Frequently (and not so frequently) Asked Questions
BRIEF: I have some questions pertaining to cynogenic glycosides...
QUESTION:
Firstly, what is the biochemical basis for the symptoms of cynide piosoning such
as excitement, gasping, staggering, paralysis, convulsion, coma etc.
ANSWER:
Cyanide binds to cytochrome (inhibits cytochrome oxidase), and hemoglobin
interfering with both oxidative phosphorylation and the proper transport of
oxygen in the body. The body's rhodanese reaction can combine some with
thiosulfate to detoxify it and eliminate it as thiocyanate, and nitrites can be
administered at just the right dose to prevent absorption into body cells by
creating methemoglobin. Of course, excess methemoglobing can kill you, too.
QUESTION:
Secondly, apart from cooking of cassava, for example, what other methods can be
adopted to minimise the level of cynide piosoning in some plants such as
cassava.In which parts of the plants are the cynogenic glycosides most likely to
be concentrated?
ANSWER:
Soaking, rinsing and drying the cassava helps, too, by allowing the HCN to be
released, then volatilized.
QUESTION:
How is the aglycone separated from the glycoside? How is the HCN released?
What are the enzymes responsible for the synthesis and degredation of the
glycoside?
ANSWER:
There are enzymes (beta-glucosidase, hydroxynitrile lyase, etc.) in the plant
that do this when the plant is first injured.