Methyl arachidonate

Fig. 17 Separation of isomerized methyl arachidonate. Sample size 100 fig. Flow rate 1.0 ml/min 0.125% ACN in hexane. UV detection at 210 nm. Groups A = four trans B = three trans, one cis C = two trans, two cis D = one trans, three cis E = four cis.

Singlet oxygen, in the excited state ( 02), reacts relatively slowly with CHOL via a non-radical mechanism the rate constant for 02 addition to CHOL is 6.7 x lO moL1 s-1, which is about 25% that of methyl arachidonate (Girotti, 2001). Only three hydroperoxides are produced in 102-mediated reactions 3(3-hydroxycholest-6-ene-5a-hydroperoxide... 

Orr (43) used dimethyl sulfoxide as a free radical sink to inhibit the effect of Cu and ascorbic acid on catalase and 8-glucuronidase as well as the degradation of hyaluronic acid. The formation of a radical from ascorbic acid and Cu in water was detected by EPR (44). Based on an EPR spectroscopic study of ascorbic acid during oxidation of methyl-arachidonate-enriched liposomes, ascorbic acid may be important in preventing free radical damage in the central nervous system (45). 

CTI reactions of methyl linoleate [35], y-linolenate [35], and arachidonate [36] catalyzed by thiyl radicals have been studied in some detail. Each isolated double bond in PUFA behaves independently as discussed above. Indeed, the time profiles of methyl linoleate disappearance and formation of mono-trans and di-trans isomers in these experiments indicated that the CTI occurs stepwise (Scheme 6.5). The number of possible geometrical isomers increases according to 2n, where n is the number of double bonds, and the complete analysis may be difficult and incomplete for high unsaturation as in the case of methyl arachidonate. 

Leukotrienes. Prostaglandins and Related Compounds.- Examples of the use of the Wittig reaction in the synthesis of compounds related to arachidonic acid include an efficient synthesis of methyl arachidonate (148) by a three-carbon homologation sequence involving (3,3-diisopropoxy-propyl)triphenylphosphorane (149).91 Both diastereomers of trioxilin B3... 

Methylacrylic acid, see B-00040 Methyl arachidonate hydroperoxides, M-OOOlO... 

Figure 6 A typical gas-liquid chromatogram of total bovine milk FAME prepared by NaOCHsfmethanol (10 min at SO C) followed by HCI/methanol (10 min at 80°C), and separated on a 100 m fused silica capillary column (SP-2560) Supelco Inc., Bellefonte, PA). I, iso a, anteiso numbers 1-20 are arbitrary consecutive numbering of all peaks in the region between 18 0 and 18 2o6 using this column. (22 6/>3) is not present in these milk samples but the position at which it should emerge in the chromatogram is indicated. Insert the methyl eicosanoate (20 0) to methyl arachidonate (20 4/>6) region of the GLC of total bovine fatty acid methyl esters prepared by using conventional catalysts. Reproduced with permission from Kramer JKG, Fellner V, Dugan MER, Sauer FD, Mossoba MM, and Yurawecz MP (1997) Lipids 32 1219-1228.

At least 1 ester is hydrolyzed. Methyl formate is hydrolyzed. Methyl arachidonate is hydrolyzed. Ethyl oleate is hydrolyzed. 

Photosensitized oxidation of long-chain PUFA produces the hydroperoxides expected by concerted addition of oxygen at each unsaturated carbon positions. Thus, methyl arachidonate produced a mixture of 8 isomers with hydroperoxide on carbons 5,6, 8,9,11,12,14 and 15. Methyl 5,8,11,14,17-eicosapentaenoate (EPA) produced a mixture of 10 isomers with hydroperoxides on carbons 5, 6,... 

Linoleic and arachidonic acids are the most effective of the acids in clearing up the skin symptoms resulting from pyridoxine deficiency or from fat deficiency. Quackenbush and co-workers (1942a) are of the opinion that linoleic acid is more effective than linolenic acid as an antidermatitis factor. In line with this result. Burr et al. (1940) reported that com oil (which has no linolenic acid) is more potent in preventing the skin disorders of fat-deficient animals than is linseed oil (which is relatively rich in linolenic acid at the expense of linoleic acid). In fact, the ability of natural fats to counteract the skin disorders has been found to be in proportion to the linoleic acid content of the diet. According to Richardson et al. (1941) methyl arachidonate and methyl linoleate are equally effective in the treatment of the dermatitis produced by vitamin Be deficiency. 

---