The absorption and transport of dietary cholesterol in the presence of peanut oil or randomized peanut oil

Peanut oil has been shown to be unexpectedly atherogenic for cholesterol-fed rats, rabbits and rhesus monkeys. However, randomization (rearrangement of fatty acids to random distribution) of peanut oil significantly reduced its atherogenicity for rabbits and monkeys. This study was conducted to investigate whether the absorption and transport of dietary cholesterol was altered in the presence of peanut oil or randomized peanut oil, thereby accounting for the difference in the atherogenicity of the two diets. Intestinal lymph fistula rats were infused intraduodenally with a lipid emulsion at a rate of 3 ml/hr. The lipid emulsion contained either peanut oil (control) or randomized peanut oil (experimental) (10 mM),¹⁴C-cholesterol (1.3 mM) and sodium taurocholate (19 mM) in phosphate-buffered saline, pH 6.4. Lymph triglyceride, cholesterol and phospholipid outputs were similar in both groups of rats during fasting and subsequently during lipid infusion. Comparable recovery of¹⁴C-cholesterol from the intestinal lumen and the intestinal mucosa of the control and the experimental rats showed that the absorotion and transport of dietary cholesterol were similar in both groups of rats. Analyses of thefatty acid of both lymph and intestinal mucosal lipid again failed to reveal a difference between the 2 groups of rats. It is concluded that the difference in the atherogenicity between the peanut oil and the randomized peanut oil is probably caused by events subsequent to the release of cholesterol containing chylomicrons and very low density lipoproteins by the small intestinal epithelial cells.     

Effect of plant sterols,fatty acids and lecithin on cholesterol absorption in vivo in the rat

The inhibitory effect of plant sterols, fatty acids and lecithin on cholesterol intestnal absorption was studied in the unanesthetized rat using a single pass perfusion technique. Bile was excluded from the perfused intestine. Cholesterol absorption did not change following the additions of cholestanol, cholestanone, lanosterol, stigmasterol and β-sitosterol. A 3-fold increase in the molarity of cholestanol and β-sitosterol or the separate additions of the saturated short and medium chain fatty acids, butyric and octanoic, also did not change cholesterol absorption. The unsaturated long chain fatty acids, oleic, linoleic, linolenic and arachidonic, inhibited cholesterol absorption. Lecithin additions at concentrations of 0.1–1.5 mM caused a progressive, dose-related inhibition of cholesterol absorption. The inhibitory effect of these agents on cholesterol absorption is likely to have been caused by changes in cholesterol solubility in the micelle and shifts in the partition coefficient of cholesterol away from the cell membrane to the micelle.     

Intestinal lymph absorption of butter,corn oil,cod liver oil,menhaden oil,and eicosapentaenoic and docosahexaenoic acid ethyl esters in rats

Adult male rats were surgically given a drainage catheter in the main mesenteric lymph duct. After an overnight fast, five groups of rats received intragastrically, in one bolus, butter, corn oil (CO), cod liver oil (CLO), menhaden oil (MO), or ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids (K80). Intestinal lymph was collected in these conscious animals, each hour during the first 6 h and in a single sample for the next 18 h. The absorption peak appeared earlier after MO and CO than after CLO administration. The quantities of triglycerides recovered during the first 6 h were significantly lower after butter (91 mg) and K80 (54 mg) administration than for the other three oils. No difference was observed between the vegetable oil and the two marine oils (CO=173 mg, CLO=148 mg, MO=180 mg). The total triglyceride recovered in 24 h was highest after CLO (410 mg) and lowest with K80 (146 mg). An increase in the weight percentage of some characteristic fatty acids of the lipid mixtures was observed: oleic acid for butter, oleic and linoleic acids for CO, EPA and DHA for CLO, MO, and K80. Chylomicrons were the largest with CO, more numerous and smaller with CLO, and the smallest with K80. Results obtained illustrated the relation between gastrointestinal hydrolysis, enterocyte biochemical events, and lymph triglyceride absorption profiles as related to the composition and distribution of triglyceride fatty acids.     

