Jojoba , wax esters

Fats and oils are one of the oldest classes of chemical compounds used by humans. Animal fats were prized for edibiUty, candles, lamp oils, and conversion to soap. Fats and oils are composed primarily of triglycerides (1), esters of glycerol and fatty acids. However, some oils such as sperm whale (1), jojoba (2), and orange roughy (3) are largely composed of wax esters (2). Waxes (qv) are esters of fatty acids with long-chain aUphatic alcohols, sterols, tocopherols, or similar materials. 

Jojoba wax, used in candles and cosmetics, is partially composed of the ester of stearic acid and a straight-chain C22 alcohol. Draw the structure of this ester. 

The jojoba plant (Simmondsia chinensis) produces wax esters rather than tri-acylglycerols in its seeds and it has become a significant crop for the cosmetic sector. Its wax consists mainly of long-chain fatty acids linked to long-chain fatty alcohols. 

Waxes are common forms of high-energy storage, in the oils of fish and other marine animals. The major lipids of commercial whale oil consist of approximately 65 percent waxes and 35 percent TAG. The lipids of Australian orange roughy (Hoplostethus atlanticus) and dory fish oils are 97.1 and 90.9 percent wax esters, respectively.58 Essentially all the oil in jojoba (Simmondsia chiensis) seed is in wax form. Whale and jojoba oils have been valued for stability in cosmetics and heavy-duty lubrication applications. 

Garver et al. (1992) developed an assay that measures the activity of the acyl-CoA alcohol transacyiase involved in the biosynthesis of storage liquid wax esters in jojoba and some microbes and algae. 

Jojoba oil is not a triacylglycerol but a mixture of wax esters based mainly on 20 1 and 22 1 acids and alcohols. It contains C40, C42, and C44 esters with two isolated double bonds (one in the acyl chain and one in the alkyl chain). The oil serves as replacement for sperm whale oil, which is proscribed in most countries because the sperm whale is an endangered species. At present, jojoba oil is a high-priced oil used mainly in cosmetics, but it has excellent lubricating properties and could be used extensively for this purpose if available in sufficient quantity at an appropriate price. 

Another oil of interest for lubricants is jojoba oil as a replacement of sperm whale oil, the use of which is now banned. Jojoba oil is not a triglyceride but is a wax ester composed mainly of straight chain esters of C20-C22 monounsaturated acids and alcohols. The major constituents, shown in Fig. 6.11, are eicosenyl and docosenyl eicosenoates, where m = 9 and n = 10, 12 ... 

Wax ester synthesis Wax ester synthase, fatty acid reductase, fatty acid elongase Jojoba Arabidopsis... 

Jojoba oil consists primarily of wax esters of the acids listed here and long-chain alcohols. Kapok oil also contains up to 15% cyclopropene acids. 

The composition of hpids on the surface of leaves, stems, and fruits is quite different from that of hpids that form intracellular membranes. Their role is the protection of sensitive plant tissues against the loss of water and other biologically important volatiles. Waxes (i.e., esters of FA with monofunctional alcohols) are the most important components of these lipids. Some plant waxes are of commercial importance, such as camauba or candellila wax. They are solid at room temperature and in temperate climates, with the exception of liquid jojoba wax, and are plastic or even liquid in tropical climates. They contain bound saturated long-chain FA and alcohols. Waxes on the surface of apples and other fruits from temperate zones are solids or semisolid pastes, consisting of terpenes, ceryl cerotate, ceryl palmitate, and other esters. In the wax from lettuce leaves, higher alcohols prevail, with only small amounts of free FA (Bakker et al., 1998). Other components, such as alkanes, ketones, esters, secondary alcohols, were detected in other vegetables (e.g., in kale or rutabaga). 

Jojoba (jojoba oil). A perennial, dioecious plant (Sim-mondsia chinensis, Buxaceae) indigenous to California and Mexico. Oil content of seeds 45-50%, protein up to 30%. J. oil mp. 6.8-7°C, bp. 389°C. J. oil is an exception among the plant oils since it does not contain triglycerides but ra er a liquid wax ester. The main components of J. oil are docosenyl eicosenoate (37 %), eicosenyl eicosenoate (24%), and eicoseny 1 do-cosenoate (11%), thus mainly wax esters with 40 and 42 C atoms. The wax esters of J. oils are very stable to oxidation (see linoleic acid) since they consist to > 95% of mono-unsaturated fatty alcohols and acids of the ffl9-series. 

