Linoleic Acid Ethyl Ester Research Articles

Fatty acids and their esters from Cicuta virosa L.

n-Hexane and chloroform fractions of aerial parts and roots of Cicuta virosa L. were investigated by GC-MS. As a result of the study 25 fatty acids and their esters have been identified. Two unsaturated esters such as linoleic acid ethyl ester (IX, 16.66%), and n- hexadecanoic acid ethyl ester (VII, 10.12%), the fatty acid n-hexadecanioc acid (VI, 8.10%) made up the bulk of the aerial parts. Four unsaturated esters such as linoleic acid ethyl ester (IX, 10.15%), dibutylphthalate (XII, 9.55%), n-hexadecanoic acid ethyl ester (VII, 8.19%) and 9, 12, 15 - octadecatrienoic acid ethyl ester (X, 5.9%), two fatty acids as n-hexadecanoic acid (VI, 8,15%) and 9,12-octadecadienoic acid (VIII, 4,5%) predominated in the roots of Cicuta virosa L. These known fatty acids and their esters were found for the first time in this plant species. DOI: http://dx.doi.org/10.5564/mjc.v14i0.203 Mongolian Journal of Chemistry 14 (40), 2013, p71-74

Optimization of Ethanol Supercritical Fluid Extraction of Medicinal Compounds from St. John's Wort by Central Composite Design

Extraction of medicinal compounds from St John's Wort was performed using supercritical ethanol. The supercritical fluid extraction parameters were optimized via response surface methodology which included a central composite design. The independent variables were extraction temperature (ranging from 300°C to 340°C), extraction times (ranging from 60 to 120 min), and plant concentration (ranging from 8% to 12%). The response was the St John's Wort extract yield. The extraction temperature was the most significant factor which affects St John's Wort yields according to statistical results. The coefficient of determination was estimated to be 0.98 which indicates the effectiveness of the model and its adaptability to the experimental data. The extract of St John's Wort was comprised of a wide array of compounds including phenols, acids, acid esters, and alkanes. The most prominent components of the extract of St. John's Wort in terms of their relative concentrations were linoleic acid ethyl ester, oleic acid ethyl ester, hexadecanoic acid ethyl ester, and nonacosane.

Antimicrobial and Cytotoxic Activities and GC-MS Analysis of Phytocomponents of Methanolic Extract of Curculigo pilosa (Schum and Thonn) Engl. (Hypoxidaceae) Rhizomes

Objectives: To investigate the antimicrobial and cytotoxic activities of crude methanol extract of Curculigo pilosa (Schum and Thonn) Engl. (Hypoxidaceae) rhizomes and its solvent soluble fractions and to analyze the most active fraction by Gas Chromatography Mass Spectrometry (GC-MS) technique.Place and Duration of Study: Department of Chemistry and Department of Microbiology, School of Natural and Applied Sciences, Federal University of Technology, Minna, Nigeria in June, 2012.Methodology: Shade air-dried powder of Curculigo pilosa rhizomes was extracted with methanol by Soxhlet extraction. Crude methanol extract of Curculigo pilosa root (CCPM) and the solvent soluble fractions namely: n-hexane (CPH), chloroform (CPC), ethylacetate (CPE), n-butanol (CPB) and residue (CPM) were obtained. Phytochemical constituents of the most active fraction (methanol residue) of Curculigo pilosarhizomes were determined using GC-MS technique.Results: The antimicrobial activity of some solvent fractions tested except n-hexane fraction appears to be promising with Minimum Inhibitory Concentration (MIC) ranging from 0.09–6.25 mg/mL. However, ethyl acetate and n-butanol fractions showed antibacterial activity against highest number of bacterial strains. The results revealed that methanolic residue was more potent than derived fractions. Cytotoxicity assay results indicated weak cytotoxic activity of the crude C. pilosa methanol root extract as displayed by its LC50(764.07μg/mL). The qualitative phytochemical evaluation indicates the presence of chemical constituents such as flavonoids, terpenoid, saponins, tannins, alkaloids, cardiac glycosides, steroid and anthraquinone. The quantitative analysis of its metabolites depicts alkaloids (12.80±0.49), saponins (54.49±0.33), flavonoids (44.88±0.36), tannins (69.49±0.65), phenols (50.40±0.34), oxalates (10.95±0.63), cyanides (44.87±0.70) and phytate (15.00±0.05). The major phytocomponents identified by GC-MS analysis in the combined fractions of C. pilosa methanolic residue indicated that there were different types of high and low molecular weight compounds. In particular, it revealed the presence of 3-eicosyne (8.98%), pentadecanoic acid (2.41%) hexadecanoic acid (31.18%), octadecanoic acid (1.52%) 9-octadecenoic acid (24.42%), linoleic acid ethyl ester(3.93%), androstan-3-one (5.90%), 1-phenanthrenenmethanol (5.78%), 1,2-benzenedicarboxylic acid (4.59%), hexanedioc acid (13.38%), 8,11-octadecadienoic acid (9.02%), nonadecane (3.52%), ethanol-2, 2-oxybis (20.75%), propane-1-(1-methylethoxy) (8.05%) and 2, 6,10-dodecatriene-1-ol (5.14%).Conclusion: In this study, some of the phytocompounds identified are biologically important and may have contributed to the observed antimicrobial activity, hence their therapeutic significance which may support the ethnomedicinal uses of C. pilosa in the treatment of venereal diseases in humans.

