12 Gums and Mucilage.ppt
- 1. GUMS AND MUCILAGE Kampala international university- western campus
- 2. Gums and Mucilage • Gums and mucilage have similar constitutuons and on hydrolysis yield a mixture of sugar and uronic acids. • Gums are considered to be pathological products formed upon injury of the plant or owing to unfavourable conditions such as draught, by a breakdown of cellwalls (extracellular formation gummosis)
- 3. Gums and mucilage • Conversely, mucilage are generally normal products of metabolism formed within the cell (intracellular formation) and may represent storage material, a water storage reservoir or a protection for germinating seeds. • They are often found in quantity in the epidermal cells of leaves, e.g senna, in seed coats (linseed, psyllium etc.) roots (marshmallow) and barks (slippery elm)
- 4. TRAGACANTH • The BP/EP define Tragacanth as “the air- hardened gummy exudate flowing naturally or obtained ty incision, from the trunk and branches of Astragalus gummifer and certain other species of Astragalus from Western Asia • The genus (Fam. Leguminosae) contains some 2000 species and those that yield gum are chiefly thorny shrubs found in the mountainous districts of Anatolta, Syria, Iraq, Iran and the former USSR
- 5. Tragacanth • The so-called Persian tragacanth has been traditionally employed in the UK, with Anatolian tragacanth finding a considerable market on the continent of Europe. • The term Persian tragacanth is used by Pharmacists to denote the better grades of tragacanth produced in Iran and Turkish Kurdistan.
- 6. Formation • The mode of formation of tragacanth is entirely different from that of Acacia, the gum exuding Immediately after injury and therefore being performed in the plant, where as Acacia is slowly produced after injury. • A section of tragacanth seem shows that the cell walls of the pith and medullary rays are gradually transformed into gum, the change being termed ‘gummoasis’. • The gum absorbs water and a considerable pressure in set up within the stem.
- 7. Botanica sources • The requirement for precise botanical soursespecifications and satisfactory analytical procedures for tragacanth, necessitated by the legal aspects covering its use as a food additive, has rendered the above BP definition somewhat inadequate. • A survey of the Turkish gum – producting species has indicated that A microcephalus is the principal species employed with smaller amounts of A gummifer and A kurdicus being collected.
- 8. Collection. • Most of the plants from which tragacanth is collected grow at altitude of 1000 – 3000m. • The shrubs are very thorny; each of their compound leaves has a stout, sharply pointed rachis which persists after the plants in their first year, but this is of poor quality and unfit for commercial use
- 9. Collection • The plants are therefore tapped in the second year • The earth is taken away from the base to a depth of 5cm 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 incion so that the gum will exude more freely. • The wedge is generally left in the cut for some 12 – 24 hours before being withdrawn
- 10. Collection • The gum exudes and is collected 2 days after the incision. • Some of the plants are burned at the top after having had the incision made. • The plant then sickens and gives off a greater quantity of gum. • However, this practice is not universal, as many plants cannot recover their strength and are killed by the burning
- 11. Collection • The gum obtained after burning is of lower quality than that obtained by incision only and is reddish in colour and dirty looking • The crop becomes available in August – Septermber.
- 12. Characters • The official Persian tragacanth occurs in flattened ribbons up to 25 mm long and 12 mm wide • The surface shows a number of ridges which indicates the successive, temporary stoppages of flow from the incision. • Fine furrows parallel to the margin of the flake are produced by the uneven edges of the incision. • The gum is white or very pale yellowish white in colour, translucent and horny. • It breaks with a short fracrure, is odourless and has little taste
- 13. Characters • Tragacanth swells into a gelatinous mass when placed in water, but only a small portion dissolves. • On the addition of a dilute solution of Iodine to a fragment previously soaked in water, relatively few blue points are visible. • With stronger Iodine solution the gum acquires a greenish colour.