Effect of candicidin on cholesterol and bile acid metabolism in the rat

Sterol metabolism studies were carried out in rats maintained on a diet containing a polyene antibiotic, candicidin, (30 mg/kg/day) for 2-1/2 months. Compared to the controls, the candicidintreated animals had a smaller food intake and weight gain during this period. There was no difference between the 2 groups in serum cholesterol levels, biliary cholesterol or bile acid concentrations. However, in the experimental group, liver cholesterol content decreased by 27% and hepatic HMG-CoA reductase increased by 36%. Candicidin administration produced an 84% increase in neutral sterol output without change in bile acid output. Cholesterol absorption was reduced 80% by candicidin feeding. The weight of ventral prostate was reduced 33% by candicidin administration. Prostatic HMG-CoA reductase levels were 3 times higher than those of the liver, but enzyme activity was unchanged by candicidin treatment.     

Linoleic acid absorption in the unaesthetized rat: Mechanism of transport and influence of luminal factors on absorption

Linoleic acid intestinal absorption was studied in the unanesthetized rat. At low (21–1260 μM) intraluminal concentrations, absorption took place by facilitated diffusion; while at high (1.26–2.5 mM) concentrations, simple diffusion was the predominant mechanism of transport. At low concentrations (840 μM), the equimolar additions of oleic, linolenic, and arachidonic acids or lecithin inhibited the absorption of linoleic acid. Substitution of potassium for sodium in the buffer solution, substitution of Tween 80 for sodium taurocholate, or decrease in the hydrogen ion concentration all resulted in decreased rate of linoleic acid's absorption. These experiments demonstrate that linoleic acid is absorbed by a concentration-dependent dual mechanism of transport. The absorption rate is modified by the pH, surfactant type and concentration, the simultaneous presence of other polyunsaturated fatty acids, and the thickness of the unstirred water layer.     

Fish oil prevents change in arachidonic acid and cholesterol content in rat caused by dietary cholesterol

Rats were fed diets high in either saturated fat (beef tallow) or α-linolenic acid (linseed oil) or eicosapentaenoic and docosahexaenoic acids (fish oil) with or without 2% cholesterol supplementation. Consumption of linseed oil and fish oil diets for 28 days lowered arachidonic acid content of plasma, liver and heart phospholipids. Addition of 2% cholesterol to diets containing beef tallow or linseed oil lowered 20∶4ω6 levels but failed to reduce 20∶4ω6 levels when fed in combination with fish oil. Feeding ω3 fatty acids lowered plasma cholesterol levels. Addition of 2% cholesterol to the beef tallow or linseed oil diet increased plasma cholesterol concentrations but not when fish oil was fed. Feeding the fish oil diet reduced the cholesterol content of liver, whereas feeding the linseed oil diet did not. Dietary cholesterol supplementation elevated the cholesterol concentration in liver in the order: linseed oil > beef tallow > fish oil (8.6-, 5.5-, 2.6-fold, respectively). Feeding fish oil and cholesterol apparently reduced 20∶4ω6 levels in plasma and tissue lipids. Fish oil accentuates the 20∶4ω6 lowering effect of dietary cholesterol and appears to prevent accumulation of cholesterol in plasma and tissue lipids under a high dietary load of cholesterol.     

Formation of lymph chylomicron phosphatidylcholines in the rat during the absorption of safflower oil or triolein