Pyrolysis of the Lysimachia foenum-graecum Hance extract by online pyrolysis-gas chromatography-mass spectrometry

In order to study the pyrolytic properties of Lysimachia foenum-graecum Hance extract, it was pyrolysed and detected by online pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The pyrolytic experimental conditions were designed to simulate the real combustion conditions inside a burning cigarette. The sample was heated at 30 degrees C/s from 300 to 900 degrees C (held for 5 s) under the flow of 9% oxygen in nitrogen. The pyrolytic components and volatile components were compared. The results showed that 64 pyrolytic components were detected, with 88.27% of the total peak area, including linoleic acid ethyl ester (10.33%), hexadecanoic acid, ethyl ester (9.12%), 9,12,15-octadecatrienoic acid, (Z,Z,Z) - (8.03%), 2-furan-carboxaldehyde, 5-(hydroxymethyl) - (6.02%), neophytadiene (5.12%), heptadecanoic acid, ethyl ester (4.50%), acetic acid, phenyl ester (3.51%), 5-methoxy-2, 2-di-methylindan-1-one (2.73%). The number of pyrolytic components was more than that of the volatile components, and 20 components were identified in both pyrolytic components and volatile components, including higher fatty acids and their esters, neophytadiene, 2-furancarboxaldehyde, (hydroxymethyl)-, and 2 (5H)-furanone, 3-hydroxy-4, 5-dimethyl-. The on-line pyrolysis was similar to the real cigarette combustion conditions. The method is a simple, rapid and good qualitative method for the pyrolysis.

Investigation of possible endogenous formation of furan in Fischer-344 rat

A sensitive headspace solid phase micro-extraction gas chromatography/mass spectrometry analytical procedure was used to determine the furan content in blood and liver tissue. The method was employed to investigate in vivo metabolism leading to possible furan formation by feeding both 13C labeled and unlabeled (native) ascorbic acid, linoleic acid ethyl ester, or glucose to Fischer-344 rats. Rats were fed via oral intubation 0.16–0.96 g of a test compound in two 3 h intervals, and sacrificed 6 h later. The liver and blood tissues were collected and analyzed for the presence of furan. No significant formation of 13C labeled or native furan was observed from the substrates tested. Only minute traces attributable to 13C labeled furan were detected in blood and liver of rats fed ascorbic acid or linoleic acid ethyl ester but not glucose. Native furan was found in tissues of all animals tested. However, animals administered orally d4-furan at doses similar to those expected from the contribution of native furan in rat feed, showed no detectable levels of d4-furan. Data indicate the possibility that there is an endogenous formation of furan from substrates other than those tested in this study.