Jojoba (Simmondsia chinensis) is a shrub that is native to the Sonoran desert its seed contains 50% of a liquid wax ester. The linear wax ester has a main fatty acid frag-... 

Definition Complex mixt. of esters produced by transesterification of jojoba oil and hydrogenated jojoba wax... 

Oils, jojoba, prod, with hydrogenated jojoba wax. See Jojoba esters Oils, lanolin. See Lanolin oil Oils, lanolin, 2-methylpropanoate. See Isobutylated lanolin oil Oils, mink, ethoxylated. See Mink oil PEG-13 esters... 

Isosorbide laurate Isostearamidopropyl morpholine lactate Isostearic acid Isostearyl alcohol Isostearyl avocadate Isostearyl behenate Isostearyl benzoate Isostearyl erucate Isostearyl glyceryl pentaerythrityl ether Isostearyl isononanoate Isostearyl isostearate Isostearyl lactate Isostearyl myristate Isostearyl neopentanoate Isostearyl octanoate Isotridecyl cocoate Isotridecyl isononanoate Isotridecyl myristate Japan (Rhus succedanea) wax Japan wax, synthetic Jojoba alcohol Jojoba esters Jojoba (Buxus chinensis) oil Jojoba oil, synthetic Jojoba wax... 

Elongation of fatty acids is important in two commercial oil seeds, rape and jojoba. Most varieties of rape accumulate large quantities of d5-13-docosenoic (erucic) acid in their seed triacylglycerols. This is formed by elongation of oleic acid and the reactions have been studied in rape and the closely related Crambe abyssinica (Appleby etaL, 1974). Elongation in jojoba (which accumulates lipid as wax esters) uses a system with oleoyl-CoA and malonyl-CoA as substrates. The enzymes involved have been studied in jojoba and other plants where very-long-chain fatty acids are synthesized (Pollard and Stumpf, 1980). 

Wax esters from jojoba (Simmondsia chinensis, Simmonds-iaceae) consist of molecules with mostly C20 acid (monoene) esterified with about an equal mixture of C20 and C22 alcohols (monoene) (Yermanos, 1978 1981 Miwa, 1971). In studies of the biosynthesis of the fatty acids and alcohols in slices of fresh jojoba cotyledons, a radioactive label from glucose was incorporated into all carbons of both the C20 and C22 acids and alcohols. In contrast, exogenous acetate was used almost entirely for chain elongation from endoge-... 

For the last several years, there has been much interest in jojoba, Simmondsia chinensis, a plant native to the southwestern United States and Mexico, because of the presence of liquid wax esters in the seeds (Wisniak, 1988). Numerous schemes to convert desert land into orchards of these plants have been proposed. The oil is an excellent lubricant, has good emollient properties, and may replace sperm whale oil for many uses. As the fatty acid combination of Limnanthes douglasii (meadowfoam, Limnanthaceae) is quite similar to that of jojoba, the synthesis of a similar wax ester by hydrolysis and reduction followed by esterification has been proposed (Miwa and Wolff, 1962). 

Pollard, M. R., J. B. Ohlrogge, and P. K. Stumpf, Wax ester formation in the developing jojoba seed, in Proceedings of the 3rd International Conference on Joboba, (D. M. Yermanos, ed.), 71-81, International Committee on Jojoba and the Dept, of Botany and Plant Science, University of California Press, Riverside, 1978. 

The in vivo data of Ohlrogge et al. (1978a) with developing jojoba cotyledons and of Pollard et al. (1979) with extracts of these tissues are equally compelling. These workers clearly showed that under m vivo conditions only [ CJoleic acid was the precursor of the four principal components making up the wax esters in this tissue, namely, c/s-ll-eicosenoic acid, c/s-13-docosen-oic acid, c/ -l 1-eicosenol, and cw-13-docosenol, and that [ K ]oleic acid was synthesized de novo in a compartment of the cell other than where the modifications of oleic acid occurred (see Section IV,3). 

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