Very long-chain fatty alcohols

How the aliphatic monomers are incorporated into the suberin polymer is not known. Presumably, activated co-hydroxy acids and dicarboxylic acids are ester-ified to the hydroxyl groups as found in cutin biosynthesis. The long chain fatty alcohols might be incorporated into suberin via esterification with phenylpro-panoic acids such as ferulic acid, followed by peroxidase-catalyzed polymerization of the phenolic derivative. This suggestion is based on the finding that ferulic acid esters of very long chain fatty alcohols are frequently found in sub-erin-associated waxes. The recently cloned hydroxycinnamoyl-CoA tyramine N-(hydroxycinnamoyl) transferase [77] may produce a tyramide derivative of the phenolic compound that may then be incorporated into the polymer by a peroxidase. The glycerol triester composed of a fatty acid, caffeic acid and a>-hydroxy acid found in the suberin associated wax [40] may also be incorporated into the polymer by a peroxidase. 

Hargrove, J.L., Greenspan, P, and Hartle, D.K. 2004. Nutritional significance, and metabolism of very long chain fatty alcohols and acids from dietary waxes. Exp. Biol. Med. 229 215-226. 

In insects, especially Diptera, several pioneer studies reviewed by Blomquist et al. (1987) established that long chain hydrocarbons, some of which play a pheromone role, were derived from very long chain fatty acids by reduction and decarboxylation. Thus, pheromone biosynthesis shares steps with those leading to basic lipid molecules and also with those of the well-known pheromones of Lepidoptera (Roelofs and Wolf, 1988). All often display several double bonds located in various positions while the volatile butterfly compounds bear functional groups (acetate, aldehyde or alcohol) and aliphatic chains with 12-16 carbons. Contact pheromones of flies have much longer chains (21C-39C) (Pennanec h et al., 1991). 

Another possible application where the typically low viscosity of microemulsions is very useful is in the preparation of alternative fuels for diesel engines. Such hybrid fuel microemulsions containing vegetable oil [13] and alcohols, with 1-butanol [14] or a lower trialkylamine [15] acting as surfactant attracted interest some years ago, and such systems were tested for their practical application [16]. Similar systems containing triglyceride, aqueous ethanol, and 1-butanol [17] or long-chain fatty alcohols [18] were also studied for the same purpose. 

The other hpid polymer, suberin, is a heteropolymer, consisting of an aliphatic polyester associated with cross-linked polyaromatics and embedded waxes. Upon transesterification of suberin, the monomers released include C16-C28 m-hydroxy fatty acids and C16-C26 ct, -dicarboxyhc acids, the latter of which are diagnostic monomers, unsubstituted very-long-chain fatty acids (VLCFAs C>i8) and alcohols, glycerol and ferulate. Usually the major components of suberin are -hydroxy derivatives of palmitic and/or oleic acids, but in some cases oo-hydroxy C220 also is a dominant component [37]. Dicarboxylic FAs derived from further oxidation of the -hydroxy-FAs are also found in suberin. 

The components of plant cuticular waxes have been reviewed by Kolattukudy (1980). Major components include hydrocarbons, very-long-chain fatty acids, alcohols and monoesters. These and minor components are shown in Table 2.5. 

The wax associated with suberin has also been examined, but only recently. Hydrocarbons, wax esters, very-long-chain fatty acids, alcohols and terpenes have all been found. These are all typical... 

Polymerization of fine emulsions achieved by using a combination of a typical surfactant such as sodium dodecyl sulfate and a long-chain fatty alcohol. This gives rise to spontaneous emulsification of the monomer into very fine droplets. In this case the polymerization can be carried out by using a water-soluble or a monomer-soluble initiator (27). The latex particle size distribution is the same as for microsuspension poljunerization. 

In E. dendroides leaf v ax triterpenoids were found in amounts of 26% in addition to the common wax lipids. The triterpenols B-amyrin and lupeol were identified in this wax with the aid of TLC, GC, GC/MS and comparison with authentic samples. These alcohols were found not only free but also esterified with very long chain fatty acids. At last B-amyrin and lupeol were present in form of their corresponding ketones,too. A12-01ean-en-3-one and A20-lupen-3-one could be isolated by TLC and were identified by chemical reactions and their mass spectra. All these triterpenoids showed the typical colour reaction v ith carbazole and could be checked by TLC in this manner (1). 

Subsequent to the adsorption onto a surface, surfactants, especially long chain fatty acids and alcohols tend to undergo alterations such as two-dimensional associations in the adsorbed layer, presumably at rates kinetically independent of preliminary steps. These intra-layer reactions have been shown to be very slow. 

Special cases of solid lubrication arc boundary anil IIP (extreme pressure) lubrication In both cases ihe solid lubricant is formed by chemical reaction of special compounds, usually applied as oil solutions, with the metallic rubbing surfaces Typical boundary lubricants are the fatty acids which react with the metal surface to form metallic soaps which then carry the load. Strongly adsorbed hut nonreacting substances of linear structure, such as long chain tally alcohols, can also act as boundary lubricants but only under very mild conditions... 

Waxes are also esters of fatty acids. However, the alcohol in a wax is not glycerol it is often a very long chain alcohol. For example, one of the main compounds in beeswax is myricyl palmitate,... 

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