GC-MS analysis of volatile secondary metabolites in “Mediterranean” and “Continental”Festuca arundinacea(Poaceae) infected with the fungal endophyteNeotyphodium coenophialumstrain AR542

Summary Profiles of volatile secondary metabolites (VSM) in Mediterranean and Continental Festuca arundinacea, either endophyte free or infected with the fungal endophyte Neotyphodium coenophialum strain AR542, were determined using gas chromatography-mass spectrometry (GC-MS). The profile of VSM in the endophyte-free Mediterranean F. arundinacea germplasm was similar to that of endophyte-free Continental F. arundinacea germplasm. However, the VSM profile in AR542-infected Mediterranean F. arundinacea was different to that in AR542-infected Continental F. arundinacea. Compound 1, identified as N-acetylnorloline, was detected in AR542-infected Mediterranean F. arundinacea as being sevenfold greater compared with its level in AR542-infected Continental F. arundinacea. Levels of compounds 2, 4, and 5 detected in AR542-infected Mediterranean F. arundinacea were significantly lower when compared with their levels in the AR542-infected Continental F. arundinacea. Levels of compound 3 were similar in both germplasms infected with endophyte strain AR542. The levels of compounds 2, 4, and 5 but not compound 3 were different between AR542 infected and endophyte free depending on germplasm. On the basis of the mass spectra obtained, compounds 2, 3, 4, and 5 were identified as tridecanoic acid methyl ester, n-capric acid, 11, 14, 17-eicosatrienoic acid, and linoleic acid ethyl ester, respectively. Our results highlight key differences between the Mediterranean and Continental germplasms. Comparison of the VSM of AR542-infected Mediterranean F. arundinacea with AR542-infected Continental F. arundinacea showed that there are quantitative differences between the two germplasms. These differences, which may impact on grazing systems involving horses, most probably arose as a result of intrinsic genetic differences between the two germplasms and are yet to be indentified.

PRODUCTION AND OXIDATIVE STABILITY OF A SOYBEAN OIL CONTAINING CONJUGATED LINOLEIC ACID PRODUCED BY LIPASE CATALYSIS

Soybean oil with conjugated linoleic acid (CLA) was produced by a lipase-catalyzed transesterification with soybean oil and the ethyl ester of the acid. The product, soybean oil–CLA was purified by molecular distillation, and its oxidative stability was investigated. The maximum content of the CLA in the soybean oil was 36.2% under the optimal biocatalytic conditions of 60C, 140 U Lipozyme RM IM (from Rhizomucor miehei) per gram reaction mixture and a 3:1 molar ratio of the conjugated linoleic acid ethyl ester to soybean oil. In comparison to soybean oil, the modified soybean oil with CLA was slightly decreased (P > 0.05) in oxidative stability, but it increased fivefold with the addition of tert-butylhydroquinone to a final concentration of 100 mg/Kg oil. PRACTICAL APPLICATIONS Conjugated linoleic acid (CLA) can play roles in application of anticancer and antiatherogenic. Unfortunately, CLA (and/or its ethyl ester) has an irritant effect on stomach, and studies of the sensory characteristics have revealed that the milk contained 1% or 2% CLA exhibited low intensities of a “grassy/vegetable oil” flavor. However, these problems can be easily solved by incorporating CLA into triacylglycerol. This work incorporated CLA into soybean oil by tranesterification of soybean oil and CLA-ethyl ester. The modified soybean oil enriched with CLA has potential application in milk and dairy products in supplementing of CLA.