- 14. Constituents • Tragacanth consists of a water soluble fraction known as tragacanthin and a water insoluble fraction known as bassorin, they have molecular weights of the order of 840000. • Both are insoluble in alcohol. • Tragacanthin and bassorin may be separated by ordinary filtration of an extremely dilute mucilage and tragacanthin may be estimated by evaporation of an allquot portion of the filtrate.
- 15. Uses. • Tragacanth is used in Pharmacy as a suspending agent for insoluble powders, etc. • Or used as a binding agent in pills and tablets • As substitutes become available its use in the food industry is declining.
- 16. STERCULIA GUM • Stercullia (Karaya Gum, Indian Tragacanth, Bassora Tragacanth) is the dried gummy exudate obtained from the tree Sterculia urens (Fam, Sterculiaceae). • It is produced in India, Pakistan and to a small extent in Africa. • The gum is of relatively recent introduction. • It was generally regarded during the early part of the last century as an adulterant and inferior substitute for tragacanth.
- 17. Collection and preparation. • In central and northern India (Ashra Pradesh, Madhya, Pradesh, Rajasthan and Uttar Pradesh) two collections are made each year, before and after the monsson season. In April – June and in September respectively. • The first collection goes a gum affording the highest viscosity. • Blazes of about 1 sq ft in area, are made in the larger trees (smaller trees are tapped) and the gum immediately exudes the flow is greatest during the first 24 hours and continues for several days
- 18. Collection • The dried irregular masses weighing up to several pounds are picked off and transported to village centres for purchase by Bombay merchants. • The Indian merchants remove excess bark and roughly sort the gum into two grades, It is further graded in Europe and the USA • According to colour and presence of foreign organic matter (mainly bark) • It is finally sold as a granulated (crystal), or finely powdered product.
- 19. Characters • Good guality gum occurs in irregular almost colourless translucent, striated masses weighing up to 25g or more. • Medium grades have a marked pinkish tinge, while the lower grades are very dark and contain considerable amount of bark. • Karaya gum has marked odour of acetic acid, and when hydrolyzed with 5% phosphoric acid, has a volatile acidity (BP) of not less than 14% tragacanth, about 2-3%)
- 20. Characters • When boiled with solution of potash, it becomes slightly brownish (tragacanth, canary yellow) • Keraya also differs from tragacanth in that it contains no starch and stains pink with a solution of ruthenum red. • In water sterculia gum has slow solubility but swells to many times its original volume. • This means that the processing of the gum influences the final product the coarser granulated grades give a discontinuous grain dispersion, whereas the fine powder affords an apparently homogenous dispersion.
- 21. constituents • Partial acid hydrolysis of sterculia yields D- galactose, L-rhamnose, D-galacturonic acids, an acid trisaccharide and acetic acid; • The galacturonic acid and rhamnose units are the branching points within the molecule. • Uronic acid residues represent about 37% of the gum
- 22. Uses • The granular grades of sterculia are used as a bulk laxative, being second only to psyllium seed in use in this respect. • The powdered gum is used in lozenges, pastes and denture fixative powders, and it has proved particularly useful as an adhesive for stoma appliances. • As a bulk laxative and stimulant it is available, with frangula, as granules.
- 23. ACACIA GUM • Acacia (Gum Arabic) is a dried gum obtained from the stem and branches of Acacia senegal Wild and some other species of Acacia (Fam Leguminosae). • A senegal is a tree about 6m high, which is abundant in the Sudan, particularly in the province of Kordofan, in Central Africa in West Africa. • The tree is known in Kordofan as Hashab and in Senegambia as Verek
- 24. Acacia Gum • The best gum is that produced in Kordofan from tapped trees, but some Senegal and Nigerian gum is of good quality. • Apart from Acacia Gardens, wild, self- sown plants are the main source of the gum
- 25. Collection and preparation • Some gum exudes from the trees as a result of cracking of the bark, but the most esteemed Kordofan variety is obtained from trees about 6 years old, tapped in February and March, or earlier, in September after the rains, when the leaves fall. • The gum is collected in leather bags and is conveyed in sacks to El Obeid and other centres, mostly along the railway. • Here the gum is garbled to free it from sand and vegetable debris and is sorted
- 26. Characters • Bleached Kordofan Acacia, when available occurs in rounded or void tears up to about 3 cm diameter, or in angular fragments. • The outer surface bears numerous fine cracks which from during the ‘ripening’ and make the tears opaque. • The gum is white or very pale yellow in colour. • The tears break rapidly with a somewhat glassy fracture, and much of the drug consists of small pieces. • It is odourless and has a bland and mucilaginous taste.
