Absorption of Di- and triglycerides by intestinal slices in vitro

The uptake by hamster intestinal rings of labeled 1,3-diolein and triolein in bile salt emulsions was studied. About 6% of triolein was taken up from emulsions containing glycerides and fatty acid in 6 mM sodium taurodeoxycholate. Lesser uptake was noted when triolein was emulsified with lecithin, cholesterol and bile salt; lowest uptake (3%) was observed from triolein-lecithincholesterol emulsions prepared without bile salt. Absorption of 1,3-diolein from bile salt emulsion was greater and acylation to triglyceride was observed. Diglycerides and triglycerides in small quantity may be absorbed intact from a micellar phase.     

Applications of chromatographic techniques to evaluate enzymatic hydrolysis of oxidized and polymeric triglycerides by pancreatic lipase in vitro

With the aim of studying the susceptibility to enzymatic hydrolysis of oxidized and polymeric triglycerides (TG) that are formed during frying, various chromatographic techniques were applied in combination, i.e., adsorption chromatography, high-performance size-exclusion chromatography (HPSEC), and thin-layer chromatography-flame ionization detection (TLC-FID). Polar fractions, isolated by adsorption chromatography from thermoxidized trilinolein as model system, and real used frying fats and oils, were analyzed by HPSEC before and after incubation with pancreatic lipase in vitro. Also, the influence of degradation level of used frying oils on hydrolysis of intact TG was investigated with the additional aid of TLC-FID. Results showed the high hydrolysis rate of oxidized TG monomers in contrast to the significant discrimination of pancreatic lipase against TG dimers and, particularly, TG polymers. On the other hand, hydrolysis of intact TG can be affected by the presence of dimers and polymers in abused frying oils.     

In vitro studies on interaction of rat pancreatic lipase and colipase with biliary lipids

Lipase and colipase were prepared separately from rat pancreatic juice, and their respective interaction with biliary lipids was investigated by gel filtration on agarose in the presence of a micellar solution of sodium taurocholate. It was found that the cofactor can associate with the biliary lipids, whereas the enzyme forms a high mol wt complex only in the presence of colipase. It is suggested that biliary phospholipids might participate in the in vivo formation of the enzyme-cofactor substrate complex at the triglyceride-water interface in the presence of bile salts.     

用13C-NMR表征高乙烯含量乙烯-丙烯无规共聚物的结构与性能

采用淤浆聚合法,使用3种聚丙烯催化剂制备了高乙烯含量乙烯-丙烯无规共聚物,并采用核磁共振碳谱对共聚物结构和性能进行了表征。结果表明:在相同聚合条件下,使用二醇酯化合物作为内给电子体的ND催化剂同已商业化的两种Ziegler-Natta催化剂CAT1和CAT2聚合得到的乙烯-丙烯无规共聚物中的乙烯摩尔分数接近,为75%~78%;使用ND催化剂聚合得到的乙烯-丙烯无规共聚物链段中乙烯-丙烯单元序列分布更均匀;使用ND催化剂聚合得到的乙烯-丙烯无规共聚物中橡胶相相对含量高于采用CAT1和CAT2催化剂。     

Effect of ethanol on plasma triglycerides in male and female rats

A single large dose of ethanol was given to fasted rats and to rats fed a fat-free diet containing orotic acid. An increased plasma triglyceride concentration after ethanol feeding was consistently found in fasted male rats, while the results in fasted female rats varied between the experiments. The total rate of triglyceride secretion into the plasma in fasted rats was estimated as the Triton-induced hypertriglyceridemia 6–7.5 hr after ethanol feeding. The effect of ethanol on the triglyceride secretion from extrahepatic sources was estimated in the same way in rats, with the hepatic triglyceride secretion blocked by orotic acid. Ethanol enhanced the Triton-induced hypertriglyceridemia in both male and female fasted rats, but to a greater extent in male rats. Ethanol did not stimulate the extrahepatic triglyceride secretion during this period.     

