Ethanolamides, fatty acid

Cannabinoid structure-activity requirements (SAR) literature has primarily focused on CBj-receptor affinities of fatty acid ethanolamides, such as AEA and its analogs. Recently, however, Sugiura has begun to develop an SAR for 2-AG and its analogs based on a functional assay of Ca + mobilization (Sugiura et al., 1999 Sugiura and Waku, 2000). Because of their difference in basis, each of these SARs will be presented separately here. 

Endocannabinoid SAR at the CB receptors can be divided into studies of head group- and acyl chain requirements for high-affinity binding. 

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In addition to anandamide, several other endogenous polyunsaturated fatty acid derivatives were also found to act as cannabimimetics. They are all now collectively referred to as endocannabinoids. Soon after the discovery of anandamide, two more fatty acid ethanolamides were isolated and found to bind to CB1 preparations with affinities similar to that of anandamide (anandamide CB1 binding affinity K = 39.2 nM, according to Hanus et al., 1993). These were the homo-y-linolenylethanol-amide (CB1 K[ = 53.4 nM) and 7,10,13,16-docosatetraenylethanolamide (CB1 K[ = 34.4 nM) (Fig. 2). All three V-acylethanolamide endocannabinoids were found to be CB1 agonists in the MVD test (Pertwee, 1994). 

Hanus L, Gopher A, Almog S, Mechoulam R. Two new unsaturated fatty acid ethanolamides in brain that bind to the cannabinoid receptor. J Med... 

Pertwee RG, Griffin G, Hanus L, Mechoulam R. Effects of two endogenous fatty acid ethanolamides on mouse vasa deferentia. Eur J Pharmacol 1994 259 115-120. 

Our research group expected that additional polyunsaturated fatty acid ethanolamides may be present in the brain. We also identified in porcine brain another two putative endocannabinoids, namely homo-y-linoleoylethanolamide (K = 53.4 5-5 nM) and 7,10,13,16-docosatetraenoylethanolamide (K = 34.4 3.2 nM). The isolation of these two compounds as constituents of porcine brain that bind to the cannabinoid receptor demonstrated that anandamide is not the sole representative of this class of potential mediators. 

Besides serving as biological precursors for fatty acid ethanolamides (FAEs), NAPEs have been recently shown to play a physiological role on their own, reducing food intake and arousal after a fat-containing meal (Gillum et al., 2008). 

At 140 to 160°C, the fatty acid can react 1) with the amino group on the EOA to form a fatty acid ethanolamide, 2) with the hydroxyl group on the EOA to give a fatty acid aminoethyl ester or 3) with both groups to form a di-fatty acid ethanolamide ester46. 

Figure 5.3 Bioactive fatty acid ethanolamides in porcine brain.

Berdyshev EV, Boichot E, Germain N, AUain N, Anger J-P, Lagente V (1997) Influence of fatty acid ethanolamides and A -tetrahydro-cannabinol on cytokine and arachidonate release by mononuclear cells. Eur J Pharmacol 330 231-240. 

The manufacture of fatty acid ethanolamides can start from a fatty acid or from the ester, acid chloride or acid anhydride, which is reacted with a monoethanolamine or diethanolamine. Industrially, fatty acids or fatty acid esters are exclusively used. In general, the procedure followed is to take one component and add the other component dropwise. Thereafter the mixture is heated to 130 to 180° and one mol of water or if using the fatty acid ester, one mole of alcohol is driven off per mol of acid. 

Modification of 5-HT2 receptor mediated behavior in the rat by Oleamide and the Role of Cannabinoid Receptors. Neuropharmacol 1999 38 533-541. Chemische Fabrik Verfahren zur Darstellung labiler unsymmetrischer Alka-mine der cyclischen Acetonbasen auf elektrolytischem Wege 1898 DE 96362 Chemische Werke Huls Aktiengesellschaft Process for the Manufacture of Fatty Acid Ethanolamides 1975 GB 1,384,471... 

