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Complexation of Cesium 137 by the Cap Pigments of the Bay Boletus (Xerocomus badius).

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[l] C. Paulmier (Ed.): Selenium Reagents nndlnfermediatesin Organic S-vnlheS I S , Pergamon. Oxford 1986.
[2] S. Patai, Z. Rappoport (Eds.): The Chemistry of Orgunir Selenium nnd
Tellurium Compounds. Wiley, Chichester 1986.
[3] K. Kondo, S. Yokoyama, N. Miyoshi, S. Murai, N. Sonoda, Angew.
Chem. 91 (1979) 160; Angew. Chem. Inr. Ed. Engl. I8 (1979) 691.
[4] For the reaction of 2 with amines, see: K . Kondo, S. Yokoyama,
N. Miyoshi, S. Murai. N. Sonoda, Angew. Chem. 91 (1979) 161; Angew.
Chem. hi.Ed. Engl. 18 (1979) 692.
[5] Compound 2 can be stored at - 30°C in T H F solution under acidic
conditions for a few months and then gradually decomposes to carbon
monoxide and selenium.
[6] In the absence of triethylamine, this Se-S exchange reaction was quite
slow. A possible pathway is given by Equation (e).
comus badius).“ -41 By contrast, cepe (Boletus edulis), a closely related edible mushroom, concentrates this radionuclide
to only a small extent.
We reported earlier that the brown pileus of the bay boletus contains the unusual pulvinic acid derivatives badione A
1 and norbadione A 2, which are absent in cepe.[’] Since 1
and 2 are present in the fungus as potassium c ~ m p l e x e s , [ ~ - ~ ~
we examined whether these pigments play a role in the concentration of 137Csby bay boletus.
[7] Generated 3 was introduced into a T H F solution of diethylamine at
- YO ‘C. and the solution was stirred for 1 h at below - 20°C. The 4
(R’ = R2 = Et) thereby formed was esteritied by methyl iodide to give 5 u .
The yield of 3 was determined by GLC analysis of 5 a (88%).
[El A T H F solution of 1 (R’ = R2 = Et), prepared by reaction of diethylaniine ( 5 mmol) and selenium ( 1 mmol) with carbon monoxide, and di-npropylamine (5 mmol) was stirred at 20 ’C for 30 min. Quenching the
reaction mixture with methyl iodide (15 mmol) gave a 46:54 mixture of
Sr-methyl A’,N-diethylselenocarbamate 6 a and Se-methyl N.N-di-npropylselenocarbamate 6b. A similar reaction of 1, R’ = R’ = n-propyl,
withdiethylaminegave a48:52mixtureof6aand6b.Theseresultsstrongly suggest that an equilibrium, as shown in Equation (d) is set up.
[9] A direct nucleophilic attack of amine at the carbonyl carbon of 1 is not
likely because of the steric hindrance of the alkyl group: see K. Kondo,
N. Sonoda, K. Yoshida, M. Koishi, S. Tsutsumi, Chem. Letf. 1972, 401.
[lo] Direct reaction of amines with elemental sulfur and carbon monoxide
requires severe conditions (90-120”C, 13-27atm CO, 60-62%); see
D. W. Grisley. Jr., J. A. Stephens, J . Org. Chem. 26 (1961) 3568.
[ I l l For other preparative methods for S-alkyl thiocarbamates 5, see a)
H. Tilles, J . .4m. Chem. Soc. 81 (1959) 714; b) H. Eilingsfeld, L. Mobius,
Chem Bcr. 98(1965) 1 2 9 3 ; ~K.
) Akibd, N. Inamoto, J. Chem. Soc. Chem.
Commun. 1973.13: d) R. Riemschneider, J . Am. Soc. Chem. 78 (1956) 844.
[12] The selenium-catalyzed synthesis of S-alkyl thiocarbamates 5 from primary amines. carbon monoxide, and organic disulfides has been reported by
P. Koch [13].
[13] P. Koch, Tefruhedron Lett. 1975, 2087.
[14] The reaction without selenium catalyst under similar conditions was very
sluggish and gave only a trace amount of 5a.
[lS] Compound 5 c (Benthiocarb) is an important herbicide for rice crops and
is produced industrially on a large scale 116.171; 5 e (EPTC) possesses
outstanding effectiveness and selectivity for control of annual grasses and
many broadleaved weeds [ l l a , 18).
[16] W. Chin-Hsien, Synthesis 1981. 622.
(1 71 H. Sugiyama. J . $with. Org. Chem. Jpn. 38 (1980) 555.
[IS] H. J . Sanders, Chem. Eng. News 59 (1981) No. 31, p. 20.