The chylomicron phosphatidylcholines from rats fed safflower oil or triolein were isolated and separated into four different fractions according to the degree of unsaturation. Fraction 1, which was rich in palmitic, stearic and oleic acid, was a minor fraction (7.6–11.6 mole%) during the absorption of safflower oil, but was quantitatively important (27–51 mole%) after triolein feeding when significant amounts of dioleoylphosphatidylcholine were present. Fraction 2, which was a major fraction in all the experiments, contained linoleic acid in combination with a saturated or monounsaturated fatty acid. The third fraction contained mainly linoleic acid and was present only after safflower oil feeding. This indicates that dilinoleoyl-phosphatidylcholine is formed in the intestine after ingestion of linoleic acid. Fraction 4, which was rich in arachidonic acid and saturated fatty acids, accounted for 15–20 mole% of the chylomicron phosphatidylcholines with both kinds of fat meals. Incorporation of³H-choline indicated that the dilinoleoyl- and dioleoyl-phosphatidylcholines were formed by synthesis de novo while the majority of the rem aining phosphatidylcholines originated partly from acylated biliary lysolecithins and partly from the existing pool of mucosal phospholipids not formed during active fat absorption.     

Effects of randomization of partially hydrogenated corn oil on fatty acid and cholesterol absorption,and tissue lipid levels in rats

Randomization of partially hydrogenated corn oil containing approximately 45% oftrans octadecenoic acid only slightly, but not significantly, increased the lymphatic fatty acid absorption in rats. No effect of randomization was observed on cholesterol absorption. When rats were fed these fats at the 8.8% level (with 1.2% safflower oil) for three weeks, the concentrations of serum cholesterol, and serum and liver phospholipid were significantly higher in randomized fat than in control fat, which was composed of 9% high-oleic safflower oil and 1% palm oil. Liver cholesterol tended to be higher in randomized fat. In contrast, nonrandomized fat was not hyperlipidemic compared to control fat. Although the fatty acid composition of liver phospholipids suggested a possible interference oftrans fatty acid with the metabolism of linoleic acid to arachidonic acid, there was no effect of randomization. In the two hydrogenated fat groups,trans octadecenoic acid was incorporated and distributed similarly in adipose tissue triacylglycerol. These observations indicated that randomization of partially hydrogenated fat is not beneficial to various lipid parameters in rats.     

Kinetics of absorption,equilibration (or distribution), and excretion of orally and intraperitoneally administered cholesterol in the rat

Resorption and metabolism of cholesterol administered intraperitoneally and per os have been described in the rat utilizing a technique of double isotopic labeling. Depending upon the route of administration, these parameters vary to a large degree. Alimentary cholesterol is progressively resorbed over a period of 10 hr, while the maximal blood level of cholesterol is attained after the 6th hr following intraperitoneal injection. On the other hand, cholesterol administered per os is more rapidly utilized in biliary acid synthesis than cholesterol administered intraperitoneally. In the range of concentrations utilized in this work (10–300 μg and 0.2–300 μg, respectively, administered to the rat, orally and intraperitoneally), the rate of cholesterol resorption remained constant.     

Lipolysis of corn,peanut and randomized peanut oils

Corn oil, peanut oil and randomized peanut oil exhibit different atherogenic potentials; peanut oil being more atherogenic than the other oils. This study was conducted to ascertain if the atherogenicity of these oils was related to their rates of lipolysis. Using both pancreatic lipase and milk lipoprotein lipase (LPL), it was shown that the rated of lipolysis were corn oil>peanut oil>randomized peanut oil. The rates of lipolysis are not related to atherogenicity and may be affected by the distribution of long-chain saturated fatty acids in the component triglycerides.     

Effects of triolein or oleic acid on lymphatic recovery of docosahexaenoic acid given as ethyl ester and their intramolecular distribution in lymph triglyceride of rats

Effects of oleic acid or triolein on lymphatic recovery of docosahexaenoic acid (DHA) given as an ethyl ester were examined in rats with cannulated thoracic ducts. Lymphatic recovery of ethyl DHA given with oleic acid or triolein was significantly higher than in rats given ethyl DHA alone. DHA distrbuted almost exclusively at the 1-and 3-position of triglyceride in lymph collected at 0–3 h after the administration, when it was given with oleic acid or triolein. A small part of DHA distributed at the 2-position when ethyl DHA was the sole fatty acid given. Oleic acid given as free acid or triolein with ethyl DHA was a major fatty acid at the 2-position. Intramolecular distribution of DHA and oleic acid in lymph triglyceride was similar when ethyl DHA was given with oleic acid or triolein.     