负离子聚合法合成丁二烯-异戊二烯无规共聚物的序列结构

以正丁基锂(n-BuLi)为引发剂、十二烷基苯磺酸钠(SDBS)为调节剂,在环己烷中对丁二烯(Bd)和异戊二烯(Ip)进行负离子聚合制得Bd-Ip共聚物,考察了反应温度、单体配比及调节体系对Ip共聚活性及共聚物序列分布的影响。结果表明,提高反应温度或增加Ip单体含量、SDBS/n-BuLi(摩尔比)由0/1.0增大到0.5/1.0,均可提高Ip共聚活性;共聚物序列分布服从一级Markov统计模型,在70℃、Ip/Bd(质量比)5/5、SDBS/n-BuLi(摩尔比)0.5/1.0、单体质量浓度0.12 g/mL的条件下,在共聚物中Ip、Bd 2种单元的同等长度单元组浓度趋于一致,所得共聚物的无规化程度高。     

Absorption by rats of tocopherols present in edible vegetable oils

The absorption of tocopherols (α, γ, and σ) and fatty acids from rapeseed (RO), soybean (SOO), and sunflower (SUO) oil, both from the natural oils and from the oils following moderate heating (180°C for 15 min), was measured in lymphcannulated rats. Oils were administered as emulsions through a gastrostomy tube, and lymph samples were collected for 24 h. The composition of tocopherols in oils and lymph fractions was measured by high-performance liquid chromatography, and fatty acids were measured by gas-liquid chromatography. The highest accumulated transport of α-tocopherol was observed after SUO administration, the lowest after SOO, with RO in between, corresponding to their relative contents (41.6±8.8, 32.7±5.0, and 24.9±4.3 μg at 24 h after administration of SUO, RO, and SOO, respectively). The calculated recoveries (in %) 24 h after oil administration were 21.4±4.5, 45.7±7.0, and 78.8±13.5 for SUO, RO, and SOO, respectively, suggesting that the absorption efficiency decreased when the α-tocopherol concentration increased. The recovery of α-tocopherol was higher than the recoveries of γ-and σ-tocopherol, indicating that the different tocopherols were not absorbed to the same extent or with similar rates. No differences between unheated and heated oils were observed in the absorption of tocopherols, whereas heating led to lower absorption of fatty acids, thus showing no direct association between absorption of tocopherols and fatty acids.     

Protective effect of biliary lipids on rat pancreatic lipase and colipase

The effect of biliary components on the inactivation of rat pancreatic lipase and colipase was studied. In vitro incubations of these proteins were performed at 37 C in the presence or absence of trypsin, under various conditions. The influences of bile lipoprotein complex, bile salts below or above the critical micellar concentration (CMC), or albumin were investigated. The results showed that albumin and bile salts below the CMC had no protective effect on the inactivation rate of lipase or colipase. Under both denaturating conditions, bile salts above the CMC had a very slight effect, whereas the presence of the bile lipoprotein complex maintained lipase and colipase activity. The magnitude of this effect was related to the biliary phospholipid concentration. By means of gel filtration, the protective effect of bile was found to be due to associations of bile lipoprotein complex with these proteins in presence of bile salts. A correlation between the amount of colipase and the protection of lipase in the presence of biliary phospholipids was observed. Intestinal content of rats with normal and diverted bile secretion was submitted to the same in vitro incubation, and the enzyme was more stable in the segments containing biliary phospholipids. This suggests that the interaction between the bile lipoprotein complex, colipase and lipase in the presence of bile salts could have an important role in the intestinal lumen by retaining the enzyme activity.     

