George O. Burr

Comparative Curative Values of Unsaturated Fatty Acids in Fat Deficiency.

Conclusions Unsaturated fatty acids (linoleic, linolenic, arachidonic and cod liver oil acids) show differences in growth and skin effects. They should no longer be treated as an interchangeable group but should be used individually in nutrition studies.

The antioxidant properties of nordihydroguaiaretic acid

SummaryA description is given of the antioxidant properties of nordihydroguaiaretic acid. This substance is readily obtained in substantial yields from a common plant(Larrea divaricata) and compares favorably with other highly effective inhibitors of the phenolic type.It is more soluble in fats than hydroquinone but not as soluble as the tocopherols. Within the limits of these experiments, and at optimal concentrations, it appears to have no deleterious effects on the qualities of lards.Its effectiveness in stabilizing fats is to some extent carried over into baked products.Ascorbic acid enhances its effectiveness.

Comparative rates of oxidation of isomeric linolenic acids and their esters

Conclusion1. The maximum velocities of oxygen absorption as measured by the Warburg-Barcroft respirometer at 40° and expressed as mols 02/mol substance/100 minutes was found for a series of octadecatrienoic acids and their esters to be as follows:alpha-eleostearic acid, 2.68;beta-eleostearic acid, 1.02; pseudo-eleostearic acid, 0.64; methyl pseudo-eleostearate, 0.42; alpha-linolenic acid, 0.52; ethyl linolenate, 0.24.2. The data showed the effect of spatial configuration as well as type of unsaturation and functional grouping on the oxidation reaction.3. The apparently pure fatty compounds were found to have induction periods, pointing to the autocatalytic nature of the oxidation reaction.

On the Fatty Acids Essential in Nutrition.

Conclusion The recently reported cases of skin lesions discussed here were produced under conditions which indicate a lack of some growth factor. In no case were conditions such that uncomplicated fat-deficiency could result. It would be impossible, therefore, for these rats to respond to small doses of unsaturated fats. An adequate supply of all water soluble growth factors must be fed if the typical fat deficiency results are to be obtained. Growth should approximate that given by the daily consumption of 0.65 gm. or more of high grade dried yeast.

The thiocyanogen value of linolenic acid

Ethyl linolenate (Wijs iodine number 247.3; theory 248.5) was prepared by the debromination of purified hexabromostearic acid. The thiocyanogen value determined exactly as recommended by the Committee on Analysis of Commercial Fats and Oils, [Ind. Eng. Chem. Anal. Ed.8: 234 (1936)] was found to be 151.2, corresponding to a corrected value of 167.3 for the free linolenic acid, rather than the theoretical value of 182.5. Data are presented to show the effects of time, excess and concentration of reagent. The thiocyanogen number of linolenic acid is proved to be an empirical value which, however, is reproducible under carefully controlled conditions. Several improvements of technique found to insure reproductibility of results are discussed in detail.

The linoleic acid content of seed fats and the isomerism of linoleic acid

The linoleic acid content of a series of seed fats was determined by the thiocyanometric and the tetrabromide-precipitation methods in a search for isomeric linoleic acids. The results indicated the presence of only one form of linoleic acid. The tetrabromide number was shown to be affected by the pronounced solubility of alpha tetrabromostearic acid in the other bromides and in the solid acids, its determination therefore being of only limited value. The thiocyanogen numbers of pure linoleic and linolenic acids were found to be empirical values differing markedly from the theoretical constants, requiring a revision of the accepted equations for the calculation of the per cent concentration of the unsaturated acids in oils and mixed fatty acids.

Photoelectric Spectrophotometry Applied to Studies in Fat Metabolism.

Conclusion Eleostearic acid is quickly changed to a new acid in vivo. Distribution and metabolism of this acid has been followed by spectroscopic analysis and large differences found among several tissues.

Synthesis of Fats by Green Plants

1. An apparatus is described which permits aliquot parts of gas streams to be collected from the respiration chamber at desired intervals. 2. A method is described in detail for making a seal to inclose an attached leaf or fruit in the respiratory chamber, without apparent injury to the plant. 3. Under the described experimental conditions, no diffusion of either carbon dioxide or oxygen through petioles could be detected. 4. Data presented show that a considerable quantity of fat is synthesized within the castor bean fruit. 5. The possibility of translocation of some fat is discussed, and it is concluded that more detailed analytical data are required for determining whether some type of lipid is slowly moved into castor bean fruits during periods of low respiration quotients.

On the Nutritive Value of Certain Oils.

Conclusion From the data at hand it would seem that the highly unsaturated fatty acids of cod liver oil can be used by fat deficient rats for growth, but that their scaly skin is cured only by linolic and linolenic acids, which, apparently are lacking in cod liver oil. It may prove possible to isolate a fat which will cure the skin without producing growth, as indicated by Sinclairs experience. The fat deficiency may therefore resolve itself into 2 factors. It so happens that linolic and linoienic acids seem to relieve both growth and skin abnormalities. The relative values of several fatty acids in the prevention of the above symptoms as well as kidney degeneration is being included in our present studies.

Iodine Numbers of Serum Lipids in Rats Fed on Fat-Free Diets.

Summary (1) The cholesterol and total fatty acids of the serum in rats fed on a fat-free diet were found to be lower than in control animals. (2) The iodine number of the serum fatty acids from rats fed on fat-free diets indicates that the fatty acids are less unsaturated than those of controls.