endosperms are separated by mechanical ‘sifting’ process. Thus, the crude guar gum is converted to a purified form (i.e. devoid of cotyledons), which is then repeatedly pulverized and shifted for several hours till a final white powder or granular product is obtained.

Morphology

History

Guar gum is a dietary fibre obtained from the endosperm of the Indian cluster bean. The endosperm can account for more than 40% of the seed weight and is separated and ground to form commercial guar gum. Guar gum has been used for centuries as a thickening agent for foods and pharmaceuticals. It continues to find extensive use for these applications and also is used by the paper, textile and oil-drilling industries.

Chemical Constituents

The water-soluble part of guar gum contains mainly of a high molecular weight hydrocolloidal polysaccharide, that is, galactomannan, which is commonly known as guaran. Guaran consists of linear chains of (1→4)—β—D— mannopyranosyl units with α—D—galactopyranosyl units attached by (1→6) linkages. However, the ratio of D— galactose to D—mannose is 1: 2. The gum also contains about 5–7% of proteins.

Chemical Tests

1. On being treated with iodine solution (0.1 N), it fails to give olive-green colouration.

2. It does not produce pink colour when treated with Ruthenium Red solution (distinction from sterculia gum and agar).

3. A 2% solution of lead acetate gives an instant white precipitate with guar gum (distinction from sterculia gum and acacia).

4. A solution of guar gum (0.25 g in 10 ml of water) when mixed with 0.5 ml of benzidine (1% in ethanol) and 0.5 ml of hydrogen peroxide produces no blue colouration (distinction from gum acacia).

5. Aqueous solution of guar gum is converted to a gel by addition of a small amount of borax.

Uses

Guar gum is used as a protective colloid, a binding and disintegrating agent, emulsifying agent, bulk laxative, appetite depressant and in peptic ulcer therapy. Industrially, it is used in paper manufacturing, printing, polishing, textiles and also in food and cosmetic industries. Guar gum is extensively used as flocculent in ore-dressing and treatment of water.

Guar gum has been shown to decrease serum total cholesterol levels by about 10–15% and low-density lipoprotein cholesterol (LDL-cholesterol) by up to 25% without any significant effect on triglycerides or high-density lipoprotein cholesterol (HDL-cholesterol) levels.

The ability of guar to affect gastrointestinal transit may contribute to its hypoglycemic activity. Guar reduces postprandial glucose and insulin levels in both healthy and diabetic subjects and may be a useful adjunct in the treatment of noninsulin-dependent diabetes.

Guar gum remains important ingredient in over-thecounter weight loss preparations. Even in the absence of weight loss, guar supplementation for 2 weeks reduced blood pressure by 9% in moderately overweight men.

Toxicology

In the colon, guar gum is fermented to short-chain fatty acids. Both guar and its resultant by-products do not appear to be absorbed by the gut. The most common adverse effects, therefore, are gastrointestinal, including gastrointestinal pain, nausea, diarrhoea and flatulence. Approximately half of those taking guar experience flatulence; this usually occurs early in treatment and resolves with continued use. Starting with doses of about 3 g three times a day, not to exceed 15 g per day, can minimize gastrointestinal effects.

Guar gum may affect the absorption of concomitantly administered drugs. Bezafibrate, acetaminophen (e.g. Tylenol), digoxin (e.g. Lanoxin), glipizide (e.g. Glucotrol) or glyburide (e.g. DiaBeta, Micronase) are generally unaffected by concomitant administration. The ingestion of more than 30 g of guar per day by diabetic patients did not adversely affect mineral balances after six months. Guar gum in a weight-loss product has been implicated in esophageal obstruction in a patient who exceeded the recommended dosage. In a recent review, 18 cases of esophageal obstruction, seven cases of small bowel obstruction, and possibly one death were associated with the use of Cal-Ban 3000, a guar gum containing diet pill. The water-retaining capacity of the gum permits it to swell to 10- to 20-fold and may lead to luminal obstruction, particularly when an anatomic predisposition exists. Guar always should be taken with large amounts of liquid. Occupational asthma has been observed among those working with guar gum. Because of its potential to affect glycemic control, guar gum should be used cautiously by diabetic patients.

Marketed Product

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HONEY

Synonyms

Madhu, Madh, Mel, Purified Honey.

Biological Source

Honey is a viscid and sweet secretion stored in the honey comb by various species of bees, such as Apis mellifera, Apis dorsata, Apis florea, Apis indica and other species of Apis, belonging to family Apideae (Order: Hymenotera).

Geographical Source

Honey is available in abundance in Africa, India, Jamaica, Australia, California, Chili, Great Britain and New Zealand.

