From anacardic acid

Since cardanols can be obtained from anacardic acids and cardols from orsellinic acids, the methods outlined have a general applicability to a range of phenolic lipids. Reference has been made largely to the phenols of the Anacardiacae but the methods are likely to be applicable to other phenolic systems, and those with methylene-interrupted structures at different side-chain positions. Alkynes and phosphorans have both proved invaluable in synthetic studies but attention should be drawn to the very elegant use of ailenic compounds in the polyethenoid (arachidonic) series (ref. 168) which has a potential application with phenolic lipids. Methods for the synthesis of leukotrienes are also relevant for the methylene group-interrupted structures of phenolic lipids (169). 

Reduction of isoanacardic aldehyde gave a methylol which could also be synthesised directly from cardanol together with formation of some of the 4,6-bis-methylol. The monomethylol compound isoanacardic alcohol was an effective solvent extractant for the borate anion (ref. 279, 293). The isomeric compound, anacardic alcohol (ref. 88) was similarly obtained from anacardic acid (ref. 180). This In conjunction with the teriary amine Aliquat 336 was highly effective for the solvent extraction of the borate anion (ref. 293). Both these substances were comparable in properties to the 2,6-bis(hydroxymethyl) derivatives of 4-t nonylphenol and to 4-t octyl-2-chloro-6-hydroxymethylphenol (ref. 294). 

Several small molecule modulators (SMM) of p300 and PCAF have been developed (Varier et al, 2004). Recently, the first naturally occurring HAT inhibitor anacardic acid was isolated from cashew nut shell liquid, which inhibits the HAT activity of both p300 and PCAF very effectively (Balasubramanyam et al, 2003). By using anacardic acid as a synthon, an amide derivative of anacardic acid, CTPB, has been synthesized, which is the only known small molecule activator of any histone acetyltransferase, in this case, p300. However, cells are impermeable or... 

Castillo-Juarez 1, Rivero-Cruz F, Celis H. (2007) Anti-Helicobacter pylori activity of anacardic acids from Amphipterygium adstringens. J Ethnopharmacol 114 12-11. 

Contradictory results were obtained from studies with berKamide analogs of anacardic acid. While CTPB 4 (Figure 11.2) was reported to be an activator of p300 [13], the related cyano-benzamides S and 6 (Figure 11.2) aded as cell-permeable inhibitors of p300, exhibiting a similar profile to anacardic acid [15]. 

In the phenolic lipids such as the alkylphenols from Anacardium occidentals, semi-synthetic transformations have been described which exploit the functionality of the component phenols, cardanol, cardol and anacardic acid (ref. 104). A number of reactions are shown for... 

AR occur in cashew nut shells as a fraction of other oil components like cardols, cardanols and anacardic acid. A comparative study on the extraction of cashew nut shell liquid (CNSL) was presented by Shobha and Ravindranath (50). The study involved the extraction of the cashew nut shell by supercritical CO2 or pentane. The pentane extraction was carried out on 50g steamed or fresh cashew nut shells in lOOmL solvent. Supercritical CO2 extraction was performed on 300g freshly broken cashew nut shells at 25 MPa and 40 C with the CO2 flow kept at 4-5Kg/h for 17,5h with extract collection every 2.5h. The resorcinolic lipid fraction obtained by supercritical CO2 represented 82% of the equivalent obtained by pentane extraction of fresh cashew nut shells and 70% of the extraction of steamed material. Despite this appreciable variation on the ratio of the total cardols and cardanols from one mediod to other, the relative proportion of the enomers in each group was very similar (50). Generally, the extraction yield obtained by supercritical CO2 was lower (= 60%) than that obtained by the classical solvent extraction methods (50), however, the product was nearly colorless. One of the major problems in the industrial application of CNSL is the very dark brown color of the solvent extracted product. 

Alkylphenols with long alkyl groups have been identified from many plants [91]. Anacardic acids (Ginkgolic acids) are the most intensively... 

