Gum Acacia, Gum sudani, Acacia gum, Arabic gum, Acacia, Senegal gum, Indian gum.
Indian gum is the dried gummy exudation obtained from the stem and branches of Acacia arabica wild, belonging to family Leguminosae.
The plant is found in India, Sri Lanka and Africa. In India, it occurs in Punjab, Rajasthan and Western ghats.
Cultivation and Collection:
It is a common member of the dry monsoon forests of India. It is an evergreen tree with a short trunk. It is not cultivated on a commercial scale. Gum is collected from wild-grown plants, made free of bark and foreign organic matter, dried in sun, which also results in partial bleaching of gum.
Colour: Tears are cream-brown to red in colour, while powder is light brown in colour.
Taste: Bland and mucilaginous
Size and shape: Irregular broken tears of varying size.
The tears are glossy and marked with minute fissures and are brittle in nature. The pieces of broken tears are with angular fragments and blistering surfaces, breaking with difficulty, and with a conchoidal fracture.
It is soluble in water. The watery solution is viscous and acidic. It is insoluble in alcohol.
It should contain no more than 15 % of moisture and 5 % of ash; Indian gum should not contain tannin, starch and dextrin.
It consists principally of arabin, which is a complex mixture of calcium, magnesium and potassium salts of arabic acid. Arabic acid on hydrolysis gives L-rhamnose, D-galactose and D-glucuronic acid. It also contains an enzyme oxidase.
1. Solution of lead sub-acetate gelatinizes the aqueous solution of Indian gum.
2. It does not produce a pink colour solution of ruthenium red.
3. To the aqueous solution of gum acacia, add 0.5 ml of a solution of hydrogen peroxide and 0.5 ml of a solution of benzidine in alcohol (1 % solution), shake it well. The blue colour is produced (due to the oxidase enzyme). Benzidine is carcinogenic, therefore, the test is no longer advocated.
4. Hydrolyse the aqueous solution of gum acacia in presence of dilute hydrochloric acid, by boiling. To it add Fehling’s solutions A and B and heat again. A red precipitate is observed, which confirms the presence of reducing sugar as the product of hydrolysis.
Acacia is a demulcent. It is also administered intravenously in haemolysis. In the form of mucilage, it is used as a suspending agent, specifically in mixtures with resinous substances. Acacia is a good emulsifying agent for fixed oils, volatile oils and also for liquid paraffin. It is a good binding agent and is used in the preparation of lozenges, pastilles and compressed tablets. It is a gum of choice, as it is compatible with other plant hydrocolloids, as well as, starches and carbohydrates.
Tests for Purity of Indian Acacia:
1. Dilute 1 ml of the solution of gum with 10 ml of water and keep for a few hours. No sedimentation should take place.
2. To 1 ml of solution, add 4 ml of water, boil, cool and add 2 drops of N/10 iodine. Brown colour indicates the presence of dextrin, whereas blue colour is due to starch. This test should be negative with authentic drugs.
3. With a few drops of 0.1 % ferric chloride to 1 ml of the solution, blue or black colour (due to
tannins) should be produced.
Substitutes and Adulterants:
B.P. variety consists of gum obtained from Acacia senegal willo, (Leguminosae), a plant of African origin and grown in Africa. The tears are rounded or ovoid and about 5 – 40 mm in diameter. Tears are yellowish-white in colour. It can be used as a substitute for Indian gum.
Indian gum is adulterated with gum ghatti, obtained from Anogeissus J/atifolia (Combretaceae), which is distinguished from the genuine drug by the following characters. Its outer surface is dull and without fissures. It shows a very slight precipitate with lead subacetate solution and its aqueous solution is highly viscous. Starch, tragacanth, dextrin and sterculia gum are the other adulterants of acacia.
Acacia or powdered acacia should be stored in a cool dry place in air-tight containers.