Collection and Preparation

The nectar of the flowers is a watery solution containing 25% sucrose and 75% water. The worker bee sucks this nectar through its hollow tube of mouth (proboscis) and deposits in honey-sac located in abdomen. The enzyme invertase present in saliva of the bee converts nectar into invert sugar, which is partially utilized by the bee and the remaining is deposited into honey comb. Honey comb is smoked to remove the bees and honey is obtained by applying the pressure to it or allowing it to drain naturally. The honey of commerce is heated to 80°C and allowed to stand.

Morphology

History

The honey used for flavouring medicinal was first known historically as a flavoured sweetening agent and was once the official honey of the National Formulary. Its use dates back to ancient times, with Egyptian medical texts (between 2600 and 2200 B.C.) mentioning honey in at least 900 remedies.Almost all early cultures universally hailed honey for its sweetening and nutritional qualities, as well as its topical healing properties for sores, wounds and skin ulcers. During war time it was used on wounds as an antiseptic by the ancient Egyptians, Greeks, Romans, Chinese, and even by the Germans as late as World War I.

The 1811 edition of The Edinburgh New Dispensatory states, ‘From the earliest ages, honey has been employed as a medicine, it forms an excellent gargle and facilitates the expectoration of viscid phlegm; and is sometimes employed as an emollient application to abscesses, and as a detergent to ulcers’. It has consistently appeared in modern use for the same purposes by the laity and medical profession. Today, bees are commonly kept in Europe, the Americas, Africa and Asia; at least 300,000 tons of honey is produced annually.

Chemical Constituents

The average composition of honey is as follows: Moisture 14–24%, Dextrose 23–36%, Levulose (Fructose) 30–47%, Sucrose 0.4–6%, Dextrin and Gums 0–7% and Ash 0.1–0.8%. Besides, it is found to contain small amounts of essential oil, beeswax, pollen grains, formic acid, acetic acid, succinic acid, maltose, dextrin, colouring pigments, vitamins and an admixture of enzymes, for example, diastase, invertase and inulase. Interestingly, the sugar contents in honey varies widely from one country to another as it is exclusively governed by the source of the nectar (availability of fragment flowers in the region) and also the enzymatic activity solely controlling the conversion into honey.

Chemical Tests

Adulteration in honey is determined by the following tests:

Fiehe’s Test for Artificial Invert Sugar: Honey (10 ml) is shaken with petroleum or solvent ether (5 ml) for 5–10 min. The upper ethereal layer is separated and evaporated in a china dish. On addition of 1% solution of resorcinol in hydrochloric acid (1 ml) a transient red colour is formed in natural honey while in artificial honey the colour persists for sometime.

Reduction of Fehling’s Solution: To an aqueous solution of honey (2 ml) Fehling’s solutions A and B are added and the reaction mixture is heated on a steam bath for 5–10 min. A brick red colour is produced due to the presence of reducing sugars.

Limit Tests: The limit tests of chloride, sulphate and ash (0.5%) are compared with the pharmacopoeial specifications.

Uses

Honey shows mild laxative, bactericidal, sedative, antiseptic and alkaline characters. It is used for cold, cough, fever, sore eye and throat, tongue and duodenal ulcers, liver disorders, constipation, diarrhoea, kidney and other urinary disorders, pulmonary tuberculosis, marasmus, rickets, scurvy and insomnia. It is applied as a remedy on open wounds after surgery. It prevents infection and promotes healing. Honey works quicker than many antibiotics because it is easily absorbed into the blood stream. It is also useful in healing of carbuncles, chaps, scalds, whitlows and skin inflammation; as vermicide; locally as an excipient, in the treatment of aphthae and other infection of the oral mucous membrane. It is recommended in the treatment of preoperative cancer. Honey, mixed with onion juice, is a good remedy for arteriosclerosis in brain. Diet rich in honey is recommended for infants, convalescents, diabetic patients and invalids.

Interestingly, potent antibacterial peptides (apidaecins and abaecin) have been isolated and characterized in the honeybee (Apis mellifera) itself and a new potent antibacterial protein named royalisin has been found in the royal jelly of the honeybee.

Adulterant and Substitutes

Due to the relatively high price of pure honey, it is invariably adulterated ether with artificial invert sugar or simply with cane-sugar syrup. These adulterants or cheaper substituents not only alter the optical property of honey but also its natural aroma and fragrance.

