Donald M. Sand

Furanoid fatty acids from fish lipids

Fatty acids, recently reported as constitutents of certain fish lipids, were identified to be derivatives of furan (furanoid fish fatty acids). 12,15-Epoxy-13,14-dimethyleicosa-12,14-dienoic acid is predominant among the furan acids and is associated withbis-homologs in regard to chain length. Monomethyl acids, such as 12,15-epoxy-13-methyleicosa-12,14-dienoic, are present in appreciable amounts. The structures were concluded from oxidative degradations, from mass spectrometry of methyl esters of the novel acids and fatty acids derived from them by opening the ring, and from nuclear magnetic resonance, infrared, and Raman spectra. The results from chemical procedures and from spectrometric methods were in aggreement with those obtained with authentic methyl 9,12-epoxyoctadeca-9,11-dienoate. The number of substituents at the furan ring greatly influences hydrogenation, hydrogenolysis, and hydrolysis reactions of the ring.

Retroconversion of docosahexaenoic acid in the rat.

Abstract 1. 1. Uniformly 14 C-labeled 4,7,10,13,16,19-docosahexaenoic acid was fed to normal rats and to rats at two stages of essential fatty acid deficiency. All groups incorporated about 17% of 14 C fed into liver lipids. Normal rats retroconverted the hexaenoic acid to 7,10,13,16,19-docosapentaenoic and 5,8,11,14,17-eicosapentaenoic acids. These three acids were in phospholipids and, to about 20%, in triglycerides. The deficient rats retroconverted the hexaenoic acid to a much lesser extent and radioactivity in their triglycerides was much lower. 2. 2. The radioactivity in the carboxyl groups of 4,7,10,13,16,19-docosahexaenoic and 5,8,11,14,17-eicosapentaenoic acids corresponded closely to an even distribution of 4 C in the chain. However, radioactivity in the carboxyl group of 7,10,13,16,19-docosapentaenoic acid was much lower than calculated for even distribution. At least 75% of this acid must have been reconstituted from a C 20 chain.

Retroconversion of polyunsaturated fatty acids in vivo by partial degradation and hydrogenation

Abstract 1. 1. 4,7,10,13,16-Docosapentaenoate, randomly labelled with 14C was given to fat deficient rats. After 10 h about 13% of the radioactivity of all liver fatty acids was located in 5,8,11,14-eicosatetraenoic (arachidonic) acid. 2. 2. Degradation of the arachidonic acid by decarboxylation and by ozonization showed that random labelling has been maintained in the course of the conversion. Therefore, the retroconversion of the pentaenoic into the tetraenoic acid must imply, besides degradation by not more than two carbon atoms, the biohydrogenation of the double bond closest to the carboxyl group. 3. 3. Known procedures for decarboxylation of acids with HN3 + H2SO4 have been modified and a method has been developed for measuring the molarity of CO2 in hyamine + CH3OH on small scale. This permits convenient measurement of the molar activity of 14CO2 by scintillation counting.

Catabolism of fish furan fatty acids to urofuran acids in the rat

A mixture of long-chain furan fatty acids was prepared as methyl esters from testes lipids of Northern pike (Esox lucius). Upon feeding these esters to rats, dicarboxylic acids, which still contained the furan structure, were found in the urine. The first phase of a rapid but incomplete catabolism is beta-oxidation of the proximal chain of the furan fatty acids. It proceeds to a distance of three carbon atoms from the ring. omega-Oxidation of the terminal alkyl chain, followed by alpha-oxidation gives rise to a second alkylcarboxyl chain with five carbon atoms or less. The ring methyl substituents of the precursor acids seem to be more resistant to oxidation than the alkyl substituent with three or five carbon atoms. The urinary catabolites from furan fatty acids in the rat are similar to furan acids found in human urine, but only one of the structures occurs in both sources.

A new group of essential fatty acids and their comparison with other polyenoic fatty acids

Abstract 1. 1. Polyenoic C 17 , acids, mainly 9,12-heptadecadienoic and6,9,12-heptadecatrienoic with some 6,9,12,15-heptadecatetraenoic; polyenoic C 16 acids, mainly 9,12-hexadecadienoic and 6,9,12-hexadecatrienoic; and 10,13-nonadecadienoic acid were fed as methyl esters for 50 days to fat-deficient rats and their effects on fat deficiency symptoms were compared with those of linoleic acid and of fat-free diet. 2. 2. The polyenoic C 17 , acids cured the external symptoms nearly as well as linoleic acid. Weight gain and food efficiencies were equal with both acids. Accordingly, fatty acids derived from 9,12-heptadecadienoic acid have essentiality similar to those derived from linoleic acid. The triene/tetraene ratio in liver lipids is applicable as index of essential fatty acid nutrition when modified from 5,8,11-eicosatrienoic/ arachidonic to 5,8,11-eicosatrienoic/5,8,11,14-nonadecatetraenoic acids. 3. 3. Deficiency symptoms increased with polyenoic C 16 and 10,13-nonadecadienoic acids as with the fat-free diet. 4. 4. Fatty acids of the liver were analyzed. 9,12-Heptadecadienoic acid is converted up to 4,7,10,13,16-heneicosapentaenoic acid with 5,8,11,14-nonadecatetraenoic being prominent. Similarly, 6,9,12,15-heptadecatetraenoic acid is converted up to 4,7,10,13,16,19-heneicosahexaenoic acid. Conversion products from other unusual dietary acids were identified but are very minor in amount. 5. 5. Acids which converted readily were also essential and acids which converted only to a minor extent were not essential. Conversion and essentiality may require the same double-bond structure and both properties may be functionally correlated. However, such hypothesis can still be disputed since the essentiality of isomers of arachidonic and similar acids is not yet known.