Burstein and Hunter (1995) observed that THC stimulated the biosynthesis of anandamide in neuroblastoma cells employing either ethanolamine or arachidonic acid as the label. Anandamide bios5mthesis has also been shown to occur in primary cultures of rat brain neurons labelled with [H]-ethanolamine when stimulated with ionomycin, a Ca ionophore (Di Marzo et al. 1994). These authors proposed an alternate model for the biosynthesis of anandamide in which N-arachidonoyl phosphatidyl ethanolamine is cleaved by a phospholipase D activity to yield phosphatidic acid and ararchidonoylethanolamide. This model is based upon extensive studies undertaken by Schmid and collaborators (1990), who have shown that fatty acid ethanolamide formation results from the N-acylation of phosphatidyl ethanolamine by a transacylase to form N-acyl phosphatidylethanolamine. Possibly resulting from postmortem changes, this compound is subsequently hydrolyzed to the fatty acid ethanolamide and the corresponding phosphatide by a phosphodiesterase, phospholipase D. 

Interestingly, the enzymatic activities found for anandamide amidase may be related to those reported in the literature for the hydrolysis of other fatty acid amides. Bachur and Udenfriend (1966) and Schmid and colleagues (1990) described a rat liver microsomal enzyme that hydrolyzed fatty acid ethanolamides. Natarajan and colleagues (1984) described activity in a dog brain microsomal fraction that hydrolyzed... 

Light stains on a wool fabric were identified as a mixture of mineral oil (using TLC) and fatty acid ethanolamide (using IRS). Such mixtures are used as antifoaming agents. 

Berdyshev et al. (1997) examined the effects of anandamide, palmitoylethanolamide and THC on the production of TNF-a, IL-4, IL-6, IL-8, IL-10, IFN-y, p55, and p75 TNF-a soluble receptors expressed by stimulated human peripheral blood mononuclear cells as well as [ H]-arachidonic acid release by non-stimulated and N-formyl-Met-Leu-Phe (fMLP)-stimulalcd human monocytes. Anandamide diminished IL-6 and IL-8 production at low nanomolar concentrations and inhibited the production of TNF-a, IFN-y, IL-4, and p75 TNF-a soluble receptors at higher concentrations (i.e., micromolar levels). Palmitoylethanolamide inhibited IL-4, IL-6, and IL-8 synthesis and the production of p75 TNF-a soluble receptors at concentrations similar to those of anandamide but did not affect TNF-a and IFN-y production. Neither anandamide nor palmitoylethanolamide influenced IL-10 synthesis. THC, on the other hand, exerted a biphasic effect on pro-inflammatory cytokine production. TNF-a, IL-6, and IL-8 synthesis was inhibited maximally by 3 nM THC but stimulated by 3 pM THC. A similar effect was observed for IL-8 and IFN-y. The level of IL-4, IL-10, and p75 TNF-a soluble receptors was diminished by 3 pM THC. [ H]-Arachidonate release was stimulated only by high THC and anandamide concentrations. Based on these observations, the investigators suggested that the inhibitory properties of anandamide, palmitoylethanolamide, and THC are determined by the activation of peripheral-type cannabinoid receptors (i.e., CB2) and that various endogenous fatty acid ethanolamides also participate in the regulation of the immune response. 

Fatty acid ethanolamides and isopropanolamides are solid or waxy products insoluble in water. Diethanolamides are usually pastes or liquids and show better dispersibility in water. In institutional and household formulations, shampoos, bath and shower preparations, fatty alkanolamides play the role of foam stabiliser, thickener, corrosion inhibitor, and ancillary agent that improves the skin compatibility of anionic surfactants. Undecylenic ethanolamide and undecylenic diethanolamide act as fungicides also [47]. Use of diethanolamine derivatives has legislative limitations today in some countries (but not its amides) because they are proved to be precursors of carcinogenic nitrosoamines. The probability of the nitrosoamine formation is assumed to increase in the presence of formaldehyde and formaldehyde-releasing preservatives [44-46]. 

FIGURE 2.4 Conformational memories (CM) results for a series of fatty acid ethanolamides [22 4,... 

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