Toxic metabolic products

The final class of pharmacotherapy drugs alters the metabolism of certain target drugs, thereby causing a build up of toxic metabolic products that make a person feel extremely ill. The best known of these metabolism-modifiers is Antabuse (disulfiram), a drug primarily used to discourage people from drinking alcohol. 

Excipients manufactured by fermentation processes, such as dextrose, citric acid, mannitol, and trehalose, should be specially controlled for endotoxin levels. Mycotoxin (highly toxic metabolic products of certain fimgi species) contamination of an excipient derived from natural material has not been specifically addressed by regulatory authorities. The German health authority issued a draft guideline in 1997 where a limit was specified for Aflotoxins Mi, Bi, and the sum of Bi, B2, Gi, and G2 in the starting material for pharmaceutical products. 

A major problem in aU drug discovery programs is to discover compounds with good pharmacokinetics. Although it is possible to examine the metabolism of the drug in animals, it has often been difficult to predict what would happen in man. The obvious implications of drug metabolism are an effect on half-life in vivo and the production of toxic metabolic products. 

Suicide substrate I An enzyme substrate that itself is not toxic but that produces a toxic metabolic product. 

Phosohlinids Phosphatidylcholine, Phosphatidylethanolamine, Phosphatidylinositol (196) Many sp. HIV Accumulation of toxic metabolic products into the HIV memberanes [12] [128]... 

Ptomaines. Name, derived from modern Greek ptoma=cadaver, for the so-called cadaveric poisons formed from putrefying proteins. The enzymatic decarboxylation products of the amino acids lysine and L-omithine ( cadaverine and putrescine), previously known as R, are, however, relatively non-toxic biogenic amines. Today the name P. is used for the toxic metabolic products of putrefactive bacteria that colonize rotting, protein-containing foodstuffs such as meat, fish, etc. These P. have widely differing chemical structures their activities are purported to be similar to those of the plant toxins such as strychnine, atropine, etc.. 

The possibility that nervous symptoms in vegans might be associated with toxic metabolic products such as p-hydroxyphenylpyruvic acid and cyanide was explored. The average daily thiocyanate excretion was higher in vegans than in nonvegans and could be reduced by injections of vitamin Bis. 

Biodegradation results from ground and water metabolism by environmental microorganisms. These microorganisms will feed on disposed materials, sometimes after acclimation and transform them into smaller biodegradation products. In the best cases, biodegradation results in the transformation of synthetic chemicals into innocuous compounds. In the worst cases, an innocuous parent chemical could be transformed into a stable but toxic metabolic product. 

This is used as a sulphydryl donor in the treatment of paracetamol poisoning. It has side effects of its own which include nausea, vomiting and drowsiness. It must be given early, otherwise it is ineffective since paracetamol oxidation to toxic metabolic products will already have occurred. In addition, cysteamine itself, or any sulphydryl donor, could precipitate hepatic coma in a patient with overt liver damage (21 ). 

The special topics discussed are (i) the biological aspects of heterocyclic compounds, i.e. their biosynthesis, toxicity, metabolism, role in biochemical pathways, and their uses as pharmaceuticals, agrochemicals and veterinary products (ii) the use of heterocyclic compounds in polymers, dyestuffs and pigments, photographic chemicals, semiconductors and additives of various kinds and (iii) the use of heterocyclic compounds as intermediates in the synthesis of non-heterocyclic compounds. 

Antibiosis Inhibition or lysis of an organism mediated by metabolic products of the antagonist these products include lytic agents, enzymes, volatile compounds, and other toxic substances. 

Toxic reactions occur by several mechanisms activation of metabolism, production of reactive intermediates and subsequent reactions with cell macromolecules, changing receptor responses, or through abnormal defence reactions. Several compounds cause toxicity by mimicking the organism s own hormones or neurotransmitters, or activating the body s endogenous receptors in some non-physiological way. ... 

Any substance present in great excess can inhibit growth or even cause death. Metabolic products are often toxic to the organism that produces them. Thus, a batch fermentation can be limited by accumulation of products as well as by depletion of the substrate. A simple model for growth in the presence of an inhibitor is... 

The transformation and metabolism products of pesticides in plants may not only be of acute toxicity, but also may have other properties. Phosmet, for example, transforms into phthalimide and phthalic acid, teratogenic substances [21]. 

Hu TL (2001) Kinetics of azoreductase and assessment of toxicity of metabolic products from azo dyes by Pseudomonas luteola. Wat Sci Technol 43 261-269... 

Environmental agents that influence microsomal reactions will influence hexachloroethane toxicity. The production of tetrachloroethene as a metabolite is increased by agents like phenobarbital that induce certain cytochrome P-450 isozymes (Nastainczyk et al. 1982a Thompson et al. 1984). Exposure to food material or other xenobiotics that influence the availability of mixed function oxidase enzymes and/or cofactors will change the reaction rate and end products of hexachloroethane metabolism and thus influence its toxicity. 

Vacuoles (70-78) are membrane-bound regions of the cell filled with cell sap. Vacuoles are surrounded by a tonoplast (vacuolar membranes) and are diverse with distinct functions. Most investigators believe that lysosomes and the plant vacuoles are the same. Vacuoles develop turgor pressure and maintain tissue rigidity. They are storage components for various metabolites such as reserve proteins in seeds and malic acid in crassulacean acid metabolism (CAM) plants. Vacuoles canremove toxic secondary products and are the sites of pigment deposition. 

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