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At least 235 records · Page 13Linked to original sources
PubMed1998

Catabolic fate of dietary trilinoleoylglycerol hydroperoxides in rat gastrointestines.

To elucidate whether dietary lipid peroxides are absorbed in the body, the catabolic fate of trilinoleoylglycerol hydroperoxides (TL-OOH), in the gastrointestines of rats was examined. Oxidized trilinoleoylglycerol with a peroxide value of 1000 meq/kg, 0.5 or 20 mg, was dosed intragastrically to rat together with 59.5 or 40 mg unoxidized trilinoleoylglycerol, respectively. The fate of TL-OOH in gastric and intestinal lumina was determined by high-performance liquid chromatography periodically until 240 min after treatment. At low dose, TL-OOH was soon broken down to linoleic acid hydroperoxides (LA-OOH) and hydroxyls, probably through gastric lipases, whereas at high dose, TL-OOH was retained in the stomach. In both cases, TL-OOH did not reach the intestines, though the unoxidized lipids moved to the intestines. When LA-OOH was given intragastrically, the lipids decomposed in the stomach, and linoleic acid hydroxyls, hexanal, 9-oxononanoic acid, and two novel compounds were detected 30 min after treatment. The novel compounds were identified to be epoxyketones, 11-oxo-12,13-epoxy-9- and 11-oxo-9,10-epoxy-12-octadecenoic acids. Thus, dietary TL-OOH was broken down in the stomach releasing, LA-OOH which decomposed further, and did not reach the intestines.

Animals↗
PubMed2000

Evidence for covalent binding between copper ions and cyclodextrin cavity: a vibrational circular dichroism study.

Vibrational absorption and circular dichroism (VCD) spectra were obtained for parent cyclodextrins, hydroxyl deuterated alpha-cyclodextrin, cyclodextrin-copper complexes, and for the cyclodextrin inclusion complexes with Methyl Orange, methyloxirane, 1-propanol, and substituted cyclohexanones, in the solution phase. Changes in the VCD spectra, reflecting perturbations of cyclodextrin cavity, were found in the case of an inclusion complex with Methyl Orange, but for the remaining inclusion complexes measurable changes in VCD were not found. Significant changes observed in the VCD spectra of cyclodextrin-copper complexes suggest that the covalent binding of copper ions to the hydroxyl groups of cyclodextrin is involved.

1-Propanol↗
PubMed2003

Addition reactions at the 16(17) double bond of 3-methoxy-13alpha-estra-1,3,5(10),16-tetraene.

The epoxidation, the addition of hypobromous acid, and the hydroboration of 3-methoxy-13alpha-estra-1,3,5(10),16-tetraene 1 with diborane, catecholborane, and 9-BBN were investigated in order to determine the stereochemical outcome and to synthesize new 13alpha-estra-1,3,5(10)-trienes for biological and conformational investigations. It was shown that the sterically demanding reagent 9-BBN participated in a preferred beta attack (53% 16betaOH 10, 34% 17betaOH 8, 13% 16alphaOH 11). This stereochemical result is in agreement with that from another cis addition reaction, the recently described OsO4 dihydroxylation of 1 [Steroids 68 (2003) 113]. With smaller reagents such as B2H6, catecholborane, or magnesium monoperoxyphthalate, a diminished stereoselectivity was observed with only a slight excess of beta attack. The ionic trans addition of hypobromous acid gave two 17-bromo-16-alcohols with 16beta,17alpha (4, 76%) and 16alpha,17beta configuration (5, 24%) formed by trans cleavage of the 16,17alpha- and beta-bromonium ion at position 16. The same regioselective and stereoselective course was found for the cleavage of the 16alpha,17alpha- and 16beta,17beta-epoxides (3 and 2) with hydrazoic acid (3-->16betaN3,17alphaOH 7, 2-->16alphaN3,17betaOH 6). The stereochemistry of the addition reactions to 1 can be explained in terms of a twist-boat conformation involving the C ring of compound 1. From a synthetic viewpoint the synthesis of the beta-epoxide 2 from the bromohydrin 4, the cleavage of this epoxide to 16alpha-substituted-17beta-hydroxy compounds, such as 6, and hydroboration/oxidation with 9-BBN to the hitherto unknown 16beta-hydroxy compound 10 are useful procedures. The bromohydrin 5 is the first 13alpha-steroid with a 17beta-bromo substituent. X-ray analysis revealed twist-boat and 16beta-envelope conformations for rings C and D, respectively.

Borohydrides↗
PubMed2007

Trans-10, cis-12-conjugated linoleic acid increases phagocytosis of porcine peripheral blood polymorphonuclear cells in vitro.

Trans-10, cis-12-conjugated linoleic acid (t10c12-CLA) has been shown to alter immune function. PPARgamma has been shown to potentially play an important role in regulating inflammatory and immune responses by modulating the activity of monocytes and macrophages. Previous studies have indicated that the phagocytic capacity of porcine peripheral blood polymorphonuclear cells (PMN) was enhanced by the culture supernatant fraction from t10c12-CL-stimulated porcine peripheral blood mononuclear cells (PBMC) but not by t10c12-CLA itself. In the present study, we examined the effects of t10c12-CLA on PPARgamma and TNF-alpha expression of porcine PBMC and the phagocytic capacity of PMN. t10c12-CLA increased TNF-alpha mRNA expression and production by PBMC. The phagocytic capacity of porcine PMN was enhanced by either culture supernatant fraction from PBMC treated with t10c12-CLA or recombinant porcine (rp) TNF-alpha. Anti-rpTNF-alpha polyclonal antibody inhibited the enhancement of PMN phagocytic capacity. t10c12-CLA also up regulated PPARgamma mRNA expression in porcine PBMC. Bisphenol A diglycidyl ether, a PPARgamma antagonist, not only completely negated the t10c12-CLA-stimulating effects on TNF-alpha expression and production by porcine PBMC, but also decreased the enhancement of PMN phagocytic capacity by the t10c12-CLA-stimulated porcine PBMC culture supernatant fraction. These results suggest that t10c12-CLA has an immunostimulating effect on porcine PMN phagocytic capacity, which is mediated by TNF-alpha from PBMC via a PPARgamma-dependent pathway.

