Amino pyrolysis product

As to the origins of the major N compounds identified, it is possible that at least a portion of some of these compounds are pyrolysis products of amino acids, peptides, proteins, [18] and porphyrins (a component of chlorophyll), [19] or originate from the microbial decomposition of plant lignins and other phenolics in the presence of ammonia. [20] Of considerable interest are the identifications aromatic and aliphatic nitriles. Nitriles can be formed from amines with the loss of 2 H2, from amides with the loss of H20, and also by reacting n-alkanoic acid with NH3. [21] The detection of long-chain alkyl- and dialkyl-nitriles points to the presence in the soil or SOM of long-chain amines... 

Dean, M. A., A. S. Dhaliwal, and W. R. Jones. Effects of Zingiberaceae rhizome extract of the infectivity of cyanophage LPP-1. Trans 111 State Acad Sci Suppl 1987 80 Abstr 83. Morita, K., M. Hara, and T. Kada. Studies on natural desmutagens screening for vegetable and fruits factors active in inactivation of mutagenic pyrolysis products from amino acids. Agr Biol Chem 1978 42(6) 1235-1238. 

Ceramic-type materials that contain no organic linkage units can be prepared by the pyrolysis of cyclic or high polymeric aminophosphazenes. An example is shown in reaction (44). Under appropriate conditions, pyrolysis products that correspond to phosphorus-nitride are formed. Polyphosphazenes that contain both amino and borazine side groups yield phosphorus-nitrogen-boron ceramics following pyrolysis 94,95 The conversion of a formable polymer into a ceramic has many potential advantages for the controlled synthesis and fabrication of advanced ceramics. This principle is discussed in more detail in Chapter 9. 

The results for amino acids show that the main pyrolysis products are similar to the ion fragmentation that takes place upon electron impact. For the case of peptides and proteins, most of the effort has been done in obtaining ions of large fragments in order to account as much as possible for the protein structure [24]. Several mass spectra of substituted diketopiperazines obtained from peptide pyrolysis are shown in Figures 3.6.6 a to 3.6.6 f. The fragments generated in their mass spectra are similar to some small molecules obtained in amino acid pyrolysis. 

The amino acid pyrolysis is relevant for protein pyrolysis because certain compounds in the pyrolysate are the same when the substance to be pyrolysed is the amino acid or a peptide formed from that specific amino acid (see Section 13.2). The main pyrolysis products of several amino acids are given in Table 12.1.2 [3,4]. 

Table 12.1.2. The main pyrolysis products of several amino acids. 

Besides the determination of major pyrolysis products for amino acids, a special issue is the formation of several mutagenic compounds (heterocyclic amines) during pyrolysis. These types of compounds were detected in traces in the pyrolysates of amino acids, and the finding is very important as the amino acids are components of proteins and are present in food. Some of these compounds isolated from pyrolysates performed at 550 C from several amino acids [5,6] are shown below ... 

Another main type of pyrolysis products for peptides includes the diketopiperazines (DKP) and their secondary fragmentation products. The formation of DKP from oligopeptides showed that the generation of DKPs always takes place from neighboring amino acids. The mechanism of DKP formation seems to be the following ... 

The production of DKPs when one amino acid is proline leads to the formation of bicyclic compounds. As an example, several pyrolysis products for Val-Pro and Pro-Val obtained by Curie point pyrolysis at 510° C are given in Table 12.2.2. 

Some breakdown, as well as cyclisation reactions, can be expected for most of the coded amino acids when they are held at temperatures around and above 200 °C. These processes lead to decarboxylation, side-chain loss to form glycine and formation of amines, furans, pyrroles and pyridines, typically. Higher temperatures (850-1000 °C) cause all the common amino acids to decompose to HCN as the major pyrolysis product, together with C02 and the hydrocarbon derived from the side-chain. 

M21. Manabe, S., Yanagisawa, H., Ishikawa, S., et al., Accumulation of 2-amino-6-methyldipyri-do[l,2-a 3, 2 d]imidazole and 2-aminodipyrido[l,2 fl 3, 2 d]imidazole, carcinogenic glutamic acid pyrolysis products, in plasma of patients with uremia. Cancer Res. 47, 6150-6155 (1987). 

Mita, S., Yamazoe, Y., Kamataki, T., and Kato, R., Metabolic activation of a tryptophan pyrolysis product, 3-amino-l-methyl-5H-pyrido[4,3-b]indole (TRP-P-2) by isolated rat liver nuclei, Cancer Lett., 14, 261, 1981. 

Hosaka, S., Matsushima, T., Hirono, I., and Sugimura, T., Carcinogenic activity of 3-amino-l-methyl-5H-pyrido [4,3-b]indole (Trp-P-2), a pyrolysis product of tryptophan, Cancer Lett., 13, 23, 1981. 

