Samin

The July 1977 issue of the Journal of Chemical Educa tion contains an article enti tied Formation of Nitro samines in Food and in the Digestive System... 

Gold and Linder (17) studied the esterase catalyzed hydrolysis of A-(-)-acetoxymethyl-(l-phenylethyl)nitrosamine. They found that the stereochemistry of 1-phenylethanol produced in the reaction was the same as that observed in the base catalyzed hydrolysis of the nitrosamine and also of N-(l-phenylethyl)nitrosocarbamate. These results indicated that the same diazotate was produced in all three reactions. The fact that no irreversible inhibition of the enzymatic hydrolysis of the nitrosamine was observed, while extensive irreversible inhibition was obtained with the nitrosocarba-mate, led these workers to conclude that the a-hydroxynitro-samine produced by the hydrolysis had sufficient stability to diffuse away from the active site of the enzyme. 

N- ace t y Halos a m i n n u r o n i c acid. Other archaeal species contain cell walls made from thick polysaccharide layers containing acetate, glucuronic acid, galacto-samine, and glucose. 

Scheme 11.17 Diastereoselective formation of a tetrahydrofuran nucleus via 5-exo-trig alkyl radical cyclization on to an allene functionality in the course of a total synthesis of (+)-samin (56) [75], a)33 67 mixture of diastereomers.

Many DOHs, such as L-mycarose, L-epivancosamine, L-noviose or L-dauno-samine, show an L configuration. Formation of L-DOH requires the action of a 5- or 3,5-epimerase. The epimerase EvaD from the biosynthesis pathway of L-epivancosamine was shown to act as a 5-epimerase on the intermediate thymidine-5 -diphospho-3-amino-2,3,6-trideoxy-D-tIireo-hexopyranos-4-ulose [10]. On the... 

Histamine is rapidly degraded by oxidative de-samination by the diaminooxidase histaminase, acetylation of the NH2-group, methylation of the ring and oxidation of the methylhistamines by the mono-aminoxidase. The main metabolites are the N-methyl-imidazole acetic acid and the imidazole acetic acid. Histamine interacts with at least four different specific receptors Hi to H4 (see Table 1). 

Life Sci 1991 48(12) 1173-1177. Crebelli, R., L. Conti, S. Fuselli, P. Leopardi, A. Zijno, and A. Carere. Put-ther studies on the comutagenic activity of cigarette smoke condensate. Mutat Res 1991 259(1) 29-36. Padma, P. R., A. J. Amonkar, and S. V. Bhide. Effect of long-term treatment of two tobacco-specific N-nitro-samines on the vitamin A status of mice. Nutr Cancer 1991 15(3—4) 217-220. 

Brunnemann, A. Rivenson, and S. S. Hecht. Tobacco specific N-nitro-samines occurrence and bioassays. lARC Sci Publ 1982 (41) 309-318. 

Archer, M. C. Tannenbaum, S. R. Wishnok, J. S. Nitro-samine formation in the presence of carbonyl compounds. In Walker, E. A. Bogovski, P. Griciute, L., Eds. "Environmental N-Nitroso Compounds. Analysis and Formation" lARC Scientific Publication No. 14 International Agency for Research on Cancer Lyon, France, 1976 pp. 141-145. 

In conclusion, we demonstrate by this preliminary review of our work that the base-catalyzed fragmentation of B-hydroxynitro-samines is a general transformation. The rate of the transformation is a significant function of structure as well as the catalyst and the conditions. Several other base-catalyzed transformations of nitrosamines have been observed and all of these reactions are expected to be of significance in the area of nitrosamine carcinogenesis. 

Examination of the observed and predicted values for log (I/D50) in Table 5 reveals that there are at least four types of compounds that are apparently not well-described by equation 4. These include compounds with hydroxy groups (e.g. compounds 20, 21, 22), compounds with chemically reactive a-hydrogens (e.g., allylic or benzylic systems, No s 9, 14), and compounds with extensive branching at the a-carbon (No s 4, 11). Acyclic nitro-samines, with one or two apparent exceptions (12), appear to constitute a separate reaction series (29). 

No. Class Protein Source Mol. wt. Man Gal Fuc G Total neutral sugars GN GalN Total hexo- samine Sialic acid Total sugar residues Refer- ences... 

Substance Source Sulfate D-Mannose D-Calactose L-Fucose sugar CN GalN samine acid acid sugar ences... 

Holt, G. D. and Hart, G. W. (1986). The subcellular distribution of terminal N-acetylgluco-samine moieties. Localization of a novel protein-saccharide linkage, -linked GlcNAc. ]. Biol. Chem. 261, 8049-8057. 

Hoff, J. E. 1963. Determination of N-acetylglucosamine-l-phosphate and IV-acetylgluco-samine in milk. J. Dairy Sci. 46, 573-574. 

In Rus) 20)T.C. J.Ovenston C.A. Parker, JSCI 66, 394-5 (1947) (Detn of nitro-samine content of proplnts stabilized with EtCentr) 21)P.Meunier A.Vinet, "Chromatographic et Mesomerie, Adsorption et Resonance , Masson et Cie, Paris (1947) 22)S.Weisberger, PATR 1662 (1947)... 

In the other method (h), the effluent from the HPLC column was mixed with a mixture of concentrated H2S04, glacial acetic acid, and KI solution, and the mixture was passed through a Teflon reaction coil kept immersed in a 70-80°C water bath. As before, the carrier gas, introduced after denitrosation, carried the liberated NO through a series of cold traps into the TEA. The system worked well with aqueous mobile phases but not with normal-phase solvents. Response for NPRO was linear from 3.5 to 900 ng injection, with a coefficient of variation of 3-5%. The temperature of the reaction coil seemed to be critical for the determination of A-nitro-samines, which are difficult to denitrosate with HI. While a temperature of 23°C was adequate for the denitrosation of NPRO and several A-nitrosoureas, a much higher temperature (up to 70°C) was required for comparable response from NDMA or NPYR. 

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