Tricholoma muscarium Tricholomic acid

Substances related to MSG and purine 5 -ribonucleotides include peptides, amino acids (e.g. cysteine, homocysteine, cysteine S-sulfonic acid, aspartic acid, a-amino adipic acid, a-methyl glutamic acid, tricholomic acid, ibotenic acid), pyrrolidone carboxylic acid, 3-methyl thiopropyl amine, and others [2, 10], They are of less commercial interest than MSG, IMP, and GMP. Chemical structures of some of these substances are depicted in Fig. 3.53. Relative umami effects of some are shown in Tab. 3.49. Tricholomic acid and ibotenic acid have been found in the mushrooms Tricholoma muscarium and Amanita stroboliformis, respectively. 

The synthesis of tricholomic acid (751), an unusual amino acid isolated from tricholoma muscarium, uses an aldol condensation between 590 and 745 (a glycine acyl anion equivalent) to establish the absolute configuration of the amino functionality early in the synthesis (Scheme 108) [140]. The aldol reaction produces a 3 2 mixture of diastereomers that can be separated as in the form of the corresponding N-Cbz benzyl esters 746 and 747. 

In theTohoku area (northeast area of Honshu island) in Japan, there was a custom in which grilled Tricholoma muscarium (Tricholomataceae) was used for the purpose of killing flies. Takemoto et al. conducted research to isolate the active component(s) of this mushroom, and they succeeded in isolating an active component named tricholomic acid and elucidated its chemical structure [10].The active component was identified as a dihydro derivative of ibotenic acid, and it possessed powerfiil fly-killing activity... 

Two other amino acids (tricholomic and ibotenic acids) have been identified as having flavor potentiator properties. Tricholomic and ibotenic acids were found originally in Japanese mushrooms (Tricholoma muscarium and Aminita strobili-forms, respectively) by Takemoto et al. [3-5] and Takemoto and Nakajima [6,7]. These amino acids were of particular interest since they were found to be effective in killing the common house fly. While both amino acids have lower sensory thresholds for potentiating effects than either MSG or the 5 -nucleotides, they have not found commercial application. 

Amanitas, such as fly agaric (Amanita muscaria), contain a toxic derivative of isoxazole known as ibotenic acid (2-57), which is biosynthesised from glutamic add. Hallucinogenic effects also shows its dihydroderivative tricholomic (dihydroibotenic) acid (2-58), which is a component of Tricholoma muscarium mushrooms (see Section 10.3.2.9.3). 

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