Subsequently, this approach to the synthesis of C15 phenolic lipids consisted in the route ArCi - ArCis. It has proved generally convenient for the synthesis of the unsaturated anacardic acids. From the methodological view it is also an aspect of the use of acyclic intermediates discussed in the next section since the starting material ethyl 2-methoxy-6-methylbenzoate is prepared from ethyl acetoacetate. 

The first synthesis modelled on biomimetic lines was directed to obtaining anacardic acids by way of polyketides [237] and later to a (17 l)-orsellinic acid [43]. A less complicated approach based on the Michael addition of ethyl acetoacetate and ethyl octadec-2-enoate, has led to a C15 orsellinic acid, Fig (4)-56, 2,4-dihydroxy-6n-pentadecylbenzoic, considered to be the biogenetic precursor of the cashew phenols [238], notably cardol, by decarboxylation. The use of bromine at the aromatisation stage in this synthesis precluded the extension of the method to components with unsaturated side-chains, although bromination with copper(ii)bromide and thermal debromination offers an alternative procedure. In a more recent approach, by the use of an oxazole intermediate and its addition to ethyl acetoacetate, (15 0) and (15 1) anacardic acid have been obtained [239] as shown in Scheme 5a, b. The 8(Z),1 l(Z)-diene and 8(Z),1 l(Z),14-triene have also been synthesised [240] by way of ethyl 6-(7-formylheptyl)-2-methoxybenzoate (C), prepared from acyclic sources, rather than, as in previous work, by semisynthesis from the ozonisation of urushiol. 

Antimicrobial base materials formulated with metal and amine salts of anacardic acid, said to be non-irritative, have been proposed for cosmetic use [270]. It is of interest that anacardic acid and 2(E)-hexenal isolated from the cashew apple to which the pendant kernel (the external seed) is attached have been found to exhibit antibacterial activity against the Gram-negative bacterium, Helicobacter pylori, which is considered to cause acute gastritis [271]. The same compounds also inhibit the enzyme urease. 

Antialgal activity, termed zoosporicidal activity or antagonism to the asexual spores of certain algae and fungi, for example of the phytopathenogenic organism, Aphanomyces cochliodes by anacardic acids from unripe Ginkgo biloba fruit has been studied [18] and found to lead to motility inhibition and lysis of the zoospores. 

The most significant developments in biological uses of anacardic acids have been in studies of specific inhibitive action towards enzymes. Thus for example, the action of P-lactamase which cleaves the four-membered ring in penicillins, was specifically inhibited by (15 3)-anacardic acid obtained from Spondias mombin [45,278][68,69]. This botanical source is a little known member of the Anacardiaceae [279]. 

Of the (13 0), (15 1), (17 1), and (17 2)-anacardic acids, the (17 2) is the most active inhibitor [280] of glycerol 3-phosphate dehydrogenase (GPDH) and nearly comparable in action to the adipostatins [201,281 ][72], (15 0)-cardol derivatives, potentially of interest in human obesity studies. Inhibition of lipid biosynthesis in bacteria, yeast and animal cells by anacardic acids from Ginkgo biloba has also been reported by the same authors [282]. 

In the marine environment there has been the first reported occurrence of so-called antifouling (namely, anticrustaceous activity) by (15 0)-anacardic acid. Thus bioassay-directed fractionation of the dichloromethane extract from twigs of Ozoroa insignis containing the phenolic lipid, was used with larvae from Artemia salina as a model to investigate the activity [296]. 

Medium within 60 min (Fig. lOd). Zoosporicidal activities of other two commercial tannins, Quebracho and Mimosa were similar to that of Lannea tannin. In contrast, 22 lw7-anacardic acid (27) isolated from the Ginkgo biloba caused shrinkage of zoospores followed by bursting at a single point of each spore without forming any characteristic fragmentation of cellular materials [104]. 

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