[lUl Compound 1, R ’ = Rz = Et, was completely decomposed by addition of
elemental sulfur, and metallic selenium was recovered. GLC analysis after
addition of Me1 showed that the product 5 a was pure; Se-methyl N,N-di0.01 O h ) .
ethylselenocarbamate 6 a was not detected (i
CompIexation of Cesium 137 by the Cap Pigments
of the Bay Boletus (Xevocomus badius)
By Dieter C. Aumann, Gabriele Cjooth, Bert Sreffan, and
Wolfgang Steglich *
Investigations of the amount of radionuclides present in
fungi after the reactor accident at Chernobyl have repeatedly
shown high amounts of cesium 137 in the bay boletus (Xero[*] Prof. Dr. W. Steglich, Dr. B. Steffan
lnstitut fur Organische Chemie und Biochemie der Universitit
Gerhard-Domagk-Strasse 1, D-5300 Bonn 1 (FRG)
Prof. Dr. D. C. Aumann. Dr. G. Clooth
Institut fur Physikalische Chemie der Universitat,
Abteilung Nuklearchemie
Wegelerstrasse 12, D-5300 Bonn 1 (FRG)
Angew. Chem. Inr. Ed. Engl. 28 (1989) No. 4
To this end, the brown pileus of fresh bay boletus[81was
peeled off and, like the rest of the fungus, measured in a
gamma spectrometerr9](Table 1). The ratio of the specific
activities gives an enrichment factor of 3.4 for 137Csin the
p i l e ~ s . [An
~ ] analogous experiment with cepe gave an enrichment factor of only 0.6.
The weight ratio of pileus pigment to the rest of the fungus
is very difficult to determine precisely by peeling the fruiting
body. In a further experiment, therefore, the outsides of the
pilei of three fresh bay boleti were carefully washed with
dimethyl sulfoxide (DMSO), resulting in nearly complete
dissolution of the pigment. Chromatographic purification
on Sephadex LH-20 (eluant: methanol containing 5 YO
DMSO) afforded 12 mg of a mixture of complexes 1 and 2
(according to NMR spectroscopy), which was measured in
the gamma spectrometer. An enrichment factor of 87 _+ 10
for 137Csin the pileus pigments was derived from the specific
activity of the pigments (11 316 i 1184 Bq/kg) and that of
the “washed” fungi (130 7 Bq/kg fresh weight). Interestingly, an even larger enrichment factor (138 f 18) was obtained for the “normal” complexing metal 40K.[101This is
also revealed by a comparison of the X-ray emission spectra
of the pileus and the isolated pigment complex (Fig.
The binding of cesium to norbadione 2 is corroborated by
an independent experiment using a standard solution of
Table 1. Enrichment of I3’Cs in the pileus of bay boletus
Activity :
A, IBqIkgl Ial
X. hndius
E. edulis
E. erythropus
+ SO
** 7
fruiting body
A, [Bq/kgl la1
100 20
87 12
8.8 f 3.3
3.4 0.8
0.6 k 0.1
2.6 f 1.5
[a] Based on fresh weight: collected near Bonn in September 1987.
(<> VCH Verlugsgrsellsch~rfi
mhH. 0-6940 Weinheim. 1989
0570-0833j89j0404-0453 $02.50/0
E lkeVl
in the norbadione fraction after chromatography on Sephadex LH-20. Thus. norbadione is a much better hgand for
cesium compared with simple pulvinic acids."31 We ascribe
this to the presence of two pulvinic acid chains in 1 and 2,
which, according to models, offer good spatial prerequisites
for the complexation of a potassium or cesium ion. The
detailed structure of the complexes, as well as the determination of the complexation constants, is the goal of further
Other mushrooms that contain pigments of the badione or
norbadione type in their ~ i l e i ' ' ~can
] also strongly concentrate '"Cs. An example is Boletus e r ~ ~ t h r o p u swhich
exhibits an enrichment factor of 2.6 & 1.5 (Table 1). Surprisingly, the pileus of the American boletus Boletus mirabilis
collected on Vancouver Island in September 1987 contains
twice as much 13'Cs as the bay boletus fungi collected near
Bonn, although no significant fall-out from Chernobyl was
recorded in western Canada. Since B. mirabilis shows high
values for I3'Cs and particularly low values for 134Cs,the
contamination in this case must have occurred earlier.['51 In
an older sample of B. erythropus (Bonn, 1982), the amount
of 134Cswas below the limits of detection.
The results presented here show that bay boletus and
B. erythropus, in contrast to cepe, contain pileus pigments
that bind potassium and cesium ions absorbed from the environment by the mycelia and transported to the fruiting body.
These findings explain the different enrichment factors
found for these fungi.
Received: December 29, 1988,
supplemented: January 17, 1989 [Z 3093 IE]
German version: Angew. Chrm. fOf (1989) 495
Fig. 1. X-ray emission spectrum of a) the pileus of bay boletus and b) the
pigment complex isolated with DMSO. Ordinate: counts.
