Neurotoxin, ammonia

A starch-glycine mixture, heated at 290°C, was significantly different from the starch control in its composition of alkoxyphenols and imidazoles in the involatile phase, and pyrazine, pyridine, methylpyridine, and dimeth-ylpyrroles in the volatile phase (Umano and Shibamoto, 1984). The neurotoxin 4(5)-methylimidazole appeared in the vapor phase when ammonia, but not amino acids, was the nitrogen source (Tomasik et al., 1989b). A corn starch-sucrose combination inhibited the Maillard reaction (Lee and Woo, 1988). 

The decreased hepatic metabolism of endogenous, nitrogenous neurotoxins together with their simultaneously increased formation in the intestine are generally considered to be responsible for the development of HE. Such neurotoxins include ammonia, mercaptans, short-chain or medium-chain fatty acids, phenols, etc. (s. tab. 15.1)... 

Synergy Endogenous neurotoxins display a synergistic effect, i.e. the neurotoxic concentration of ammonia always depends on the concentration of the other endogenous neuro toxins. 

These amino acid anhydrides are usuaiiy made with phosgene. The use of dimethyi carbonate shouid be tested in the preparation of the monomers. Poiyaspartic acid can be made by heating aspartic acid without soivent to form a polysuccinimide which is then hydrolyzed (12.34).186 It can also be made directly from maleic anhydride and ammonia. It promises to be useful as a scale inhibitor in water, an antiredeposition agent in detergents, and such. Gamma-irradiation converts it to a biodegradable superabsorbent material that takes up 3400 g water per gram of dry polymer.187 (Most superabsorbent polymers are based on acrylamide, a neurotoxin.)... 

Acuteorchronic hepatic failure may result in coma. This is believed to be due to the failing liver s inability to remove neurotoxins such as ammonia from the blood. 

Ammonia as a Neurotoxin. Several compelling reasons underlie the belief that ammonia is a major toxin contributing to the symptoms of hepatic encephalopathy (1,2,5,6,7). Ammonia is toxic to the brain in... 

PAA is an acrylate polymer formed from the monomer acrylamide, which is a neurotoxin that causes peripheral neuropathy. Non-polymerised remnants of acrylamide in PAA pose some potential risks. It is claimed that, people unintentionally absorb around 25 pg of acrylamide daily from the environment, which may account for a significant number of cancer cases. Although there is no solid proof so far for a connection between acrylamide intake and cancer, it remains under investigation, and acrylamide can still be considered as a probable human carcinogen. On a health hazard spectrum, acrylamide registers 2 (3 = a very high hazard to health 2 = a medium hazard, and 1 = harmful to health arsenic scores highly at 2.3, while one of the lowest scores is ammonia at 1.0) [37]. 

In this chapter, we will discuss the last of the major families of simple organic compounds—the amines. Amines are relatives of ammonia that abound in nature and piay an important role in many modern technoiogies. Exampies of important amines are the painkiller morphine, found in poppy seeds, and putrescine, one of several polyamines responsible for the unpleasant odor of decaying fiesh. A diamine that is largely the creation of humans is 1,6-diaminohexane, used in the synthesis of nylon. Amine derivatives, known as quaternary ammonium salts, also touch our daily lives in the form of synthetic detergents. Several neurotoxins also belong to this family of compounds. They are toxic because they interfere with the key role that acetylcholine, also a quaternary ammonium salt, plays in the transmission of nerve impulses. 

Cesium acetate was further used to convert a secondary alcohol in the synthesis of (—)-dysiherbaine, a natural product isolated from a marine sponge shown to act as a neurotoxin. In this case, the alcohol to be inverted was first converted into a nosylate using nosyl chloride, DMAP, and triethyl ammonia. The following application of cesium acetate was then used without the addition of crown ether, yielding the inverted alcohol after hydrolysis with potassium carbonate in sodium bicarbonate and methanol (eq 3). Importantly, cesium acetate did not interfere with the epoxide or olefin present in the natural product precursor. ... 

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