Bitter almond

cyanogenic glycoside

1. CYANOGENETIC GLYCOSIDES MRS.REKHA AMIT BHALERAO ASSISTANT PROFESSOR PHARMACEUTICAL CHEMISTRY PES MODERN COLLEGE OF PHARMACY, FOR LADIES

2. CYANOGENETIC GLYCOSIDES They are also called as cyanophore glycosides, because of the presence of hydrocyanic acid in the aglycone moiety. The interest about such compounds was generated, while studying cyanides from different organisms. One of the prominent cyanogenetic glycosides from plants is amygdalin which was isolated long back in 1830.

3. Most of these glycosides contain derivatives of mandelonitrile i.e. nitrile of mandelic acid. This substance yields on hydrolysis, hydrocyanic acid and benzaldehyde . Because of this, they may be also considered as aldehyde glycosides. About 110 families of plant kingdom have been reported to contain cyanogenetic glycosides. Rosaceae being prominent amongst them. The cyanogenetic glycoside containing drugs do not exert a specific category of pharmacological activity, but are used for different pharmaceutical purposes.

4. Many of them are used as flavouring agents. Some of these glycosides worth mentioning here are amygdalin from bitter almonds, Prunasin from wild cherry bark, Linamarin from linseed, Manihotoxin from Manihot utilissima , sambunigrin from Sambucus nigra , etc. Identification of cyanogenetic glycosides is based on liberation of hydrocyanic acid on hydrolysis which changes sodium picrate into sodium purpurate , as is evident from colour change from yellow to brick-red.

5. BITTER ALMOND Synonym: Amygdala amara Biological Source: Bitter almonds are dried ripe seeds of plants, Prunus amygdalus Batsch var amara (D.C.) ( Focke ), family Rosaceae . Geographical Source: Bitter almond trees are native Of Iran and Asia minor. At present, they are extensively in Sicily, Italy, Spain, Portugal, South France, and Morocco. The bitter almond trees cannot be easily distinguished botanically, from sweet almond trees ( Prunus communis ).

6. Macroscopic Characters Colour - Brown Odour - Odourless Taste- Bitter Size - About 20 mm in length, 125 mm in width and 10 mm in thickness. Shape - Flattened, oblong, ovoid in shape with markings on testa .

7. Chemical Constituents Bitter almonds contain about 40 to 50 per cent of a bland fixed oil, 20 per cent of proteins, an enzyme emulsin and a colourless crystalline bitter glycoside known as amygdalin (1 to 3 per cent). Bitter almonds also contain 0.5 per cent of volatile oil. Amygdalin on hydrolysis due to emulsion in presence of water decomposes into benzaldehyde and hydrocyanic acid.

8. Hydrocyanic acid is very poisonous and makes the drug unsuitable for internal consumption. Sweet almonds do not contain amygdalin (bitter glycoside) and hence are not bitter in taste. Due absence of amygdalin , they do not produce volatile oil on hydrolysis. Bitter almond oil contains 80 per cent of benzaldehyde and about 2 to 6 per cent of hydrocyanic acid.

9. Uses Bitter almonds are used as sedative due to hydrocyanic acid content. The oil is used in demulcent skin lotion. It is also used in the preparation of amygdalin , bitter almond water, in perfumery and in the form of liquors. Bitter almond oil should not be used for flavouring of foods.

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