GUMS & MUCILAGE

1. GUMS & MUCILAGE

2. Gums & mucilage have similar constitutions and on hydrolysis yield a mixture of sugars & uronic acids. Gums are considered to be pathological products, While mucilage is formed by normal metabolism. GUMS & MUCILAGE

3. Gums are amorphous translucent substances which are insoluble in alcohol & most organic solvents. It is soluble in water & gives a viscous, sticky solution. Other gums are swollen by absorbing water to form a jelly-like mass. GUMS

4. Gums consist of Ca, Mg & K-salts of polyuronides. Gums can be hydrolysed by prolonged boiling with dilute acids to yeild a mixture of sugars and uronic acids. Sugars = monosaccharides (mainly galactose, arabinose, xylose). GUMS: CONSTITUENTS

5. Gums are commonly found in trees & shrubs of a number of Families, especially Leguminosae Rosaceae Sterculiaceae Rutaceae GUMS: OCCURRENCE

6. Gums are abnormal products, formed by injury of the plant unfavourable conditions (e.g. drought) By a breakdown of cell walls (A process of extracellular formation called gummosis). GUMS: FORMATION

7. Mucilages are generally normal products of metabolism formed within the cell (intracellular formation). Fx of Mucilages Storage material Water storage reservoir Protection for germinating seeds. MUCILAGE

8. Mucilage is often found in Epidermal leaf cells (Senna) Seed coats (linseeds, psyllium) Roots (marshmallow) Barks (Slippery elm) MUCILAGE: OCCURRENCE

9. Herbs containing gums Tragacanth gum Sterculia gum Acacia gum Herbs containing mucilages Psyllium HERBS

10. DEFINITION: Tragacanth is the “air hardened gummy exudate flowing naturally or obtained by incision, from the trunk & branches of Astragalus gummifer (Labillardiere) & certain other spp. of Astragalus.” GEOGRAPHICAL SOURCES: W. Asia, Syria, Iraq, Iran & Russia. TRAGACANTH

11. Tragacanth is the gum that exudes immediately after injury of the plant occurs & is therefore pre-formed in the plant. A section of a tragacanth stem shows that the cell walls of the pith & medullary rays are gradually transformed into gum (gummosis). The gum absorbs water & an increase in P occurs within the stem – leading to the immediate exudation. TRAGACANTH FORMATION

12. A. gummifer A. kurdicus A. echidnaeformis A. gossypinus microcephalus RIGHT: A. micrcephalus BOTANICAL SOURCES OF TRAGACANTH

13. Most plants from which tragacanth is collected grows at an altitude of 1000-3000 m. Collection method varies according to the location. COLLECTION OF TRAGACANTH

14. METHODS OF COLLECTION: The gum can be obtained from the plants in the 1st year (this is then of poor quality & unfit for commercial use). Plants are normally tapped after the 2nd year. The earth is taken away from the base to a depth of 5 cm. The exposed part is incised with a sharp knife & a wedge-shaped piece of wood is used to open the incision for the gum to exude easily. The wedge is left in the cut for up to 24 hrs, & the gum is collected for 2 days after incision. Some of the plants are burned at the top after having had the incision made – the plant is then sickened & gives off a greater quantity of gum. This practice is however not universal, as many plants cannot recover and are killed by the burning. Gum obtained by burning is of lower quality than that obtained by incision only, and is reddish and dirty looking.

15. Tragacanth is graded into several qualities. The best grades form the official drug, while the lower grades are used in food, textile & other industries. Tragacanth is an expensive commodity: due to the scarcity & extra treatments & tests needed to meet the microbial requirements. GRADES OF TRAGACANTH

16. CHARACTERS OF TRAGACANTH Official Persian tragacanth occurs in flattened ribbons (of up to 25 mm long & 12 mm wide). The surface shows number of ridges that indicates the temporary stoppages of flow from the inclusion. The gum is white or white-yellow in colour & translucent. It is odourless & has little taste. Tragacanth swells into a gelatinous mass when placed in water, but only a small portion will dissolve. With strong iodine solutions, a previously soaked gum will turn a slight green colour, otherwise only a few blue spots will be visible with a dilute solution of iodine.

