Organic Molecule in Mushrooms Binds Radioactive Atoms

May 17, 2002 by  

Ist Bioremediation die Antwort auf die Entfernung von Radioaktivität in der

Natur und die Lösung von Unglücken wie Chernobyl?
Eine Studie in English von John K. Borchardt.

Work with edible mushrooms suggests it could, but also illustrates how radioactive
materials can enter the food chain.
Uptake of highly toxic metals from polluted environments by
plants or fungi, particularly mushrooms,
and their subsequent transmission up the food chain to man
is a significant health concern.
While quantification of this uptake has been studied extensively,

little is known about the molecular mechanisms of the uptake
and fixation of metal cations in mushrooms.
Now work by Université of Strasbourg chemists has indicated
a mechanism
by which the edible bay boletus (Xerocomus badius) mushroom
can capture caesium-137,
released in large amounts in the Chernobyl nuclear plant disaster.

The key is binding of the caesium to a complex organic molecule
called norbadione A.
s this chemical structure indicates, norbadione
A is a naphthalenoid pulvinic derivative containing seven protonation
: two enol, two carboxyl and three phenol groups. Anne-Marie
and co-workers studied the binding of caesium with norbadione
A using potentiometry,
absorption spectrophotometry, electrospray mass spectrometry
(ESMS) and proton nuclear magnetic resonance (NMR).
This array of analytical techniques enabled the characterisation
of two caesium complexes with norbadione A,
a 1:1 caesium?norbadione A complex and a 2:1 complex as well
as the determination of the stability constants of these complexes at
pH 6. Caesium binding to norbadione A is sensitive to acidity*.
Interestingly, once an atom of caesium binds to norbadione A,
a second atom binds even more readily.
Chemical structure information on five different protonated
norbadione A species was determined from proton N
MR experiments in a methanol/water solvent. ESMS data indicated
that decarboxylated norbadione A species still co-ordinate one or two caesium
ions. The enolate groups are thought to play a key role in the complexation
of caesium to norbadione A.
Could a chemical treatment of soil using norbadione A remove
radioactvity from the environment?
Much work remains including the ability to manufacture large
quantities of norbadione
A by chemical or biotechnological synthesis.


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