Comparison of the clearances of serum chylomicron triglycerides enriched with eicosapentaenoic acid or oleic acid

Rat mesenteric lymph chylomicrons containing triglycerides enriched with either [¹⁴C]oleic acid (OA) or [¹⁴C]-eicosapentaenoic acid (EPA) were prepared by ultracentrifugation of lymph samples collected for 6 hr after a single duodenal infusion of an emulsion containing either fatty acid. These chylomicrons were injected into the jugular vein of recipient rats and, at various time intervals, blood was drawn and serum was assayed for radioactivity. In separate animals, serum lipoprotein fractions were separated by ultracentrifugation, and the redistribution of labeled fatty acid among circulating lipoproteins was determined by liquid scintillation spectrometry. When the early disappearance rates (10 min) of either total serum radioactivity or specifically the chylomicron fraction were compared, there were no differences between the groups receiving OA-or EPA-enriched chylomicrons. However, disappearance rates of EPA-enriched chylomicrons were slower than those of OA-enriched chylomicrons from 25 to 90 min. The small but significant differences in the disappearance rates for the longer time periods cannot be ascertained without further studies. At 5 min after injection of either type of chylomicron, the d<1.006 g/ml lipoprotein fraction of serum chylomicrons and very low density lipoproteins contained almost 90% of the original radioactivity. By 240 min, when less than 2% of the radioactivity remained, this radioactivity in the d<1.006 g/ml fraction was 43–46%, with concomitant increases in the low and high density lipoprotein fractions and in the lipoprotein-free serum. Deceased.     

Separation of triglycerides by column chromatography on silica impregnated with silver nitrate

Silicagel impregnated with silver nitrate was used for the column-chromatographic separation of closely related triglycerides. Good results were obtained with 20\s-100 mg of the following glyceride mixtures:

1. 1.
   Dipalmito-elaidin and dipalmito-olein.     
   
   

Recovery of triglycerides from used frying oil by extraction with liquid and supercritical ethane

The extraction of triglycerides from used frying oil with liquid and supercritical ethane has been studied in a semibatch system at different temperatures (25-80 °C) and pressures (150-250 kg/cm²). It has been found that isobaric decreases of temperature and isothermal increases of pressure lead to both increasing extraction yields and decreasing separation efficiencies. Lipid fractions recovered in the high density region had acceptable concentrations of polar compounds.Results with ethane have been compared to those reported for CO₂ in earlier works. At similar reduced densities of the solvents, oil solubility in ethane was higher than in CO₂, being the separation efficiency of polar fractions slightly better when using ethane.The extraction process was further analyzed in a packed countercurrent column. At optimum conditions (250 kg/cm², 25 °C, and solvent-to-oil ratio 45 g:g) about 85% of the triglycerides were recovered, being 11.2% the polar content of the triglyceride fraction recovered.     

Composition of fatty acids and structure of triglycerides in medium and low erucic acid rapeseed

Total triglycerides in medium (MEAR) and low (LEAR) erucic acid cultivars of rapeseed were fractionated by argentation chromatography into twelve and ten fractions, respectively. Gas liquid chromatography of the fatty acids in the triglyceride fractions and their 2-monoglycerides was used to evaluate the structural characteristics of the individual fractions. Fractionation occurred on the basis of degree of unsaturation, molecular weight and positional characteristics. The most mobile fractions contained 34–50% of saturated fatty acids while the less mobile had 59–65% of polyunsaturated fatty acids. In the medium erucic acid oil, long chain fatty acids (C20–C22) were found in all fractions, but four fractions of low erucic acid oil were essentially free of long chain acids. Two of these fractions in the latter oil, which represented 44% of the total triglycerides, were glycerol trioleate and dioleoyllinoleoylglycerol. The majority of the 2-positions were occupied by unsaturated C18 fatty acids, generally in the order of linoleic ≥linolenic> oleic acids. The saturated and long chain fatty acids occurred predominantly in the 1-and 3-positions. The various fractions of medium and low erucic acid oils were similar in structural composition except that eicosenoic and erucic acids substituted for oleic acid in some external positions. Erucic acid did not appear to substitute directly for oleic acid in the 2-position.     

