Positional Fatty Acid Composition Research Articles

Camphor Tree Seed Kernel Oil Reduces Body Fat Deposition and Improves Blood Lipids in Rats.

The total and positional fatty acid composition in camphor tree (Cinnamomum camphora) seed kernel oil (CKO) were analyzed, and for the first time, the effect of CKO on body fat deposition and blood lipids in rats was studied. The major fatty acids in CKO were determined to be decanoic acid (C10:0, 51.49%) and dodecanoic acid (C12:0, 40.08%), and uniformly distributed at Sn-1, 3, and Sn-2 positions in triglyceride (TG). Rats were randomly divided into control, CKO, lard, and soybean oil groups. At the end of the experiment, levels of blood lipids and the fats of abdomen in the rats were measured. The main organ were weighted and used for the histological examination. The results showed that body weight and fat deposition in CKO group were significantly lower than the lard and soybean groups. Moderate consumption of CKO was found to improve the levels of blood TG and low density lipoprotein cholesterol.

Cloning, heterologous expression and biochemical characterization of plastidial sn-glycerol-3-phosphate acyltransferase from Helianthus annuus

The acyl-[acyl carrier protein]:sn-1-glycerol-3-phosphate acyltransferase (GPAT; E.C. 2.3.1.15) catalyzes the first step of glycerolipid assembly within the stroma of the chloroplast. In the present study, the sunflower (Helianthus annuus, L.) stromal GPAT was cloned, sequenced and characterized. We identified a single ORF of 1344base pairs that encoded a GPAT sharing strong sequence homology with the plastidial GPAT from Arabidopsis thaliana (ATS1, At1g32200). Gene expression studies showed that the highest transcript levels occurred in green tissues in which chloroplasts are abundant. The corresponding mature protein was heterologously overexpressed in Escherichia coli for purification and biochemical characterization. In vitro assays using radiolabelled acyl-ACPs and glycerol-3-phosphate as substrates revealed a strong preference for oleic versus palmitic acid, and weak activity towards stearic acid. The positional fatty acid composition of relevant chloroplast phospholipids from sunflower leaves did not reflect the in vitro GPAT specificity, suggesting a more complex scenario with mixed substrates at different concentrations, competition with other acyl-ACP consuming enzymatic reactions, etc. In summary, this study has confirmed the affinity of this enzyme which would partly explain the resistance to cold temperatures observed in sunflower plants.

Production of human fat milk analogue containing α-linolenic acid by solvent-free enzymatic interesterification

Human milk fat (HMF) analogue was synthesized by lipase-catalysed interesterification of tripalmitin with extra virgin olive oil, and flaxseed oil in a solvent-free media. Lipozyme® TL IM, immobilized sn-1,3 specific lipase, was used as biocatalysts. Substrate molar ratio, reaction temperature and reaction time were used to model and to optimize the reaction conditions via response surface methodology. Good quadratic models were obtained for the incorporation of palmitic acid and α-linolenic acid. At the optimal conditions generated from the model, the palmitic acid and α-linolenic acid contents of the product were found to be 25.2 g/100 g and 15.9 g/100 g, respectively. The chemical properties (free fatty acid, iodine value, and saponification value), sn-2 positional fatty acid composition, and sterol composition of the final structured lipid (SL) were determined. Furthermore, the oxidative stability of the SL and the SLs with antioxidants (BHT, gallic acid, and rosemary extract) was evaluated. The peroxide and thiobarbituric acid reactive substances (TBARS) values of the SLs showed they had antioxidant activity on the SL. The HMF analogue synthesized in this study may have potential use in infant formulas to provide omega-3 fatty acids (α-linolenic acid).

