Chemistry of the Lipides

Abstract

Since the chemistry of the lipides was reviewed by Hilditch (1) in 1953, new and interesting fatty acids have been discovered and the mechanisms of autoxidation and of fat -synthesis have become better understood, as has the relationship between fatty acid composition and species. In this review it -is proposed to emphasise items selected from publications that have become available during the year ending November, 1955.FATTY ACIDS Estimation and separation.-As a means of separating fatty acid mixtures paper chromatography has continued to prove a useful field of research. To separate fatty acids within the range C2 to C24, filter paper impregnated with high boiling point petroleum hydrocarbon as the stationary phase has been used with the following solvents f o r the mobile phase: aqueous methanol (2, 3), methanol-acetone mixtures (2), and aqueous acetic acid (4, 5). Ac cording to Kaufmann & Nitsch (4) acetic acid-water mixtures give sharper separations than the diluted alcohols and may even be used to separate oleic and linoleic acids (6). To secure reproducible results Spiteri (5) has empha sised the need for care in the method of impregnating filter paper with the stationary phase. He also showed the sensitivity of the method by providing evidence for the occurrence of behenic and lignoceric acids in olive oil. Tp lo cate the acid, bromocresol green (2), ammoniacal silver nitrate (5), copper acetate-potassium ferrocyanide (4), and rhodamine B (4) have been �sed.

The isolation of iso- and (+)-anteiso-fatty acids of the C15 and C17 series from shark (Galeorhinus australis Macleay) liver oil

“…Based on the optical rotations of relevant fractions as compared with the purified acids (cf. Shorland et al 1955) the percentages of anteiso-acids were calculated as C15, 0-11, and C17, 0-18 %. No reliable estimate of the i8o-acids could be made, but from the amounts isolated it appears that they are present in proportions similar to those of the anteiso-acids.…”

“…In ruminants the odd-numbered i8o-and anteisoacids in the depot and milk fats were considered by El-Shazly (1952) to be formed by the addition of acetate units to isovaleric and (+ )-2-methylbutyric acid derived from leucine and isoleucine by the action of bacteria in the rumen. Shorland et al (1955) have suggested that the normal oddnumbered fatty acids might similarly arise from propionic and valeric acids present in the rumen. The origin of the odd-numbered normal, isoand anteiso-acids of shark-liver oil cannot at present be determined.…”

“…in diameter (Dixon, 1949) and column E (Shorland, 1952). As previously described (Shorland, Gerson & Hansen, 1955), this permitted a partial separation of straightand branched-chain isomers. The final selection of fractions for the isolation of the branchedchain fatty acids was made from the soluble fractions obtained during the isolation of the corresponding normal acids previously described (Morice & Shorland, 1955), and from the lower-boiling-point fractions of methyl esters of 0u5 acids, giving a total of 19-03 g. of acids, denoted F.…”

Seasonal changes in the fatty acid composition of ewe-milk fat

“…The anteiso acids were allowed for in calculating the fatty acid compositions. i8oand n-Odd-numbered acids have been found in cow-milk (Shorland, 1956) but, as there is no DISCUSSION satisfactory analytical technique for determining the percentages present, they have not been recorded in the As shown in Table 2, the New Zealand and English present work. (Hilditch & Jasperson, 1944) ewe-milk fats are…”