Fatty acid derivatives, functionalization

Fatty acid and fatty acid derivatives function as signaiing moiecuies... 

Hydroformylation is the process of coupling carbon monoxide to an olefin with a reductive catalyst and hydrogen to produce an aldehyde-functionalized substrate. This coupling is typically followed by hydrogenation to produce a primary hydroxyl group. Several academic and commercial programs have participated in the development of hydroformylated triglycerides and fatty acid derivatives for use in polyurethanes. Two main processes for the hydroformylation of seed oils have been utilized. 

In the fatty acid derivatives (Chart 8.3.FA/PO), the identity of prostaglandins from gorgonians and alcyonaceans in the sea, and mammals on land, has stimulated much experimentation (Varvas 1994) and computer calculations (Hess 1999). Although it is expected that biosynthetic routes in the sea differ from land because of the large phylogenetic distances of the organisms and the different functions of the metabolites at issue (Pietra 1995), details about the biosynthetic pathways are still to come (Varvas 1994). 

TEicosanoids are paracrine hormones, substances that act only on cells near the point of hormone synthesis instead of being transported in the blood to act on cells in other tissues or organs. These fatty acid derivatives have a variety of dramatic effects on vertebrate tissues. They are known to be involved in reproductive function in the inflammation, fever, and pain associated with injury or disease in the formation of blood clots and the regulation of blood pressure in gastric acid secretion and in a variety of other processes important in human health or disease. 

Yet another variant for the metabolism of arachi-donic acid is the formation of leukotrienes, a series of fatty acid derivatives with a conjugated triene functionality, and first isolated from leukocytes. In a representative pathway (others have... 

The ene-yne CM of fatty acid-derived terminal alkenes with several alkyne derivatives was shown by Bruneau et al. [75], These reactions, which led to renewable conjugated dienes, were performed in a one-pot two-step procedure. In the first step, the ethenolysis of methyl oleate was performed in the presence of the first-generation Hoveyda-Grubbs catalyst (2.5 mol%) using dimethyl carbonate as solvent at room temperature. After completion of the ethenolysis (90% conversion), C4 (1 mol%) and the corresponding alkyne (0.5 equivalents with respect to olefins) were added and the reaction was run at 40°C for 2 h (Scheme 9). The desired dienes were thus obtained in high yields close to the maximum theoretical value (50%). Moreover, in order to maximize the formation of functional dienes, the same reaction sequence was applied to the diester obtained by SM of methyl oleate. In this way, the yield of functional dienes was increased up to 90% depending on the... 

Prostaglandins are fatty acid derivatives that are even more powerful biochemical regulators than steroids. They are called prostaglandins because they were first isolated from secretions of the prostate gland. They were later found to be present in all body tissues and fluids, usually in minute quantities. Prostaglandins affect many body systems, including the nervous system, smooth muscle, blood, and the reproductive system. They play important roles in regulating such diverse functions as blood... 

Certain pathological conditions can lead to a life-threatening rise in the blood levels of the ketone bodies. Most common of these conditions is diabetic ketosis in patients with insulin-dependent diabetes mellitus. The absence of insulin has two major biochemical consequences. First, the liver cannot absorb glucose and consequently cannot provide oxaloacetate to process fatty acid-derived acetyl CoA (Section 17.3.1). Second, insulin normally curtails fatty acid mobilization by adipose tissue. The liver thus produces large amounts of ketone bodies, which are moderately strong acids. The result is severe acidosis. The decrease in pH impairs tissue function, most importantly in the central nervous system. 

The use of chemical aids and technologies to stabilize lipids also represents a need to evaluate the balance between positive attributes that may reduce the risk of exposure to dietary oxidized lipids, or alternatively, negative consesquences, such as generation of tran -fatty acids derived from selective hydrogenation of vegetable oils. This chapter is intended to update the information on topics of toxicity and safety of fats and oils described earlier (6), as they relate to (1) natural consitutents of fats and oils (2) derived products of oxidation and hydrogenation (3) occurance of natural and pollutant contaminants and (4) additives used to preserve the stability, functionality, and nutritional quality of many constituents present in fats and oils. 

Common name (systematic name in brackets). 2) Number of carbon atoms number of carbon-carbon double bonds. The systematic name of fatty acids derives from the total number of carbon atoms of the chain (for example, hexadeca for 16 atoms "octadeca for 18 atoms,...), the other numbers designing the carbon atoms bearing the carbon-carbon double bonds. For example, linoleic acid is the 9,12-Octadecadienoic acid which has 2 double bonds beared on the 9th and 12th carbon atoms, the I being attributed to the carboxylic acid function (Fig. I A). 

Recently Liu and Weller [84] have reviewed the arachidonic acid metabolism in filarial parasites and other helminths. Arachidonic acid (AA) is a 20 carbon polyunsaturated fatty acid derived from dietary fatty acids. In human tissues, AA is usually present in the esterified form such as glycerolipids, phospholipids and neutral lipids. The free AA, released by phospholipases, undergoes various enzymatic oxygenations to form local mediators such as prostaglandins and leukotrienes, which are collectively known as eicosanoids (Chart 9). These eicosanoids are associated with platelet aggregation, vasodilation, leukocyte inflammatory and immune functions and cellular adhesion [85]. 

Arthropods produce a wide range of metabolites derived from simple fatty acid or polyacetate precursors. The most well-studied fatty acid-derived natural products are no doubt the volatile sex pheromones prevalent among the Lepidoptera, although fatty acids and derivatives also function in additional roles, including defense, as well as in their recently discovered capacity as elicitors of plant defense mechanisms. Fatty acids furthermore serve as biosynthetic precursors to some important families of defensive alkaloids, such as the coccinellines and polyazamacrolides (PAMLs) (Section 2.04.6.1). As mentioned earlier, volatile pheromones are discussed in Chapter 4.04. 

The other known pathway of UFAs synthesis, by action of fatty acid desaturases, functions only in aerobic organisms, where desaturation of full-length fatty acids to unsaturated derivatives can occur (Tocher et al., 1998). 

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