Rapid and direct quantitative analysis of positional fatty acids in triacylglycerols using 13C NMR

AbstractThere is increasing evidence that the positional fatty acid composition (FAC) of TAG is more important than total FAC with regard to nutrition values of edible oils and fats. A rapid and direct regiospecific analysis of positional fatty acids in TAG using 13C NMR was developed to overcome the tedious conventional methods which involve enzymatic hydrolysis, Grignard chemical degradation, and chromatography analysis. A set of NMR data acquisition parameters and processing methods had proven their excellent versatility and applicability on various types of oils and fats, with systematic error of 1.0 mol%. It was found that there are discrepancies between the regiospecific analysis results obtained by the current method and by conventional methods. Probable acyl migration occurring in the hydrolysis process in conventional methods is a noted problem. As the current 13C NMR method is a direct measurement and no hydrolysis of the sample is needed, acyl migration during the analysis is eliminated. As a result, the saturation level is always higher at sn‐1, 3 positions and lower at sn‐2 position in TAG structure of oils in the regiospecific data obtained from the current 13C NMR than that from conventional methods. In the absence of laborious chemical derivatization, this method is simple, accurate, and user‐friendly for researchers, especially for nutritionists to support their nutritional studies from the perspective of positional FAC of edible oils and fats.

Comparative study of trans fatty acid content in 2005 and 2008 processed foods from Korean market

Trans fatty acids (t-FA) contents were analyzed in 26 food items that were collected from Korean grocery stores in 2005 and 2008. Lipid was extracted through Soxhlet and Mojonnier methods. Fatty acid profile, including t-FA and positional fatty acid composition was analyzed by gas chromatography. The comparative study of fatty acids composition including t-FA was employed in 2005 and 2008. Among the analyzed food items, most of the food items showed higher lipid content in 2005 than in 2008. Some food items such as biscuits (0.4–7.2 g/100 g of food), fried snacks (0.1–3.6 g/100 g of food), and cookies (0.4–2.4 g/100 g of food) contained relatively higher level of t-FA than other food groups (cracker, processed chocolate, and ice cream) in 2005. Comparing t-FA content in 2005, it was considerably decreased up to 91.5% in 2008 whereas saturated fatty acids (SFA) were increased up to 43.3% in the analyzed food items.

Diacylglycerol acyltransferase in maturing safflower seeds: its influences on the fatty acid composition of triacylglycerol and on the rate of triacylglycerol synthesis

Diacylglycerol acyltransferase in a particulate preparation from maturing safflower seeds showed no strict selectivity for acyl-CoA when acyl-CoA substrates were administered as mixtures. This suggested that the fatty acid composition of position 3 in safflower triacyl- sn-glycerol exclusively depends on the acyl-CoA composition in the cell. The specific activity of the acylation was approximately 3 nmol/min per mg protein of the preparation under the optimum assay conditions. This low activity and other data appeared to indicate that the diacylglycerol acyltransferase reaction may be the rate-limiting step in triacylglycerol synthesis in vivo.

1-Acyl-sn-glycerol-3-phosphate acyltransferase in maturing safflower seeds and its contribution to the non-random fatty acid distribution of triacylglycerol.

