Free and Ester

One of the first attempts to improve retention of cholesterol ester was that of Idelman (1964, 1965), who studied the lipid droplets in the adrenal gland and was able to reduce their extraction with the use of partial dehydration, in which the highest ethanol concentration was 70%, and dehydration was completed by a mixture of 70% ethanol and Epon containing the accelerators. That study was corroborated and further extended by Friihling et al. (1969), who determined the extent of extraction by radiochemical determination after injection of cholesterol- to intact rats. During the first hour after injection most of the labeled cholesterol recovered in the adrenal was in the free form, but later on it became esterified therefore, this system provided a good model for the study of the compound in its free and esterified form. It became apparent that it was possible to reduce the loss of labeled cholesterol ester to 11-13%, when dehydration was carried through 70% or even 80% ethanol, but that abso- 

In another study on the adrenal, taken 18 hours after injection of tritiated free cholesterol (Moses et ah, 1969), up to 90% of labeled cholesterol, presumably in esterified form (see Friihling et al., 1969) could be retained in adrenal tissue fixed in 2% osmium tetroxide for 24 hours. These authors used a partial dehydration schedule, which omitted absolute ethanol and propylene oxide and used Epon 812 as final dehydrating agent. 

A far better preservation of cholesterol, whether free or esterified, was obtained in the liver after intravenous injection of labeled chylomicrons, by the use of Aquon (O. Stein et al., 1969). The latter is a highly water-miscible derivative of Epon, and its preparation has been described by Gibbons (1959). This resin was used both for dehydration and embedding and allowed retention of 67-73% of the label in the tissue, irrespective whether the cholesterol ester amounted to 68 or 15%. 

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I. Pastorova, C.G. de Koster, J.J. Boon, Analytical study of free and ester bound benzoic and cinnamic acids of gum benzoin resins by GC MS and HPLC frit FAB MS, Phytochemical... 

Kritchevsky, D. and Tepper, S.A. 1961. The free and ester sterol content of various foodstuffs. J. Nutr. 74, 441-444. 

IAA after hydrolysis with 7 N alkali minus the free and ester IAA, Seedlings and fruits are fresh weight, seeds are air dry and yeast cells contain 30% dry matter. 

Lipase-catalyzed conversion of FAStEs to sterols in the presence of MeOH was applied to astaxanthin FA esters to free astaxanthin, because a screening test showed that commercial lipases did not hydrolyze astaxanthin FA esters. A mixture of astaxanthin and its mono- and diesters (5 80 15, by mol) was treated in the presence of 50wt% water with 5 mol EtOH for FAs in astaxanthin esters using P. aeruginosa lipase. After the reaction, the molar ratio of astaxanthin and its mono- and diesters was 89 10 1, showing that the lipase efficiently converts astaxanthin esters to free astaxanthin. The free form was also purified by n-hexane fractionation with 69% recovery of the initial content of astaxanthin in the mixture of its free and ester forms (Nagao et al., 2003). 

Further work on the free and ester-bound triterpenoid alcohols in cellular subtractions of Calendula officinalis flowers has appeared. An investigation of the mass spectral fragmentation of pentacyclic hydrocarbons in petroleum has been published. ... 

Demethylation of Free and Ester-linked Ferulic Acid by Sonicated Cellular Extracts of SR3. The O-demethylase activity of the SR3 strain was not excreted in the culture medium. To demethylate ferulic acid esterified to WEAX, which cannot penetrate the cells, a cell extract of SR3 strain was prepared by anaerobic sonication (MSON 05 Bio block, 20 Hz, 3 cycles of sonication of 2 min 2 s pulses separated by 2 s lag phase). The sonicated cellular extract of SR3 was tested in anaerobiose on free ferulic acid and esterified ferulic acid at 37 °C with a bacteria protein/ferulic acid ratio of 100 mg/ mol. Composition of reaction medium has been chosen in agreement with previous works on the demethylation of methoxylated phenolic compounds by other strains.15 20-22 In order to limit the viscosity of the medium, a 0.5% arabinoxylan concentration was used, corresponding to a 50 / M ferulic acid concentration. 

