Desaturation of isomeric trans-octadecenoic acids by rat liver microsomes

Mahfouz, Mahmoud; Valicenti, A.J.; Holman, Ralph T.

doi:10.1016/0005-2760(80)90047-8

Cited by 99 publications

(33 citation statements)

References 33 publications

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“…Logically, the higher level of 9c,15c-18:2 could originate from 18:3n-3 supporting the theory that winter samples came from animals fed higher levels of forages. A pathway for 18:3n-3 biohydrogenation to 9c,15c-18:2 has not yet been proposed (Destaillats et al 2005), but alternatively it could be an endogenous^9-desaturation product of 15c-18:1 (Mahfouz et al 1980). …”

Section: Muscle Compositionmentioning

confidence: 99%

Survey of the fatty acid composition of Canadian beef: Backfat and longissimus lumborum muscle

Aldai¹,

Dugan²,

Rolland³

et al. 2009

Can. J. Anim. Sci.

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. 2009. Survey of the fatty acid composition of Canadian beef: Backfat and longissimus lumborum muscle. Can. J. Anim. Sci. 89: 315Á329. A survey of Canadian retail beef was undertaken with emphasis on the trans fatty acid (TFA) and conjugated linoleic acid (CLA) isomers, and compared with current health recommendations. Thirty striploin steaks were collected in the winter and summer from major grocery stores in Calgary (Alberta, Canada). Steak fatty acid compositions (backfat and longissimus lumborum muscle analysed separately) showed minor seasonal differences with lower total saturates (PB0.05) and higher total monounsaturates (PB 0.01) in winter, but no differences in total polyunsaturated fatty acids. The ratio of n-6 and n-3 polyunsaturated fatty acid in longissimus lumborum averaged 5.8. The average TFA content in longissimus lumborum was 0.128 g 100 g(1 serving size, and 10t-18:1 was found to be the predominant isomer (32% of total trans), while vaccenic acid was second most abundant (15% of total trans). The CLA content in longissimus lumborum was similar to that of backfat, ranging from 0.43 to 0.60% of total fatty acids and rumenic acid represented 60% of total isomers. Overall, there is still room for improvement in the saturated, mono-and polyunsaturated fatty acid composition of Canadian beef to meet general dietary guidelines for human consumption and additional targets should include reducing 10t-18:1 while increasing both rumenic and vaccenic acids. Les auteurs ont entrepris une enqueˆte sur le baeuf canadien vendu au de´tail en insistant sur les isome`res des acides gras trans (AGT) et de l'acide linole´ique conjugue´(ALC), puis ils ont compare´leurs re´sultats aux recommandations actuelles relatives a`la sante´. À cette fin, ils ont recueilli trente beefsteaks d'entrecoˆte dans les principales e´piceries de Calgary (Alberta, Canada) en hiver et en e´te´. La composition en acides gras de la viande (analyse distincte du gras dorsal et du longissimus lumborum) re´ve`le de faibles variations saisonnie`res, avec une plus basse concentration totale d'acides gras sature´s (PB0,05) et une concentration plus e´leve´e d'acides gras monoinsature´s (P B0,01) en hiver, sans e´cart au niveau de la concentration totale d'acides gras polyinsature´s. Le ratio entre les AGP n-6 et n-3 dans le longissimus lumborum s'e´tablissait en moyenne a`5,8. Le longissimus lumborum was renferme en moyenne 0,128 g d'AGT par portion de 100 g et l'isome`re pre´dominant est le 10t-18:1 (32 % de la concentration totale d'AGT), l'acide vacce´nique arrivant au deuxie`me rang (15 % de la concentration totale d'AGT). Le lngissimus lumborum contient autant d'ALC que le gras dorsal, soit de 0,43 a`0,60 %, l'acide rume´nique constituant 60 % de l'ensemble des isome`res. Globalement, en ce qui concerne la composition en acides gras mono et polyinsature´s, le baeuf canadien a encore du chemin a`faire avant de respecter les directives ge´ne´rales eu e´gard a`l'alimentation humaine, et on devrait envisager de re´duire le ratio de 10t-18:1 a...

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Section: Muscle Compositionmentioning

confidence: 99%

Survey of the fatty acid composition of Canadian beef: Backfat and longissimus lumborum muscle

Aldai¹,

Dugan²,

Rolland³

et al. 2009

Can. J. Anim. Sci.

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“…Therefore for an increase in the mean melting point of long chain fatty acid precursors to occur, decreases in ruminal 18:0 outflow must be accompanied by collective increases in TFA that cannot be desaturated by SCD in the ruminant mammary gland. Studies involving incubations with rat liver microsomes demonstrated that isomers of trans 18:1 with double bonds at D4 to 7 and D11 to 15 but not D8 to 10 can serve as substrates for SCD in vitro with the extent of conversion being dependent on double-bond position (Mahfouz et al, 1980;Pollard et al, 1980) with the implication that trans-8 18:1, trans-9 18:1 and trans-10 18:1 are not desaturated in the ruminant mammary gland. Although post-ruminal infusions of trans-9 18:1 (Rindsig and Schultz, 1974;Tyburczy et al, 2008) have been shown to have no effect on lipogenesis in the lactating cow, under the specified conditions of these experiments the supply of 18:0 at the mammary gland remained unchanged, and therefore these observations do not provide a rigorous test of the possible role of lowered milk fat fluidity in the etiology of diet-induced MFD.…”

mentioning

confidence: 99%

Role of trans fatty acids in the nutritional regulation of mammary lipogenesis in ruminants