A 20,000 X g particulate preparation isolated from maturing safflower seeds catalyzed the acylation of 1-acyl-sn-glycerol 3-phosphate with acyl-CoA to form phosphatidate. The specific activity of the reaction exceeded 200 nmol min-1 mg protein-1. Although this preparation was also capable of catalyzing the acylation of sn-glycerol 3-phosphate with acyl-CoA, the hydrolysis of phosphatidate, and the acylation of 1,2-diacylglycerol, phosphatidate was the only major product when the preparation was incubated with 1-acyl-glycerol-3-P and acyl-CoA. The enzyme responsible for this phosphatidate synthesis, 1-acyl-glycerol-3-P acyltransferase, showed a strict acyl-CoA specificity. The relative order of specificity for acyl-CoA was linoleoyl = oleoyl greater than palmitoleoyl greater than elaidoyl greater than cis-vaccenoyl greater than stearoyl = palmitoyl. This observation strongly suggests that the fatty acid composition of position 2 in phosphatidate synthesized in vivo primarily depends on both the acyl-CoA specificity of the 1-acyl-glycerol-3-P acyltransferase and the fatty acid composition of the acyl-CoA pool in the cell. Thus, the absence of saturated fatty acids at position 2 of safflower triacylglycerol may be explained in terms of the acyl-CoA specificity of the 1-acyl-glycerol-3-P acyltransferase. The fatty acid moiety esterified at position 1 of glycerol-3-P also affected the effectiveness of the reaction. The 1-acyl-glycerol-3-P acyltransferase utilized 1-acyl-glycerol-3-P molecular species in the following order of effectiveness: linoleoyl = oleoyl greater than palmitoyl. With a rise in incubation temperature, the initial rates of acylation with unsaturated acyl-CoA species increased more rapidly than those for saturated acyl-CoA species. A similar tendency was observed for saturated and unsaturated acyl acceptors. These data suggest that affinity of the acyltransferase for substrates may vary in response to changes in temperature, and that 1-acyl-glycerol-3-P acyltransferase may be involved in the alteration of the individual fatty acid compositions at positions 1 and 2 of glycerolipids in tissues grown at different temperatures. Based on these findings, further metabolism of 1-acyl-glycerol-3-P acyltransferase products could be the major factor determining the non-random distribution of fatty acids in safflower triacylglycerol.

Sn-Glycerol-3-phosphate acyltransferase in a particulate fraction from maturing safflower seeds

The properties of the acyl-CoA: sn-glycerol-3-phosphate O-acyltransferase in a 20,0000 g particulate fraction from maturing safflower seeds were investigated. The optimum pH of the reaction was 7.2. The apparent K m for glycerophosphate was 0.54 m m. Only monoacylglycerophosphate was accumulated in the particulate fraction under normal conditions. Position 1 of glycerophosphate was exclusively esterified with either palmitoyl-CoA or linoleoyl-CoA as acyl donor, while 2-acylglycerophosphate was the minor product. The specificity and selectivity of the acyltransferase for acyl-CoA were broad and somewhat affected by temperature. The concentration of glycerophosphate did not affect the selectivity. These observations suggested that the fatty acid composition of position 1 of safflower triacylglycerol must primarily depend on the composition of the acyl-CoA pool in the site of synthesis, and that growth temperature and the acyl-CoA selectivity of the glycerophosphate acyltransferase may be rather minor factors regarding regulation of the fatty acid composition of position 1 in triacylglycerol.

Positional Fatty Acid Composition in Total and Acetone-Precipitated Amniotic Fluid Lecithin

Lindback, T. Positional Fatty Acid Composition in Total and Acetone-Precipitated Amniotic Fluid Lecithin. Scand. J. clin. Lab. Invest. 36, 683–687, 1976.The fatty acid composition of lecithin has been determined separately at the 1- and 2-position in 22 samples of amniotic fluid. Palmitic acid (16:0) was the main fatty acid present at both carbon atom positions throughout the last trimester. Myristic acid (14:0) was present in very small amounts only. There was no evidence of 1-palmitoyl/2-myristoyl lecithin being present in more than trace amounts before 35 weeks of gestation. The positional specificity of the methylation pathway is therefore doubtful. Acetone precipitation of lecithin did not alter the observed fatty acid composition at either position, indicating that this procedure precipitates the different lecithin subspecies in equal proportion, without any preference for disaturated species. This method therefore fails to isolate a lecithin fraction with a specific fatty acid composition.

177: Positional fatty acid composition in total and acetone-precipitated amniotic fluid lecithin

The fatty acid composition of lecithin has been determined separately at the 1- and 2-position in 22 samples of amniotic fluid. Palmitic acid (16:0) was the principal fatty acid present at both carbon atoms throughout the last trimester. Myristic acid (14:0) was present in very small amounts only. There was no evidence of 1-palmitoyl/2-myristoyl lecithin being present in other than trace amounts prior to 35 weeks gestation. Acetone precipitation of lecithin did not alter the observed fatty acid composition at either position, indicating that this procedure precipitates the different lecithin subspecies in equal proportion, without any preference for disaturated species. It therefore fails to isolate a lecithin fraction with a specific fatty acid composition.

