Hydroxy palmitic acid

The synthesis of y-DL is the most prominent example for the microbial production of fragrance lactones. Nevertheless, the biotransformation route via P-oxidation and lactonization (Fig. 1) in yeast can be applied for the production of several lactones provided that a suitable hydroxy fatty acid as starting material is available. For example, ricinoleic acid, the starting compound for the production of y-DL, can be isolated in large quantities from castor oil. However, other hydroxy fatty acids are more difficult to obtain. For instance, researchers from Takasago International Corporation reported the conversion of 11-hydroxy palmitic acid ethyl ester to 8-decalactone by the yeast Candida sorbophila (Mitsuhashi and limori 2004). 0.13 g substrate in 30 itiL culture medium yielded 0.019 g 8-decalactone in 96 % ee optical purity after 11 days. 

Soybeans also contain 170 47 ppm of cerebrosides in which the sugar is glucose and the chief fatty acid is 2-hydroxy palmitic acid (54). Traces of ceramides also are present. These are believed to play a role in cell signaling in the soybean plant. 

Another nonlactonic QS signal is 3-hydroxy palmitic acid methyl ester 17 from Rahtonia solamcearum, which controls exopolysaccharide production similar to the S. meliloti autoinducers." ... 

Unsaturated and saturated fatty aldehydes such as (Z, Z, Z)-8, 11, 14-heptadecatrienal, (Z, Z)-8, 11-heptadecadienal, (Z)-8-heptadecenal, (Z, Z, Z)-7, 10, 13-hexadecatrienal, pentadecanal, ( , Z, Z)-2, 4, 7-decatrienal, ( , Z)-2, 6-nonadienal and ( )-2-nonenal have been identified in essential oils from edible seaweeds as characteristic major compounds. The enzymatic formations of the long-chain fatty aldehydes from fatty acids such as linolenic acid, linoleic acid, oleic acid and palmitic acid, respectively, have been demonstrated. Based on enzymatic formation of (2/ )-hydroxy-palmitic acid and 2-oxo-palmitic acid from palmitic acid during biogeneration of pentadecanal and on incubation experiments of synthetic (25)- or (2/ )-hydroxy-palmitic acid and 2-oxo-palmitic acid as substrates with crude enzyme solution of Viva pertusa, the biogeneration mechanism of long chain aldehydes via oxylipins is discussed. 

Figure 5. HPLC analysis of MTPA esters of 2-hydroxy-palmitic acid from thalli of U. pertusa.

Figure 6. Syntheses of (S)-2-hydroxy- and (/ )-2-hydroxy-palmitic acid.

Cerebrosides have been isolated from Phycomyces blakeslearus (3), a fungus often found on animals dung, by extraction of mycelia with acetone and chloroform/methanol mixtures and purified on a silicic acid column, followed by a Florisil column. The bases obtained after hydrolysis were all phytosphingosine homologs ranging in length from C17 to C22. Palmitic,stearic, oleic, linoleic and hydroxy palmitic acids were the major fatty... 

SLs are also polar cell membrane lipids, but they are typically present in much lower concentration than PLs. Soybeans are a relatively rich source of SLs (Vesper et al., 1999), and ceramides and cerebrosides are the primary SL classes in soybeans. SLs contain a sphingoid long-chain (CIS) drhydroxy base and an a-hydroxy fatty acyl chain that is linked to the base by an amide bond. The main soybean ceramide molecular species is a trihydroxy base (4-hydroxy-trans 8-sphingenine) V -acylated with a-hydroxy lignoceric acid (C24 0). The main soybean cerebroside molecular species is a dihydroxy base trans A-trans 8-sphingediene) V acylated with a-hydroxy palmitic acid. The general molecular structures of ceramide and cerebroside are shown in Fig. 10.4. 

The polysaccharide moiety of the lipopolysaccharide of Schizothrix calcicola contains 2-amino-2-deoxy-D-glucose, D-galactose, D-glucose, D-mannose, D-xylose, and L-rhamnose. In contrast to many enterobacterial lipopoly-saccharides, the major fatty acid component has been identified as 3-hydroxy-palmitic acid and not 3-hydroxymyristic acid. 

Scheme 5.5 Synthesis of a C30 a,(o-diester derived from (O-hydroxy palmitic acid.