Effects of Lewis acid catalysts on the esterification kinetics of castor oil with oleic acid

The effects of two Lewis acid catalysts, tin chloride and cobalt chloride, on the kinetics of the esterification reaction between castor oil and oleic acid have been investigated. Uncatalyzed and catalyzed reactions were carried out both in the presence of excess oil and with equivalent amounts of reactants at various temperatures. The reaction, with respect to castor oil concentration, is first-order in all cases, whereas with acid concentration the reaction was observed to change from second-order for the uncatalyzed reaction to first-order for tin chloride-catalyzed and to zero-order for cobalt chloride-catalyzed reactions. The order (with respect to acid) also changed with temperature for the cobalt chloride-catalyzed reaction.     

DDT absorption and chylomicron transport in rat

Male rats were fed 100 nM dichlorodiphenyltrichloroethane-¹⁴C in oil by gastric tube. Recovery of dichlorodiphenyltrichloroethane-¹⁴C in thoracic duct lymph was 60% in 12 hr. Lymph dichlorodiphenyltrichloroethane-¹⁴C (97%) occurred in lipoproteins of d<1.006, designated chylomicrons. Mechanical separation of chylomicron triglyceride core (labeled with triglyceride-³H) from chylomicron membrane (labeled with phospholipid-³²P) showed that 97% dichlorodiphenyltrichloroethane-¹⁴C was present in triglyceride core. To investigate possible association of plasma clearance of the two core lipids, rats were pulse injected with chylomicrons, doubly labeled with triglyceride-³H and dichlorodiphenyltrichloroethane-¹⁴C. The decay of dichlorodiphenyltrichloroethane-¹⁴C in sequential serum samples was rapid (T^1/2=2 min) and was independent of triglyceride-³H decay. In tissues removed 14 min after injection of chylomicrons, 30% administered dichlorodiphenyltrichloroethane-¹⁴C was found in liver but only 1% in adipose tissue. In hepatectomized (eviscerated) rats, the decay of serum dichlorodiphenyltrichloroethane-¹⁴C (T^1/2=10 min) was also independent of and more rapid than triglyceride-³H decay. With sucrose density gradients, it was shown that chylomicron dichlorodiphenyltrichloroethane-¹⁴C transferred to higher density serum proteins in vitro and in vivo and to bovine albumin in vitro. Thus, dichlorodiphenyltrichloroethane was transported from intestine largely in the triglyderide phase of chylomicrons; disappearance of chylomicron-dichlorodiphenyltrichloroethane from the systemic circulation was rapid and partly independent of the presence of the liver and of triglyceride hydrolysis; some dichlorodiphenyltrichloroethane was transported from serum chylomicrons to albumin or other plasma proteins before tissue uptake.     

The kinetics of the esterification reaction between castor oil and oleic acid

In this study, esterification of castor oil with oleic acid was investigated in view of the reaction kinetics under various conditions. Potassium hydroxide,p-toluenesulfonic acid and tin chloride (SnCl₂2H₂O) were used as catalysts. Reaction was carried out at 200°C, 225°C and 250° C by using equivalent proportions of the reactants. For tin chloride, experimental data fitted the second-order rate equation, while for the other catalysts the obtained data fitted the third-order rate equation.     

Esterification of oleic acid in soybean oil on zeolite catalysts with different acidity

The catalytic activity of zeolites was studied in the esterification of oleic acid with methanol in soybean oil. The influences of acidity and pore structure of the zeolites were investigated in relation to conversion of the oleic acid on the zeolite catalysts. H⁺ ion exchanged ZSM-5 (HMFI) and mordenite (HMOR) zeolites conducted with different Si/Al ratio were employed to examine an influence of acidity in the reaction. Conversion of oleic acid was about 80% on HMOR zeolites and HMFI(25) zeolite. The conversion of oleic acid was improved as the amount of acid site increased. The amount of acid site of the zeolites affected significantly the catalytic activity in the esterification of oleic acid.     

