Studies are reported on changes in fatty acid and lipid class composition in developing soybeans picked at intervals from ca. nine days after flowering to maturity. In the early stages of development of the

SUMMARY Studies were carried out on the fractionation and analysis of egg lipid by several new techniques employing thin‐layer chromatography. The fatty acid composition of the major lipid classes and subfractions thereof was determined by a combination of alkali‐isomerization and gas‐liquid chromatography. The positional arrangements of the fatty acids in the glycerides and lecithin fraction were determined. The fatty acids in lecithin were distributed mainly in one type, the α‐saturated β‐unsaturated type, in contrast to the fatty acids of triglycerides.

The autoxidation of polyunsaturated lipids is initiated by a discrete reaction occurring prior to the formation ofstable hydroperoxides. The products of the initiating reaction were detected by thin‐layer chromatography and by ultraviolet spectral analysis. The reaction initiating autoxidation does not necessarily involve interactions with metals, although it is catalyzed by some heavy metals when these are present in sufficient concentrations. ॅ‐Tocopherol does not inhibit the initiation reaction, and in general, the stability of preparations of esters of polyunsaturated fatty acids is related to the content of prooxygenic substances resulting from this reaction. By taking special precautions to remove these prooxygenic substances, methyl esters containing as many as six double bonds were prepared having significant induction periods at 40C during which there was no measurable uptake of oxygen.

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Effects of diets containing mixtures of safflower oil, hydrogenated coconut oil with elaidate of linolelaidate on growth, fatty acid composition, serum lecithin: cholesterol acyl transferase (LCAT) and postheparin plasma lipoprotein lipase activities in essential fatty acid (EFA) deficient rats were determined. Addition of trans fatty acids to the diet lowered the growth response to linoleic acid. Both elaidate and linolelaidate accumulated in the serum and liver, imparied the conversion of oleic acid to eicosatrienoic acid and linoleic acid to arachidonic acid, and the incorporation of eicosatrienoic acid into cholesteryl esters. Trans fatty acids also influenced the fatty acid composition of testicular lipids, but much lower amounts of these acids accumlated in tests than in liver or serum. Serum lecithin:cholesterol acyl transferase activity was elevated by an EFA deficiency, was unaffected by dietary elaidate, but was significantly decreased by linolelaidate. These effects were nullified by the addition of safflower oil to the diet. Postheparin plasma extrahepatic and hepatic lipase activities were also affected by an EFA deficiency, and by the addition of elaidate or linolelaidate alone or in combination with safflower oil to the diets of EFA deficient rats. It is suggested that trans fatty acids exhibit particular effects on the metabolism of lipids in addition to aggravation of an EFA deficiency.

A procedure is described for the quantitative analysis of neutral and phospholipids by thinlayer chromatography (TLC) employing densitometry. The chromatophates are prepared with the usual solvent systems. The spots are charred under standard conditions and analyzed with a Photovolt Corp. densitometer equipped with a special stage designed for holding 20ȕ20 cm chromatoplates. Each spot on the chromatoplate gives a peak of density values which is used for quantitative analysis.Radioactive lipids are analyzed by autoradiography by the densitometry of radiograms of chromatoplates developed from X‐ray films.The precision of the method is demonstrated on model mixtures of mono, di‐and triglycerides, neural and phospholipids and C14 labeled lipids.Results of the analysis of several samples of rat liver lipids compared closely to those obtained by silicic acid column chromatography.

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SummaryA sample of debromination methyl linoleate has been autoxidized to a peroxide value of 671 m.e./kg. at approximately 0°C. in the dark. An essentially pure concentrate of methyl octadecadienoate monohy‐droperoxide was quantitatively separated; infrared and ultraviolet spectral studies were made on the peroxide concentrate and on the corresponding hydroxyl derivative obtained by reducing the peroxides with stannous chloride.The infrared data showed no conjugated peroxides having geometric configurations other than cis, trans; the same data also showed that the peroxide concentrate contained at least 90% conjugated cis,trans forms. Calculations based on ultraviolet spectrophotometric methods also indicated that the peroxides were at least 90% conjugated. The remaining 10% of the sample is most likely nonconjugated diene hydroperoxide. Since analogous cis, cis conjugated dienes have not been isolated and their infrared and ultraviolet properties are unknown, their presence here in small amounts is possible. Ultraviolet and infrared spectra of the reduced compounds conform closely to those of the peroxides except for reduction in the intensity of the OH bond at 2.88 μ.The infrared absorption spectra of the C−H structure and carbonyl groups of an essentially pure conjugated cis, trans methyl octadecadienoate monohydroperoxide were recorded, using a LiF prism.The infrared absorption spectra of the C−H strucfraction isolated from methyl linoleate autoxidized in the dark at 24°C. indicated that appreciable amounts of conjugated trans, trans hydroperoxides were present, in addition to those of the cis, trans type. It is possible that the conjugated cis, trans isomers were formed originally but were labile at the higher temperature and in the presence of catalysts (e.g., peroxides) were transformed to the thermodynamically more stable conjugated trans, trans isomer.