Identification of conjugated linoleic acid elongation and β-oxidation products by coupled silver-ion HPLC APPI-MS

Atmospheric pressure photoionisation (APPI) was used in combination with silver-ion (Ag(+))-HPLC for detection of (conjugated) fatty acid methyl esters (FAME) by tandem-mass spectrometry. APPI-MS of methyl esters of conjugated linoleic acid showed an increase in signal-to-noise ratio by a factor of 40 compared to atmospheric pressure chemical ionization in the positive mode. It was possible to identify double bond position, configuration and chain length of FAME based on chromatographic separation and mass detection. The developed LC-MS method is useful for the analysis of CLA elongation and beta-oxidation products, especially with trans,trans-configuration, which are difficult to analyze by conventional GC-MS techniques.

Antioxidant Properties of Methanolic Extracts from Leaves of Rhazya stricta

Because of increased safety concerns about synthetic antioxidants, exploitation of cheaper and safer sources of antioxidants based on natural origin is the focus of research nowadays. Rhazya stricta is a medicinally important plant native to South Asia. Extraction of antioxidants was carried out in different solvent systems, i.e., water, 80% methanol, 70% ethanol, and diethyl ether. The methanolic extract exhibited the highest total phenolic content among the extracts; therefore for further studies the methanolic extract was employed. Antioxidant activity measurement in the linoleic acid system, metal chelating activity, reducing power, scavenging effect on 1,1-diphenyl-2-picrylhydrazyl free radical, and superoxide anion radical scavenging activity were taken as the parameters for assessment of antioxidant potential of methanolic extracts. Results were compared with alpha-tocopherol and the synthetic antioxidant butylated hydroxyanisole. The antioxidant potential of methanolic extracts of R. stricta leaves was comparable with previously exploited potent antioxidants and is strongly concentration dependent.

Evaluation of the antioxidant capacity of limonin, nomilin, and limonin glucoside

The antioxidant capacity (AOC) of three representative citrus limonoids, limonin, nomilin, and limonin glucoside, was examined by the oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), beta-carotene-linoleic acid bleaching, and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assays. Pure compounds and proper negative (cinnamic acid) and positive (2,6-di-tert-butyl-4-methylphenol (BHT) and ascorbic acid) controls were used to remove any ambiguity in interpreting results. In all cases, limonin and nomilin gave results equivalent to those of cinnamic acid, indicating that they do not possess any inherent AOC and should not be considered antioxidants. Similar results were observed for limonin glucoside, with the exception of an anomalous result obtained from the beta-carotene-linoleic acid bleaching assay. Limonin glucoside was deemed not to be an antioxidant on the basis of the three unequivocal assays.

Lipoxygenase from banana leaf: purification and characterization of an enzyme that catalyzes linoleic acid oxygenation at the 9-position

The objective of the present study was to purify and characterize the lipoxygenase (LOX) from banana leaf (Giant Cavendishii, AAA), an unutilized bioresource. LOX was extracted, isolated, and purified 327-fold using 25-50% saturation of ammonium sulfate fractionation, hydroxyapatite column separation, and gel filtration on Superdex 200. The molecular mass of the purified LOX was 85 kDa, K(m) was 0.15 mM, and V(max) was 2.4 microM/min.mg using linoleic acid as substrate. Triton X-100 was required in the extraction medium; otherwise, no LOX activity was detected. LOX activity increased with the concentration of Triton X-100 with an optimum at 0.1%. The optimal pH of the purified LOX from banana leaf was 6.2, and optimal temperature was 40 degrees C. The LOX showed the highest reactivity toward 18:2 followed by 18:3 and 20:4. A very low reaction rate was observed toward 20:5 and 22:6. On the basis of retention time in normal phase HPLC, the products of 18:2 or 18:3 catalyzed by purified LOX were hydroperoxyoctadecadienoic acid or hydroperoxyoctadecatrienoic acid. It seems that 9-LOX is the predominant enzyme in banana leaf. Banada leaf dried at 110 degrees C for 2 h developed algal aroma. Banana leaf extract stored at 10 degrees C for 12 h formed an oolong tea-like flavor. Banana leaf extract reacted with 18:2 or soybean oil pretreated with bacterial lipase produced green and melon-like aroma, whereas the same reaction with 18:3 produced a sweet, fruity, cucumber-like flavor note.