Tamano, S., Tsuda, H., Tatematsu, M., Hasegawa, R., Imaida, K., and Ito, N., Induction of gamma-glutamyl transpeptidase positive foci in rat liver by pyrolysis products of amino acids, Gann, 72, 747, 1981. 

In relation to food intake, pyrolysis products of L-tryptophan in which highly mutagenic y-carboline, tryptophan-P-1 (3-amino-l, 4-dimethyl-5H-pyrido[4,3-b] indole and tryptophan-P-2 (3-amino-l-methyl-5H-pyrido[4,3-b] indole are formed and can be activated to mutagens in liver. Implications of such events in liver carcinogenesis are discussed in Chapter 6. 

In 1969, at the 4th ASIC symposium in Amsterdam, Merritt et al. (1970) asserted that the object of research on the composition of the constituents of coffee aroma is not the mere compilation of lists, but the relationship of the compounds to their precursors, in order to establish a mechanism for their formation, and ultimately for controlling the quality of the product. Merritt et al. (1970) tried to correlate the composition of green and roasted coffees and gave a list of some pyrolysis products of various amino acids, observing that proteins containing the same amino acids produce the same pyrolysates. After having identified 16 other constituents, the authors hoped that new techniques will lead to more direct correlations between the aroma and their precursors, providing a more secure basis to evaluate and control the quality of coffee. 

Pyridines have been identified among the pyrolysis products of model reactions involving amino acids and sugars, for instance by Ledl and Severin (1973), Mussinan and Katz (1973), and Baltes and Bochmann (1987d). The latter authors identified 15 pyridines present in coffee flavor, 13 of them also being present in reactions of serine and/or threonine, with or without sucrose, under coffee-roasting conditions. Pyridines can also be formed by thermal degradation of Amadori intermediates (van den... 

For Viani and Horman (1974), pyridine represents 25% of the pyrolysis products of a trigonelline monohydrate sample. Pyridine has been found in model reactions between glucose and amino acids (Kato et al., 1973b), when heating serine and/or threonine with or without sucrose under coffee-roasting conditions (Baltes and Bochmann, 1987d who found it also in coffee). Mottram (1991) explained the possible formation of pyridine by reaction of ammonia on 2,4-pentadienal. 

It has been identified in the pyrolysis products of amino acids by Kato et al. (1973a). Baltes and Bochmann (1987d) observed its formation when heating threonine alone with sucrose or mixtures of serine and threonine, with or without sucrose. 

Table lV.B-4 lists several polynuclear (V-heterocyclic amines that exhibit extremely high mutagenicity levels in the Ames bioassay, are amino acid pyrolysis products, and have been identihed in various broiled, fried, or roasted foodstuffs as well as in CSC [Sugimura (3828c)]. On a per microgram basis, B[fl]P in the Ames bioassay with Salmonella typhimu-rium (Strain TA 98) shows about 200 revertants/pg. Several of the amino acid-derived compounds in Table lV.B-4 exceed the B[fl]P effect with the TA 98 strain by factors ranging from about 10 to over 2100. 

Of the known carcinogenic pyrolysis products of the amino acids, so far only 2-amino-3-methylhnidazo(4,5-/)quinoline has been detected in trace amounts of 0.26 ng in the smoke of a Japanese filter cigarette [Yamashita et al. (4368)]. 

Apparently, Hoffmann and Hecht had overlooked not only the reports of the identification in CSC of several other known carcinogenic pyrolysis products of amino acids, for example, 2-amino-97/-pyrido[2,3-fc]indole (AaC) and 2-ami-no-3-methyl-97/-pyrido[2,3-fc]indole (MeAaC) (4388) or... 

In the late 1970s, Japanese investigators, in their detailed studies of components of various cooked foods, isolated and identified the first of a series of Af-heterocyclic amines as pyrolysis products of several amino acids. Sugimura et al. (3829) reported the isolation and identification of 3 -am ino-1,4-dimethyl-5//-py rido[4,3 -fcjindole (designated as Trp-P-1) IV and 3-amino-l-methyl-5//-pyrido[4,3-fc] indole (Trp-P-2) V (Figure XVII.F-2) from tryptophan pyrolysates. 

Rodgman also discussed the already identified and other possible theoretical relationships (Figure XVII.F-5) between tryptophan XX and 9//-pyrido[3,4-( ]indole (norharman) II its methyl homolog l-methyl-9//-pyrido[3,4-fc]indole (harman) III and other substituted norharmans VI, R = C2H5, CH3CH=CH, and -C4H9, the tryptophan pyrolysis products 3-amino-1,4-dimethyl-5/7-pyrido-[4,3-( Jindole (Trp-P-1) IV and 3-amino-l-methyl-5//-pyrido[4,3-( ] indole (Trp-P-2) V the alkyl- and dialkyl-indoles indole-... 

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