Amavadin

Amavadin is a vanadium-containing anion found in three species of poisonous Amanita mushrooms: A. muscaria, A. regalis, and A. velatipes.^[1] Amavadin was first isolated and identified in 1972 by Kneifel and Bayer.^[2] This anion, which appears as a blue solution, is an eight-coordinate vanadium complex.^[1] A Ca²⁺ cation is often used to crystallize amavadin to obtain a good quality X-ray diffraction.^[1] Oxidized amavadin can be isolated as its PPh₄⁺ salt. The oxidized form contains vanadium(V), which can be used to obtain an NMR spectrum.^[3]

Amanita muscaria contains amavadin

Amavadin

Ball-and-stick model of the amavadin dianion
Names
IUPAC name bis[N-[(1S)-1-(carboxy-κO)ethyl]-N-(hydroxy-κO)-L-alaninato(2-)-.κN,κO]-vanadium
Identifiers
CAS Number	12705-99-6 Y
3D model (JSmol)	Interactive image
ChemSpider	52085372 dihydric acid
PubChem CID	119025631 dihydric acid
UNII	5J3H8J7S42
InChI InChI=1S/2C6H10NO5.V/c2*1-3(5(8)9)7(12)4(2)6(10)11;/h2*3-4H,1-2H3,(H,8,9)(H,10,11);/q2*-1;+4/p-4 Key: JFEAKSQUSDDXGF-UHFFFAOYSA-J
SMILES CC(C(=O)[O-])N(C(C)C(=O)[O-])[O-].CC(C(=O)[O-])N(C(C)C(=O)[O-])[O-].[V+4]
Properties
Chemical formula	[V{NO[CH(CH3)CO2]2}2]2−
Molar mass	398.94 g/mol
Appearance	Light blue in solution
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Preparation

The formation of amavadin begins with the formation of two tetradentate ligands.^[3]

2 HON(CH(CH₃)CO₂H)₂ + VO²⁺ → [V{NO[CH(CH₃)CO₂]₂}₂]²⁻ + H₂O + 4 H⁺

Structure and properties

The ligand precursor found in amavadin (left), the ligand (center) and H₃(HIDA) (right).

The ligand found in amavadin was first synthesized in 1954.^[4] Amavadin contains vanadium(IV). Initially, amavadin was thought to have a vanadyl, VO²⁺, center. In 1993, it was discovered by crystallographic characterization that amavadin is not a vanadyl ion compound. Instead, it is an octacoordinated vanadium(IV) complex. This complex is bonded to two tetradentate ligands derived from N-hydroxyimino-2,2'-dipropionic acid, H₃(HIDPA), ligands.^[5] The ligands coordinate through the nitrogen and the three oxygen centers.

Amavadin is a C₂-symmetric anion with a 2− charge. The twofold axis bisects the vanadium atom perpendicular to the two NO ligands. The anion features five chiral centers, one at vanadium and the four carbon atoms having S stereochemistry.^[1] There are two possible diastereomers for the ligands, (S,S)-(S,S)-Δ and (S,S)-(S,S)-Λ.

Biological function

The biological function of amavadin is still unknown, yet it has been thought that it uses H₂O₂ and acts as a peroxidase to aid the regeneration of damaged tissues.^[3] Amavadin may serve as a toxin for protection of the mushroom.^[6]