Toxicology

Generally, honey is considered safe as a sweet food product, a gargle and cough-soothing agent, and a topical product for minor sores and wounds. However, medical reports indicate that honey can be harmful when fed to infants because some batches contain spores of Clostridium botulinum, which can multiply in the intestines and result in botulism poisoning. Infant botulism is seen most commonly in 2- to 3-month-old infants after ingestion of botulinal spores that colonize in the GIT as well as toxin production in vivo. Infant botulism is not produced by ingestion of preformed toxin, as is the case in food borne botulism. Clinical symptoms include constipation fallowed by neuromuscular paralysis (starting with the cranial nerves and then proceeding to the peripheral and respiratory musculature). Cases are frequently related to ingestion of honey, house dust and soil contaminated with Clostridium botulinum. Intense management under hospital emergency conditions and trivalent antitoxin are recommended, although use of the latter in infant botulism has not been adequately investigated.

Marketed Product

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TRAGACANTH

Synonyms

Goat’s thorn, gum dragon, gum tragacanth, hog gum.

Biological Source

It is the air dried gummy exudates, flowing naturally or obtained by incision, from the stems and branches of Astragalus gummifer Labill and certain other species of Astragalus, belonging to family Leguminosae.

Geographical Source

Various species of Astragalus which yield gum are abundantly found in the mountainous region of Turkey, Syria, Iran, Iraq and the former U.S.S.R. at an altitude of about 1,000–3,000 m. Two important varieties of tragacanth, that is, Persian tragacanth and Smyrana or Anatolian tragacanth come from Iran and turkey respectively. In India it is found wild in Kumaon and Garhwal region. The approximate distribution of a number of gumproducing species found in the areas where tragacanth is collected is shown in Table 14.1.

Cultivation, Collection and Preparation

Most of the plants from which tragacanth is collected grow at an altitude of 1,000–3,000 m. The shrubs are very thorny; each of their compound leaves has a stout, sharply pointed rachis which persists after the fall of the leaflets. The mode of collection varies somewhat in different districts, but the following details of collection in the province of Far are typical.

Gums can be obtained from the plants in their first year but is then said to be of poor quality and unfit for commercial use. The plants are therefore tapped in the second year. The earth is taken away from the base to depth of 5 cm, and the exposed part is incised with a sharp knife having a thin cutting edge. A wedge-shaped piece of wood is used by the collector to force open the incision so that the gum exudes more freely. The wedge is generally left in the cut for some 12–24 h before being withdrawn. The gum exudes and is collected 2 days after the incision.

After collection, the gum is graded as ribbons and flakes which are further categorized into various sub-grades on the basis of shape, size and colour (Table 14.2). The best grades form the official drug, while the lower grades are used in the food, textile and other industries.

Morphology

Chemical Constituents

Interestingly, tragacanth comprises two vital fractions: first, being water soluble and is termed as ‘tragacanthin’ and the second, being water insoluble and is known as ‘bassorin’. Both are not soluble in alcohol. The said two components may be separated by carrying out the simple filtration of very dilute mucilage of tragacanth and are found to be present in concentrations ranging from 60% to 70% for bassorin and 30–40% for tragacanthin. Bassorin actually gets swelled up in water to form a gel, whereas tragacanthin forms an instant colloidal solution. It has been established that no methoxyl groups are present in the tragacanthin fraction, whereas the bassorin fraction comprised approximately 5.38% methoxyl moieties. Rowson (1937) suggested that the gums having higher methoxyl content, that is, possessing higher bassorin contents yielded the most viscous mucilage.

Chemical Tests

An aqueous solution of tragacanth on boiling with conc. HCl does not develop a red colour.

It does not produce red colour with ruthenium red solution.

When a solution of tragacanth is boiled with few drops of FeCl3 [aqueous 10% (w/v)], it produces a deep-yellow precipitate.

It gives a heavy precipitate with lead acetate.

When tragacanth and precipitated copper oxide are made to dissolve in conc. NH4 OH, it yields a meager precipitate.

Uses

It is used as a demulcent in cough and cold preparations and to manage diarrhoea. It is used as an emollient in cosmetics. Tragacanth is used as a thickening, suspending and as an emulsifying agent. It is used along with acacia as a suspending agent. Mucilage of tragacanth is used as a binding agent in the tablets and also as an excipient in the pills. Tragacanth powder is used as an adhesive. It is also used in lotions for external use and also in spermicidal jellies. It is also used as a stabilizer for ice cream in 0.2–0.3% concentration and also in sauces. Tragacanth has been reported to inhibit the growth of cancer cells in vitro and in vivo.