ZmPUMP encodes a fully functional monocot plant uncoupling mitochondrial protein whose affinity to fatty acid is increased with the introduction of a His pair at the second matrix loop

Uncoupling proteins (UCPs) are specialized mitochondrial transporter proteins that uncouple respiration from ATP synthesis. In this study, cDNA encoding maize uncoupling protein (ZmPUMP) was expressed in Escherichia coli and recombinant ZmPUMP reconstituted in liposomes. ZmPUMP activity was associated with a linoleic acid (LA)-mediated H(+) efflux with K(m) of 56.36+/-0.27microM and V(max) of 66.9micromolH(+)min(-1)(mgprot)(-1). LA-mediated H(+) fluxes were sensitive to ATP inhibition with K(i) of 2.61+/-0.36mM (at pH 7.2), a value similar to those for dicot UCPs. ZmPUMP was also used to investigate the importance of a histidine pair present in the second matrix loop of mammalian UCP1 and absent in plant UCPs. ZmPUMP with introduced His pair (Lys155His and Ala157His) displayed a 1.55-fold increase in LA-affinity while its activity remained unchanged. Our data indicate conserved properties of plant UCPs and suggest an enhancing but not essential role of the histidine pair in proton transport mechanism.

Quantitation of furan and methylfuran formed in different precursor systems by proton transfer reaction mass spectrometry

Furan has recently received attention as a possibly hazardous compound occurring in certain thermally processed foods. Previous model studies have revealed three main precursor systems producing furan upon thermal treatment, i.e., ascorbic acid, Maillard precursors, and polyunsaturated lipids. We employed proton transfer reaction mass spectrometry (PTR-MS) as an on-line monitoring technique to study furan formation. Unambiguous identification and quantitation in the headspace was achieved by PTR-MS/gas chromatography-mass spectrometry coupling. Ascorbic acid showed the highest potential to generate furan, followed by glyceryl trilinolenate. Some of the reaction samples generated methylfuran as well, such as Maillard systems containing alanine and threonine as well as lipids based on linolenic acid. The furan yields from ascorbic acid were lowered in an oxygen-free atmosphere (30%) or in the presence of reducing agents (e.g., sulfite, 60%), indicating the important role of oxidation steps in the furan formation pathway. Furthermore, already simple binary mixtures of ascorbic acid and amino acids, sugars, or lipids reduced furan by 50-95%. These data suggest that more complex reaction systems result in much lower furan amounts as compared to the individual precursors, most likely due to competing reaction pathways.

Effects of body condition score at parturition and postpartum supplemental fat on metabolite and hormone concentrations of beef cows and their suckling calves1