Supercritical carbon dioxide extraction of CLA-ethyl ester

Supercritical carbon dioxide (SC-CO2) extraction of Conjugated linoleic acid (CLA) ethyl ester was investigated at pressures in the range of 9 to 10.5 MPa and temperature gradients ranging from 0°C to 21°C. The content of CLA-ethyl ester in the fraction was analyzed with gas chromatography (GC). The experimental results indicated that the rate of extraction would rise with the increase of pressure when temperature gradient was given. Moreover, the extraction pressure had insignificant influence on the selectivity of CLA-ethyl ester in SC-CO2. When pressure was fixed, setting certain temperature gradient can improve the selectivity of CLA-ethyl ester in SC-CO2, and CLA-ethyl ester can be concentrated more effectively than without a temperature gradient. The acid value and peroxide value of the fractions were reduced obviously, compared to the raw material. The optimal condition is pressure at 10 MPa and temperature gradient at 11°C.

Structure elucidation of components with inhibitory activities of atopic dermatitis from Actinidia arguta

Atopic dermatitis is a common, chronic fluctuating skin disease. Over the last 30 years, prevalence of atopic dermatitis and other atopic allergic disorders has been continuously increased [1]. Therefore, the importance of research regarding the treatment of atopic dermatitis is also increasing. The fruits of Actinidia arguta (AA) were generally used as a traditional medicine for skin diseases, diuretic effect, diabetes mellitus and osteoporosis. Recently, it has been reported that AA possesses both in vivo and in vitro anti-inflammatory effects [2]. Although Actinidia arguta has high inhibitory effects on allergic diseases, the active compounds have not been identified. In this study, activity-guided isolation of the extract of the dried fruits from AA using in vitro ELISA assay for IL-4 and luciferase assay [3], led to the purification of five fatty acid compounds. The active compounds were identified as α-linolenic acid (C18:3), linoleic acid (C18:2), α-linolenic acid ethyl ester (ethyl linolenate, C18:3), linoleic acid ethyl ester (ethyl linoleate, C18:2) and stearic acid ethyl ester (ethyl stearate, C18:0), respectively. The results suggest that these five active compounds are potent inhibitors of PMA- and A23187-induced IL-4 promoter activity and IL-4 production in RBL-2H3 cells without cell toxicity.

Effect of docosahexaenoic acid on brain 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity in male ICR mice

We investigated the influence of docosahexaenoic acid ethyl ester (DHA-EE) on 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity in the brains of adult and aged mice. Male mice (Crlj:CD-1) were fed diets containing 3% lard plus 2% linoleic acid ethyl ester (LA-EE), or 2% DHA-EE, for 3 months. The brain HMG-CoA reductase activity of 8-month-old (adult) mice was not significantly influenced by dietary intake of DHA-EE. However, in 18-month-old (aged) mice, its activity was enhanced with dietary intake of DHA-EE. Brain HMG-CoA reductase activity and brain cholesterol content significantly increased with age. Hepatic HMG-CoA reductase activity and the cholesterol content of both adult and aged mice were reduced in DHA-EE diet groups, compared with LA-EE diet groups. The DHA percentages of brain and liver microsomal fractions increased with the intake of DHA-EE in adult and aged mice. These results suggest that DHA may enhance brain HMG-CoA reductase activity in aged mice.

Comparison of volatile components of Marchantia convoluta obtained by supercritical carbon dioxide extraction and petrol ether extraction

The volatile components of Marchantia convoluta were obtained by petrol ether extraction and supercritical (carbon dioxide) extraction methods. These oils were analysed by capillary gas chromatography with mass spectrometric detector (GC-MS). The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters, such as pressure, temperature, modifier volume and extraction time, on the supercritical fluid extraction (SFE) of M. convoluta oil were investigated. A total of 11 compounds accounting for 73.62% of SFE extracts were identified. 22, 23-dihydro-stigmasterol (31.26%), n-hexadecanoic acid (20.35%), stigmasterol (4.55%) and octadecanoic acid (5.75%) were the major compounds identified in M. convoluta SFE extracts. The SFE method has been compared with petrol ether extraction method. SFE products were found to be markedly different from the corresponding petrol ether extract. A total of 10 compounds accounting for 74.04% of petrol ether extraction (PEE) extract were identified. Hexadecanoic acid ethyl ester (36.97%), ethyloleate (10.47%), E-11-hexadecenoic acid ethyl ester (9.77%) and linoleic acid ethyl ester (4.63%) were the major compounds identified.