The polyunsaturated alcohols in wax esters of fish roe

duced by direct inlet. At a higher voltage (70 ev), when there was a greater degree of fragmentation, the intensity of this ion was reduced (25-35%). The base peak observed at 70 ev was m/e = 57 (C4H9+). The pyrolysis GLC-MS of dipalmitoyl phosphatidyl ethanolamine gave rise to the same mass spectrum observed from dipalmitin and dipalmitoyl lecithin. The same generalized fragmentations were observed from the GLC-MS of 1,3-dilaurin, 1,3-dimyristin, 1,3-distearin and 1-palmitoyl-3-stearin. In no case was a molecular ion observed; only the ion corresponding to M-18 was found. One would expect that lysophosphatidyl compounds would also pyrolyze to the corresponding monoglyceride moiety. Accordingly, 1 monopalmitoyl phosphatidyl choline, when subjected to the pyrolysis conditions previously outlined, yielded a product with the same mass s p e c t r u m as t h a t o b t a i n e d f r o m 1-monopalmitin. These spectra exhibited the same base peak at m/e 98. The same characteristic spectra were also obtained from a homologous series of 1-monoglycerides (C12 C l g ) including l-monoolein. Under identical GLC conditions no pyrolysis of sphingomyelin was observed. Since the C-O bond in the phosphate ester is somewhat weaker (85 Kcal/mole) than the O-P bond (95 Kcal/mole), its preferential destruction on pyrolysis of phosphoglycerides is to be expected. These pyrolysis products would give rise to the same compounds as the corresponding dehydrated diglycerides, namely the diacyl esters of propenediol.

Syntheses of radioactive furan fatty acids

A novel route for the synthesis of naturally occurring furan fatty acids with particular emphasis on labeling with14C is described. Methyl [2-14C] 9-(5-pentyl-3,4-dimethyl-2-furyl)nonanoate was synthesized from 3,4-dimethyl-2-pentylfuran by a new route. [3-14C]11-(5-Pentyl-3-methyl-2-furyl)undecanoate and [2-14C] 9-(5-pentyl-2-furyl)nonanoate were prepared from their lower homologs. The label was introduced in all cases by means of the Arndt-Eistert method for chain elongation, using14CH2N2. Comparisons of yields show that, with increasing number of substituents on the ring, the furan compounds are increasingly subject to uncontrollable side reactions.

Inhibition of blood platelet aggregation by dioxo-ene compounds.

Compounds with a conjugated oxo-ene-oxo system were tested for inhibition of blood platelet aggregation. All compounds with this structure in trans configuration were effective inhibitors of aggregation induced by thrombin and by arachidonic acid. While the oxo-trans-ene-oxo system is prerequisite for such activity, other structural features of the compounds may be varied without loss of activity. Inhibition is exemplified by 9,12-dioxo-trans-10- and 10,13-dioxo-trans-11-octadecenoic acids and their methyl esters, by 11,14-dioxo-trans-12- eicosenoic acid, by 4,7-dioxo-trans-5- decene and by trans- dibenzoylethylene . The half-inhibition concentrations are in the order of 2-6 microM, with complete inhibition at 8-20 microM. According to experiments with the inhibiting 9,12-dioxo-trans-10-octadecenoic acid, the normal oxygenation of exogenous arachidonic acid by platelets is not affected but the thrombin-induced internal release of this acid seems to be abolished by the inhibitor. The inhibition of aggregation in the presence of exogenous arachidonic acid and its products suggests that the inhibitor also interferes with other events leading to aggregation. By implication from other properties of the oxo-trans-ene-oxo system, reaction with SH groups may be a mechanism for inhibition.

Oxidation of fatty alcohols to acids in the caecum of a gourami (Trichogaster cosby)

Oxidation of fatty alcohols to acids in gourami caeca was investigated by measuring the reduction of NAD+ and the formation of labeled hexadecanoic acid from [1(-14)C]hexadecanol. Virtually all dehydrogenase activity is in the microsomal fraction. Maximal activity is obtained with NAD+ as cofactor whereas with NADP+ 60% of that activity is obtained. The enzyme is rather specific for long chain alcohols and 2 NADH are formed for each molecule of hexadecanol oxidized to acid. It is stabilized by mercaptoethanol, and completely inhibited by p-chloromercuribenzoate. The activity is optimal at pH 9.5. At higher pH, small amounts of aldehyde are found. The first reaction in the sequence, fatty alcohol leads to aldehyde leads to acid seems to occur under the more physiological condition at a much slower rate than the second reaction so that free aldehyde is not detected. Addition of palmitic acid indicated an uncompetitive product inhibition. The oxidation of alcohol to acid is reversible only to a very minor extent even in the presence of NADPH, CoA, ATP and Mg2+. Location, activity and properties of the enzyme are in agreement with the earlier observation from dietary experiments that in the gourami fatty alcohols of wax esters are oxidized to acids in the course of absorption.

Nonconversion of 5,11,14-eicosatrienoic into arachidonic acid by rats

Methyl ester of [U-14C]5,11,14-20∶3 was administered to essential fatty acid deficient rats. In contrast to a report by Takagi, it was found that the trienoic acid was not converted into arachidonic acid.