Adulterant and Substitutes

Tragacanth gum of lower grades known as hog tragacanth is used in textile industry and in the manufacture of pickles. The gum varies from yellowish brown to almost black. Citral gum obtained from A. strobiliferus is also used as an adulterant. Karaya gum which is sometimes known as sterculia gum or Indian tragacanth is invariably used as a substitute for gum tragacanth.

Toxicology

Tragacanth is generally recognized as safe (GRAS) in the United States for food use. There is no indication that dietary supplementation for up to 21 days has any significant adverse effects in man. Tragacanth is highly susceptible to bacterial degradation and preparations contaminated with enterobecteria have been reported to have caused fetal deaths when administered intraperitoneally (i.p.) to pregnant mice. A cross sensitivity to the asthma-induced effects of quillaja bark has been observed for gum tragacanth.

SODIUM ALGINATE

Synonyms

Algin, Alginic acid sodium salt, Sodium polymannuronate, Kelgin, Minus, Protanal.

Biological Source

Sodium alginate is the sodium salt of alginic acid. Alginic acid is a polyuronic acid composed of reduced mannuronic and glucoronic acids, which are obtained from the algal growth of the species of family Phaeophyceae. The common species are Macrocystis pyrifera, Laminaria hyperborea, Laminaria digitata, Ascophyllum nodosum and Durvillaea lessonia. It is a purified carbohydrate extracted from brown seaweed (algae) by treatment of dilute alkali.

Geographical Source

Sea-weeds are found in Atlantic and Pacific oceans, particularly in coastal lines of Japan, United States, Canada, Australia and Scotland. In India, it is found near the coast of Saurashtra. The largest production of algin is in United States and U.K.

Collection and Preparation

The brown coloured algae are used for extraction of alginic acid. The colour is due to carotenoid pigment present in it. M. pyrifera, the principal source for global supply, is a perennial plant that lives from 8 to 12 years, and grows, as much as, 30 cm per day. This giant kelp is found mainly in Pacific Ocean. It grows on stands from 15 m to 1.5 km in width and several km in length. The mechanical harvesting is done about four times a year.

Morphology

History

Alginic acid, a hard, horny polysaccharide, was first isolated by the English chemist Stanford in 1883 and in Britain was first marketed in 1910. The commercial production of algin first began in 1929 in United States Since then it is produced in U.K., France, Norway and Japan. The present total algin production is estimated to be more than 15,000 tones per annum.

Identification Tests

Precipitate formation with Calcium chloride To a 0.5% solution of the sample in sodium hydroxide, add one-fifth of its volume of a 2.5% solution of calcium chloride. A voluminous, gelatinous precipitate is formed. This test distinguishes sodium alginate from gum arabic, sodium carboxymethyl cellulose, carrageenan, gelatin, gum ghatti, karaya gum and tragacanth gum.

Precipitate formation with Ammonium sulphate To a 0.5% solution of the sample in sodium hydroxide, add one-half of its volume of a saturated solution of ammonium sulphate. No precipitate is formed. This test distinguishes sodium alginate from agar, sodium carboxymethyl cellulose, carrageenan, methyl cellulose and starch.

Test for alginate Moisten 1–5 mg of the sample with water and add 1 ml of acid ferric sulphate. Within 5 min, a cherry-red colour develops that finally becomes deep purple.

Chemical Constituents

Algin consists chiefly of the sodium salt of alginic acid, a linear polymer of L-guluronic acid and D-mannuronic acid; the chain length is long and varies (mol. wt. from 35,000 to 1.5 × 106 ) with the method of isolation and the source of the algae. Mannuronic acid is the major component.. The alginic acid molecule appears to be a copolymer of 1, 4-linked mannopyranosyluronic acid units, of 1, 4-linked gulopyranosyluronic acid units, and of segments where these uronic acids alternate with 1, 4-linkages.

Uses

Capsules containing sodium alginate and calcium carbonate are used to protect inflamed areas near the entrance to the stomach. The acidity of the stomach causes formation of insoluble alginic acid and carbon dioxide; the alginic acid rises to the top of the stomach contents and forms a protective layer.

Marketed Product

Each 100 ml of Lamina G solution manufactured by Taejoon Pharm Co. Ltd, Seoul contains 5.0g of sodium alginate. It is mainly used for the treatment of Gastric and duodenal ulcer, erosive gastritis, reflux esophagitis (usual dosage is 20–60 ml orally three to four times daily before meal) and Hemostasis in gastric biopsy (usual dosage is 10–30 ml by endoscope, followed by 30 ml orally).