To determine the effects of BCS at parturition and postpartum lipid supplementation on blood metabolite and hormone concentrations, 3-yr-old Angus x Gelbvieh beef cows, which were nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of BW) at parturition, were used in a 2-yr experiment (n = 36/yr). Beginning at 3 d postpartum, cows within each BCS were assigned randomly to be fed hay and a low-fat control supplement or lipid supplements with either cracked high-linoleate or high-oleate safflower seeds until d 61 of lactation. The diets were formulated to be isonitrogenous and isocaloric, and the safflower seed supplements were formulated to achieve 5% DMI as fat. On d 31 and 61 of lactation, blood samples were collected preprandially and then hourly postprandially (at 0, 1, 2, 3, and 4 h). Serum insulin (P = 0.27) and glucose (P = 0.64) were not affected by BCS at parturition. The mean concentrations of plasma NEFA (P = 0.08) and beta-hydroxybutyrate (P = 0.08) tended to be greater, and serum IGF-I was greater (P < 0.001) in BCS 6 than BCS 4 cows. Conversely, serum GH was greater (P = 0.003) for BCS 4 cows, indicating that regulation of IGF by GH may have been uncoupled in BCS 4 cows. The postpartum diet did not affect NEFA (P = 0.94), glucose (P = 0.15), IGF-I (P = 0.33), or GH (P = 0.62) concentrations. Oleate-supplemented cows had greater (P = 0.03) serum insulin concentrations, whereas control cows had greater (P = 0.01) plasma beta-hydroxybutyrate concentrations. Concentrations of NEFA (P = 0.05) and glucose (P < 0.001) were greater, and beta-hydroxybutyrate tended (P = 0.07), to be greater at d 3, whereas serum IGF-I was greater (P = 0.003) at d 6 of lactation. Similar concentrations of NEFA, glucose, GH, and IGF-I indicate that the nutritional status of beef cows during early lactation was not influenced by lipid supplementation. However, perturbations of the somatotropic axis in BCS 4 cows indicate that the influence of energy balance and BCS of the cow at parturition on postpartum performance should be considered when making managerial decisions.

Linoleic acid derivative DCP-LA improves learning impairment in SAMP8

In the water-maze test, the linoleic acid derivative, 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA) (1 mg/kg, intraperitoneally), significantly shortened the prolonged latency for accelerated-senescence-prone mice 8 (SAMP8), reaching a level similar to the latency for accelerated-senescence-resistant mice 1 (SAMR1) as control. In the open-field test to assess motor activity, it was confirmed that the DCP-LA effect is not due to increased motor activity. In the passive avoidance test to assess fear memory, DCP-LA had no effect on the latency of acquisition and retention for SAMP8. The results of the present study, thus, suggest that DCP-LA could improve age-related learning impairment by enhancing cognitive functions.

Antioxidant and photoprotective properties of an extract from buckwheat herb (Fagopyrum esculentum MOENCH)

In recent years, the incidence of skin cancer has risen remarkably. Sun light, especially the included ultraviolet (UV)-radiation, is seen as important trigger for the development of skin cancer. Thus, there is an increasing interest in the development of UV-protective substances to use them as sun care products. One approach is the topical application of herbal antioxidants. Plant-derived antioxidants are often extracts and therefore contain a complex mixture of constituents, like flavonoids and polyphenols, which contribute to the overall activity of the extract. In the present study an extract from buckwheat herb was compared to rutin, which is the main constituent of the extract, regarding their antioxidant and radical scavenging activity. Additionally, the photoprotective properties of the extract were compared to those of a commercial UV absorber. The antioxidant activity was quantified regarding the reactivity versus the 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH). The photoprotective properties of the extract were examined by the inhibition of the photosensitized lipid peroxidation of linolic acid. In the DPPH assay, the extract had significantly better antioxidant activity than pure rutin. The extract prevented more effectively the UV-induced peroxidation of linolic acid than rutin itself or the commercial UV absorber. The use of the extract from buckwheat herb seems to be more beneficial than the use of pure rutin. This can be referred to the presence of minor phenolic compounds in the extract. The results indicate that it is advisable to use antioxidants rather than only UV absorber to obtain a maximum of photo protection.

Kinetic studies of the interaction of fatty acids with phosphatidylcholine vesicles (liposomes)