17. CONSTITUENTS OF TRAGACANTH A water-soluble fraction (tragacanthin) A water-insoluble fraction (bassorin) (Both these are insoluble in alcohol) Sugar Uronic acids On hydrolysis: Galacturonic acid D-galactopyranose L-arabinofuransoe D- xylopyranose

18. ALLIED HERBS & ADULTERATION Chitral gum - A. strobiliferus Sterculia gum (Karaya gum) – used to adulterate Tragacanth Insoluble Shiraz gum: a gum of doubtful botanical origin imported from Iran – distinguished from Tragacanth in that it contains no starch

19. Uses as a suspending agent for insoluble powders Binding agent in pills & tablets. Food industry - additive USES OF TRAGACANTH GUM

20. DEFINITION: Sterculia gum is the gummy exudate obtained from the tree, Sterculia urens (Sterculiaceae). COMMON NAMES: Karaya gum, Indian Tragacanth, Bassora Tragacanth GEOGRAPHICAL SOURCES: India, Pakistan & Africa. STERCULIA GUM

21. The gum is of relatively recent introduction, being generally regarded as an adulterant & inferior substitute for tragacanth. Now, however, it has shown to be superior to the other gums in certain respects, & is official in the BP. HISTORY OF STERCULIA GUM

22. COLLECTION & PREPARATION 2 collections are made each year: before & after monsoon season. The 1st collection gives a gum which has the highest viscosity. Smaller trees are tapped, but blazes are made in the bigger trees up to 1 square foot in area & the gum immediately starts to exudate. The flow is greatest in the 1st 24 hours, & continuous for several days. The dried, irregular masses, weighing up to several kgs, are packed off & transported. Indian merchants remove excessive bark & roughly sort the gum into 2 grades. It is then further graded in Europe & USA according to colour & presence of foreign organic matter (mainly bark). It is finally sold as granulated (crystal) or a finely powdered product. In some areas, over-production & destructive tapping methods have lead to a serious decline in the natural tree population and has necessitated the introduction of a 10 year bans on collection.

23. Good quality gum occurs in irregular, almost colourless, translucent, striated masses. Weight: 25 g (or more) Medium grades: pinkish tinge Lower grades: very dark & contain a large amount of bark. Sterculia gum has the distinct odour of acetic acid. STERCULIA GUM CHARACTERISTICS

24. When boiled with a solution of potash, sterculia gum turns slightly brown, while tragacanth turns canary yellow. Sterculia also contains no starch & stains pink with a solution of ruthenium red. STERCULIA & TRAGACANTH

25. STERCULIA CONSTITUENTS Uronic acids Partial hydrolysis yields • D-galactose • L-rhamnose • D-galacturonic acid • Acetic acid

26. Granular grades are used as a bulk laxative (second only to psyllium seed in use as a bulk laxative). Powdered gum is used in lozenges, pastes & denture fixture powders. USES OF STERCULIA GUM

27. DEFINITION: Acacia gum is a dried gum obtained from the stem & branches of Acacia senegal & some other spp of Acacia (Leguminoseae). COMMON NAMES: Gum Arabic GEOGRPAHICAL SOURCES: Kordofan, Senegal & Nigeria ACACIA GUM

28. COLLECTION & PREPARATION Some gum exudates from trees as a result of the cracking of the bark, but most of the best Kordofan is obtained from trees 6 years old, tapped in February & March, or after the rains when the leaves fall. A small axe is used to make a transverse incision in the bark. The axe is then twisted so that the bark is loosened. Strips are then pulled off above & below the cut. A portion of the cambium is then bared. This cambium then produces new phloem & in about 30 days the tears of gum which have formed on the surface may be picked off. The gum is collected in leather bags. It is then cleaned from sand & vegetable debris & sorted. This is then transported to different countries for sale. Spray-dried acacia is becoming of increasing importance and is included as a monograph in the BP. In addition to its general usefulness, it has a further advantage of a low viable bacterial count.

29. Cleaned (not bleached) Kordofan gum has few cracks on the surface  relatively transparent. Slightly pink-yellow in colour. Tears are usually not very uniform in size (some are quite small, others have a diameter of >4 cm). The better qualities of Senegal gum closely resemble the Kordofan - are vermiform in shape, and the gum is also more yellow in colour. CHARACTERISTICS OF ACACIA

30. Acacia is almost completely soluble in an equal weight of water (solution takes place rather slowly). This solution is slightly acidic & becomes more so on keeping, especially if hot water is used to make the solution. It is viscid & when diluted, does not deposit on standing. TESTS FOR IDENTIFICATION & PURIFICATION

31. CONSTITUENTS OF ACACIA Consists mainly of arabin (Ca-salt [with traces of Mg & K] of arabic acid). • Galactose • Arabinose • Rhamnose • Uronic acids • Oxidase enzyme • 14 % water On hydrolysis • L-rhamnopyranose • D-galactopyranosse • L-arabinofuransose

32. Used as a general stabilizer in emulsions Lozenges Demulcent properties  used in diarrhoea, coughs, sore throats. It also has a wide spread use in the food, drink & other industries. USES & ACTIONS OF ACACIA

33. ALLIED HERBS Talka gum – very broken & very variable in composition (some tears are almost colourless, while others are brown). Ghatti/Indian gum (Anogeissus latiolia) – produced in the same locations & in a similar manner as acacia. It resembles talka in possessing tears of various colours. Aqueous dispersions of the gum have a viscosity between that of acacia & talka gum. West African Gum Combretum (Combretumnigricans) – not allowed as a food additive, but is exploited as an adulterant for acacia.