PECTIN

Pectin, in general, is a group of polysaccharides found in nature in the primary cell walls of all seed bearing plants and are invariably located in the middle lamella. It has been observed that these specific polysaccharides actually function in combination with both cellulose and hamicellulose as an intercellular cementing substance. One of the richest sources of pectin is lemon or orange rind which contains about 30% of this polysaccharide. Evaluation and standardization of pectin is based on its ‘Gelly-grade’ that is, its setting capacity by the addition of sugar. Usually, pectin having ‘gelly grade’ of 100, 150 and 200 are recommended for medicinal and food usages.

Biological Source

Pectin is a purified polysaccharide substance obtained from the various plant sources such as inner peel of citrus fruits, apple, raw papaya, etc. Numbers of plants sources of pectin are mentioned below

Geographical Source

Lemon and oranges are mostly grown in India, Africa and other tropical countries. Apple is grown in the Himalayas, California, many European countries and the countries located in the Mediterranean climatic zone.

Preparation

The specific method of preparation of pectin is solely guided by the source of raw material, that is, lemon/orange rind or apple pomace; besides the attempt to prepare either low methoxy group or high methoxy group pectins.

Morphology

Chemical Constituents

Pectin is a polysaccharide with a variable molecular weight ranging from 20,000 to 400,000 depending on the number of carbohydrate linkages. The core of the molecule is formed by linked D-polygalacturonate and L-rhamnose residues. The neutral sugars D-galactose, L-arabinose, D-xylose and L-fructose form the side chains on the pectin molecule. Once extracted, pectin occurs as a coarse or fine yellowish powder that is highly water soluble and forms thick colloidal solutions. The parent compound, protopectin, is insoluble, but is readily converted by hydrolysis into pectinic acids (also known generically as pectins).

Chemical Tests

A 10% (w/v) solution gives rise to a solid gel on cooling.

A transparent gel or semigel results by the interaction of 5 ml of 1 % solution of pectin with 1 ml of 2 % solution of KOH and subsequently setting aside the mixture at an ambient temperature for 15 min. The resulting gel on acidification with dilute HC1 and brisk shaking yields a voluminous and gelatinous colourless precipitate which on warming turns into white and flocculent.

Uses

Pectin is used as an emulsifier, gelling agent and also as a thickening agent. It is a major component of antidiarrhoeal formulation. Pectin is a protective colloid which assists absorption of toxin in the gastro-intestinal tract. It is used as haemostatic in cases of haemorrhage. As a thickener it is largely used in the preparation of sauces, jams and ketchups in food industry.

Toxicology

Pectin is a fermentable fibre that results in the production of short-chain fatty acids and methane. Concomitant administration of pectin with beta-carotene containing foods or supplements can reduce levels of beta-carotene by more than one-half. There is some indication that concomitant ingestion of pectin with high energy diets may reduce the availability of these diets, as demonstrated in a controlled trial of undernourished children; urea production was also shown to be lower in children who ingested pectin with their caloric supplement.

KARAYA GUM

Synonyms

Indian tragacanth, Sterculia gum, Karaya gum, Bassora tragacanth, kadaya, mucara, kadira, katila, kullo.

Biological Source

Gum karaya is a dried, gummy exudates obtained from the tree Sterculia urens (Roxburgh); Sterculia villosa (Roxburgh), Sterculia tragacantha (Lindley) or other species of Sterculia, belonging to family Sterculiaceae.

Geographical Source

The S. urens is found in India especially in the Gujarat region and in the central provinces.

Collection and Preparation

The gum is obtained from the Sterculia species by making incisions and, thereafter, collecting the plant exudates usually after a gap of 24 h. The large irregular masses of gums (tears) which weigh between 250 g to 1 kg approximately are hand picked and dispatched to the various collecting centres. The gum is usually tapped during the dry season spreading over from March to June. Each healthy fully grown tree yields from 1 to 5 kg of gum per year; and such operations may be performed about five times during its lifetime. In short, the large bulky lumps (tears) are broken to small pieces to cause effective drying. The foreign particles, for example, pieces of bark, sand particles and leaves are removed. Thus, purified gum is available in two varieties, namely:

Granular or Crystal Gum: Having a particle size ranging between 6 to 30 mesh, and

Powdered Gum: Having particle size of 150 mesh

Morphology

History

Karaya gum has been used commercially for about 100 years. Its use became widespread during the early 20th century, when it was used as an adulterant or alternative for tragacanth gum. However, experience indicated that karaya possessed certain physiochemical properties that made it more useful than tragacanth; furthermore, karaya gum was less expensive. Traditionally, India is the largest producer and exporter of karaya gum. Increasing amounts are exported by African countries. Currently the gum is used in a variety of products, including cosmetics, hair sprays, and lotions, to provide bulk. The bark is astringent.