The kinetics of addition of fatty acids (as alkaline solutions of the fatty acid anions) to pre-existing unilamellar phospholipid vesicles (mean diameter 100 nm) has been studied. The phospholipid DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) has been mainly used, together with three fatty acids, oleic acid (cis-9-octadecenoic acid), linoleic acid (cis,cis-9,12-octadecadienoic acid) and capric acid (decanoic acid). Experiments were performed above as well as below the main phase transition temperature (Tm) of DMPC vesicles. The pH chosen to study the fatty acid vesicle interaction (after fatty acid and vesicle mixing) was 8.5 in the case of oleic acid and linoleic acid and 7.4 for capric acid. In the absence of any pre-existing phospholipid vesicles, the addition of alkaline solutions of the fatty acid anions to corresponding buffer solutions of pH 8.5 or 7.4 leads to a partial protonation of the fatty acid anions again resulting in the formation of fatty acid vesicles. This process is rather slow, taking place over a period of hours/days, and the vesicles formed are very polydisperse and include a range of vesicle sizes/shapes. However, in the presence of pre-existing phospholipid vesicles the added fatty acids equilibrate readily within a few minutes and the size of the vesicles that form are then closely related to the size of the originally present phospholipid vesicles; the vesicles formed being generally somewhat larger than the pre-existing vesicles. In the case of the phospholipid DMPC, the mixed fatty acid/phospholipid vesicle system is often formed rather rapidly (particularly above Tm), so that stopped-flow methods have been applied to follow the kinetics of the process. It is proposed that most of the fatty acid molecules are initially rapidly incorporated into the bilayers of the pre-exisiting phospholipid vesicles as monomers, rather than that the added fatty acids form separate fatty acid vesicles. The mean vesicle sizes formed in the systems investigated have been analysed by using dynamic light scattering measurements. The behaviour of the DMPC system was found to be slightly different from the POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) system studied before, but the results are consistent with a model that involves growth and subsequent fission of the mixed vesicles. The study provides further support of the "matrix effect" in this type of system [S. Lonchin, P.L. Luisi, P. Walde, B.H. Robinson, J. Phys. Chem. B 103 (1999) 10910-10916]. The pre-existing DMPC vesicles act as a kind of seed to control the behavior of the system in the presence of added fatty acid anions.

Factors affecting conjugated linoleic acid content in milk and meat

Conjugated linoleic acid (CLA) has been recently studied mainly because of its potential in protecting against cancer, atherogenesis, and diabetes. Conjugated linoleic acid (CLA) is a collective term for a series of conjugated dienoic positional and geometrical isomers of linoleic acid, which are found in relative abundance in milk and tissue fat of ruminants compared with other foods. The cis-9, trans-11 isomer is the principle dietary form of CLA found in ruminant products and is produced by partial ruminal biohydrogenation of linoleic acid or by endogenous synthesis in the tissues themselves. The CLA content in milk and meat is affected by several factors, such as animal's breed, age, diet, and management factors related to feed supplements affecting the diet. Conjugated linoleic acid in milk or meat has been shown to be a stable compound under normal cooking and storage conditions. Total CLA content in milk or dairy products ranges from 0.34 to 1.07% of total fat. Total CLA content in raw or processed beef ranges from 0.12 to 0.68% of total fat. It is currently estimated that the average adult consumes only one third to one half of the amount of CLA that has been shown to reduce cancer in animal studies. For this reason, increasing the CLA contents of milk and meat has the potential to raise the nutritive and therapeutic values of dairy products and meat.

In vitro antioxidant activity and scavenging effects of Cinnamomum verum leaf extract assayed by different methodologies

The free radical scavenging capacity and antioxidant activities of the methanolic extract of Cinnamomum verum leaf (CLE) were studied and compared to antioxidant compounds like trolox, butylated hydroxyl anisole, gallic acid and ascorbic acid. The CLE exhibited free radical scavenging activity, especially against DPPH radical and ABTS radical cation. They also exhibited reducing power and metal ion chelating activity, along with hydroxyl radical scavenging activity. The peroxidation inhibiting activity of CLE recorded using the linoleic acid emulsion system, showed very good antioxidant activity.