Positional fatty acid composition in total and acetone-precipitated amniotic fluid lecithin.

The fatty acid composition of lecithin has been determined separately at the 1- and 2-position in 22 samples of amniotic fluid. Palmitic acid (16:0) was the main fatty acid present at both carbon atom positions throughout the last trimester. Myristic acid (14:0) was present in very small amounts only. There was no evidence of 1-palmitoyl/2-myristoyl lecithin being present in more than trace amounts before 35 weeks of gestation. The positional specificity of the methylation pathway is therefore doubtful. Acetone precipitation of lecithin did not alter the observed fatty acid composition at either position, indicating that this procedure precipitates the different lecithin subspecies in equal proportion, without any preference for disaturated species. This method therefore fails to isolate a lecithin fraction with a specific fatty acid composition.

Effects of fatty acid concentration and positional specificity on maize triglyceride structure.

The effects of fatty acid concentration and positional specificity on maize triglyceride structure were evaluated from the stereospecific analyses of triglycerides from 12 genotypes. The fatty acids at each position were influenced by the fatty acid concentration in the total triglyceride except for the saturates in the 2 position. The fatty acid concentration had the greatest effect on the fatty acid composition of position 3. The existence of positional specificity was evident from the nonrandom distribution of the fatty acids among the three positions of the triglycerides. The concentration and positional specificity effects could be separated in selected genotypes and their crosses. This indicated different genetic controls for each effect.

Deposition of Triglycerides of Increased Carbon Number in Irradiated Rat Marrow

gamma radiation involves primarily the stimulation of triglyceride formation. This metabolic alteration appears morphologically as an increased number of fat cells, which reaches a maximum approximately 1 week after total-body irradiation (TBI). Triglycerides of femoral bone marrow, liver, plasma, and perirenal fat were isolated by preparative thin-layer chromatography (TLC) from control and irradiated (800 R) Carworth Farms Nelson strain rats. The purified triglyceride fractions were separated further by Ag (NH3)2+ TLC and by gas-liquid chromatography (GLC). Stereospecific fatty acid analysis of the triglycerides was also done. The period for maximal triglyceride biosynthesis was 3 to 4 days after TBI. The pattern of irradiated marrow triglycerides on the argentation layers was similar to the control pattern, but GLC showed that the newly formed triglycerides in the irradiated bone marrow had a higher carbon number than those in control marrow. This change was not found in the triglycerides of other tissues examined before and after TBI. In both control and irradiated animals, plasma and liver contained triglycerides of higher carbon number than did bone marrow and adipose tissue. Stereospecific analysis of the fatty acid positions of the triglycerides showed that the change in triglyceride type caused by irradiation was due to a shift in the distribution of the C-16 and C-18 fatty acids in positions 1 and 3. No change occurred in the fatty acid composition of position 2 after irradiation. 1Under contract with the U. S. Atomic Energy Commission. 142

Stereospecific analysis of triglycerides: an alternative method

A new method for the stereospecific analysis of triglycerides is demonstrated on a corn oil which had been analyzed by an earlier method. The triglyceride (1,2,3-triacyl L-glycerol) was partially degraded by means of methyl magnesium bromide. The 1,3-diglyceride was then isolated, and converted into l-2-phosphatidyl phenol, from which phospholipase A cleaved the fatty acids from position 1. The remaining lysophosphatide was analyzed to yield the fatty acids at position 3 of the original triglyceride. The fatty acid composition of position 2 was determined after hydrolysis of the corn oil with pancreatic lipase. This method has the advantage over the one reported previously of yielding direct analyses of the fatty acids in each of the three positions.