Eicosenoic acid

Laschewsky A, Ringsdorf H and Schmidt G 1988 Polymerization of eicosenoic acid and octadecyl fumarate in Langmuir-Blodgett multilayers PoiymerlS 448-56... 

Only a few specific kinds of lipids can be identified on the basis of the characteristic features of the FA profile and the presence of specific biomarkers. For example, oils obtained from the seeds of Brassicaceae, such as rapeseed oil, are characterized by abundant amounts of uncommon FA such as gondoic (Z-11 -eicosenoic) acid and erucic (Z-13-docosenoic) acid and, after ageing their oxidation products. Other examples are reported in Table 7.2 and in Chapter 1. 

The Lesquerella seed yields roughly 20-25 % oil by weight. The functional fatty acid from the profile is mainly the 20-carbon lesquerolic acid, or 14-hydroxy-ll-eicosenoic acid (Fig. 9). 

Escolar and oilfish contain a mixture of wax esters with different carbon-chain length, mainly C32, C34, C36, and C38, formed by combining different fatty acids and fatty alcohols. The dominant fatty acids in escolar and oilfish wax esters are the monounsaturated fatty acids (Table 1.3), namely oleic acid (18 1 oo9) and eicosenoic acid (20 loo9), while the dominant fatty alcohols are saturated and monoenoic fatty alcohols (Table 1.4), known as cetyl alcohol (16 0) and oleyl alcohol (18 1 9). PUFA, which are trace components in muscle wax esters, are commonly found in wax esters from roe, they include 20 4o)6, 20 5(b3, 22 5cd3 and 22 6 3. These differences could be due to the functional role in muscle for providing buoyancy, while that of roe is to store energy and key essential PUFA for fry development (Lee and Patton, 1989). 

Miwa and Yamamoto (31) described a simple and rapid method with high accuracy and reliability for the determination of C8 0-C22 6 fatty acids, which occur in esterified forms in dietary fats and oils and in living cells [the biological effects of routinely consumed fats and oils are of wide interest because of their impact on human health and nutrition (28,29), in particular, the ratio of cu-3 polyunsaturated fatty acid to w-6 polyunsaturated fatty acids (w-3/cu-6) seems to be associated with atherosclerosis and breast and colon cancers (30)]. They report improved separation of 29 saturated and mono- and polyunsaturated fatty acids (C8-C22), including cis-trans isomers and double-bond positional isomers, as hydrazides formed by direct derivatization with 2-nitrophenylhydrazine hydrochloride (2-NPH HC1) of saponified samples without extraction. The column consisted of a J sphere ODS-M 80 column (particle size 4 /xm, 250 X 4.6-mm ID), packed closely with spherical silica encapsulated to reach a carbon content of about 14% with end-capped octadecyl-bonded-spherical silica (ODS), maintained at 50°C. The solvent system was acetonitrile-water (86 14, v/v) maintained at pH 4-5 by adding 0.1 M hydrochloric acid with a flow rate of 2.0 ml/min. Separation was performed within only 22 min by a simple isocratic elution (Fig. 6). The resolution of double-bond positional isomers, such as y-linolenic ( >-6) and a-linolenic acid ( >-3) hydrazides and w-9, >-12, and >-15 eicosenoic acid hydrazides was achieved by use of this column. 

Figure 5.1. Structures of (a) vinyl stearate, (b) octadecyl fumarate, (c) octadecyl maleate and (d) 2-eicosenoic acid.

Ricinoleic acid (i -12-hydroxy-9-cw-octadecenoic acid) (Fig. 6) accounts for 80-90% of fatty acids in castor oil (from Ricinus communis). It is found in other plant species and in the sclerotia of the ergot fungus Claviceps purpurea). Lesquerolic acid (i -14-hydroxy-ll-cw-eicosenoic acid), which is a C20 homolog of ricinoleic acid, occurs in Lesquerella species (up to 70% of total fatty acids). Isoricinoleic acid (i -9-hydroxy-12-cw-octadecenoic acid, or 9-OH 18 2 12c) is a major acid in the Wrightia species. In plants, several C16 and C18 mono, di, and trihydroxy fatty acids are stmctural components of cutin (a polyester constituent of plant cuticle). 

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