Atomistic simulation studies of cholesteryl oleates: model for the core of lipoprotein particles

We have conducted molecular dynamics simulations to gain insight into the atomic-scale properties of an isotropic system of cholesteryl oleate (CO) molecules. Cholesteryl esters are major constituents of low density lipoprotein particles, the key players in the formation of atherosclerosis, as well as the storage form of cholesterol. Here the aim is to clarify structural and dynamical properties of CO molecules under conditions, which are suggestive of those in the core of low density lipoprotein particles. The simulations in the fluid phase indicate that the system of CO molecules is characterized by an absence of translational order, as expected, while the orientational order between distinct CO molecules is significant at short distances, persisting over a molecular size. As for intramolecular properties, the bonds along the oleate chain are observed to be weakly ordered with respect to the sterol structure, unlike the bonds along the short hydrocarbon chain of cholesterol where the ordering is significant. The orientational distribution of the oleate chain as a whole with respect to the sterol moiety is of broad nature, having a major amount of extended and a less considerable proportion of bended structures. Distinct transient peaks at specific angles also appear. The diffusion of CO molecules is found to be a slow process and characterized by a diffusion coefficient of the order of 2x10(-9) cm2/s. This is considerably slower than diffusion, e.g., in ordered domains of lipid membranes rich in sphingomyelin and cholesterol. Analysis of the rotational diffusion rates and trans-to-gauche transition rates yield results consistent with experiments.

Electron-Transfer Oxidation Properties of Unsaturated Fatty Acids and Mechanistic Insight into Lipoxygenases

Rate constants of photoinduced electron-transfer oxidation of unsaturated fatty acids with a series of singlet excited states of oxidants in acetonitrile at 298 K were examined and the resulting electron-transfer rate constants (k(et)) were evaluated in light of the free energy relationship of electron transfer to determine the one-electron oxidation potentials (E(ox)) of unsaturated fatty acids and the intrinsic barrier of electron transfer. The k(et) values of linoleic acid with a series of oxidants are the same as the corresponding k(et) values of methyl linoleate, linolenic acid, and arachidonic acid, leading to the same E(ox) value of linoleic acid, methyl linoleate, linolenic acid, and arachidonic acid (1.76 V vs SCE), which is significantly lower than that of oleic acid (2.03 V vs SCE) as indicated by the smaller k(et) values of oleic acid than those of other unsaturated fatty acids. The radical cation of linoleic acid produced in photoinduced electron transfer from linoleic acid to the singlet excited state of 10-methylacridinium ion as well as that of 9,10-dicyanoanthracene was detected by laser flash photolysis experiments. The apparent rate constant of deprotonation of the radical cation of linoleic acid was determined as 8.1 x 10(3) s(-1). In the presence of oxygen, the addition of oxygen to the deprotonated radical produces the peroxyl radical, which has successfully been detected by ESR. No thermal electron transfer or proton-coupled electron transfer has occurred from linoleic acid to a strong one-electron oxidant, Ru(bpy)3(3+) (bpy = 2,2'-bipyridine) or Fe(bpy)3(3+). The present results on the electron-transfer and proton-transfer properties of unsaturated fatty acids provide valuable mechanistic insight into lipoxygenases to clarify the proton-coupled electron-transfer process in the catalytic function.

On the relationships of substrate orientation, hydrogen abstraction, and product stereochemistry in single and double dioxygenations by soybean lipoxygenase-1 and its Ala542Gly mutant

