Methyl sterculate

Synthesis of methyl sterculate (3, 255). Williams and Sgoutas3 have shortened Gensler s synthesis of methyl sterculate (3) by direct decarbethoxylation of one... 

Methylpodocaipic acid, 42 Methyl propiolate, 547 Methyl propynoate, 220 N-Methylpyrrolidine, 345, 355,462,463 Methyl sterculate, 436 a-Methylstyrene, 493 /3-Methylstyrene, 71, 292 Methylsuccinic anhydride, 357... 

In the case of the 1,2-diiodidc 3, derived by adding iodine to methyl sterculate, the elimination of halogen to give 4 was achieved using aqueous potassium hydroxide, although only in low yield ( 20%). ... 

Decarbonylation of cyclopropene acids. In a study of the synthesis of methyl sterculate (6) from methyl stearolate (1), Gensler et al.1 were unable to repeat the apparently straightforward synthesis based on addition of the Simmons-Smith reagent described in 1, 1021-1022. They were also unable to eifect addition of methylene generated by cuprous bromide decomposition of diazomethane. However, the reaction of (1) with diazoacetic ester in the presence of copper bronze, followed by hydrolysis, gives the cyclopropene diacid (2) in 70-90% yield. 

The reaction of methyl stearolate (1) with diazoacetic ester in the presence of copper bronze produces a diester, which is hydrolyzed to the diacid (2). This is converted into the diacid chloride (3). Treatment with zinc chloride or other Lewis acid effects selective decarbonylation to give the cyclopropenium ion (4). Methanol is then added to convert the acid chloride grouping into the methyl ester (5). Finally reduction with sodium borohydride gives methyl sterculate (6). 

The synthesis of a novel cyclopropyl analog of arachidonic acid [7] via a convergent synthesis that employed methyl (lR,25)-2-formylcyclopropane-carboxylate in conjunction with the ylide from (3Z,6Z)-pentadeca-3,6-dienyl(triphenyl)-phosphonium iodide was reported (62). A new approach to cyclopropene fatty acids has been developed for the synthesis of methyl sterculate [8] and methyl 2-hydroxy-sterculate this involves the 1,2-deiodination of 1,2-diiodocyclopropanes with butyllithium at low temperature (63). The synthesis of deuterated cyclopropene fatty esters structurally related to palmitic and myristic acids has been reported (64). 

Methods of determining cyclopropene acids continue to be developed (Fisher and Schuller, 1981 Vickery, 1980). Methyl malvalate and methyl sterculate have been separated by spinning band distillation (Pawlowski a/., 1981). 

Table 22. Hepatocarcinoma Incidence in Trout Fed Aflatoxin B] and and Methyl Sterculate (MS) ...

R.gracilis was grown at either 15 or SO C In N-limiting media (+/- methyl sterculate) in baffled shake flasks in an orbital incubator operating at 150 r.p.m. [2]. Stationary-phase cultures were harvested by centrifugation, freeze-dried and lipids extracted [3]. Individual lipid classes were separated by t.I.c. and analysed by g.I.c. [2]. 

Methyl sterculate and methyl malvalate were prepared from trans-esterified Sterculia foetida oil by a combination of urea clathration and reverse phase HPLC [8]. The methyl esters were added to cultures of Ustilago maydis (DC) Cda. and Fusarium oxysporum Schlecht in small quantities of methanol. Control cultures received methanol alone. 

The synthesis of labelled and unlabelled methyl malvalate (20) and methyl sterculate (21) has attracted attention. In the best known route an acetylenic... 

Methyl sterculate (21) was also obtained from methyl stearolate (18 1 9a), albeit in lower yield ( 10%), by irradiation in the presence of diazomethane. ... 

Acyl Lipid Metabolism in Rhodotorula gracilis (CBS 3043) and the Effects of Methyl Sterculate on Fatty Acid... 

ACYL LIPID METABOLISM IN RHODOTORULA GRACILIS (CBS 3043) AND THE EFFECTS OF METHYL STERCULATE ON FATTY ACID DESATURATION... 

Table 1 Effect of Methyl Sterculate on the Fatty Acid Composition of the Major Acyl Lipids in R. gracilis... 

R gracilis was grown for 24hrs (stationary phase) in N-llmlted media methyl sterculate (Ijxl/ml of culture. Methyl sterculate = 84% pure). Results are means (n=3). 

Table 2 The Effect of Methyl Sterculate on the Incorporation of Labelled Acetate and Ammonium Stearate Into C g Unsaturated Acids of R gracilis...

The acyl compositions of the phospholipids and of the trlacylglycerol pool were determined for R. gracilis grown in a N-llmlted media containing methyl sterculate. In all of the acyl lipids studied (Table 1), the oleate content was observed to fall and that of stearate rise. Indicating inhibition of the A9 desaturase. In addition, the relative proportion of llnolenate In these acyl lipids was increased. This Increase In llnolenate was most pronounced in the phospholipids, and In phosphatidylcholine, llnolenlc acid was found to be the major fatty acid present. 

The effects of methyl sterculate on R gracilis were also studied via the use of (l- C]acetate and ammonium [ 1- C]stearate as possible precursors for oleic acid synthesis (Table 2). When labelled stearate was the precursor molecule, methyl sterculate was able to decrease the conversion of stearate to oleate from approximately 40% to 4%, whilst In samples In which (1- x]acetate was the precursor, very little Inhibition was observed. Such evidence Implies that the conversion of acetate to oleate Is by a route which Is not susceptible to sterculate Inhibition. Similar observations have been reported for both plant and mammalian" desaturase systems. 

In work performed by Jeffcoat and Pollard, the Inhibitory form of stercullc acid In mammalian tissue was reported to be sterculoyl-CoA. If this Is also true for R. gracilis, we may tentatively propose that the alternative route of oleic acid synthesis In the presence of methyl sterculate Is via a A9 desaturase system that Is capable of desaturatlng stearate when attached to a complex lipid. Further desaturation of phospholipid substrate to llnoleate and then llnolenate would explain the lack of sterculate Inhibition of the latter s S3rnthesls. These possibilities are being Investigated. 

---