Bio-guided isolation of cholinesterase inhibitors from the bulbs of

In a search for potential acetylcholinesterase (AChE) inhibitors, the ethanol extract of the bulbs of Crinum x powellii (Amaryllidaceae) was found to demonstrate a marked inhibition of this enzyme. Using a bio-guided isolation strategy, linoleic acid ethyl ester has been identified as the compound responsible for this inhibition. Three other molecules - the alkaloid hippadine, the glycosylated benzyl alcohol derivative calleryanin and 4'-hydroxy-7-methoxyflavan - were also isolated and characterized for the first time from Crinum x powellii. The structures of these compounds were elucidated by spectrometric methods including EI, D/CI mass spectrometry, (1)H, (13)C and 2D NMR experiments. Linoleic acid was also found to inhibit AChE.

Essential fatty acids for larval mud crab Scylla serrata: implications of lack of the ability to bioconvert C18 unsaturated fatty acids to highly unsaturated fatty acids

This study was conducted to examine the effect of essential fatty acids (EFA) on the survival, development and bioconversion of fatty acids in mud crab Scylla serrata larvae. Mud crab larvae held in 1-l plastic beakers (30 ind/l) were fed rotifers that had been enriched with oleic acid (18:1 n−9, OA), linoleic acid (18:2 n−6, LA), linolenic acid (18:3 n−3, LNA), eicosapentaenoic acid (20:5 n−3, EPA) and docosahexaenoic acid (22:6 n−3, DHA) ethyl ester oil during the zoea (Z)1 and Z2 stage. Upon reaching the Z3 stage, rotifers were shifted to unenriched Artemia or Artemia enriched with either EPA or DHA ethyl ester. Further in order to allow comparison of the effect of the enriched rotifers on the fatty acid composition of the Z2 stage larvae, larvae fed enriched rotifers were harvested upon reaching the Z2 stage for fatty acid analysis. The survival of mud crab larvae was more strongly affected by the EFA contained in the Artemia compared to rotifers. Mud crab larvae fed unenriched Artemia showed EFA deficiency signs such as lower survival, longer intermolt period, and a narrower carapace width at the first crab stage, indicating that DHA was superior to that of EPA and followed by LNA and LA. The fatty acid composition of the whole body of Z2 larvae fed rotifers enriched with OA, LA or LNA revealed that the content (g/100 g larvae) of EPA decreased from 1.2 to 0.4–0.8 and DHA decreased from 0.5 to 0.1–0.2, respectively. Moreover, the contents of monoenes increased from 1.4 to 2.5–3.2, indicating dietary EFA deficiency. We conclude that mud crab larvae have a limited or negligible capability to convert C18 unsaturated fatty acids to highly unsaturated fatty acids.

Lipase‐catalyzed incorporation of conjugated linoleic acid into tricaprylin

AbstractThree commercially available immobilized lipases, Novozym 435 from Candida antarctica, Lipozyme IM from Rhizomucor miehei, and Lipase PS‐C from Pseudomonas cepacia, were used as biocatalysts for the interesterification of conjugated linoleic acid (CLA) ethyl ester and tricaprylin. The reactions were carried out in hexane, and the products were analyzed by gas‐liquid chromatography. The effects of molar ratio, enzyme load, incubation time, and temperature on CLA incorporation were investigated. Novozym 435, as compared to Lipozyme IM and Lipase PC‐C, showed the highest degree of CLA incorporation into tricaprylin. By hydrolysis with pancreatic lipase, it was found that Lipozyme IM and Lipase PS‐C exhibited high selectivity for the sn‐1,3 position of the triacylglycerol early in the interesterification, with small extents of incorporation of CLA into the sn‐2 position, probably due to acyl migration, at later reaction times. A small extent of sn‐1,3 selectivity during interesterification by Novozym 435 was observed.