Recent findings associate the control of stereochemistry in lipoxygenase (LOX) catalysis with a conserved active site alanine for S configuration hydroperoxide products, or a corresponding glycine for R stereoconfiguration. To further elucidate the mechanistic basis for this stereocontrol we compared the stereoselectivity of the initiating hydrogen abstraction in soybean LOX-1 and an Ala542Gly mutant that converts linoleic acid to both 13S and 9R configuration hydroperoxide products. Using 11R-(3)H- and 11S-(3)H-labeled linoleic acid substrates to examine the initial hydrogen abstraction, we found that all the primary hydroperoxide products were formed with an identical and highly stereoselective pro-S hydrogen abstraction from C-11 of the substrate (97-99% pro-S-selective). This strongly suggests that 9R and 13S oxygenations occur with the same binding orientation of substrate in the active site, and as the equivalent 9R and 13S products were formed from a bulky ester derivative (1-palmitoyl-2-linoleoylphosphatidylcholine), one can infer that the orientation is tail-first. Both the EPR spectrum and the reaction kinetics were altered by the R product-inducing Ala-Gly mutation, indicating a substantial influence of this Ala-Gly substitution extending to the environment of the active site iron. To examine also the reversed orientation of substrate binding, we studied oxygenation of the 15S-hydroperoxide of arachidonic acid by the Ala542Gly mutant soybean LOX-1. In addition to the usual 5S, 15S- and 8S, 15S-dihydroperoxides, a new product was formed and identified by high-performance liquid chromatography, UV, gas chromatography-mass spectrometry, and NMR as 9R, 15S-dihydroperoxyeicosa-5Z,7E,11Z,13E-tetraenoic acid, the R configuration "partner" of the normal 5S,15S product. This provides evidence that both tail-first and carboxylate end-first binding of substrate can be associated with S or R partnerships in product formation in the same active site.

Enzymatic synthesis of l-ascorbyl linoleate in organic media

A novel L-ascorbyl fatty acid ester, L-ascorbyl linoleate was successfully prepared by enzymatic esterification and transesterification in a non-aqueous medium using immobilized lipase as biocatalyst. Changes in enzymatic activity and product yield were studied for the following variable: the nature of the fatty acid, the fatty acid concentration and water content. The yield of synthesis for the C18 unsaturated fatty acids were higher than for the C18 saturated fatty acid. Initial enzyme concentration does not affect the equilibrium of the reaction. And the product yield (33.5%) in the transesterification was higher than that of the esterification (21.8%) at a high-substrate concentration 0.3 M. The medium water content was found to have a distinct influence on the L-ascorbyl linoleate synthesis.

Resistance of Lactobacillus plantarum KCTC 3099 from Kimchi to oxidative stress

The antioxidative capacity of two lactic acid bacteria isolated from Kimchi, a Korean fermented food, was evaluated by measuring the resistance to reactive oxygen species (ROS) and compared with that of Lactobacillus rhamnosus GG as a positive control. Both intact cells and cell-free extracts of Lactobacillus plantarum KCTC 3099 exhibited higher antioxidative activity in inhibiting lipid peroxidation among the strains evaluated with an inhibitory level of 38.6% and 48.5%, respectively. To evaluate the resistance of the two lactic acid bacteria to ROS, we tested their survival in the presence of 1 mM hydrogen peroxide, 0.4 mM hydroxyl radicals, and superoxide anions induced by 10 mM paraquat. L. plantarum KCTC 3099 was viable even after 8 hours in the presence of both 1 mM hydrogen peroxide and 0.4 mM hydroxyl radicals. Moreover, the survival of L. plantarum KCTC 3099 was not affected by superoxide anions generated by using paraquat, indicating that it has resistance to superoxide anions. To define the antioxidative mechanism, superoxide dismutase (SOD) and metal ion chelating activities were determined. L. plantarum KCTC 3099 presented little SOD activity, but had the higher level of chelating activity for both Fe2+ and Cu2+ metal ions at 13.6 ppm and 23.9 ppm, respectively. These results suggested that the antioxidative capacity of L. plantarum KCTC 3099 is apparently caused by chelating metal ions rather than by SOD activation.