Extraction of oleic acid from soybean oil and jojoba oil-phase diagrams

Formamide,N-methylformamide,N-dimethylformamide, dimethylsulfoxide, 1,2-butanediol, and 2-butane-1,4-diol were considered as potential extractants of fatty acids from soybean and jojoba oils. Ternary liquid-liquid phase diagrams at 298.15 K, distribution, and selectivity coefficients of oleic acid are reported. Of the investigated solvents, onlyN-methylformamide and 1,2-butanediol have desirable extraction characteristics.     

Effect of dietary fat saturation of absorption and intestinal secretion of cholesterol by the hypercholesterolemic rat

The fate of an oral dose of [4-¹⁴C] cholesterol given to rats grown on diets with 20% safflower oil or 20% hydrogenated coconut oil was determined by analysis of digestive tract, feces and tissues. The pattern of isotope distribution did not support the view that rats fed a saturated fat absorb less cholesterol than those fed an unsaturated fat. Fasted animals growth on the diet with 5% of these two fats and beef fallow showed no clear difference in the amount of digitonin-peecipitable sterol in their intestines. A shorter transit time for intestinal contents was observed with the saturated fat groups. It is concluded that neither absorption of cholesterol from the gut nor secretion of β-hydroxy sterol into the gut accounts for the hypocholesterolemic effect of polyunsaturated fat. Journal Paper No. 4951 AES, Purdue University.     

Effect of calcium on absorption of fatty acid by rat jejunum in vitro

The effect of Ca⁺⁺ on jejunal osmiophilic particles was studied in a recirculating system which was not contaminated with plasma lipoproteins. An isolated, infused segment of rat jejunum was suspended in a bath of liquid paraffin. Transudate, containing osmiophilic particles, appeared like beads of sweat on the serosal surface, and fell to the bottom of the bath. In the range of 25–38 C, 30 C proved to be optimal for histological preservation of villous architecture. Production of transudate, 20 mg/min/g of jejunum, and transport of [¹⁴C] oleate proceeded nearly linearly after the first 30 min. Necrosis of mid-villus and crypt cells became obvious by light microscopy after one hour. Therefore, transudate was collected between the period of 30–60 min. Shadow casting of transudates, produced when saline was infused, revealed that 86±9 (SD) % of osmiophilic particles was <800 Å in diameter; 13±8% was 800–1000 Å; 0.4±0.5% was 1000–2000 Å. Corresponding values were 58±10, 25±5, and 16±5% when 5 mM [¹⁴C] oleate+2.5 mM monoolein was infused; 75% of the transported [¹⁴C] appeared in triglyceride. Adding 2 mM Ca⁺⁺ to the infusion doubled the transport of [¹⁴C] triglyceride without increasing particle size further. We conclude that luminal Ca⁺⁺ increases the absorption of luminal fatty acid by rat jejunum in vitro.     

Effect of peanut shell content on mechanical,thermal, and biodegradable properties of peanut shell/polylactic acid biocomposites

Peanut shell (PNS) was combined with polylactic acid (PLA) to form biocomposites. The biocomposites, with up to 40 wt% PNS, were prepared using a twin–screw extruder. The effect of PNS content on the thermal, mechanical, thermomechanical, morphological, and biodegradable properties was studied. The results showed that the addition of PNS caused a reduction of the melting temperature and the decomposition temperature. Furthermore, the crystallinity of the biocomposites slightly increased with increasing PNS up to 30 wt%. The morphological study showed poor interfacial adhesion between the PNS and PLA matrix. Nevertheless, the mechanical properties revealed that the maximum tensile strength and Young's modulus were at a 30 wt% PNS loading and decreased as more PNS was incorporated into the PLA matrix. The impact strength decreased with an increase in PNS content. The addition of PNS showed significantly improvement of the storage modulus of PLA at high temperature (>80°C). Moreover, the presence of PNS enhanced the biodegradability of the biocomposites. POLYM. COMPOS., 38:682–690, 2017. © 2015 Society of Plastics Engineers