Chemical Constituents

Karaya gum is partially acetylated polysaccharide containing about 8% acetyl groups and about 37% uronic acid residues. It undergoes hydrolysis in an acidic medium to produce D-galactose, L-rhamnose, D-galacturonic acid and a trisaccharide acidic substance. It contains a branched heteropolysaccharide moiety having a major chain of 1, 4-linked α- D-galacturonic acid along with 1, 2-linked L-rhamnopyranose units with a short D-glucopyranosyluronic acid containing the side chains attached 1→3 to the main chain, that is, D-galactouronic acid moieties.

Chemical Test

To 1 g of powdered Karaya Gum, add 50 ml of water and mix. A viscous solution is produced and it is acidic.

Add 0.4 g of powdered Karaya Gum to 10 ml of an ethanol-water mixture (3:2), and mix. The powder is swelling.

It readily produces a pink colour with a solution of ruthenium red.

Uses

Karaya gum is not digested or absorbed systemically. Medicinally, karaya gum is an effective bulk laxative, as gum particles absorbs water and swells to 60–100 times their original volume. The mechanism of action is an increase in the volume of the gut contents. Karaya gum should be taken with plenty of fluid and it may take a few days for effects to be noticeable. It also has been used as an adhesive for dental fixtures and ostomy equipment, and as a base for salicylic acid patches. The demulcent properties of the gum make it useful as an ingredient in lozenges to relieve sore throat. A protective coating of karaya gum applied to dentures has been shown to reduce bacterial adhesion by 98%. The use of karaya gum as a carrier for drugs with differing solubility in aqueous medium has been investigated. In pharma industry, it is also used as emulsifier, thickener and stabilizer. Karaya gum is also used in paper and textile industries.

Adulterant and Substitutes

It is used as a substitute for gum tragacanth.

BAEL

Synonyms

Bael fruits, Bel, Indian Bael, Bengal Quince, Belan.

Biological Source

Bael consists of the unripe or half-ripe fruits or their slices or irregular pieces of Aegle marmelos Corr., belonging to family Rutaceae.

Geographical Source

Sub-Himalayan tract and throughout India, especially Central and Southern India, Burma, occurring as wild and also cultivated.

Collection

Tree is deciduous about 12 m in height. It is a sacred tree and the leaves known as Bilipatra are used for worshipping Lord Shiva. The tree has strong, straight spines, compound trifoliate leaves and berry fruit. Fruits are collected during April–May. After collection, epicarp removed and usually cut into transverse slices or irregular pieces.

Chemical Constituents

The chief constituent of the drug is marmelosin A, B and C (0.5%), which is a furocoumarin. Other coumarins are marmesin, psoralin and umbelliferone. The drug also contains carbohydrates (11–17%), protein, volatile oil and tannins. The pulp also contains good amount of vitamins C and A. Two alkaloids O-methylhalfordinol and isopentylhalfordinol have been isolated from fruits. Other alkaloids reported in the drug are angelenine, marmeline and dictamine.

Morphology

AGAR

History

The history of agar and agarose extends back to centuries and the utility of the compounds closely follow the emergence and development of the discipline of microbiology. The gel like properties of agar are purported to have been first observed by a Chinese Emperor in the mid sixteenth century. Soon thereafter, a flourishing agar manufacturing industry was established in Japan. The Japanese dominance of the trade in agar only ended with World War II. Following World War II, the manufacturing of agar spread to other countries around the globe. For example, in the United States, the copious sea weed beds found along the Southern California coast has made the San Diego area a hot bed of agar manufacture. Today, the manufacture and sale of agar is lucrative and has spawned a competitive industry.

Collection

The red algae are grown in rocks in shallow water or on the bamboos by placing them in the ocean. Collection of the algae is usually made in summer (May and October). The bamboos are taken out and the seaweeds are stripped off. Algae are dried, beaten with sticks and shaken to remove the sand and shell attached to them. Then the entire material is taken to high altitude, washed with water and bleached by keeping them in trays in the sunlight, sprinkling water and rotating them periodically. The agar is then boiled; one part of algae with 50 parts of water acidified with acetic acid or dilute sulphuric acid. The hot extract is subjected for coarse and fine filtration using cloth to remove the large and small impurities present in them. The filtered extract is then transferred into wooden trough which on cooling forms a jelly like mass. The mass thus obtained is then passed through screw press to obtain strips of agar. These strips contain water and to remove the water present in them, the agar strips are placed in open air to get the benefits of the Japanese climate. During this season, Japan has a very warm day and the nights are very cold with a temperature less than 0°C. As a result of this climate the water present on top of the strips are converted into ice at night, and during day they are reconverted to water and the excess water present in them are removed. Then, these strips are again dried in the sunlight in trays.

