We developed a novel method to measure hydroxyoctadecadienoic acid (HODE) levels in biological fluids and tissue samples. This method can be used to measure the oxidation products of linoleic acid. Reduction and saponification enabled us to measure hydroperoxides and hydroxides of both free and esterified forms of linoleic acid as total HODE, which includes the enzymatic and non-enzymatic products 9- and 13-(Z, E)-HODEs; the non-enzymatic free radical-mediated products 9- and 13-(E, E)-HODEs; and the specific non-enzymatic singlet oxygen-mediated products 10- and 12-(Z, E)-HODEs. We have recently reported HODE levels in plasma and erythrocytes from healthy volunteers and patients with several diseases and determined that its levels are much higher in patients with lifestyle-related diseases than in healthy volunteers. Furthermore, 10- and 12-(Z, E)-HODE plasma levels can serve as promising biomarkers for the early detection of diabetes. Thus, HODE is a useful biomarker for the assessment of oxidative status, and its efficiency as a biomarker can be improved by using it in combination with other typical biomarkers. This review article focuses on lipid peroxidation biomarkers, including HODE, and discusses their potential in practical and clinical applications in disease prediction.
Lauric fat cocoa butter replacer (LCBR) was produced from a blend of krabok seed fat (KSF) and coconut oil (CO). Four fat blends with different ratios of KSF/CO (20/80, 40/60, 60/40 and 80/20 (%wt)), CO, KSF and a commercial LCBR (C-LCBR) were characterized using various techniques. It was found that blend 60/40 exhibited SFC curve and crystallization/melting behavior most similar to that of C-LCBR. The blend met the requirements to be considered as LCBR and has potential as an alternative to commercial LCBR that are being used nowadays and hence it was recommended as LCBR (called R-LCBR). The polymorphic behavior of both C-LCBR and R-LCBR was investigated and both fats displayed mainly short spacing pattern associated with β’ polymorph, a required polymorph for LCBR. The compatibility between R-LCBR and CB was investigated by mixing the R-LCBR with CB in different proportions and softening due to the eutectic effect was observed in the mixed fats. This limits the proportion of CB and the R-LCBR in compound coatings to no more than 5% of CB in the total fat phase.
Waste cooking oil (WCO) was chemically modified via epoxidation using H2O2 followed by transesterification with methanol and branched alcohols (isooctanol, isotridecanol and isooctadecanol) to produce bio-lubricants with improved oxidative stability and low temperature properties. Physicochemical properties of synthesized bio-lubricants such as pour point (PP), cloud point (CP), viscosity, viscosity index (VI), oxidative stability, and corrosion resistant property were determined according to standard methods. The synthesized bio-lubricants showed improved low temperature flow performances compared with WCO, which can be attributing to the introduction of branched chains in their molecular structures. What’s more, the oxidation stability of the WCO showed more than 10 folds improvement due to the elimination of –C=C–bonds in the WCO molecule. Tribological performances of these bio-lubricants were also investigated using four-ball friction and wear tester. Experimental results showed that derivatives of WCO exhibited favorable physicochemical properties and tribological performances which making them good candidates in formulating eco-friendly lubricants.
A rapid method for determining the carbonyl value of frying oils has been developed using Fourier-transform infrared (FTIR) spectroscopy and chemometrics. One hundred and fifty-six frying oils with different carbonyl values were collected from an actual potato frying process. FTIR spectra in the range of 4000–650 cm−1 were scanned with a FTIR spectroscopy apparatus using the attenuated total reflectance (ATR) method. A good calibration model was obtained using the partial least-squares (PLS) regression method with full cross validation for predicting the carbonyl value of frying oils. For the model, the coefficients of determination (R2), standard errors of cross validation (SECV) and standard errors of prediction (SEP) were 0.99, 1.87 μmol g−1 and 1.93 μmol g−1, respectively. Moreover, standard deviation ratios of reference data in the validation sample set to the SEP were higher than 3. This study shows that the carbonyl value of frying oils can be successfully determined to a high accuracy using FTIR spectroscopy combined with PLS regression.