Transesterification of conjugated linoleic acid and tricaprylin by lipases in organic solvents

Lipase-catalyzed transesterification of tricaprylin with conjugated linoleic acid (CLA) ethyl ester was performed to produce triacylglycerols containing conjugated linoleic acid. Six commercially available lipases, and seven solvents were screened for their ability to incorporate CLA into tricaprylin. The transesterification reaction was performed by incubating a 1:2 mole ratio of tricaprylin and CLA ethyl ester in 3 ml solvents at 55°C, and the products were analyzed by gas chromatography. Three lipases, Novozym 435, Lipozym IM and lipase PS-C were chosen to allow a comparison of transesterification activity in our model reaction. The highest CLA incorporation with Novozym 435 and Lipozym IM was achieved in hexane while isooctane produced the highest CLA incorporation with lipase PS-C. Lipase PS-C gave higher CLA incorporation into tricaprylin when fatty acid was used as the acyl donor than other lipases did. Lipozym IM and lipase PS-C had not restrict specificity to sn-1, 3 positions, even though they had high specificity at sn-1, 3 positions. Novozym 435 among lipases tested was the most effective on the incorporation of CLA into tricaprylin.

Transition-metal trifluoromethane-sulphonates-recyclable catalysts for the synthesis of branched fatty derivatives byDiels-Alder reactions at unsaturated fatty esters

Diels-Alder reactions of conjugated linoleic acid ethyl ester (1) with different quinones and with a variety of α/β-unsaturated aldehydes and ketones are described in this paper. Using Sc(OTf) 3 or Cu(OTf) 2 as catalysts the reactions can be carried out at 25-40 °C with good yields. For the first time in oleochemistry it is possible to prepare Diels-Alder cycloadditions with catalyst concentrations of 10 mol-% instead of stoichiometric amounts of Lewis acids. Furthermore, the reaction time was partly shortened drastically. The catalyst Sc(OTf) 3 can be removed by a simple extraction of the organic layer with water. After evaporation of the aqueous phase to dryness the catalyst can be reused without loss of yield.

Determining efficacy of cancer chemopreventive agents using a cell-free system concomitant with DNA adduction

The large (>2000) and expanding number of natural and synthetic agents with potential cancer chemopreventive properties renders it economically and physically impossible to test each of these agents for their efficacy in the widely accepted 2-year animal bioassay and clinical trials. Therefore, there is a growing need for relevant short-term screening tests to study these compounds such that only the most efficacious ones undergo extensive long-term studies. We have previously reported in a pilot study that the use of a microsome-mediated test system concomitant with DNA adduction is a pertinent and relevant model for rapidly studying the efficacy and mechanisms of cancer chemopreventive agents. We have extended this study to investigate 26 additional agents for their potential chemopreventive abilities by studying their effects on microsome-mediated benzo[ a]pyrene (BP)-DNA adduction. These agents had differential effects on the two major adducts of BP-DNA, i.e., BP-7,8-diol-9,10-epoxide (BPDE)-deoxyguanosine (dG) and 9-OH-BP-dG-derived adducts. These agents were therefore categorized into five classes. Three test agents (ellagic acid, genistein and oltipraz) were strong inhibitors of both adducts. These agents diminished BP-DNA adduction by 65–95% and were categorized as Class I agents. Six other agents (benzyl isocyanate, R(+)-1-phenylethyl isocyanate, linoleic acid ethyl ester, (+)-biotin, indole-3-carboxylic acid and β-carotene) moderately inhibited both BP-DNA adducts (25–64%); these compounds were identified as Class II agents. Six additional test agents inhibited only one adduct selectively and nine others were ineffective; these agents were categorized as Class III and Class IV, respectively. Interestingly, seven test agents enhanced BPDE-dG or 9-OH-BP-dG or both adducts and were categorized as Class V agents. Four of these Class V agents concomitantly inhibited BPDE-dG while enhancing 9-OH-BP-dG. This emphasizes the importance of studying individual DNA adducts in contrast to total DNA binding. In conclusion, Class I and Class II agents may be good candidates for further chemoprevention studies.

