Epoxystearic acid

Epoxystearic acid has been detected in human urine at concentrations of about 2 nmol/L (Ulsaker Tcicn, 1995), probably occurring as a result of the oxidation of unsaturated fatty acid by cytochrome P450 (Laniado-Schwartzman et al., 1988). 

Experimental data (see Table 1 for references) cri-9,10-Epoxystearic acid was not mutagenic in Salmonella typhimurium in the... 

Table 1. Genetic and related effects of cis-9,10-epoxystearic acid... 

The infamous fluoroacetic acid and the equally toxic naturally occurring even-numbered co-fhiorinated fatty acids were discussed in detail earlier (7), and several reviews are available (34,44, 66). Although not counted as being natural in the earlier survey (7), 4-fluorothreonine (837) is now considered to be a bona fide natural metabolite of Streptomyces cattleya (893), the stereochemistry of which has been confirmed by synthesis (894). In addition to the five oo-fluorinated fatty acids presented earlier (7), new studies of the seed oil of Dichapetalum toxicarium have uncovered 16-fluoro-palmitoleic acid (838), 18-fluorostearic acid (839), 18-fluorolinoleic acid (840), 20-fluoroarachidic acid (841), 20-fluoroeicosenoic acid (842), 18-fluoro-9,10-epoxystearic acid (843) (895), (Z)-16-fluorohexadec-7-enoic acid (844), (Z)-18-fluoroocta-dec-9-enoic acid (845), and (Z)-20-fluoroicos-9-enoic acid (846) (896). 

Reaction with epoxides. Dimethyl sulfoxide and a strong acid (2,4,6-trinitro-bcnzcncsulfonic acid, TNBSA, was used) reacts with epoxides (1) to form alkoxy-sulfonium salts (2) in good yield. Since hydrolysis of alkoxysulfonium salts proceeds exclusively by attack at sulfur, the reaction provides a stereospecific synthesis of 1,2-glycols. Thus the reaction of lis- and rrans-9,10-epoxystearic acids with DMSO-... 

Similar oxidants are used for epoxidation of esters of unsaturated carboxylic acids. Methyl oleate is oxidized with peroxybenzoic acid [295] or peroxylauric acid [174] to methyl 9,10-epoxystearate acid in respective yields of 67 and 76%. Alkaline 50% hydrogen peroxide in methanolic solution transforms diethyl ethylidenemalonate at pH 8.5-9.0 and at 35-40 C over a period of 1 h into ethyl 2-ethoxycarbonyl-2,3-epoxybutyrate in 82% yield [145], A somewhat exotic oxidizing agent, dimethyldioxirane, converts ethyl tra/u-cinnamate into ethyl 2,3-epoxyhydrocinnamate in 63% isolated yield [210]. 

Oleic acid melhylesler 9,10-Epoxystearic acid melhylesler 67... 

Epoxystearic acid-2-ethylhexyl ester. See 2-Ethylhexyl epoxystearate EPR EPR rubber. See EPM rubber EPT. See EPDM rubber... 

Synonyms 9,10-Epoxystearic acid-2-ethylhexyl ester 2-Ethylhexyl9,10-epoxyoctadecanoate Octadecanoic acid, 9,10-epoxy-, 2-ethylhexyl ester Octyl epoxystearate Empirical CjsHmO,... 

Epoxystearic acid-2-ethylhexyl ester. See 2-Ethylhexyl epoxystearate... 

On prolonged storage, even at 0-5 °C, unsaturated acids in seeds are oxidized to hydroxy and epoxy acids. The regiospecific and stereospecific nature of these reactions suggests that they are under enzymic control. For example, sunflower seeds generate 9,10-epoxystearic acid and 9,10-epoxyoctadec-12-enoic acid, both in optically active form. 

Coronaric acid (9,10-epoxyoctadec-12-enoic), a positional isomer of vernolic acid, is the second most common epoxy acid and sometimes the two acids cooccur. It is present, for example, in the seed oils of Chrysanthemum coronarium (14%), Helichrysum bracteatum (14%, including some 9,10-epoxy-octadec-12-ynoic acid) and Xeranthemum annuum (8%, along with vernolic acid and 9,10-epoxystearic acid). 

Epoxystearic acid occurs as its cis (both (-h) and (—) forms) and trans isomer. The latter is present in oroju (sulphur olive oil) whilst sal fat contains the (+)-d5-epoxy acid. 

S, Total saturated acids U, total unsaturated acids Ep, cw-9,10-epoxystearic acid SUS etc., represents the total of all triglycerides of each type. 

Cutin is composed chiefly of a C16 and/or a Cis family of monomers (Fig. 4.2). The usual components of the former are palmitic acid, 16-hydroxypalmitic acid, and 10,16-dihy-droxypalmitic and/or its positional isomers in which the midchain hydroxyl group is at C9, Cs, or C7. Monomers that could be derived from the above acids by further oxidation or reduction also have been found in cutin from some plants. The C18 family consists of stearic acid, oleic acid, linoleic acid, 18-hydroxyoleic acid, 18-hydroxy-9,10-epoxystearic acid, and 9,10,18-trihydroxystearic acid together with their A-12 unsaturated analogs. Members of the Cie family are the dominant components of the cutin of fast-growing plants, whereas the cutin of slower-growing plants with a thicker cuticle consists of a mixture of C16 and C18 monomers (Harwood, 1980). 

Croteau R, Kolattukudy P E 1975 Biosynthesis of hydroxy fatty acid polymers. Enzymatic epox-idation of 18-hydroxy oleic acid to 18-hydroxy-cis-9,10-epoxystearic acid by a particulate preparation from spinach Spinacia oleracea). Arch Biochem Biophys 170 61-72... 

Kolattukudy P E, Walton T J, Kushwaha R P S 1973 Biosynthesis of the Cjg family of cutin acids cu-hydroxyoleic acid, o>-hydroxy-9,10-epoxystearic acid, 9,10,18-trihydroxystearic acid, and the J -unsaturated analogs. Biochemistry 12 4488-4498... 

A soln. of cw-9,10-epoxystearic acid in benzene added dropwise with stirring during 10 min. to a soln. of 2,4,6-trinitrobenzenesulfonic acid in anhydrous dimethyl sulfoxide, stirring continued 15 min., stirred into excess cold ether-ethyl acetate (2 1), the solvent layer decanted, and the oily lower layer stirred 12-14 hrs. with water /hreo-9,10-dihydroxystearic acid. Y 65-70%. Also erythro- from trans-isomer, and prepn. of f. l-hydroxy-2-(alkoxysulfonium) salts, s. M. A. Khud-dus and D. Swern, Tetrah. Let. 1971, 411. 

Another hydratase converts cis- and /ra/i5-9,10-epoxystearic acids to threo- and er rAro-dihydroxy-acids, respectively. Only one enantiomeric epoxy-acid is hydrolysed and only one enantiomeric dihydroxy-acid is formed. The reaction involves water, and the oxygen from this source appears at C(10) only. ... 

---