Shingfield

Bernard

Leroux

et al. 2010

Animal

333

427

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Fat is an important constituent contributing to the organoleptic, processing and physical properties of ruminant milk. Understanding the regulation of milk fat synthesis is central to the development of nutritional strategies to enhance the nutritional value of milk, decrease milk energy secretion and improve the energy balance of lactating ruminants. Nutrition is the major environmental factor regulating the concentration and composition of fat in ruminant milk. Feeding low-fibre/high-starch diets and/or lipid supplements rich in polyunsaturated fatty acids induce milk fat depression (MFD) in the bovine, typically increase milk fat secretion in the caprine, whereas limited data in sheep suggest that the responses are more similar to the goat than the cow. Following the observation that reductions in milk fat synthesis during diet-induced MFD are associated with increases in the concentration of specific trans fatty acids in milk, the biohydrogenation theory of MFD was proposed, which attributes the causal mechanism to altered ruminal lipid metabolism leading to increased formation of specific biohydrogenation intermediates that exert anti-lipogenic effects. Trans-10, cis-12 conjugated linoleic acid (CLA) is the only biohydrogenation intermediate to have been infused at the abomasum over a range of experimental doses (1.25 to 14.0 g/day) and shown unequivocally to inhibit milk fat synthesis in ruminants. However, increases in ruminal trans-10, cis-12 CLA formation do not explain entirely diet-induced MFD, suggesting that other biohydrogenation intermediates and/or other mechanisms may also be involved. Experiments involving abomasal infusions (g/day) in lactating cows have provided evidence that cis-10, trans-12 CLA (1.2), trans-9, cis-11 CLA (5.0) and trans-10 18:1 (92.1) may also exert anti-lipogenic effects. Use of molecular-based approaches have demonstrated that mammary abundance of transcripts encoding for key lipogenic genes are reduced during MFD in the bovine, changes that are accompanied by decrease in sterol response element binding protein 1 (SREBP1) and alterations in the expression of genes related to the SREBP1 pathway. Recent studies indicate that transcription of one or more adipogenic genes is increased in subcutaneous adipose tissue in cows during acute or chronic MFD. Feeding diets of similar composition do not induce MFD or substantially alter mammary lipogenic gene expression in the goat. The available data suggests that variation in mammary fatty acid secretion and lipogenic responses to changes in diet composition between ruminants reflect inherent interspecies differences in ruminal lipid metabolism and mammary specific regulation of cellular processes and key lipogenic enzymes involved in the synthesis of milk fat triacylglycerides.Keywords: milk fat, trans fatty acids, gene expression, lipogenesis, ruminants ImplicationsUnderstanding the regulation of milk fat synthesis is central to the development of nutritional strategies to enhance the nutritional value of milk, decrease milk-energ...

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“…Almost all trans-18:1 can be desaturated by D9-desaturase in vitro (except the 8t, 9t, and 10t isomers), leading to 18:2 isomers that are conjugated such as 9c,11t and 7t,9c CLA2, MI such as 9c,12t 18:2, or NMI such as 9c,13t 18:2 [28,29]. The desaturation of vaccenic acid (11t 18:1) to rumenic acid (9c,11t 18:2) by D9-desaturase was confirmed in vivo in mammary glands [30].…”

Section: Origin Of Trans Fatty Acids In Food 31 Ruminal Biohydrogenamentioning

confidence: 99%

Trans fatty acids: Definition and occurrence in foods

Ledoux

Juanéda²,

Sébédio

2007

Euro J Lipid Sci & Tech

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Most of fatty acid double bonds are in cis configuration, but some processes may isomerise double bonds from cis to trans configuration and from their naturally occurring positions in the carbon chain. Since some fatty acids with trans double bond(s) are suspected to have adverse effects, several countries have regulated the inclusion of trans fatty acid (TFA) content labelling. The French governmental authorities requested AFSSA to propose recommendations regarding food labelling. This first article summarises the discussion on a regulatory TFA definition and reviews the occurrence and origins of TFA in foods. From a chemical point of view, a TFA is any kind of fatty acid that has one or more double bond(s) in trans configuration, but restricted TFA definitions have been proposed for food labelling purposes. These definitions exclude fatty acids with conjugated double bonds on different criteria which are commented on in this paper. Taking into account the goal of TFA labelling and the potential harmful properties of some trans conjugated fatty acids, the working group proposes the chemical definition for TFA labelling purposes. The main TFA natural origin is ruminal biohydrogenation, and therefore TFA are present in dairy products and ruminant meat. TFA are also found in domestically or industrially processed foods due to hydrogenation or heat treatment effects on oils and fats. Although the TFA molecules produced by both natural and industrial processes are often quite similar, TFA distribution profiles and levels are very different from one case to another.

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Desaturation of isomeric trans-octadecenoic acids by rat liver microsomes

Cited by 99 publications

References 33 publications

Survey of the fatty acid composition of Canadian beef: Backfat and longissimus lumborum muscle

Survey of the fatty acid composition of Canadian beef: Backfat and longissimus lumborum muscle

Role of trans fatty acids in the nutritional regulation of mammary lipogenesis in ruminants

Trans fatty acids: Definition and occurrence in foods

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