Exogenous compounds

The uses of corticosteroid antiinflammatory dmgs in veterinary medicine are many and varied. In the intact animal, the glucocorticoids and mineralcorticoids are produced in the adrenal glands. Exogenous compounds are, therefore, used for their glucogenic physiologic effect in cases where the... 

P-glycoprotein (P-gp) extrudes a wide variety of chemically unrelated endogenous and exogenous compounds out of cell membranes (for a review, see Refs. [1-4]). 

V-methyltransferase, active toward histamine and the catechol neurotransmitters, e.g., norepinephrine, is even more restrictive than COMT in terms of the metabolism of exogenous compounds. A class of compounds that does appear to be susceptible to N-methylation are azaheterocycles, particularly those that contain pyridine as part of the... 

Clark DE. 1977. The effect of hexachlorobenzene on in vivo biotransformation, residue deposition, and elimination of certain exogenous compounds and on body weight and organ weight in the rat. Dissertation Abstracts International B-The Sciences and Engineering 37(12 Pt.1) 6087-B. 

In addition to the intercellular lipids of the buccal mucosa, there appear to be other barriers which may reduce the ability of an exogenous compound to permeate the buccal mucosa. These include the salivary film and mucus layer, the basement membrane, and a metabolic barrier. 

The water molecule, either as a reactant or a product, plays an important role in the metabolism of innumerable endogenous and exogenous compounds. Water is, of course, a by-product of some metabolic redox reactions, e.g., reactions catalyzed by monooxygenases [7], However, this book focuses on non-redox reactions involving water as a reactant or a product. 

Abstract Gas chromatography (GC) is commonly used for the analysis of a myriad of compounds in neurochemistry. In this chapter various aspects of GG, including inlets, columns and detectors are discussed. Appropriate sample preparation, including extraction and derivatization techniques are also covered. In the latter portion of the chapter, examples of the analysis of specific types of endogenous and exogenous compounds by GG are dealt with. 

MenacherryS, Hubert W, Justice JB Jr. 1992. In vivo calibration of microdialysis probes for exogenous compounds. Anal Chem 64(6) 577-583. 

On the other hand, some compounds which are Included may not be true Gossypium secondary metabolites. Not only are the sources mentioned above possible contributors of exogenous compounds which have been Included in the accompanying Tables (I - X), but also it is quite possible that methods of isolation and analysis caused molecular transformation which created Isomers of true metabolites or even caused more drastic alterations. The diversity of structures which are plausible natural products is so great that it is not reasonable to exclude many of those reported simply on the basis of structure assignment. For this reason, it can be expected that some errors of inclusion have been made. 

For exogenous compounds such as drugs, various enzymes involved in both phase I and phase II metabolic routes are present, e.g. various isoforms of cytochrome p450, cytochrome b5, glucuronyl transferase and sulfotransferase [15]. 

Alkaloids play a very important role in organism metabolism and functional activity. They are metabolic products in plants, animals and micro-organisms. They occur in both vertebrates and invertebrates as endogenous and exogenous compounds. Many of them have a distributing effect on the nervous systems of animals. Alkaloids are the oldest successfully used drugs throughout the historical treatment of many diseases ... 

Kwon, I.-B. and Park, H.-H., Isoflavonoids of kudzu Pueraria lobata) and bioconversion of exogenous compounds into their malonylglucosides by its cell cultures. Foods Food Ingredients Journal of Japan, 163, 86, 1995. 

It was mentioned earher that many molecules can be formed in cosmic space before arriving on Earth. What about chiral compounds We know that amino acids are present in meteorites (Epstein et al., 1987 Pizzarello etal., 1994 Pizzarello and Cronin, 2000 Pizzarello and Weber, 2004). In this regard, of particular interest is the report on a-methyl amino acids, which have been found in L-enantiomeric excess in Murchison and Murray meteorites (Cronin and Pizzarello, 1997). These compounds are particularly resistant to racemization, and it is perhaps because of this that chirality has been preserved. It is not simple to assess whether these chiral exogenous compounds were the seeds for homochirahty of life on Earth (Bada, 1997). 

There is good reason to be optimistic about the potential future usefulness of such exogenous compounds as a continuing source of potential lead compounds. With many thousands of years of trial-and-error by evolution on her side. Mother Nature is a vastly superior experimentalist to any mere human organic chemist. Insect evolution has permitted the biosynthesis of anticoagulant molecules to ensure that a bite will provide a... 

The previous two methods of lead compound discovery exploited naturally occurring endogenous or exogenous compounds. However, of the approximately 10 small organic molecules that could theoretically exist in our world (10 of which are druglike molecules), many would be purely synthetic substances that do not occur naturally. The lead compound discovery methods discussed in sections 3.2.5 and 3.2.6 afford an... 

Oral administration of exogenous compounds can induce tissue-specific expression of previously transfected (and integrated) genes and transcription factors. Such compounds typically cause conformational changes in the transcription/activating factors that in turn cause their binding to the promotor linked to the transgene. 

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