Unesterified Sterols Research Articles

Changes in the levels and composition of the esterified and unesterified sterols of maize seedlings during germination

The levels and composition of the esterified and unesterified sterol fractions of the shoot, root, scutellum and endosperm of maize seedlings during the first 2 weeks of germination have been studied. During the germination period it was found that (i) the level of “fast-reacting” sterol esters remains constant in all four morphological units; (ii) the level of “slow-reacting” sterol esters increases in the scutellum but remains constant in the shoot, root and endosperm; (iii) the levels of both “fast-reacting” and “slow-reacting free sterols increase in the shoot and root but remain constant in the scutellum and endosperm; (iv) the composition of the shoot, scutellum and endosperm sterol mixtures does not change, β-sitosterol being the most abundant component; (v) the composition of the sterol mixture in root shows a decrease in β-sitosterol and an increase in stigmasterol such that stigmasterol becomes the most abundant component.

Rapid Method for Isolation of Unesterified Sterols and Its Application to Detection of Milk Fat Adulteration with Vegetable Oils

Unesterified sterols were isolated from 900-mg samples of fat by using a column of digitonin impregnated on Celite 545, Schwartz et al. (4), then eluting the sterols with dimethylsulfoxide. The sterols were extracted from the dimethylsulfoxide with hexane-benzene mixtures in a condition suitable for analysis by gas-liquid chromatography. The addition of 1% corn, cottonseed, soybean, or peanut oil could be easily detected by the presence of β-sitosterol. Coconut and safflower oil adulteration were detected at the 2% level. Because of small amounts of β-sitosterol present in commercial emulsifiers, ice cream fat adulterated with corn, cottonseed, soybean, or peanut oil would he detected at the 2 to 2.5% level, while coconut and safflower oil adulteration would be detected at the 4 to 5% level.

The lipids of wheat III.—Further studies of the lipids of flours from single wheat varieties of widely varying baking quality

AbstractThe work on flour lipids reported in Part II* of the series is extended to the lipids of wheats harvested in 1960‐1962 inclusive.The same lipid components were found in each of the varieties studied although English flours contained much larger amounts of unesterified sterols than U.S. varieties of the same crop year. Quantitative lipid analyses demonstrated substantial varietal, seasonal, regional and environmental differences in lipid content and composition of the samples, but tentative correlations previously reported between lipid data and baking performance of the 1960 crop flours were not sustained by 1961 and 1962 crop results. Evidence is presented suggesting that only in very special circumstances would the performance of a flour be limited by the level of unsaturated fat available for the lipoxidase/thiol oxidation mechanism.Application of three quantitative TLC methods to flour lipids is described.

The intracellular distribution of sterols in Eurycotis floridana and its possible relation to subcellular membrane structures

The roach Eurycotis floridana was reared on a semisynthetic diet containing minimal cholesterol-4-(14)C (0.005%) supplemented with cholestanol-7alpha-(3)H (0.1%), and various tissues of the insect were separated into "nuclear," "mitochondrial," and "microsomal" fractions by differential centrifugation. Muscle and salivary gland were satisfactorily fractionated and results from these are reported together with some, as yet, incomplete results for nerve. The major concentrations of unesterified sterol and lipid phosphorus were in the mitochondrial and microsomal fractions. The unesterified sterols of the subcellular fractions were separated by alumina and gas-liquid chromatography. The emergent peaks corresponding to cholesterol, cholestanol, and Delta(7)-cholestenol (a metabolite of cholestanol) were assayed for (3)H and (14)C. No sterol was confined to any one subcellular fraction. The proportions of the three sterols were closely similar in all membranous components of the same tissue, but were different in different tissues. It is suggested that the different subcellular membranes of a given tissue contain similar repeating structural units in which the individual sterols occupy sterically characteristic spaces.

The endosperm lipids of three Canadian wheats

AbstractFlour samples were prepared from intact and degermed kernels of Hard Red Spring, Soft White Spring, and Amber Durum wheats. The 舠free舡 (hexane soluble) and 舠bound舡 (hexane resistant, water‐saturatedn‐butanol extractable) lipids were extracted from the six flours and separated quantitatively by silicic acid column chromatography. Thin‐layer chromatography (TLC) was used to monitor the column and to resolve the lipid classes into components. Gas‐liquid chromatography (GLC) was used to obtain the fatty acid composition of the triglyceride, sterol ester, and phospholipid fractions, and also to determine the nature of the sterol components of the unesterified sterol and sterol ester classes.Similar patterns of lipid classes were shown by all three varieties; the differences were in the degree of dominance. In fatty acid composition some varietal differences were found but the greatest difference was between lipid classes.

The transfer of lipids between human α-lipoprotein and erythrocytes

1. 1. The transfer of palmitic acid and sterol between human α-lipoprotein and erythrocytes has been studied. 2. 2. Human erythrocytes take up palmitic acid from α-lipoprotein until all binding sites are filled. The process is very much more rapid if the lipoprotein also extra cholesterol. 3. 3. 38% of the endotenous unesterified sterol of human α-lipoprotein does not exchange with that of rat erythrocytes. 4. 4. [ 14C]Cholesterol taken up by the lipoprotein after dispersion on Celite exchanges with that of human erythrocytes but it does not behave in exactly the same way as the endogenous sterol. 5. 5. When α-lipoprotein is labelled with both cholesterol and palmitic acid and then incubated with human erythrocytes, each interferes with the transfer, to the cells, of the other.

EMBRYONIC AND POSTEMBRYONIC CHANGES IN THE LIPIDS OF ASCARIS LUMBRICOIDES EGGS

Unembryonated ascaris eggs contained amounts of saponifiable and unsaponifiable lipids estimated to exceed 50% of the protoplasmic solids. The saponifiables (75–80% of the total lipids) consisted of triglycerides and much smaller quantities of phospholipids. Volatile acids comprised a significant part of the total triglyceride fatty acids. The unsaponifiables (> 20% of the total lipids) contained ascaryl alcohol as the major component. Unesterified sterols were also present. During embryonation and postembryonic survival of the eggs, the saponifiables decreased to 25% of the initial amount present, whereas unsaponifiables remained constant. Death of the embryos coincided with failure to utilize the remaining saponifiables.

EMBRYONIC AND POSTEMBRYONIC CHANGES IN THE LIPIDS OF ASCARIS LUMBRICOIDES EGGS

Unembryonated ascaris eggs contained amounts of saponifiable and unsaponifiable lipids estimated to exceed 50% of the protoplasmic solids. The saponifiables (75–80% of the total lipids) consisted of triglycerides and much smaller quantities of phospholipids. Volatile acids comprised a significant part of the total triglyceride fatty acids. The unsaponifiables (> 20% of the total lipids) contained ascaryl alcohol as the major component. Unesterified sterols were also present. During embryonation and postembryonic survival of the eggs, the saponifiables decreased to 25% of the initial amount present, whereas unsaponifiables remained constant. Death of the embryos coincided with failure to utilize the remaining saponifiables.