cyanogenic glycoside

1. CYANOGENETIC GLYCOSIDES
MRS.REKHAAMIT 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.

10. Thank you