'37CsC1(31 Bq/100 pL). Assuming that cesium chloride is
bound by 2 in a molar ratio of 1:1, 100 pL of this solution
corresponds to approximately 5 mg of 2. When 100 pL of
this solution is treated with 2.5 mg of 2 and the reaction mixture is separated by column chromatography on
Sephadex LH-20 (eluant: MeOH), a forerun containing 15 & 1.7 Bq and a norbadione fraction containing
14.5 & 1.5 Bq are obtained. The column retains 0.1 Bq. After filtration of the norbadione fraction through a column
containing the cationic exchange resin Dowex 50-W X4, the
radioactivity of the eluate is below the limits of detection,
whereas the exchange resin now contains all the radioactivity. Thus, norbadione forms a 1 :1 complex with cesium
chloride," 'I which undergoes decomposition upon exposure
to the strongly acidic cation exchanger.
In addition to 1 and 2, simple pulvinic acids such
as atromentic acid 3a and xerocomic acid 3b['*' may be
responsible for binding cesium in fungi. When the complexation experiments described above are carried out with 3a
followed by chromatography on Sephadex LH-20, half of
the radioactivity is found in the atromentic acid fraction.
The same holds for methyl atromentate. On the other hand,
the permethyl derivative of atromentic acid displays no binding of cesium chloride. When a molar equivalent of the
137CsC1standard solution is added to a mixture containing
molar equivalents of 2 and 3a, all the radioactivity is found
VCH Verlagsgesrllschaft mhH, 0-6940 Weinheim. I989
[I] Cf., e.g., the report of the Bayerische Staatsministerium fur Landesentwicklung und Umweltfragen: Auswirkungen des Unfalls im Kernkrafiwerk
Tschernohyl auf Bayern, February 1987; radioactivity report (nuclidespecific analysis), TUV Bayern, issue IX/87.
[2] E. F. Elstner, R. Fink. W. Holl. E. Lengfelder, H. Ziegler. Oecologiu 73
(1987) 553
[3] D. Molzahn, D. Reinen, H. Behr, P. Kocksholt. P. Patzelt, Z. Mykologie,
in press.
[4] R . Seeger in Arbeitsgemeinschaft Mykologie Ostwiirttemberg (AMO) der
Deutscheu Gesellschaft fur Mykologie: Beitrage zur Kennrnis der Pihe
Mitteleuropas, Band 3, Einhorn Verlag, Schwabisch Gmiind 1987, p. 289.
151 B. Steffan, W. Steglich, Angew. Chem. 96 (1984) 435; Angew. Chem. Inr.
Ed. Engl. 2.3 (1984) 445.
[6] We thank M . Kesren, DFVLR Koln-Porz. for recording the spectra.
171 Compound 2 is also present as a potassium complex in Pisolithus tincrorim: M. Gill. D. A. Lally. Phytochemi.stry 24 (1985) 1351.
[8] Collected in autumn 1988 in the Kottenforst near Bonn. Pilei collected in
1986 and 1987 show comparable contents of 4oK, 134Cs,and '"Cs.
[9] ORTEC high-purity germanium-well detector, type GWL 110240-S.
[lo] 40K: pileus pigments 20526 f 2167 Bq/kg; remaining fungus
149 f 12 Bq/kg fresh weight.
[I 11 The norbadione-cesium chloride (1 : 1) complex gave a correct C. H. 0. C1
analysis; the amount of C s was determined by atomic absorption.
[12] W. Steglich. W. Furtner, A. Prox, Z. Naturforsch. B 2 3 (1968) 1044.
[13] Involvement of the pulvinic acid moieties in the complexation is indicated
by 'H NMR investigations on 3c. In [D,]acetone, the carboxyl protons of
3c appear, only upon cooling to 200 K. as a broad signal at d = 17.2,
whereas in the cesium chloride complex the corresponding proton gives a
sharp singlet (6 = 17.6) even at 270 K.
[I41 Review: M. Gill, W. Steglich, Prog. Chem. Org. Nat. Prod. 51 (1987) 59.
[15] Pilei: B. mirabilis (Bamfield, Vancouver Island (Canada), September
1987): "'Cs 760 k 40 Bq/kg fresh weight, " T s 40 k 10; X . badius
(Bonn, September 1988): I3'Cs 340 50, '"Cs 90 f 30; X. badius (Regensburg, October 1986): '37Cs 1373 & 126, '"Cs 457 & 80 (half-lives:
'34Cs 2.06 a, "'Cs 30.14 a). We thank Dr. H . Bed. Regensburg, for sending us X. hadius
0570-0833/89/0404-O454 d 02.SOjO
Angew. Chem. Inr. Ed. Engl. 28 (1989) No. 4
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badius, xerocomus, boletus, pigment, complexation, bay, cap, 137, cesium
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