The most common major components of cutin are derivatives of saturated C16 (palmitic) acid and unsaturated C18 acids (Fig. 4). The major component of the C16 family of acids is 9- or 10,16-dihydroxyhexadecanoic acid (and some mid-chain positional isomers), with less 16-hydroxyhexadecanoic acid and much smaller amounts of hexadecanoic acid. In some cases other derivatives are significant constituents. For example, in citrus cutin 16-hydroxy-10-oxo-C16 acid, and in young Vicia faba leaves 16-oxo-9 or 10-hydroxy C16 acid are significant... 

Figure 12.12 THM GC/MS curves of a Winsor Newton lemon alkyd paint (a) and of an alkyd sample taken from Fontana s work Concetto spaziale (1961) (b). Peak assignments 1, 1,3 dimethoxy 2 propanol 2, 1,2,3 trimethoxy propane 3, 3 methoxy 1,2 propandiol 4, 4 chloro benzenamine 5, 3 methoxy 2,2 bis(methoxymethyl) 1 propanol 6, 3 chloro N methyl benzenamine 7, 3 methoxy 2 methoxymethyl 1 propanol 8, 4 chloro N methyl benzenamine 9, phthalic anhydride 10, 3 chloro 4 methoxy benzenamine 11, suberic acid dimethyl ester 12, dimethyl phthalate 13, azelaic acid dimethyl ester 14, sebacic acid dimethyl ester 15, palmitic acid methyl ester 16, oleic acid methyl ester 17, stearic acid methyl ester 18, 12 hydroxy stearic acid methyl ester 19, 12 methoxy stearic acid methyl ester 20, styrene 21, 2 (2 methoxyethoxy) ethanol 22, 1,1 oxybis(2 methoxy ethane) 23, benzoic acid methyl ester 24, adipic acid dimethyl ester 25, hexadecenoic acid methyl ester 26, dihydroisopimaric acid methyl ester 27, dehydroabietic acid methyl ester 28, 4 epidehydroabietol...

FIGURE 3-7 Pathways for the interconversion of brain fatty acids. Palmitic acid (16 0) is the main end product of brain fatty acid synthesis. It may then be elongated, desaturated, and/or P-oxidized to form different long chain fatty acids. The monoenes (18 1 A7, 18 1 A9, 24 1 A15) are the main unsaturated fatty acids formed de novo by A9 desaturation and chain elongation. As shown, the very long chain fatty acids are a-oxidized to form a-hydroxy and odd numbered fatty acids. The polyunsaturated fatty acids are formed mainly from exogenous dietary fatty acids, such as linoleic (18 2, n-6) and a-linoleic (18 2, n-3) acids by chain elongation and desaturation at A5 and A6, as shown. A A4 desaturase has also been proposed, but its existence has been questioned. Instead, it has been shown that unsaturation at the A4 position is effected by retroconversion i.e. A6 unsaturation in the endoplasmic reticulum, followed by one cycle of P-oxidation (-C2) in peroxisomes [11], This is illustrated in the biosynthesis of DHA (22 6, n-3) above. In severe essential fatty acid deficiency, the abnormal polyenes, such as 20 3, n-9 are also synthesized de novo to substitute for the normal polyunsaturated acids. 

An early synthesis of A5-palmitoy]-.S -[2,3-bis(palmitoyloxy)propyl]cysteine employed cysteine methyl ester, however, this leads to difficulties in the saponification step of the tri-palmitoylated residue. 96 The optimized procedure, in which the cystine di-fert-butyl ester is used, 90 is outlined in Scheme 6 after N-acylation with palmitoyl chloride, the ester is reduced to the cysteine derivative for S-alkylation with l-bromopropane-2,3-diol to yield chirally defined isomers if optically pure bromo derivatives are used. Esterification of the hydroxy groups is best carried out with a 1.25-fold excess of palmitic acid, DCC, and DMAP. The use of a larger excess of palmitoyl chloride is not recommended due to purification problems. The diastereomeric mixture can be separated by silica gel chromatography using CH2Cl2/EtOAc (20 1) as eluent and the configuration was assigned by comparison with an optically pure sample obtained with 2R)- -bromopropane-2,3-diol. 

