Skip to main content

Frequently (and not so frequently) Asked Questions

Simple keyword search (one or two words only)

 


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.