Resistance of Fatty Acyl Amides to Degradation and Hydrogenation by Ruminal Microorganisms

Two in vitro trials were conducted to determine whether fatty acyl amides are degraded and hydrogenated by ruminal microorganisms. The treatments consisted of ground hay supplemented with either no lipid, linoleoyl Met ethyl ester, or free linoleic acid plus Met ethyl ester. Incubations were carried out in Erlenmeyer flasks at 39°C under CO2. Cultures were sampled at predetermined times and analyzed for long-chain fatty acids, Met, and VFA. In trial 1, the rate of disappearance of linoleic acid was lower for the amide than for the FFA (.004 and –.047/h, respectively). In trial 2, there were no differences in the rate of disappearance of linoleic acid from 0 to 6h (–.237 and –.357/h for amide and FFA, respectively), but the rates from 6 to 48h (–.003 and –.027/h for amide and FFA, respectively) were different. Linoleoyl Met cultures also had higher acetate to propionate ratio and lower loss of Met compared with free linoleic acid cultures. There was no loss of radioactivity from [14C]stearoyl Met after 24h of incubation, indicating its resistance to bacterial breakdown. The results showed that fatty acyl amides resist bacterial breakdown and prevent loss of double bonds by microbial biohydrogenation.

Hydroperoxide-Induced Broncho- and Vasoconstriction in the Isolated Rat Lung

The effects of different hydroperoxides on lung mechanics and perfusate flow rate and their mechanisms of action were studied in isolated perfused rat lungs. The administration of hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, linoleic acid hydroperoxide, and linoleic acid ethylester hydroperoxide (0.1-2 mM) to the perfusate caused a marked decrease in lung compliance, conductance, and perfusate flow rate, with constriction strength of t-butyl hydroperoxide greater than hydrogen peroxide greater than cumene hydroperoxide greater than linoleic acid ethylester hydroperoxide greater than linoleic acid hydroperoxide. Although the hydroperoxides probably had to enter lung cells to exert their effects, no relationship was found between constriction strength and amount of hydroperoxide taken up by the lung. Reduced sensitivity was apparent after repeated dosing, depending on the length of time between dosing. The addition of the iron chelator Desferal (1 mM) had no effect on the hydroperoxide-induced broncho- and vasoconstriction, although free iron was reduced by 50% in the lungs. The administration of the antioxidants diphenyl-p-phenylenediamine (50 microM) or butylated hydroxyanisole (200 microM) to the perfusate 20 min prior to the hydroperoxide attenuated the hydroperoxide-induced effects as well as arachidonic acid-induced broncho- and vasoconstriction. Our findings have shown that hydroperoxides that can enter the lung cells will also induce both vaso- and bronchoconstriction in the isolated perfused rat lung.

Activity of rat liver microsomal glutathione transferase toward products of lipid peroxidation and studies of the effect of inhibitors on glutathione-dependent protection against lipid peroxidation

Rat liver microsomal glutathione transferase displays glutathione peroxidase activity with linoleic acid hydroperoxide, linoleic acid ethyl ester hydroperoxide, and dilinoleoyl phosphatidylcholine hydroperoxide, with rates of 0.2, 0.3, and 0.3 μmol/min/mg, respectively. The activities are increased between three- and fourfold when the enzyme is activated with N-ethylmaleimide. Microsomal glutathione transferase can also conjugate 4-hydroxynon-2-enal with a specific activity of 0.5 μmol/min/mg. These findings show that the enzyme can remove harmful products of lipid peroxidation and thereby possibly protect intracellular membranes against oxidative stress. A set of glutathione transferase inhibitors (rose bengal, tributyltin acetate, S-hexylglutathione, indomethacin, cibacron blue, and bromosulfophtalein) which abolish the glutathione-dependent protection against lipid peroxidation in liver microsomes have been characterized. These inhibitors were found to be effective in the micromolar range and could prove valuable in studying the factor responsible for glutathione-dependent protection against lipid peroxidation.