[Comparison of supercritical fluid extraction and steam distillation methods for the extraction of essential oils from Schizonepeta tenuifolia Briq]

Essential oil was extracted from Schizonepeta tenuifolia Briq. by supercritical fluid extraction (SFE) and steam distillation (SD). The components extracted were determined by gas chromatography with area normalization method and identified by gas chromatography-mass spectrometry (GC-MS). The optimal chromatographic conditions were: capillary column, SE-54 (30 m x 0.25 mm i.d., 0.25 microm); column temperature, 50 degrees C (3 min) --> (5 degrees c/min) 180 degrees C (2 min --> (10 degrees C/ min) 260 degrees C 50 min); split injection, split ratio 1: 50; injector temperature, 280 degrees C. Fifty-four components were identified for the essential oils extracted by SFE, and its main components were found to be pulegone, menthone, linoleic acid chloride etc. Thirty-nine components were identified for the essential oil obtained by SD, and its main components were found to be pulegone, menthone, limonene etc. The SFE method is better than the SD method in reliability stability and reproducibility, and is thus well suitable for similar applications involving for extraction of other traditional Chinese herbal medicines.

Quantification of lipid alkyl radicals trapped with nitroxyl radical via HPLC with postcolumn thermal decomposition

Lipid alkyl radicals generated from polyunsaturated fatty acids via chemical or enzymatic H-abstraction have been a pathologically important target to quantify. In the present study, we established a novel method for the quantification of lipid alkyl radicals via nitroxyl radical spin-trapping. These labile lipid alkyl radicals were converted into nitroxyl radical-lipid alkyl radical adducts using 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-N-oxyl (CmdeltaP) (a partition coefficient between octanol and water is approximately 3) as a spin-trapping agent. The resulting CmdeltaP-lipid alkyl radical adducts were determined by HPLC with postcolumn online thermal decomposition, in which the adducts were degraded into nitroxyl radicals by heating at 100 degrees C for 2 min. The resulting nitroxyl radicals were selectively and sensitively detected by electrochemical detection. With the present method, we, for the first time, determined the lipid alkyl radicals generated from linoleic acid, linolenic acid, and arachidonic acid via soybean lipoxygenase-1 or the radical initiator 2,2'-azobis(2,4-dimethyl-valeronitrile).

Antioxidant and antiradical activities of L-carnitine

L-carnitine plays an important regulatory role in the mitochondrial transport of long-chain free fatty acids. In this study, the antioxidant activity of L-carnitine was investigated as in vitro. The antioxidant properties of the L-carnitine were evaluated by using different antioxidant assays such as 1, 1-diphenyl-2-picryl-hydrazyl free radical (DPPH.) scavenging, total antioxidant activity, reducing power, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities. Total antioxidant activity was measured according to ferric thiocyanate method. alpha-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant compounds. At the concentrations of 15, 30 and 45 microg/mL, l-carnitine showed 94.6%, 95.4% and 97.1% inhibition on lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, 45 microg/mL of standard antioxidant such as alpha-tocopherol and trolox indicated an inhibition of 88.8% and 86.2% on peroxidation of linoleic acid emulsion, respectively. In addition, L-carnitine had an effective DPPH. scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, total reducing power and metal chelating on ferrous ions activities. Also, those various antioxidant activities were compared to alpha-tocopherol and trolox as references antioxidants.

Infants with intrauterine growth restriction have impaired formation of docosahexaenoic acid in early neonatal life: a stable isotope study

This study evaluated the arachidonic acid (AA) and docosahexaenoic acid (DHA) formation from d5-labeled linoleic acid (d5-LA) and alpha-linolenic acid (d5-LNA) precursors in infants with intrauterine growth restriction (IUGR) compared with control groups matched by gestational age (GA) or birth weight. We compared DHA and AA formation from deuterated precursors d5-LA and d5-LNA in 11 infants with IUGR with 13 and 25 control subjects who were appropriate for GA and matched by GA and by birth weight, respectively. After an enteral administration of d5-LA and d5-LNA, we determined unlabeled and d5-labeled fatty acids at 24, 48, and 96 h in plasma. Absolute concentrations and area under the curve (AUC) over the 96-h study were used for analysis. Absolute concentration of d5-DHA and the product/precursor ratio of the d5-labeled AUCs indicated a less active DHA formation from LNA in infants with IUGR compared with their GA-matched (2-fold) and birth weight-matched (3-fold) control subjects. The ratios of eicosapentaenoic and n-3 docosapentaenoic acid to DHA were also affected. Similar evaluation for the n-6 series was not significant. DHA metabolism is affected in infants with IUGR; the restricted DPA to DHA conversion step seems to be principally responsible for this finding.

