ACACIA

SYNONYM:  Gum acacia, gum Arabic.

BIOLOGICAL SOURCE:  It is the dried gummy exudation obtained by making incisions on the stems and branches of Acacia senegal (African acacia) and Acacia arabica (Indian acacia) belonging to the family Leguminosae.

GEOGRAPHICAL SOURCE: A.senegal-in Sudan (Kordofan), Senegal, nigeria, Gambia.(African countries) A.arabica-Indian variety.

MACROSCOPICAL CHARACTERS:  Form: in rounded or ovoid tears, Colour: tears are cream brown to red in colour. Powder is light brown in colour. Odour: none, Taste: bland and mucilaginous, Shape: tears are irregular, broken, fracture: very brittle and the fractured surface is transparent and glossy, freely soluble in water, insoluble in alcohol and other organic solvents.

CULTIVATION AND COLLECTION: It is a common member of dry monsoon forests. It is an evergreen thorny tree with short trunk. Now a days it  is cultivated on commercial scale. The gum is produced by the living cells of phloem and cambium as a result of injury or incision to the plants by a process of gummosis by rod shaped bacteria (Bacterium acaciae).

                              Trees which are above 6 years old are selected. A transverse incision in the bark is made for peeling the loosen bark above and below the cuts to expose the cambium. The tears of gum are formed on the exposed surface due to bacterial action in about 3-6 weeks period.

                                      Tears are collected in leather bags in every 4-6 days. The gum is garbled to free it from sand and vegetable debris and occasionally exposed to sun light for 3-4 months to bleach it. This process of drying is known as Ripening. During this bleaching process numerous minute cracks are formed on the outer surface of the tears due to which the surface becomes semi opaque.

                                  Tears are graded finally on the basis of external appearance packed and exported. Gum is also spray dried and marketed for general use.

ACTIVE CONSTITUENTS: Acacia consist of carbohydrates, mainly heteropoly-saccharides. The main constituent is Arabin.  Arabin is a complex mixture of calcium, magnesium and potassium salts of arabic acid which on hydrolysis with dil Hcl yield L- arabinose, L-rhamnose, D- galactose, D-glucuronic acid. It also contains enzymes like oxidase, peroxydase, pectinase and diastase.

STANDARDS: Acacia should not contain tannin, starch, and dextrin. Moisture content-NMT 12-14%, Ash content-2.5-5%.

SUBSTITUENTS AND ADULTERANTS: Best quality acacia-A.senegal or Kordofan acacia (African variety).-round, ovoid tears, white to pale yellowish in colour.

SUBSTITUENTS:

 1. Acacia arabica (Indian acacia)-large tears of dark brown colour.

2. Acacia gummifera (Sudan)

 ADULTERANTS:

1. Anogeissus latifolia (ghatti gum, Indian gum)

2. Acacia seyal (Talka gum, East African variety)

3. Starch, dextrin, tragacanth, sterculia gum, tannins, mucilage.

USES:  Demulcent, Emollient, Suspending agent, Emulsifying agent, Binding agent, Adhesive, Binder, administered intravenously in haemolysis. STORAGE: It should be stored in cool dry place in air-tight containers.

  IDENTIFICATION TESTS:

Ø Aqueous solution is prepared by dissolving 5gm of drug in 15ml water.

Ø Slightly acidic.

Ø Microbial assay should show the absence of salmonella spp. And E.coli.

Ø  To 1ml of solution, add 4ml of Water and dilute Hydrochloric acid and boil for few minutes. Add Fehling’s solutions A and B and heat. Red precipitate is formed. (Due to the formation of cuprous oxide.)

Ø To 1 ml of the above solution molisch’s reagent is added. On addition of concentrated sulphuric acid along the side of the test tube, a purple ring is formed on the junction between the 2 layers.

Ø To the aqueous solution, Borax is added; a stiff translucent mass is obtained.

Ø To 5ml of dilute aqueous solution of acacia, add 1 ml of strong Lead sub acetate solution. Bulky white precipitate is obtained. (Due to gelatinization of gum)

Ø To 10ml of 2% w/v solution, add 2ml of 20% w/v solution of Lead acetate. No precipitate is produced.

Ø To the aqueous solution of gum, 10%solution of hydrogen peroxide and 1%solution of benzidine in alcohol are added. Shake and allow standing. Blue colour is produced due to the presence of peroxidase enzyme.

  TEST FOR PURITY:

Ø To 1ml of the solution few drops of 0.1% solution of ferric chloride is added. No colour- absence of tannins. (Blue or brown colour- due to tannins.)

Ø It does not produce pink colour with solution of Ruthenium red(Absence of mucilage)To the powder, adds 1ml of N/10 Iodine solution. No colour is produced. (Absence of starch.) (Brown colour - due to dextrin. Blue colour - due to starch.)