Metabolites endogenous

Following antibiotics production, microbial industrial fermentations have been used for the production of different metabolites endogenously produced by microorganisms, e.g., enzymes for different applications and large-scale production of bioethanol for fuel usage. 

Some microbial metabolites/endogenous mediators are used as mediators by microbes. Some microbes such as Rhodoferax ferrireducens, Geobacter metal-lireducens, Shewanella putrefaciens and Geo-bacteriaceae sulferreducens are bioelectrochemically active. These microbes directly transfer electrons via the membrane. They have the capability to form a biofilm on the anode surface. Hence, in the presence of these microbes the anodes act as an electron acceptor. 

The development of a single enantiomer as a new active substance should be described in the same manner as for any other new chemical entity. Studies should be carried out with the single enantiomer, but if development began with the race-mate then these studies may also be taken into account. Chiral conversion should be considered early on so that enantiospecific bioanalytical methods may be developed. These methods should be described in chemistry and pharmacy part of the dossier. If the opposite enantiomer is formed in vivo, then it should be evaluated in the same way as other metabolites. For endogenous human chiral compounds, enantiospecific analysis may not be necessary. The enantiomeric purity of the active ingredient used in preclinical and clinical studies should be stated. 

It has been proposed that aziridines may be more widespread in biological systems than is generally realized [190]. Many drugs such as ephedrine (124 Scheme 11.18) and pronethalol (125) and endogenous metabolites such as adrenaline (126) contain a P-aminoalcohol moiety, which may act as a precursor to an aziridine metabolite that may explain the known carcinogenicity of some of these compounds such as pronethalol. 

Cellular defense mechanisms against toxins (A multistep mechanism for elimination of toxic metabolites and xenobiotics. It involves various transport, oxidation, and conjugation steps.) are usually divided into several steps as it is visualized on Fig. 3. Organic anion transporting proteins (OATPs) are responsible for the cellular uptake of endogenous compounds and... 

The hormone peptide YY (PYY) is a 36 amino acid peptide, which is closely related to neuropeptide Y and pancreatic polypeptide. PYY is predominantly synthesised and released by intestinal endocrine cells, and can also coexist with glucagon in pancreatic acini and enteroglucagon in endocrine cells of the lower bowel. It acts on the same receptors as neuropeptide Y. The endogenous long C-terminal PYY fragment PYY3 36 is a biologically active and subtype-selective metabolite. 

Phase II metabolism The reaction of a phase I metabolite with an endogenous compound, e.g. glucuronic acid, to form a polar compound that is eliminated from the body. 

In phase 1, the pollutant is converted into a more water-soluble metabolites, by oxidation, hydrolysis, hydration, or reduction. Usually, phase 1 metabolism introduces one or more hydroxyl groups. In phase 2, a water-soluble endogenous species (usually an anion) is attached to the metabolite— very commonly through a hydroxyl group introduced during phase 1. Although this scheme describes the course of most biotransformations of lipophilic xenobiotics, there can be departures from it. 

Conjugate In biochemical toxicology, a structure (often an anion) formed by the combination of a xenobiotic (usually a phase I metabolite) with an endogenous component (e.g., glucuronate sulfate or glutathione). 

Whereas conventional poly (amino acids) are probably best grouped together with proteins, polysaccharides, and other endogenous polymeric materials, the pseudopoly (amino acids) can no longer be regarded as "natural polymers." Rather, they are synthetic polymers derived from natural metabolites (e.g., a-L-amino acids) as monomers. In this sense, pseudopoly (amino acids) are similar to polylactic acid, which is also a synthetic polymer, derived exclusively from a natural metabolite. 

Two main strategies have been used for bioremediation or bioattenuation (although this may fail to take into account stable metabolites) (a) stimulation of the activity of endogenous organisms by the addition of a substrate (bioaugmentation) or (b) inoculation with the active organisms—often isolated from the same site. 

Nonmodified silica gel is used most commonly for the separation of substances of medical interest. The separation is based on the interactions (hydrogen bonding, van der Waals forces, and ionic bonding) between the molecules of drugs, lipids, bile acids, etc., and the silica gel. Alumina has similar properties but is rarely used. Successful separation of endogenous substances, drugs, or their metabolites can also be achieved using physically or chemically modified silica gel. 

AUgayer, H. and Stenson, W.F. (1988). A comparison of effects of sulfasalazine and its metabolites on the metabolism of endogenous vs. exogenous arachidonic acid. Immunophar-macology 15 39-45. 

Hiraishi, H., Razandi, M., Terano, A. and Ivey, K.J. (1990). Antioxidant defenses of culture gastric mucosal cells against toxic oxygen metabolites. Role of glutathione redox cycle and endogenous catalase. Gastroenterology 98, A544. 

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