34. DEFINITION: Psyllium consists of the dried, ripe seeds of Plantago afra (Plantago psyllium), P. indica (P. arenaria) & P. ovata (Plantaginaceae). COMMON NAMES: Spanish or French psyllium, ispaghula, spogel seeds or Indian plantage seeds. PSYLLIUM

35. Geographical sources: France, Spain, Cuba Colour: Glossy, deep brown Shape: Boat-shaped, outline elongated ovate Length: 2 – 3 mm Weight of 100 seeds: 0.09 – 0.10g CHARACTERISTICS OF PSYLLIUM (P. afra)

36. Geographical sources: Mediterranean Europe, Egypt Colour: Dull, Black-brown Shape: boat-shaped, outline elliptical Length: 2 – 4 mm Weight of 100 seeds: 0.12 -0.14 g CHARACTERISTICS OF PSYLLIUM (P. indica)

37. Geographical sources: Pakistan, India Colour: Dull, pink grey-brown Shape: Boat-shaped, outline ovate Length: 1.5 – 0.19 g CHARACTERISTICS OF PSYLLIUM (P.ovata)

38. CONSTITUENTS OF PSYLLIUM All the seeds contain mucilage in the epidermis of the testa. 2 fractions have been separated from the mucilage • One is soluble in cold water, & the other in hot water, making a viscous solution which gels on cooling. The seeds also contain fixed oil Sugars Sterols Protein

39. Wild seeds of P. ovata & related species contain less mucilage than the cultivated variety. P. asiatica (used in Chinese medicine). ALLIED DRUGS OF PSYLLIUM

40. Demulcent Used for chronic constipation. PLANTAGO: USES & ACTIONS

41. RESINS

42. DEFINITION: “Resin” applies to product which is more or less solid, with a complex chemical nature. When heated, they will often soften & melt. RESINS

43. Resins are mixtures of resin-acids, resin alcohols (resinols), resin phenols (resinotannols), esters & resenes (chemically inert compounds). CHEMICAL COMPOSITION

44. Resins are insoluble in water. Normally insoluble in petroleum spirit. Will dissolve more or less completely in alcohol, chloroform & ether. PHYSICAL CHARACTERISTICS

45. TYPES OF RESINS Resins are very often associated with • volatile oils (oleoresins) • Gums (gum-resins) • With oil & gum (oleo-gum-resins). NB: No clear distinction can be made between these groups, since many products can be considered as belonging to more than 1 group (e.g. ammoniacum – both a resin and a gum-resin, and it contains a volatile oil). Resins may also be combined with sugars to form glycosides.

46. Oleo-resins are substances of soft or semi-liquid consistency. They are mixtures of essential oils & resins. They are especially common in the Conifers (terpentine, Canada “balsam”), and in certain dicotyledon families. OLEO-RESINS

47. Gum-resins are exudates mainly consisting of resinous compounds & gums (e.g. gamboge – exudate of Garcinia hanburyi). Oleo-gum resins are exudates containing resinous compounds, gums & some volatile oils. The resinous fractions of these products is mostly comprised of triterpenoids, or in the case of the Conifer oleo-resins, of diterpenes. Oleo-gum-resins are no longer used in pharmacy, but some still play an NB role in perfumery. GUM-RESINS & OLEO-GUM-RESINS

48. A balsam is “a particular type of natural oleo-resin, characterized by the presence of benzoic constituents, cinnamic constituents, or both types”. “Balsam” is often wrongly applied to oleo-resins such as Canada terpentine, & should be resevered for true balsams (Balsam of Peru, Tolu & storax). These contain a high amount of aromatic balsamic acids. BALSAMS

49. If balsams contain free acids, they are partially soluble in hot water (due to the solubility of the benzoic & cinnamic acids), while the aromatic esters & resins are insoluble. Benzoin is best described as a balsamic resin. BALSAMS

50. All these above mentioned products are preformed (normal physiological products) in the plant, in schizogenous or schizolysigenous ducts or cavities. Although preformed, they usually increased in injury (e.g. in the case of Pinus). Many products (e.g. benzoin & balsam of Tolu) are not formed in the plant until it has been injured (pathological origin). RESINS