The chemical composition, oxidative stability, aroma and sensory profiles of virgin olive oils from two Tunisian cultivars, Chemlali and Neb Jmel, grown in two different locations, the center and south of Tunisia, have been evaluated. There were significant differences between the oils from both cultivars when grown in the two different environments. At higher altitude, the oils showed a greater amount of oleic acid, phenols and a higher oxidative stability, while at lower altitude, the oils had higher saturated and linoleic acid contents. The aroma profiles in Chemlali and Neb Jmel cultivars were also influenced by the pedoclimatic conditions, as shown by the difference in volatiles as a function of the geographical area. The volatile compounds of the monovarietal virgin olive oils were identified and compared using headspace solid-phase microextraction (HS–SPME) technique coupled with GC–MS and GC–FID. The proportions of different classes of volatiles of the oils have shown significant differences throughout the obtained oils. These results suggest that besides the genetic factor, the agronomic conditions affect the volatile formation and, therefore, the organoleptic properties of VOO, and can be used to discriminate and characterize the Chemlali and Neb Jmel olive oils from each region.
Abstract: The aim of this study was to investigate some factors that can contribute to the formulation of aqueous-based carvacrol microemulsion that can potentially be used in food preservation or disinfection. For this purpose the capacity of formation of carvacrol microemulsion was first revealed by studying the phase behavior of that compound in five different non-ionic microemulsion systems. Factors affecting that phase behavior like the type of non-ionic surfactant and presence of solubilization enhancers were also studied. The fully dilutable microemulsion system that can incorporate high carvacrol amount, as revealed from the phase diagrams, was chosen for the antibacterial evaluation study. The same microemulsion system was re-formulated in a cationic form by substituting the non-ionic surfactant, Tween 20 (T20) with the cationic cetylpyridinium chloride (CPC). The disc diffusion method was used to evaluate the activity of these microemulsion systems against different pathogenic bacteria. Results of the phase behavior study showed that carvacrol is a challenging phenolic compound which did not lend itself easily for solubilization in a fully dilutable non-ionic microemulsion. Incorporation of some solubilization enhancers like propylene glycol (PG) or short chain alcohols can fulfill this purpose however high surfactant/carvacrol ratio (9:1) was still required to solubilize only 1.0 wt% carvacrol in dilutable microemulsion. The antibacterial evaluation study at that concentration revealed that non-ionic carvacrol microemulsion formulated with T20 and a solubilization enhancer did not exhibit better antimicrobial activity than the same concentration of carvacrol formulated in surfactant-free aqueous solution composed of water/PG (1:1). On the other hand, the CPC-formulated carvacrol microemulsion showed significantly higher antibacterial activity than T20-formulated microemulsion. Results of the current investigation shed the light on the solubilization capacity and phase behavior of carvacrol in non-ionic microemulsion and the potential of using cationic carvacrol microemulsion in disinfection and decontamination applications.
We investigated how phase behavior changes by replacing water with glycerol in water/mixture of polyglycerol polyricinoleate (PGPR) and hexaglycerol monolaurate (HGML) /vegetable oil system, and studied the effect of glycerol on o/w nano-emulsion formation using an isothermal low-energy method. In the phase behavior study, the liquid crystalline phase (Lc) + the sponge phase (L3) expanded toward lower surfactant concentration when water was replaced with glycerol in a system containing surfactant HLP (a mixture of PGPR and HGML). O/W nano-emulsions were formed by emulsification of samples in a region of Lc + L3. In the glycerol/surfactant HLP/vegetable oil system, replacing water with glycerol was responsible for the expansion of a region containing Lc + L3 toward lower surfactant concentration, and as a result, in the glycerol/surfactant HLP/vegetable oil system, the region where o/w nano-emulsions or o/w emulsions could be prepared using an isothermal low-energy emulsification method was wide, and the droplet diameter of the prepared o/w emulsions was also smaller than that in the water/surfactant HLP/vegetable oil system. Therefore, glycerol was confirmed to facilitate the preparation of nano-emulsions from a system of surfactant HLP. Moreover, in this study, we could prepare o/w nano-emulsions with a simple one-step addition of water at room temperature without using a stirrer. Thus, the present technique is highly valuable for applications in several industries.