Modern method of deep freezing is being utilized in the preparation of agar in recent development of technology. The algae which is collected is washed in running water for a day and then extracted firstly with dilute acid in steam heated digester and then with water for 30 min, the hot solution so obtained is cooled and deep freezed in an ice machine. The water present in the agar is converted to ice and these masses are powdered, melted and filtered in rotary vacuum filter. The moist agar is dried using dry air and powdered agar is obtained.

Morphology

Chemical Constituents

Agar is a complex heterosaccharide and contains two different polysaccharides known as agarose and agaropectin. Agarose is neutral galactose polymer and is responsible for the gel property of agar. It consists of D-galactose and L-galactose unit. The structure of agaropectin is not completely known, but it is believed that it consists of sulphonated polysaccharide in which galactose and uronic acid are partly esterified with sulphuric acid. Agaropectin is responsible for the viscosity of agar solution.

MANNA

Biological Source

It is saccharine exudation obtained from the stem of Fraxinus ornus Linn, belonging to family Oleaceae.

Geographical Source

It is small tree widely found in Mediterranean basin and Southern Europe. It is also reported in Spain and commercially cultivated in Sicily.

Morphology

Chemical Constituents

Manna contains 40–60% mannitol, alongwith 5–15% mannotriose, 10–15% mannotetrose. While dextrose, mucilage and small quantity of a fluorescent substance fraxin, are the other contents of manna.

Use

It is used as a laxative.

XANTHAN GUM

Production

One of the latest techniques of biotechnology, that is, recombinant DNA technology has been duly exploited for the commercial production of xanthan gum. First of all the genomic banks of Xanthomonas compestris are meticulously made in Escherichia coli by strategically mobilizing the broad-host-range cosmids being used as the vectors. Subsequently, the conjugal transfer of the genes take place from E. coli into the nonmucoid Xanthomonas compestris. Consequently, the wild type genes are duly separated by virtue of their unique ability to restore mucoid phenotype. As a result, a few of the cloned plasmids incorporated in the wild type strains of Xanthomonas compestris shall afford an increased production of xanthan gum. Interestingly, the commercial xanthan gums are available with different genetically controlled composition, molecular weights and as their respective sodium, potassium or calcium salts.

Morphology

GHATTI GUM

Cultivation and Collection

Artificial incisions are made on the tree bark in the absence of rain and gum is picked up in the month of April. The gums are graded into different grades depending upon the colour of the gum. The lighter the gum the superior its grade is. About two to three grades of Ghatti are available in the United States. The No. l Grade has low levels of ash and high viscosity. Gum is dried under sun for many days and then pulverized. It is then subjected to undergo various processes like sifting, aspiration and density table separation, for the removal of impurities.

Characters

ISPAGHULA

History

Blonde psyllium (Plantago ovata) is a low herbaceous annual plant native to Iran and India, extensively cultivated there and in other countries, including Pakistan. Black psyllium of the P. afra species is native to the western Mediterranean region, Northern Africa, and Western Asia, now cultivated in Southern France and Spain. Black psyllium of the P. indica species is native to Southeastern Europe and Asia. In commerce, blonde psyllium is obtained mainly from India, Pakistan, and Iran. Black psyllium is obtained mainly from southern France.

Psyllium has a long history of medical use in both conventional and traditional systems of medicine throughout Asia, Europe and North America. Blonde psyllium is official in the National Pharmacopeias of France, Germany, Great Britain, and the United States. Psyllium monographs also appear in the Ayurvedic Pharmacopoeia, British Herbal Pharmacopoeia, British Herbal Compendium, ESCOP Monographs, Commission E Monographs, and the German Standard License Monographs. The World Health Organization (WHO) has published a monograph on psyllium seed covering P. afra, P. indica, P. ovata, and P. asiatica (WHO, 1999). Asian psyllium seed (P. asiatica Linn or P. depressa Willd.) is official in the National pharmacopeias of China and Japan.

Cultivation and Collection

Isabgol seeds are sown in the month of November by broadcasting method. Well-drained loamy soil with a pH of 7.5–8.5, cool and dry climate is suitable for its growth. Ammonium sulphate is also added as a fertilizer. Good water supply to the plants is to be provided at 8–10 days interval, seven to eight times. Though ispaghula is not affected by pests or disease, the percentage yield is decreased to great extend due to heavy rainfall or storms. The fruits are collected in the month of March/April after the fruits are completely mature and ripe. The fruits are then dried and the seeds separated.