Although cholesterol is about 10-fold less reactive in autoxidation than PUFA there is still interest in the products that have been associated with oxidant stress. Cholesterol, free and bound to ester, is measured after separation into free and ester cholesterol by selective extraction and hydrolysis using gas chromatography-tandem mass spectrometry (GC/MS/MS) [61]. Oxidized cholesterol, oxysterols, can be analyzed using LC-MS/MS with a minimum of manipulation or by using GC/MS/MS after derivatization [62-66]. 

In studies by Chisnell [8, 9], either free 5-pH]-IAA (lAA) or 5-[ H]-IAA-w v >-in-ositol (lAInos) was applied to the endosperm of maize seedlings and the amount and distribution of labeled lAA and lAInos determined in the shoot. lAInos supplied both free and ester lAA to the mesocotyl and coleoptile. Labeled lAA applied to the endosperm supplied some of the lAA in the mesocotyl, but supplied essentially no free lAA to the coleoptile. Therefore, free lAA from the endosperm is not a source of lAA for the coleoptile. Neither lAA nor lAInos accumulated particularly in the coleoptile tip. This observation, plus the previous observation of Hall [15], which indicated that the enzyme that hydrolyzes lAInos was not confined to the coleoptile tip, leaves unanswered how the coleoptile tip controls the amount of lAA in the shoot. 

Portions of these results have been published [3, 4]. They are reproduced here (Table 3) to demonstrate that placing the plants in a horizontal position, relative to the gravity vector, induces a rapid asymmetric distribution of both free and ester lAA in the mesocotyl cortex. Since both free and ester lAA increase on the lower side of the mesocotyl cortex, the gravity effect can not be solely due to increased hydrolysis of lAA ester on the lower side [3,4]. An acceptable explanation is that either free or ester lAA selectively leaks from the lower side of the stele into the mesocotyl cortex. Since ester and free lA A are interconvertible, movement of either would be equivalent [8,9,22], and we conclude that the plant can regulate leakage from one or the other side of a horizontally placed stele. 

GC-MS Quantifications of Free and Ester Indol-3yl-Acetic Acid in Relation to Root Growth and Gravitropism... 

Fig. 3. Free and ester lAA contents (in ng SE per g fw) of whole maize roots as a function of time of culture (in days). Each value is the mean of 4 determinations of 50 roots each [adapted from 38]...

The content of free and ester IA A in maize seedling changes with time, and with the zone of tissue considered. We must therefore pay more attention to the metabolic turnover of lAA, and take into account all the aspects (transport, conjugates, other hormones,...) in determining both the auxin level in a specific tissue and its effect on observable physiological events characteristic of that tissue. 

Patterns of cholesterol biosynthesis and transport in the baboon parallel those observed in man (Kritchevsky et al., 1965). Peak specific activity of serum-free cholesterol synthesized from mevalonic acid-2-is reached within 4—10 hours and the free and esterified forms equilibrate by 72 hours. Peak specific activities of exogenously labeled serum-free and ester cholesterol are observed at three days. The specific activity of the total cholesterol of the serum a and lipoproteins is equal over a 10-day period, but there is the possibility that the specific activities of the free and ester cholesterol moieties of the serum oc and jS lipoproteins differ. The lipoprotein cholesterol findings are similar to results reported from similar human studies (Gidez and Eder, 1963). The equilibration of serum and tissue cholesterol is reached at about two weeks in the dog (Gould, 1952) and rat (Chevallier, 1953) and one month in man (Chobanian and Hollander, 1962). 

The purpose of this review is to compare the various approaches used to improve cellular lipid preservation and discuss the results obtained in the study of different lipid compounds in several tissues. This review will be confined mostly to metabolic studies performed in mammals in vivo or in vitro and will encompass the following lipid classes triglycerides, free fatty acids, cholesterol (free and ester), and phospholipids. No attempt will be made to review histo-chemical approaches to localization of lipids or radioautographic localization of steroid hormones, as these subjects were dealt with recently in a detailed way by Adams (1969) and by Stumpf (1970). 

Thus it seems possible to conclude that for the type of lipids (cholesterol, free and ester, triglycerides and phospholipids) and tissues studied (liver, adipose tissue, aorta, adrenal, intestine, nervous tissue, and macrophages) no significant translocation of the labeled lipid was observed. 

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