A-Hydroxy fatty acids

Considerable proportions of cerebroside have been detected in the starfish Asterias rubens.9Ail0 It is a glucosylceramide having a-hydroxy fatty acids (from C16 to C26) and dihydroxy bases whose major components are Cl8 and C22 bases, with one, or two, double bonds. 

The lipid moiety of the sialoglycolipids from the hepatopancreas of P. pectinifera includes a-hydroxy fatty acids, among which, the C22, C23, and C24 acids account for >90% of the mixture, and compounds whose major... 

The derivatives obtained by reaction with benzoic anhydride have longer retention times when compared to the benzoyl chloride products. We have previously shown that galactosylceramide which contains a-hydroxy fatty acids is not N-benzoylated with benzoyl chloride and reaction with benzoic anhydride or benzoyl chloride results in an identical product. Similar results have been obtained with anhydride in the presence of DMAP as illustrated in Fig. 2. The behavior of peak "b" which we have shown to be derived from a-hydroxy fatty acid containing glucosyl and galactosylceramides is illustrative. The UV response from each of the standard GSLs benzoylated by the anhydride and by the benzoyl chloride method were compared. The relative responses (chloride/anhydride) for the mono, di, tri and tetra-hexosyl ceramide were found to be 1.18, 1.15, 0.94 and 1.03 respectively. These values were not significantly different from calculated rations 1.20, 1.12, 1.09, and 1.15, based on the assumption that the anhydride method avoids amide benzoylation. The yields of the per-O-benzoylated products were similar to those obtained for the products of the benzoyl chloride method reported previously. 

Lactones are cyclic compounds formed through the intramolecular esterification of a hydroxy fatty acid. 7-Lactones and 8-lactones, with fivesided and six-sided rings, respectively have been found in cheese (Jolly and Kosikowski, 1975 Wong et al., 1975 Collins et al., 2004). The origin of the precursor hydroxy fatty acids has been ascribed to a 8-oxidation system in the mammary gland of ruminants (see Fox et al., 2000), the reduction of keto acids (Wong et al., 1975) and/or the action of lipoxygenases and other enzymes present in members of the rumen microflora (Dufosse et al., 1994). Lactones have low flavor thresholds and while their aromas are not specifically cheese-like (their aromas have been described variously as peach, apricot and coconut ), they may contribute to the overall flavor of cheese (see Collins et al., 2004). 

The bacteriostatic activity of a-hydroxy fatty acids at several pH s was reported by Eggerth (23) and analyzed by Hansch and Clayton (24). They reported the following correlations (for B. lepisepticus) ... 

R—CH2—CH—COOH + Oxidized cofactor -1- H2O a-Hydroxy fatty acid... 

This reaction is also a route for the synthesis of hydroxy fatty acids. The a-hydroxy fatty acid can be further... 

Oxidation of phytanic acid is blocked by the methyl group substituent on C-3 (the /3-position). Consequently, the first step in phytanic acid catabolism is an a-oxidation in which the molecule is converted to a a-hydroxy fatty acid. (a-Hydroxylating activity has been detected in the ER and in mitochondria.) This reaction is followed by the removal of the carboxyl group (Figure 12C). After activation to a CoA derivative, the product, pristanic acid, can be... 

Menkes, Philippart, and Concone110 determined the relationship between the concentration of the sulfatides (and cerebrosides) of the human brain and the age of the human, and found a progressive increase from birth to maturity.111 Furthermore, the proportion of the a-hydroxy fatty acids increases, together with that of the C24-fatty acids. 

Apart from saturated fatty acids, Simoneit and Mazurek (1982) observed low concentrations of unsaturated fatty acids (range C,4-Ci7) a-hydroxy fatty acids (range C 0-C24) that are known components of grass wax dicarboxylic acids (range C 0-C24) that probably arise from the direct biodegradation of hydroxy fatty acids and diterpenoidal acids occurring as diagenetic products of diterpenoids from coniferous resins. 

Finally I will call attention to novel composite microstructures from lipids and minerals. When a-hydroxy fatty acid galactocerebroside and a mixture of anioic sulfated galactocerebrosides are suspended in ethylene glycol multilayer tubules are produced. When the tubule suspension is then treated with an acidic ferric chloride solution, the tubules became covered with shards of the mineral lepidocrocite (y-FeOOH).43 Although the direct application of this organic-inorganic composite is still uncertain, but it seems to have a possibility of designing new materials. 