Morphology

Chemical Constituents

Ispaghula seeds contain about 10% mucilage which is present in the epidermis of testa. Mucilage consists of two complex polysaccharides, of which one is soluble in cold water and the other soluble in hot water. Chemically it is pentosan and aldobionic acid. Pentosan on hydrolysis yields xylose and arabinose and aldobionic acid yields galactouronic acid and rhamnose. Protein and fixed oil are present in endosperm and embryo.

Substitutes and Adulterants

P. lanceolata Linn., occurring wild in India, is adulterated in ispaghula. Its seeds are oblong elliptical in shape with yellowish brown colour. The seeds of P. asiatica, (syn. P. major L.), found in Andhra Pradesh and Tamil Nadu, are substituted to ispaghula. It is also adulterated with the seeds of P. arenaria. The seeds of Salvia aegyptica are frequently mixed which also yield copious mucilage. The seeds of P. media L. have different colour and swell very little in water. P. asiatica contains mucilage which is composed of β-1,4-linked D-xylopyranose residues having three kinds of branches.

TAMARIND

Synonyms

West Indian Tamarind, Imli.

Botanical Source

Tamarind consists of dried ripe fruits (freed from the brittle epicarp) of Tamarindus indica Linn., belonging to family Leguminosae.

Geographical Source

West Indies (Barbados), India

Collection

Tamarind is a superior indehiscent legume 5–20 cm long and 2 cm in width. Epicarps of the legumes are brittle, rough, brownish and hard. Mesocarp is the pulp and is acidic in nature with fibres which are vascular strands. Endocarp is leathery and encloses three to six seeds. Dried ripe fruits are collected, epicarp is removed and hot boiling syrup is poured over it for the purpose of preservation. Rarely sugar is also sprinkled in addition to syrup.

Morphology

Chemical Constituents

Chitin mainly consists of the aminosugar N-acetylglucosamine, which is partially deacetylated. The mostly deacetylated form of chitin is called chitosan. Chitin is present in nature usually complexed with other polysaccharides and with proteins.

CARRAGEENAN

Morphology

LOCUST BEAN GUM

History

The cultivation of locust bean trees was known before Christian era. Dioscorides referred its curative properties in the first century A.D. In Sicily, the carob trees were probably planted in 16th century. Arabs used carob seed as a unit of weight and it was labelled as carat, which in turn has become unit of weight for precious stones.

Description

STARCH

Description

Microscopic Characters

Rice Starch: The granules are simple or compound. Simple granules are polyhedral, 2–12 μ in diameter. Compound granules are ovoid and 12–30 μ × 7 to 12 μ in size. They may contain 2–150 components

Wheat Starch: Simple lenticular granules which are circular or oval in shape and 5–50 μ in diameter. Granules contain hilum at the centre and concentric faintly marked striations. Rarely, compound granules with two to four components are also observed.

Maize Starch: Granules are polyhedral or rounded, 5–31 in diameter, with distinct cavity in the centre or two to five rays cleft.

Potato Starch: Generally, found in the form of simple granules, which are sub-spherical, somewhat flattened irregularly ovoid in shape. Their sizes vary from 30–100 μ. Hilum is present near the narrower end with well-marked concentric striations.

Chemical Constituents

Starch contains chemically two different polysaccharides, such as amylose (β-amylose) and amylopectin (α-amylose), in the proportion of 1:2. Amylose is water soluble and amylopectin is water insoluble, but swells in water and is responsible for the gelatinizing property of the starch. Amylose gives blue colour with iodine, while amylopectin yields bluish black colouration.

Identification Tests

Boil 1 g of starch with 15 ml of water and cool. The translucent viscous jelly is produced.

The above jelly turns deep blue by the addition of solution of iodine. The blue colour disappears on warming and reappears on cooling.

Uses

Starch is used as a nutritive, demulcent, protective and as an absorbent. Starch is used in the preparation of dusting talcum powder for application over the skin. It is used as antidote in iodine poisoning, as a disintegrating agent in pills and tablets, and as diluent in dry extracts of crude drug. It is a diagnostic aid in the identification of crude drugs. Glycerin of starch is used as an emollient and as a base for suppositories. Starch is also a starting material for the commercial manufacture of liquid glucose, dextrose and dextrin. Starch is industrially used for the sizing of paper and cloth.

Substitutes and Adulterants

Tapioca starch or Cassava or Brazilian arrowroot- This starch is obtained from Manihot esculenta (Euphorbiaceae) and is used as substitute for starch.