SUBJECTS malic acid

Tobacco and its alkaloids have long ceased to have any therapeutic importance, but their extensive use as insecticides and the demand for nicotine for the manufacture of nicotinic acid have stimulated interest in processes of extraction and methods of estimation. On the latter subject there is a voluminous literature, of which critical resumes have been published by various authors.Recent work on this subject has been specially concerned with (1) the development of miero- and semi-miero-methods suitable for estimating nieotine in tobacco smoke and the distribution of nieotine on sprayed garden produce, in treated soils and in tobaeeo leaves,(2) the study of conditions necessary to ensure satisfactory results in using particular processes, " and (3) methods of separation and estimation of nicotine, nomicotine and anabasine in mixtures of these bases. ) In the United States and in Russia considerable interest is being shown in the cultivation of types of tobacco rich in nicotine, in finding new industrial uses for tobacco and its alkaloids, and in possible by-products from tobacco plants such as citric and malic acids, i " Surveys of information on tobacco alkaloids have been published by Jackson, i Marion and Spath and Kuffner. ... 

The stereochemistry of malic acid and its coordination compounds has been the subject of careful investigations.36188 The planarity of the five-atom a-hydroxycarboxylate group is again observed here. Conformational arrangements associated with rotation around C(2)—C(3) bond have been studied by NMR methods and have been discussed in Section 15.7.4.1. 

As already stated, the ameliorative effect of malo-lactic fermentation is equally important in the preparation of red wines—probably more so since a degree of tartrate not desirable in a red wine is often wanted in a white wine. It is also necessary to achieve bacterial stability. So long as malic acid remains in the wine and there is any presence of lactic bacteria, there is a risk, however remote, of delayed fermentation in the bottle accompanied by hazes and gassiness. In former times, French Burgundies often were subject to this accident. Finally, the slight increase of volatile acidity that accompanies malo-lactic fermentation may help to heighten and improve aroma and flavor. 

Fumaric acid is stable although it is subject to degradation by both aerobic and anaerobic microorganisms. When heated in sealed vessels with water at 150-170°C it forms ( )-malic acid. 

Similar to fumaric acid, L-malic acid is also a naturally occurring four-carbon dicarboxyhc acid and an intermediate in the TCA cycle. It has been used in many food products, primarily as an acidulant. L-Malic acid is compatible with all sugars with low hygroscopicity and good solubihty. In addition, it has therapeutic value for the treatment of hyperammoemia and liver dysfunction and as a component for amino acid infusion. L-Malic acid has been the subject of interest because of its increased application in the food industry as a citric acid replacement and its potential use as a raw material for the manufacture of biodegradable polymers. 

The ene ester 5, prepared from (L)-malic acid via 4, was subjected to the ester enolate Claisen rearrangement under Ireland conditions to give stereoselectively the C-16 to C-22 fragment 6 containing an U-trisubstituted double bond of the immunosuppressant FK-506 (7) isolated from Streptomyces tsukubaensis440. 

Donovan discovered in mountain-ash berries what he called sorbic (malic) acid, which he found in rhubarb stem he afterwards admitted the identity of sorbic and malic acids. He described the preparation of pure potash from carbonate and slaked lime, investigated whether alcohol is a product of fermentation or distillation, preparation of pure silver and of phosphorus, and denied the identity of ordinary (frictional) electricity, voltaic electricity, magneto-electricity, and thermo-electricity. He wrote on alchemical and chemical physicians and the use of hyoscyamus — both in titles only, and on smelting lead, as well as on pharmaceutical and medical subjects in the Dublin Journal of Medicine and Chemistry (1839-46). Donovan invented a gas lamp, a gas table-lamp, a hygrometer, and an apparatus for filtration out of contact with air. Donovan s solution is a i per cent solution of equal weights of arsenious and mercuric iodides used in the treatment of skin diseases. 

Detection and result The chromatogram was dried in a stream of warm air for 10 min, immersed in the reagent solution for 3 s and then subjected to intense UV radiation (high pressure lamp, A = 365 nm) for up to 10 min. Terephthalic (hRf 0 - 5), pimelic (hRf 55), suberic (hRf 60), sebacic (hRf 65 — 70) and benzoic acids (hRf 70 — 75) together with sorbic, malic, adipic, citric, tartaric, lactic and fumaric acids only exhibited a reaction on silica gel layers at higher concentrations. 4-Hydroxybenzoic, salicylic and acetylsalicylic acids fluoresced light blue after irradiation. The detection limit per chromatogram zone was 0.5 pg for salicylic acid and more than 5 pg for benzoic acid. 

Other studies on the influence of tablet excipients on dmg decomposition have identified problems with stearate salts and it has been suggested that these salts should be avoided as tablet lubricants if the active component is subject to hydroxide-ion-catalysed degradation. The degradative effect of the alkali stearates is inhibited in the presence of malic, hexamic or maleic acids owing, it is thought, to competition for the lubricant cation between the dmg and the additive acid. 

Yeast invertase,30 32 33 acid phosphatase,29 32 35 37 39 urease,29 /3-glucosi-dase,29 dCMP-amino hydrolase31 and malic enzyme34 36 have been immobilized in gel form on both flat and capillary membranes. Cellulosic and polyamide polymers have been used as supporting membrane matrices. In all instances, immobilized enzymes behave in a manner almost identical to their behavior in homogenous solution, independent of the nature of the polymer. Neither allosteric nor pseudo-allosteric enzymes, proteins whose kinetic behavior is affected by the presence of particular compounds in the reaction environment (ligands), show different kinetic behavior, as they do when subjected to less gentle immobilization procedures.31 34 36... 

The acids present in a given wine are determined by the grape variety, climate, presence of gray rot [Botrytis cinerea), yeasts, bacteria, and various treatments to which the wine may be subjected (sulfur dioxide, ascorbic acid, acidification, desacidifica-tion). There are at least 50 different acids in wine ranging in concentration from 1 or 2gl (tartaric, malic, succinic acids) to hundreds of mgl (citric, lactic, acetic acids) to tens of mgl (pyruvic, shikimic acids). However, tartaric, malic (depending on the MLF), acetic, and succinic acids constitute 80-90% of total complement of wine acids. 

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