Mushrooms, vanadium

Muonium chemistry gaseous phase, 28 119-120 liquid mixtures, 28 120-122 radical formation and reactions, 28 122-130 Mushrooms, vanadium in, 35 96-97 Mutagenesis, site-directed, flavocytochrome bj, 36 289-290 MXj-... 

Catalytic Activity of Some Vanadium Peroxo Complexes Structural Properties of Vanadium Peroxo Complexes Vanadium in Mushrooms Vanadium in Coal... 

Key Words vanadivim bromoperoxidase catalysis mushrooms vanadium-porphyrins oil... 

High levels of vanadium are found in the mushroom Amanita muscaria and in marine tuni-cates (sea squirts). In the former organism, a siderophore-like ligand that binds vanadium(IV)... 

It may be there to poison predators.614 The vanadium-accumulating species also synthesize several complex, yellow catechol-type chelating agents (somewhat similar to enterobactin Fig. 16-1) which presumably complex V(V) and perhaps also reduce it to V(III).615 Vanadium is also accumulated by other marine organisms and by the mushroom Amanita muscaria. 

Apparently, vanadium is present in the (IV) state The first EPR spectrum reported of an extract of the cap of the mushroom showed clearly an EPR signal characteristic of oxo-vanadium(IV) (97). Although the vanadium concentration in some mushrooms is low, it should be noted that they are similar to those reported for a number of seaweeds that may contain vanadium bromoperoxidases (27). 

In 1972 Bayer and Kneifel isolated (98) a pale blue compound from A. muscaria containing vanadium, which they named amavadine. They proposed (98,99) that it consisted of a complex of AT-hydroxyimino-a,a -dipropionic acid with in a 2 1 ratio. From a comparison of the EPR spectra of segments of frozen mushrooms with those of vanadyl complexes of various amino acids, it was concluded (100,101) that this proposal was not very likely. However, Krauss et al. (102) synthesized amavadine and compared its EPR properties with the complex extracted from the mushroom and concluded that it was the same. Others were unable to reproduce the synthesis (103), although models analogous to amavadine were reported. The synthesis of the ligand N-hydroxy-a,a -iminodipropionic acid, and related compounds was, however, later confirmed (104-106). The stereochemistry and total synthesis of the vanadium compound of A. muscaria has now been elucidated (107). 

Despite all these structural studies the physiological function of amavadine in mushrooms is still elusive. A suggestion has been made (106) that it may act as a cofactor with a protective oxidase or peroxidase function. On the other hand, the electrochemistry (111) of amavadine is such that it may have a role in electron-transfer reactions involving the vanadium(V)/(IV) redox couple. 

Diluting single crystals of oxobis(2-methylquinolin-8-olato)vanadium(IV) complexes in the solid state to overcome the difficulties of neighboring paramagnetic centers has allowed the determination of the g tensor and an estimation of the hyperfine coupling constant.573 Four simple hydroxamates form six different types of complexes with Vlv in solution that were characterized by EPR spectroscopy.574 The 1 2 complexes were also investigated in the solid state (110)-(112) and serve as important model systems for the amavadine complex which has been isolated from the mushroom Amanita muscaria.574... 

These are the introductory words in a communication on the structural characterisation of amavadin by Garner and co-workers in 1999. 1 The discovery of high amounts of vanadium in A muscaria dates back to 1931 [ 1 in an article Sur la repartition du molybdene dans la nature [on the distribution of molybdenum in nature], the comparatively high amounts of vanadium found in A. muscaria (3.3 mg kg ) and garlic (0.8 mg kg ) are noted. The vanadium compound present in Amanita muscaria, known as fly agaric or toadstool, was first isolated and characterised in 1972 by Bayer from mushrooms collected in the Black Forest (Germany), and named amavadin ... 

Quite a different chemical environment is found in the vanadium-containing material isolated from the mushroom Amanita muscaria. Bayer and Kneifel, who named and first described amavadine, " also suggested the structure shown in Figure. l Recently the preparation, proof of ligand structure, and (by implication) proof of the complex structure shown in Figure 1.7 have been established. Although the exact role of the vanadium complex in the mushroom... 

High concentrations of vanadium are also found in a few species of the mushroom genus Amanita indeed, the vanadium-containing compound found in mushrooms was named amavadine, the physiological function of which is unknown. Wever and... 

Seeds, cereal products, bread, cake and pastries, tubers and fruit generally have a low vanadium content (5-40pgkg dry matter (DM)). Mushrooms, red radish, leafy vegetables (lettuce, spinach) as well as herbs contain much higher levels of vanadium (100- 2400 pgkg- DM) (Table 27.2). 

Amavadin. Three species of Amanita mushrooms A. muscaria, the fly agaric , A. regalis, and A. velatipes concentrate vanadium to levels up to 400 times those typically found in plants. The vanadium is equally distributed between stem, skin and cap. Responsible for the accumulation is a blue, vanadium-containing compound, amavadin, first characterised from A. muscaria. It is a 1 2 complex with the dianionic ligand derived from (5,5)-2,2 -(hydroxyimino)dipropanoic acid ((5,5)-hidpaHj). 

The pale blue vanadium compound from kmanZta mu6CaA.Za, which we named Amavadin can be separated from aqueous mushroom extracts by HPLC on reversed phase columns as is displayed in Fig. 1. 

It should be emphasized that the first naturally-occurring compound containing vanadium, with unspecified biological activity was the blue substance amavadine (16) isolated from a mushroom (Amanita muscaria) (75). ESR studies showed that it was a complex of N-hy-... 

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