- 27. Characters • Cleaned and h.p.s Kordofan gum differs from the above in having fewer cracks which causes it to be more transparent, and being more yellowish or pinkish in colour. • The tears are usually of less uniform size, some being quite small, while others have a diameter of 4 cm or more. • The better qualities of Senegal gum closely resemble the Kordofan, but some of the tears are vermiform in shape and the gum is rather more yellowish in colour.
- 28. Constituents • Acacia consists mainly of arabin, the calcium salt of arabic acid. • Arabic acid may be prepared by acidifying a mucilage with hydrocloric acid and dialysing • Acacia also contains an oxidase enzyme and about 14% of water. • It yields about 2.74% of ash.
- 29. Uses • As a general stabilizer in emulsions and as a pharmaceutical necessity in lozenges, etc. • Its demulcent properties are employed in various cough, diarrhoea and throat preparations, but it is incompatible with readily oxidized materials such as phenols and the vitamin A of cod liver oil • It has widerpread use in the food, drinks and other industries.
- 30. GUAR GUM • Guar EP/BP is obtained from the ground endosperm of the leguminous plant Cyamopsis tetragonolobus, a species cultivated in India as a fodder crop. • The gum is white or off-white powder which readily forms a mucilage with water. • Examined under the microscope the powder, in a glycerol mountant, shows the thick walled endosperm cells with granular contents.
- 31. Guar Gum • The principle constituent of the gum is galactomannan which on hydrolysis gives galactose and mannose. • These sugars of the hydrolysate constitute the basis of the pharmacopoeial thin-layer chromatography test for the drug. • Other tests refer to the absence of other gums, viscosity, lossy on drying, ash and microbial contamination.
- 32. Uses • Guar gum is available as an oral hypoglycaemic drug it produces changes in gastric emptying and in the gastrointestinal transition tiime, which can delay the absorption of sugars and oligosaccharides from the gut. • Guar also lowers cholesterol levels. Possibly by binding bile salts in the gut. • However, its efficacy in the treatment of diabetes is not considered by all to be full proven. • It is also used in the food industry.
- 33. XANTHAN GUM • This gum is produced artificially by the pure culture fermentation of the bacterium Xanthomomas campestris on glucose. • It, like cellulose, consists of 1.4 – glycosidically linked chains of glucose with trisaccharide side chains on alternating anhydroglucose units. • The side chains are composed of two mannose units which encompass a glucuronic acid unit. • Xanthan gum is used as a pharmaceutical aid and in food and cosmetics industry.
- 34. PSYLLIUM • Also known as Flea Seed. • The dried ripe seeds of Plantago afra (P.psyllium). P. indica (P. arenaria ) and P. ovata (Fam. Plantaginaceae). • The US national formulary incudes both species under the name Plantago Seed. • The BP describes the seeds of the first two species under the title ‘ Psyllium’ and the husks of seeds of P. ovata are included under ‘ Ispaghula Husk’.
- 35. Constituents. • All the seeds contain mucilage in the epidermis of the testa. • The seeds may be evaluated by measuring the volume of mucilage produced after shaking the seeds with water and allowing to stand. • Two fractions have been separated from the mucilage, one is soluble in cold water and the other in hot water giving a highly viscous solution which gels on cooling
- 36. Uses • Plantago seeds are used as demulcents and in the treatment of chronic constipation. • Ispaghula husk is used for similar purpose but has a higher swelling factor