The carbohydrate components of the glycolipid were fucose and galactose in approximately equimolecular amounts. Fatty acids, forming amide group with the sphingosine bases, were a mixture of normal and a-hydroxy fatty acids. Normal C16 0,C18 0 and 2-hydroxy C18 0 were the predominant fatty acids (Figure 12, Table 5). 

Esterification of Fatty Acids. It was earlier discovered that vhile the esterification of a fatty acid leads to an inactive species, esterification of a hydroxy fatty acid still yielded an active ester (Table II). Frcm these and other experiments,... 

D-Glucose could be transferred from UDP-D-glucose to endogenous receptors by a particulate enzyme fraction from the cellular slime mould, Dictyostelium discoideum When H4-edta was incorporated into the medium, the sole product was a mono-D-glucosylceramide that contained a hydroxy fatty acid. Divalent cations were not essential but they could stimulate the reaction, whereas other sugars had little effect on the reaction. 

When triacylglycerols contain a hydroxy fatty acid then the hydroxyl group can be esterified with further fatty acids. Examples of these glycerides have been found in plants (Hitchcock, 1975) with the occurrence of tetra-, penta- and hexa- acid glycerides. The tetra-acid triacylglycerol from Sapium sebiferum oil (Sprecher etal., 1965) is an example. 

This is the only commercially important oil which contains a hydroxy fatty acid, 12-hydroxyocta-decenoic acid (ricinoleic) as its major component (Sections 1.9 and 3.2.10). It history has been traced back to the Egyptians who used it in embalming. 

Microsomal preparations from many tissues can oxidize fatty acids in the w-position. An a>-hydroxy fatty acid is formed first and this can be oxidized by NAD" and cytoplasmic enzymes to yield a dicarboxylic acid which can be further attacked by -oxidation (Greville and Tubbs, 1968). The enzyme(s) responsible for the oxidation of the... 

Free fatty acids from C12 to Cig may be attacked readily to yield either a fatty acid with one less carbon atom and CO2, or a D-a-hydroxy fatty acid. Molecular oxygen is re-... 

The separation capacities of various stationary phases for the analysis of 7 /S-a-hydroxy fatty acid esters have been... 

Plants are unique in that the structural component of their outer envelope (cuticle) consists of a hydroxy fatty acid polymer, cutin, whereas other organisms use polymers of amino acids or carbohydrates for this purpose. Underground parts and healed wound surfaces of plants are protected by another type of lipid-derived polymeric material, suberin, which is laid down outside the plasma membrane and in close contact with the inside of the cell... 

Cerebronic add, 2-hydrexyietracosanoic acid, a-hydroxyllgnocerlc acUt CH3-(CH2)2,-CHOH-COOH, a hydroxy fatty acid, M, 384.63, m.p. 101 C, present in various glycolipids. 

Purdy RE, Kolattukudy PE (1973) Depolymerization of a hydroxy fatty-acid biopolymer, cutin, by an extracellular enzyme fl om Fusarium solani pisi—isolation and some properties of the enzyme. Arch Biochem Biophys 159 61-69... 

Vapour phase chromatography has shown that the fatty acids mentioned previously are the main constituents, which are however accompanied by higher and lower homologues with 20 to 26 carbon atoms. The level of odd numbered homologous acids increases with age (Kishimoto et al. 1959). The a-hydroxy fatty acids possess the D-configuration. 

A large group of even- and odd-numbered a-hydroxy fatty acids with 20 to 26 C-atoms occurs in brain cerebrosides (see chapter BII, 2a). These acids are formed by a direct a-hydroxylation in the cytoplasmic reticulum. The loss of one C-atom of the a-hydroxy acids leads to the odd-numbered fatty acids (Fulco et al. 1961). 

The index of hydrolysis was the formation of ste (-l- C)-sph from cerebrosides containing stearic-1- C acid. The use of a detergent mixture containing sodium cholate was required for hydrolysis. The enzyme showed maximum activity at pH 4.5, at which point both the enzyme and cholate precipitated. Other substrates included naturally occurring cerebrosides (galactose containing) and showed the formation of ceramides containing normal and a-hydroxy fatty acid. Enzyme activity was seen also in rat brain, spleen, and kidney. 

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