Sulfation of a polysaccharide produced by a marine filamentous fungus Phoma herbarum YS4108 alters its antioxidant properties in vitro

Free radicals and other reactive oxygen species (ROS) are generated by all aerobic cells and are widely believed to play a significant role in aging as well as a number of degenerative or pathological diseases. This study compared the free radical-scavenging properties and antioxidant activity of YCP, a polysaccharide from the mycelium of a marine filamentous fungus Phoma herbarum YS 4108 and its two chemically sulfated derivatives YCP-S1 and YCP-S2. Sulfation, which masks hydroxyl groups of YCP polysaccharide molecule, could introduce new antioxidant activity, such as superoxide and hydroxyl radicals scavenging activity, metal chelating action, lipid peroxidation and linoleic acid oxidation inhibition capability. Furthermore, sulfated YCP was more potent than YCP at protecting erythrocytes against oxidative damage hemolysis. The current data suggest for the first time that sulfation of polysaccharide significantly increases its antioxidant activity and the chemical modification of polysaccharides may allow the preparation of derivatives with new properties and a variety of applications.

Photochemistry and phototoxicity of fluocinolone 16,17-acetonide

Fluocinolone 16,17-acetonide is a corticosteroid used topically to treat various inflammatory skin diseases. Its photoreactivity was studied under UV-A and UV-B light in aqueous buffer in the presence of oxygen. This drug is photolabile under UV-B light and, to a lesser extent, under UV-A light, which is absorbed far less. In phosphate buffer, approximately 80% of fluocinolone acetonide decomposes after 5 J/cm2 of UV-B irradiation, whereas under 30 J/cm2 of UV-A light approximately only 20% decomposes. Both the drug and its photoproducts have been evaluated through a battery of in vitro studies and found to cause photohemolysis and induce photodamage to proteins (erythrocyte ghosts, bovine serum albumin) and linoleic acid. In addition, one of the photoproducts (the 17-hydroperoxy derivative) is highly toxic in the dark. Therefore, both loss of therapeutic activity and light-induced adverse effects may be expected when patients expose themselves to sunlight after drug administration. A major mechanism for phototoxicity involves radicals forming from drug breakdown, at least under UV-B, although reactive oxygen species may play a role, particularly under UV-A.

Quantitative estimation of the effects of bile salt surfactant systems on insulin stability and permeability in the rat intestine using a mass balance model

The oral delivery of peptides and proteins is compromised by chemical and proteolytic instability as well as by permeability limitations. The aim of this study was to delineate the relative contributions of simple bile salt and bile salt:fatty acid mixed micellar systems to protein stability vs permeability enhancement in the rat intestine. Insulin disappearance from the rat intestine was evaluated when administered in simple micellar systems of sodium cholate (NaC), sodium taurocholate (NaTC) and sodium glycocholate (NaGC), and in mixed micellar systems of these bile salts and linoleic acid (LA). In-vitro stability studies were used to evaluate the extent of insulin degradation in the different micellar systems. After correction for insulin degradation in all systems a mass balance model was used to estimate the fractions of insulin absorbed for all systems. Mass balance estimates for the extent of insulin absorption in control perfusion systems were consistent with previously reported predictions of the model for ileal insulin absorption. Mass balance estimates for NaGC suggested no significant effects on the fraction of insulin absorbed relative to control. However, insulin absorption was estimated to occur to a significantly greater extent for NaTC simple micellar systems and was coincident with increased permeability of the hydrophilic marker molecule PEG 4000. The mass balance model estimated higher fractions of insulin absorbed for all mixed micellar systems in line with enhanced plasma insulin levels and higher PEG 4000 permeabilities for these systems.