A general template for synthesis of hollow microsphere with well‐defined structure

Using chitooligosaccharides (COS) as the backbones and polycaprolactones (PCL) as the branches, a novel type of amphiphilic graft copolymers with a large amount of free ? OH and ? NH₂ groups remained on the COS backbones was synthesized. The obtained Chitooligosaccharide‐graft‐poly(ε‐caprolactone)(COS‐g‐PCL) was self‐assembled into giant vesicles which served as templates for the preparation of hollow spheres of a series of metals(Au, Ag, Cu, Pt, and Pd). The method involved the initial mixing of COS‐g‐PCL and metal‐containing groups or metal ions to generate corresponding complex, followed by adding the selective solvent of water to induce the self‐assembly of the graft copolymers into giant vesicles; Metal ions were reduced and crosslinked by a subsequent calcination procedure to form metal hollow spheres. In addition, hybrid hollow spheres with fluorescent quantum dots and silica hollow spheres were also prepared by slightly modified procedures. A preliminary study on the trinitrotoluene sensor of CdS/vesicle hybrid hollow spheres revealed a considerable sensitivity, which exemplifies the distinct properties imparted by the hybrid hollow structure. All of the results demonstrate that the giant vesicles self‐assembled from COS‐g‐PCL could be utilized as effective templates for the synthesis of various hollow spheres. Using Chitooligosaccharide‐graft‐poly(ε‐caprolactone) vesicles as general templates, the hollow spheres of a series of metals such as Au, Ag, Cu, and Pt were produced. The method involved the initial absorption of metal ions from solution into the functional surface layer of the graft copolymer giant vesicles. Metal ions were reduced and crosslinked by a subsequent calcination procedure to form metal hollow spheres. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Cardiopathogenicity of soybean oil and tower rapessed oil triglycerides when fed to male rats

The triglycerides of soybean oil were purified by molecular distillation and those of Tower rapeseed oil by molecular distillation and adsorption chromatography. The original oils and the purified triglycerides were incorporated in semisynthetic diets at 20% by weight and fed for 16 weeks to weanling male Sprague-Dawley rats to compare the nutritional and pathological effects of the oils and their triglyceride fractions on rats. The study was carried out at two independent laboratories. No significant differences were observed between the results of the two establishments. The incidence of myocardial lesions was significantly higher in rats fed Tower rapeseed oil than in those fed soybean oil. Purification of the triglycerides by molecular distillation and adsorption chromatography appeared to have no major effect on the incidence of myocardial lesions. This supports our previous findings that the cardiopathogenicity of the test oils to rats resides in the triglycerides of these oils. Contribution No. 832 from Animal Research Institute and No. I-78 from Engineering and Statistical Research Institute.     

HPLC of triglycerides with gradient elution and mass detection

A gradient elution reversed phase HPLC system with a mass detector was investigated for the separation of triglycerides. A gradient based on a ternary eluent mixture is suggested. The detector was investigated in terms of linearity, reproducibility and relative response. The separation of soybean oil and some other natural triglyceride mixtures is demonstrated.     

Long and medium chain triglycerides increase plasma concentrations of ketone bodies in suckling rats

The potential of medium chain triglyceride (MCT) and long chain triglyceride (LCT) as sources of plasma ketones was investigated in suckling rats. Initially high concentrations of plasma ketones in 6-, 10-, and 17-day-old rats increased 2- to 3-fold after acute feeding of MCT. This feeding had the same effect in fed or fasted adult rats. Corn oil (as a source of LCT) induced a large increase in the plasma ketone concentration of suckling rats and a relatively small but significant increase in fasted adult rats. The LCT treatment did not affect plasma ketone levels in fed adult rats. The results show clearly that feeding either LCT or MCT will enhance hyperketonemia in suckling rats. In the livers of all animals, regardless of age, the capacity for incorporation of [1-¹⁴C] octanoate into CO₂ and acetoacetate far exceeded that for [1-¹⁴C] palmitate. The hyperketonemic action of LCT in suckling rats was accompanied by an increased activity of carnitine palmityltransferase and increased level of carnitine.