Ricinoleic acid detection

Candida strains convert ricinoleic acid into If-decalactone, which displays the fatty, fruity aroma typical of peaches. Ricinoleic acid (12-hydroxy octadec-9-enoic acid) is the major fatty acid in castor oil (approx. 80 %). The yeast can lipolyze castor oil glycerides and the liberated ricinoleic acid is subsequently metabolized via d-oxidation and eventually converted to 4-hydroxy-decanoic acid (Figure 5). Recently a European patent has been filed (20) essentially covering the same procedure. Shake culture fermentations were carried out on 100 ml scale for one week. The 4-hydroxydecanoic acid formed was converted to )f-decalactone by boiling the crude, acidified (pH 1.5) fermentation broth for a period of 10 minutes. The lactone was isolated via solvent extraction and a yield of some 5 g/1 was obtained. The same lactone was detected as the major volatile component formed when the yeast, Sporobolomyces odorus was grown in standard culture medium (21). Although the culture medium displayed an intense fruity, typical peach-like odor, the concentration of y-decalactone amounted to no more than 0.5 mg/1. 

Most TAG mixtures show little optical activity, but castor oil and those unusual oils containing acylglycerols of cyclopentene acids (e.g., chaulmoogric and hydno-carpic acids present in the seed oils of Flacourticeae) are notable exceptions. Samples containing sterols will display some optical activity dne to the presence of these optically active compounds. Becanse most edible oils have low optical activity, a method has been proposed to detect the adnlteration of edible oils with castor oil based on the optical activity of ricinoleic acid (1,2-dihydroxyoctadecenoic acid), a major constitnent of castor oil (Babn et al., 1996). 

A novel approach to identifying the presence of ergot alkaloid has been to quantify the fatty acid ricinoleic acid, (R)-12-hydroxy-(Z)-9-octadecenoic acid [32]. The acid is not usually found in grain but is a major component of the lipid portion of Claviceps. The lipid extracted from sclerotia can be analyzed for the ricinoleic acid by GC with flame ionization detection after transesterification and derivatization of the hydroxy group by silylation. There is no correlation between the content of ricinoleic acid and the ergot alkaloids and so quantitative levels of ergot alkaloids cannot be provided by this method. 

Several tissues have been used to study the mechanism of fatty acid synthesis, particularly the avocado mesocarp, spinach and lettuce chloroplasts, and etiolated barley seedlings, but some major advances have been made from studies of maturing oil-bearing seeds, e.g. castor bean (in which 90% of the fatty acid content is ricinoleic acid) and safflower, Carthamus tine tor ius (76% linoleic and 1% oleic). Oleic acid plays a central role in plant fatty acid anabolism as the precursor of the major unsaturated fatty acids, e.g. it is the first detectable fatty acid formed when acetate is fed to the developing castor bean and is itself a precursor of ricinoleic acid. 

For example, fatty acids containing hydroxy groups, e.g. ricinoleic acid (fZJ-9, 12-OH 18 1) in seeds of Ricinus communis [38], or certain positional and geometrical isomers of unsaturated fatty acids, e.g. petroselinic acid (fZ)-6 18 1) in seed lipids of Pimpinella anisum [17,19], Petroselinum crispum [29] andD. carota [39], and eleostearic acid (Z)-9, (E, E)-, 13 18 3) in the seed lipids of M. charantia [36], are not detected in the lipids of cell cultures of these plants. Vaccenicacid (fZ)-ll 18 1), however, is a constituent fatty acid of triacylglycerols and other lipids of P. crispum callus as well as various tissues of the intact plant, except seeds (Table 2) [29]. 

Czaudema, M. Kowalczyk, J. Separation of some mono-, di- and tri-unsaturated fatty acids containing 18 carbon atoms by high-performance liquid chromatography and photodiode array detection, J.Chromatogr.B, 2001, 760, 165-178. [derivatization linoleic acid linolenic acid oleic acid ricinoleic acid myristic acid palmitic acid vaccenic acid stearic acid]... 

A large number of hydroxy fatty acids occur in seed oils [71,856], and the best known of these is probably ricinoleic or 12-hydroxy-c/s-9-octadecenoic acid, which is the principle constituent of castor oil. Polyhydroxy fatty acids are present in plant cutins, while aleurltic or 9,10,16-trihydroxyhexadecanoic acid is one of the main components of shellac. Vernolic or 12,13-epoxy-c/s-9-octadecenoic acid is one of a number of epoxy fatty acids to have been detected in seed oils. 

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