Y-Hydroxybutyrate

Apart from lactic and hydroxyacetic acids, other a- and P-hydroxy acids have been small-volume specialty products produced in a variety of methods for specialized uses. y-Butyrolactone [96 8-0] which is the monomeric inner ester of y-hydroxybutyric acid [591-81-17, is a large-volume chemical derived from 1,4-butanediol (see Acetylene-derived chemicals). 

Certain bacterial species produce polymers of y-hydroxybutyric acid and other hydroxyalkanoic acids as storage polymers. These are biodegradable polymers with some desirable properties for manufacture of biodegradable packaging materials, and considerable effort is being devoted by ICI Ltd. and others to the development of bacterial fermentation processes to produce these polymers at a high molecular weight (66). 

Relkin N and Nelson T. Regulation and. properties of an NADP+ oxidoreductase which functions as a. y-hydroxybutyrate dehydrogenase. J Neurochem, 1983, 40, 1639. 

One of the classic examples of a reversible reaction that is first-order in both directions is the conversion of y-hydroxybutyric acid into its lactone in aqueous solution. 

In recent years, the abuse of y-hydroxybutyrate (GHB) has risen dramatically (LeBeau et al., 2000). This metabolite of GABA can be difficult to analyze because of its short half-life and endogenous presence. However, a simple and fast head space analysis using GC-FID with MS confirmation has been published (LeBeau et al., 2000). 

The storage and release of DA can be modified irreversibly by reserpine (3.1), just as in vesicles containing other catecholamines and serotonin. Dopamine release can be blocked specifically by y-hydroxybutyrate (4.78) or its precursor, butyrolactone, which can cross the blood-brain barrier. High doses of amphetamines do deplete the storage vesicles, but this is not their principal mode of action. Apparently, amantadine (4.79), an antiviral drug that is likewise beneficial in parkinsonism (and also perhaps to relieve fatigue in multiple sclerosis), may also act by releasing DA. 

Problem 16.24 Write the structure for the lactone formed on heating in the presence of acid (a) y-hydroxybutyric acid, (b) 6-hydroxyvaleric acid. ... 

Other neurotoxins can be formed from environmental pollutants. The solvent 1,4-butanediol is converted to y-hydroxybutyrate, which is also a drug of... 

Pentaerythitol, propionic acid Diol, y-hydroxybutyric acid 21-24, 33, 34... 

One of the classical examples of a reversible reaction is the conversion of y-hydroxybutyric acid into its lactone in an aqueous solution. In aqueous solution, the water concentration may be considered constant, so the reverse reaction follows pseudo-first-order kinetics. The following data were obtained. Determine the values of both first-order rate constants (forward and reverse). The initial acid concentration is 182.3 mol/L. 

It should be noted that in addition to the GABA(A)-R benzodiazepine-binding sites or central benzodiazepine Rs (CBZ-Rs) there are peripheral benzodiazepine Rs (PBZ-Rs) associated with the outer membrane of mitochondria in glial cells and cells of peripheral tissue and which are involved in cholesterol transport and hence in regulation of steroid hormone synthesis. The GABA(B)-Rs are metabotropic and coupled via heterotrimeric G proteins to Ca2+ and K+ channels (Chapter 5). The psychotropic GABA breakdown product y-hydroxybutyrate (GHB) also acts via heterodimeric G protein-linked receptors (see Chapter 5). 

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