Skeletal muscles can adapt to dietary interventions that affect energy metabolism. Dietary intake of medium-chain fatty acids (MCFAs) enhances mitochondrial oxidation of fatty acids (FAO) in type IIa skeletal muscle fibers. However, the effect of MCFAs diet on mitochondrial or cytoplasmic FAO-related protein expression levels in different types of muscle fibers remains unclear. This study aims to examine the effects of a high-fat diet, containing MCFAs, on mitochondrial enzyme activities and heart-type fatty acid-binding protein (H-FABP) levels in different types of skeletal muscle fibers. Five-week-old male Wistar rats were assigned to one of the following three dietary conditions: standard chow (SC, 12% of calories from fat), high-fat MCFA, or high-fat long-chain fatty acids (LCFAs) diet (60% of calories from fat for both). The animals were provided food and water ad libitum for 4 weeks, following which citrate synthase (CS) activity and H-FABP concentration were analyzed. The epididymal fat pads (EFP) were significantly smaller in the MCFA group than in the LCFA group (p < 0.05). MCFA-fed group displayed an increase in CS activity compared with that observed in SC-fed controls in all types of skeletal muscle fibers (triceps, surface portion of gastrocnemius (gasS), deep portion of gastrocnemius (gasD), and soleus; p < 0.05,). H-FABP concentration was significantly higher in the LCFA group than in both the SC-fed and MCFA-fed groups (triceps, gasS, gasD, and soleus; p < 0.05,). However, no significant difference was observed in the H-FABP concentrations between the SC-fed and MCFA-fed groups. The results of this study showed that the MCFA diet can increase the expression of the mitochondrial enzyme CS, but not that of H-FABP, in both fast- and slow-twitch muscle fibers, suggesting that H-FABP expression is dependent on the chain length of fatty acids in the cytoplasm of skeletal muscles cells.
In this study, the chitosan magnetic core-shell nanoparticles (CMNPs) was synthesized and then used as a support for immobilization of lipase. The characteristics of CMNPs, including morphology, topography and spectra type before and after immobilization were determined. The scanning electron micrographs of the CMNPs showed that they were approximately uniform spheres and the distribution chart indicated that the particles have the mean diameter of 100 nm. Kinetic parameters of Km and Vm were calculated as 1.07 mM and 29.43 U/mg for free B. cepacia lipase and 1.29 mM and 25.82 U/mg for immobilized lipase on CMNPs, respectively. The activity of immobilized lipase was 32 U/mg under optimum temperature and pH. CMNP’s were used in trasesterification reaction in order to evaluate the activity of the immobilized enzyme compared to the free enzyme. Immobilization of lipase on CMNPs improved stability and total relative activity of the enzyme. It could be concluded that CMNPs be considered as a suitable carrier for enzyme immobilization.
The ethanolysis of fish oil in various reaction medium (tert-pentanol, n-hexane and solvent free system) catalyzed by the immobilized commercial lipase Lipozyme® 435 (Candida Antarctica) at atmospheric pressure has been studied in this work. The effect of some kinetic parameters, such as the amount of lipase, temperature and the initial reactant molar ratio ethanol:oil on monoacyglyceride and ethyl ester yield has been analyzed. Experimental data were successfully correlated by a simple kinetic model based on the elementary reactions proposed in this work. At high initial reactant molar ratio the three elementary steps can be considered as irreversible. However the reaction rate constants ratio for the deacylation of monoglyceride to glycerol decreased by decreasing the molar ratio ethanol:oil. The reaction rates are slower in n-hexane as reaction medium compared to tert-pentanol and a solvent-free system, at the experimental conditions essayed in this work. In this last case, ethanol acts as solvent for reaction and as reactant.