In another investigation, the volatile compounds were isolated [19] using a Porapack Q trap by vacuum for 2 h and were then eluted with hexane. The esters were the chemical class of compounds that predominated in the samples among 21 volatile compounds detected. Ethyl butanoate, ethyl 2-methylbutano-ate, 1-butanol, ethyl hexanoate, 3-hydroxy-2-butanone, ethyl octanoate, acetic acid, linalool, palmitic acid, and oleic acid were identified in cupuacu pulp by solid-phase extracton [15]. 

Milk fat contains both keto (oxo) and hydroxy fatty acids, and earlier identifications are discussed by Jensen et al. (1967), Morrison (1970), and Kurtz (1974). In a more recent and careful study, Weihrauch et al. (1974) isolated 60 oxo acids from milk fat and positively and tentatively identified 47 with the aid of mass spectrometry. These data are presented in Table 4.9. About 85% (weight) of the oxo acids were stearates, mostly the 13-isomer, and 20% were palmitates, largely the 11-isomer. Of the unsaturated oxo acids, the 9-oxo, 12-ene, and 13-oxo, 9-ene were the predominant species. Other unsaturated oxo acids which are not listed in Table 4.9 but which were possibly present, are 15 1, 16 2, 17 1, 17 2, 17 3, 18 2, 18 3, 19 1, 19 2, and 20 1. 

There is a seemingly endless variety of fatty acids, but only a few of them predominate in any single organism. Most fatty acid chains contain an even number of carbon atoms. In higher plants the C16 palmitic acid and the C18 unsaturated oleic and linoleic acids predominate. The C18 saturated stearic acid is almost absent from plants and C20 to C24 acids are rarely present except in the outer cuticle of leaves. Certain plants contain unusual fatty acids which may be characteristic of a taxonomic group. For example, the Compositae (daisy family) contain acetylenic fatty acids and the castor bean contains the hydroxy fatty acid ricinoleic acid. 

Alpha oxidation and omega oxidation. Animal tissues degrade such straight-chain fatty acids as palmitic acid, stearic acid, and oleic acid almost entirely by (3 oxidation, but plant cells often oxidize fatty acids one carbon at a time. The initial attack may involve hydroxylation on the a-carbon atom (Eq. 17-3) to form either the d- or the L-2-hydroxy add.17 18-32 323 The L-hydroxy acids are oxidized rapidly, perhaps by dehydrogenation to the oxo acids (Eq. 17-3, step b) and oxidative decarboxylation, possibly utilizing H202 (see Eq. 15-36). The D-hydroxy acids tend to accumulate... 

The carboxylic acids can be subdivided into nonvolatile fatty acids, volatile fatty acids, hydroxy acids, dicarboxylic acids, and aromatic acids (Fig. 3). The nonvolatile fatty acids are molecules with more than five carbon atoms, such as stearic and palmitic acids, which are the degradation products of fats and triglycerides. Three different 18-C fatty acids that are important constituents of plants include oleic and linoleic acids that are abundant in plant seeds, and linolenic acid, which is abundant in plant leaves. Volatile fatty acids are short-chain molecules with one to five carbon atoms, such as acetic and valeric acid, associated with anaerobic metabolism. The hydroxy-acids are common intermediates in biochemical pathways, including the tricarboxylic acid cycle. The excretion of hydroxyacids by algae, such as the... 

Figure 9.16 Chemical structure of cutin, a biopolyester mainly composed of interester-ified hydroxy and epoxy-hydroxy fatty acids with a chain length of 16 and/or 18 carbons (Ci6 and C[s class). Also, the chemical strcuture of the aliphatic monomers of suberin, derived from the general fatty acid biosynthetic pathway, namely from palmitic (16 0), stearic (18 0), and oleic acids.

Each of the enzymatic activities located in a single polypeptide chain of the mammalian fatty acid synthetase exists as a distinct protein in E. coli. The acyl-carrier protein (ACP) of E. coli has an Mr = 8,847 and contains 4-phosphopantotheine. The dehydratase has a molecular weight of 28,000 and catalyzes either trans 2-3 or cis 3-4 dehydration of the hydroxy acid intermediates in the biosynthesis of palmitic acid. When the chain length of the hydroxy fatty acid is C[ the synthesis of palmitoleic acid is achieved as follows ... 

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