Indole from tryptophan

In the presence of nitric acids, 4-hydroxylated phenolic acids (and to some extent also hydroxylated indoles from tryptophan) conjugate with l-nitroso-2-naphthol to yield orange/red chromophores [4]. The structure of l-nitroso-2-naphthol is shown in Fig. 1.3.1. 

Scission of the side chain leaves an Ai ion which takes up a pioton to give indole from tryptophan (as with tryptophanase) or phenol from tyrosine (as with 3-tyrosinase). The side chain of the original molecule is left as the pyridoxal phosphate complex of aminoacrylic acid, and on hydrolysis the aminoacrylic acid tautomerizes to the imine of pyruvic acid which is hydrolyzed to pyruvic acid and ammonia ... 

The approaches that have been described in some detail for tryptophan synthase may be applied to other PLP-dependent enzymes. Tryptophan indole lyase, or tryptophanase, catalyzes the PLP-dependent P-elimination of indole from tryptophan to yield indole, pyruvate, and NH4+ (Equation 4). 

Tryptophan Degradation. Tryptophan desmolase catalyzes an essentially irreversible reaction. The formation of indole from tryptophan is catalyzed by a very similar but quite distinct enzyme, tryptophanase. ... 

Indeed, a common bacteriological test consists of measuring the ability of some bacteria to form indole from tryptophan. The indole ring is an excellent... 

As previously discussed, lipid oxidation is generally related to the flavor deterioration in meat and meat products. However, boar taint, an intense urinelike off-odor, is attributed primarily to the flavor synergy between two compounds in boar fat, androstenone (5-a-androst-16-ene-3-one) from testes and the fecal-like skatole (3-methyl indole) from tryptophan breakdown (125). Generally, women tend to be more sensitive to the odor than men. Skatole has also been implicated in a medicinal off-odor in beef (126). 

Indole alkaloids from Tabernaemontana plants are all biogenetically derived from tryptophan (tryptamine) and secologanine, which constitute the indole and terpenic portions, respectively, and can be classified into nine main types depending on the structural characteristics of their skeleton (Fig. 1). 

Tryptophan 4-acetic acid from tryptophan JACS 88,3941(1966) Indoles from o-azidobenzaldehydes JOC 37,719(1972)... 

The case of indole and tryptophan is peculiar because the low-lying absorption bands overlap. Box 5.2 shows how the indole absorption spectrum can be resolved into two bands from the combined measurement of the excitation spectrum and the exdtation polarization spectrum. 

This enzyme [EC 4.1.99.1], also known as L-tryptophan indole-lyase, catalyzes the hydrolysis of L-tryptophan to generate indole, pyruvate, and ammonia. The reaction requires pyridoxal phosphate and potassium ions. The enzyme can also catalyze the synthesis of tryptophan from indole and serine as well as catalyze 2,3-elimination and j8-replacement reactions of some indole-substituted tryptophan analogs of L-cysteine, L-serine, and other 3-substituted amino acids. 

Anderson and Lavton in 1977 described vinyl modification of the Witkop cyclization to give azecino[4,5,6-cd]indole 79 from tryptophane 78. But later it was proven that the product was, indeed, azocino[4,5,6-cd]indole 80 (99TL8443). The same photocyclization has been used for trichlorobutenamide 81 with the resulting formation of azocinoindole 82 instead of the expected 83 (Scheme 24). 

Indole-3-acetaldoxime (30) and 4-hydroxyphenylacetaldoxime were shown to be metabolized by plant and pest fungi to 32 and to other related indole- and 4-hydroxyphenyl carboxylic acids, however, the biochemical transformation differed between the two fungi. These biochemical transformations may be relevant to the ability of certain fungi to cause plant diseases . Compound 30 has been shown to be a key intermediate in the biosynthesis of camalexin, 3-thiazolyl-2 -yl-indole, a member of the family of phytoalexins that are produced in response to pathogen attack. It was demonstrated that CYP71A13 catalyzes the conversion of 30 to indole-3-acetonitrile, which is essential for the biosynthesis of camalexin. Thus, the literature supplies a large body of evidence for the existence of a set of enzymes dedicated to the production of the auxin, 32, from tryptophan via indole-3-acetaldoxime (30). 

The constitution of indole and skatole had been proved by synthesis, but that of the other two compounds had not been determined, and Nencki s formulae for them were accepted. Investigations by Ellinger and Gentzen in 1903, who found that in the large intestine indole was formed in large amounts from tryptophane, but skatole only in small amounts, and that skatole only gave traces of indole under the same conditions led Ellinger to doubt the accuracy of Nencki s formulae for skatoleacetic and skatolecarboxylic acids, more especially as Wislicenus and Arnold s skatolecarboxylic acid, which was synthesised from pro-pionyl formic acid phenylhydrazone had the formula... 

Carbazoles are relatively rare as natural products. There are a number of alkaloids with carbazole rings and these are derived from tryptophan and are closely related biogenetically to the indole alkaloids. 

Examination of the absorption spectra, in the visible range, of alcoholic extracts of the reaction-products revealed that that from tryptophan was the simplest. Hence it appears that tryptophan is the most satisfactory readily-available -indole derivative for use in the estimation of 2-desoxy-ribose and probably also of other 2-desoxypentoses. 

The biosynthesis of terpenoid indole alkaloids from tryptophan has long been known.1,2 In new experiments with DL-[2-14C,2, 3 - 3C2]tryptophan [as (94)], this has been confirmed for vindoline (106).35 Incorporation measured by assay for radioactivity and by n.m.r. spectroscopy was the same, thus indicating an intact incorporation (with loss, of course, of the carboxy-group) (for discussion of the particular application of 13C labelling used here, see pp. 1-2). 

The families Catenicellidae and Flustridae produce alkaloids derived from tryptophan. The majority of these contain bromine at carbon 6 of the indole ring, although some are more extensively brominated. The convolutamydines (brominated tryptophan derivates isolated from the genus Amathia in the order Ctenostomata)128 are similarly brominated at carbon 6, suggesting a common biosynthetic pathway or bacterial symbiont. 

Hoshino et al. described that in cultures of Chromobacterium violaceum, lycogalic acid (35, = chromopyrrolic acid) was derived from tryptophan [18]. It was therefore assumed that lycogalic acid (35) was formed by oxidative dimerization of 3-(indol-3-yl)pyruvic acid followed by reaction of the resulting 1,4-dicarbonyl intermediate with an equivalent of ammonia. On the basis of this idea, lycogarubin C (33) was synthesized from methyl 3-(indol-3-yl)pyruvate (37) in a simple one-pot process (Scheme 4). 

Just as terpenes could be viewed as being formed from isoprene units, alkaloids can be viewed as being derived from amino acids. Four amino acids give rise to important classes of alkaloids. As shown in Table 28.1, the pyrrolidine alkaloids are derived from the amino acid ornithine (not one of the 20 standard amino acids), the piperidine alkaloids from lysine, the isoquinoline alkaloids from tyrosine, and the indole alkaloids from tryptophan. 

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