Lysophosphatidylcholine (LPC) is amphiphilic substance, and possesses excellent physiological functions. In this study, LPC was prepared through ethanolysis of phosphatidylcholine (PC) in n-hexane or solvent free media catalyzed by Novozym 435 (from Candida antarctica), Lipozyme TLIM (from Thermomcyces lanuginosus) and Lipozyme RMIM (from Rhizomucor miehei). The results showed that three immobilized lipases from Candida Antarctica, Thermomcyces lanuginosus and Rhizomucor miehei could catalyze ethanolysis of PC efficiently. In n-hexane, the LPC conversions of ethanolysis of PC catalyzed by Novozyme 435, Lipozyme TLIM and Lipozyme RMIM could reach to 98.5 ± 1.6%, 94.6 ± 1.4% and 93.7 ± 1.8%, respectively. In solvent free media, the highest LPC conversions of ethanolysis of PC catalyzed by Novozyme 435, Lipozyme TL IM and Lipozyme RM IM were 97.7 ± 1.7%, 93.5 ± 1.2% and 93.8 ± 1.9%, respectively. The catalytic efficiencies of the three lipases were in the order of Novozyme 435 > Lipozyme TLIM > Lipozyme RMIM. Furthermore, their catalytic efficiencies in n-hexane were better than those in solvent free media.
We synthesized the naturally occurring carbasugar ampelomin A and its epimer from a common starting material. The enantiomerically pure starting material was obtained by base-catalyzed asymmetric Diels–Alder reaction of 3-hydroxy-2-pyrone and chiral acrylate. The total yield of ampelomin A was 14% in seven synthetic steps. The key step of the synthesis of ampelomin A was inversion of the stereochemistry at the C-6 position, which was achieved by stereoselective catalytic hydrogenation of the corresponding methylidene group. Further synthesis of the epimer was straightforward, because all stereogenic centers had already been introduced on the starting material; the total yield was 44% in four synthetic steps. Both the final products were obtained in pure form without contamination with undesired isomers. The reported 1H NMR chemical shift of the C-7 methyl protons and the H-5axial coupling pattern of natural ampelomin A were inconsistent with those of our synthetic product. After careful comparison of the spectra and examination of the stable conformation obtained through MM2 calculations, we present revised NMR data for ampelomin A.
Cholesterol has been suggested to play a role in stable vesicle formation by adjusting the molecular packing of the vesicular bilayer. To explore the mechanisms involved in adjusting the bilayer structure by cholesterol, the molecular packing behavior in a mimic outer layer of cationic dialkyldimethylammonium bromide (DXDAB)/cholesterol vesicular bilayer was investigated by the Langmuir monolayer approach with infrared reflection-absorption spectroscopy (IRRAS). The results indicated that the addition of cholesterol in the DXDAB Langmuir monolayers not only restrained the desorption of the DXDAB with short hydrocarbon chains, such as ditetradecyldimethylammonium bromide or dihexadecyldimethylammonium bromide, into the aqueous phase but also induced a condensing effect on the DXDAB monolayers. At a liquid-expanded (LE) state, the ordering effect of cholesterol accompanying the condensing effect occurred in the mixed DXDAB/cholesterol monolayers due to the tendency of maximizing hydrocarbon chain contact between cholesterol and the neighboring hydrocarbon chains. However, for the mixed monolayers containing the DXDAB with long hydrocarbon chains, such as dioctadecyldimethylammonium bromide (DODAB), the disordering effect of cholesterol took place at a liquid-condensed (LC) state. This was related to the molecular structure of cholesterol and hydrocarbon chain length of DODAB. The rigid sterol ring of cholesterol hindered the portion of neighboring hydrocarbon chains from motion. However, the flexible alkyl side-chain of cholesterol along with the corresponding portion of neighboring hydrocarbon chains formed a fluidic region, counteracting the enhanced conformational order induced by the sterol ring of cholesterol. Furthermore, the long hydrocarbon chains of DODAB possessed a more pronounced motion freedom, resulting in a more disordered packing of the monolayers.