CYANOGENIC GLYCOSIDES.pptx

Cyanogenic glycoside which on hydrolysis gives benzaldehyde and hydrocyanic acid. examples of this glycosides are bitter almond and wild cherry bark. in this slides bitter almond is described in detail.

1. CYANOGENIC GLYCOSIDES BITTER ALMOND

2. INTRODUCTION : They are also called as cyanophore glycosides, because of the presence of hydrocyanic acid (HCN) as aglycone moiety. These are the glycosides which on hydrolysis yields hydrocynic acid (HCN), benzaldehyde and sugars. The medicinal activity of cyanogenetic glycosides is due to presence of hydrocyanic acid. These are the characteristics of family Rosaceae. For examples Amygdalin obtained from bitter almond (Prunus amygdalus ), Prunasin obtained from wild cherry bark.

3. BITTER ALMOND Biological source : It consists of dried ripe seeds of Prunus amygdalus var amara Family : Rosaceae Geographical source : Bitter almonds trees are native of Iran and Asia At present they are widely cultivated in Sicily, Italy, Spain, Portugal, France and Morocco. Bitter almonds tress can not be easily distinguished from sweet almond trees (Prunus communis).

4. Description Colour: Brown Odour : No specific odour Taste: Bitter Shape : flattened, oblong Surface : markings on testa Size : 20 mm long, 12.5 mm wide and 8 mm thick. In form and appearance bitter almonds are usually smaller and less regular. They have a bitter taste and easily distinguished from that of the sweet almond by its characteristic odour .

5. Chemical constituents Bitter almond contain fixed oil (40 to 45%) and proteins. Enzyme emulsin. It contains colorless, crystalline glucoside – Amygdalin (2.5 to 4%). Amygdalin on hydrolysis due to presence emulsin in presence of water decompose into benzaldehyde and hydrocyanic acid. This change is effected by the emulsin contained in all the tissues of bitter almond. It contains 0.5 % of volatile oil. Sweet almonds do not contain amygdalin and hence they are not bitter in taste. Almond oil consist of a mixture of glycerides of oleic, linoleic, palmitic, myristic, palmitoleic, margaric, stearic, linolenic, arachidic, gadoleic, behenic and cruic acid. The unsaponifiable matter contains beta sitosterol, avenasterol, cholesterol, brassica sterol and tocopherols.

6. Chemical test : Grignard Reaction Test: Liberation of hydrocyanic acid on hydrolysis, changes sodium picrate (yellow colour) into sodium purpurate (brick-red colour). Procedure : First of all, dip a strip of white filter paper into a solution of picric acid (1 % w/v in water) drain and then dip into a solution of sodium carbonate (10% w/v in water) and drain. Now, place the crushed and moistened drug material in a small flask, and subsequently suspend the strip of the prepared sodium picrate paper above the material and stopper the flask with an air tight cork. Maintain the flask in a warm place for 1 hour when the liberated HCN would turn the sodium picrate paper from its original yellow colour to brick red colour due to the formation of sodium isopurpurate (Grignard’s Reaction).

7. Uses : Hydrocyanic acid is very poisonous and makes the drug unsuitable for internal administration. Bitter almonds are used as sedative due to hydrocyanic acid content. Oil is used in skin lotion as demulcent and emollient. Sweet almond oil is used as flavoring agent in food products but bitter almond oil should not be used as flavoring of foods.