Animals↗
PubMed1997

Development of a nanoscale liquid chromatography/electrospray mass spectrometry methodology for the detection and identification of DNA adducts.

In this work, the coupling of liquid nanochromatography to NanoFlow electrospray mass spectrometry was evaluated for the detection of DNA adducts. The NanoFlow ES LC/MS system was compared with the capillary and conventional ES LC/MS system by analyzing an in vitro reaction mixture resulting from the interaction of 2'-deoxyguanosine 5'-monophosphate with bisphenol A diglycidyl ether and by injecting 2'-deoxyadenosine. By using NanoFlow ES LC/MS, the mass sensitivity could be improved by a factor of 3300. Three different injection methods used in liquid nanochromatography, i.e., split, large-volume, and column-switching injections were compared in terms of sensitivity. Furthermore, NanoFlow ES LC/MS was used to detect 2'-deoxynucleotide adducts isolated from an in vitro mixture of calf thymus DNA and bisphenol A diglycidyl ether. Different 2'-deoxynucleotide adducts could be identified by monitoring typical product ions, diagnostic for the adducts.

Benzhydryl Compounds↗
PubMed1977

Synthesis and structure-activity relationship studies of cytotoxic epoxide derivatives of 7-oxabicyclo[2.2.1]heptane.

Dimethyl exo-5,6-oxido-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylate (1) and the 1-methyl homologue 2 were shown to exhibit significant cytotoxicity in the 9KB tissue culture assay. Several analogues of 1 were prepared and it was found that removal of the epoxide, or the oxygen bridge, or the 2,3 double bond from 1 resulted in loss of significant cytotoxic activity. One compound which lacked the epoxide moiety, dimethyl 1-methyl-7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate (5), also exhibited marginal cytotoxic activity.

Animals↗
PubMed2006

Synthesis of enantiopure (alphaS,betaS)- or (alphaR,betaS)-beta-amino alcohols by complete regioselective opening of aminoepoxides by organolithium reagents LiAlH4 or LiAlD4.

The reaction of chiral (2R,1'S)- or (2S,1'S)-2-(1-aminoalkyl)epoxides, 1 or 2 with a variety of organolithium compounds to obtain the corresponding (alphaS,betaS)- or (alphaR,betaS)- beta-amino alcohols in enantiopure form is reported. In both cases, the opening of the oxirane ring at C-3 proceeded with total regioselectivity. Moreover, the ring opening of aminoepoxides 1 or 2 by hydride (utilizing LiAlH4) to obtain the corresponding (2S,3S)- or (2R,3S)-3-aminoalkan-2-ols is also described. The reaction of 1 or 2 with LiAlD4 in place of LiAlH4 gave the corresponding (2S,3S)- or (2R,3S)-3-amino-1-deuterioalkan-2-ols.

Alkanes↗
PubMed2006

Photocatalytic oxidation of propylene with molecular oxygen over highly dispersed titanium, vanadium, and chromium oxides on silica.

Photocatalytic oxidation of propylene with molecular oxygen at room temperature was investigated over various silica-supported metal oxides with low loading. The photocatalytic active site is assumed to be the isolated tetrahedrally coordinated metal oxides in the ligand-to-metal charge-transferred state, such as (Mdelta- -OLdelta+). Photocatalytic epoxidation of propylene into propylene oxide was promoted over silica-supported V and Ti oxides at steady state. Over silica-supported Cr oxide, the propylene oxide formation rate was remarkably decreased with the time course in the reaction. The oxidation state and the coordination environment of the supported Ti, V, and Cr oxide species were determined by diffuse reflectance UV-vis spectroscopy (DRS) and electron spin resonance (ESR). During the photocatalytic oxidation, the oxidation state of the Ti4+ species was not varied. On the other hand, the V5+ species was partially reduced to V4+ and the Cr6+ species was successively reduced to Cr5+ and Cr3+. An isotopic tracer study of the C3H6-18O2 reaction suggests the difference of the active oxygen species between TiO2/SiO2 and V2O5/SiO2. The active oxygen species on TiO2/SiO2 is derived from molecular oxygen. On the other hand, the photogenerated products on V2O5/SiO2 incorporate the lattice oxygen of the surface metal oxide species. It is suggested that the kinds of terminal ligand (hydroxyl or oxo) of the tetrahedrally coordinated metal oxides on silica decide the active oxygen species in the photocatalytic oxidation. A photoinduced hole center on the monohydroxyl (SiO)3Ti-OH species activates molecular oxygen that reacts with propylene. In the case of the monooxo (SiO)3V=O and dioxo (SiO)2Cr=O2 species, the photoactivated lattice oxygen (OL-) directly reacts with propylene.

Alkenes↗
PubMed1998

1,3-Dichloropropene epoxides: intermediates in bioactivation of the promutagen 1,3-dichloropropene.

1,3-Dichloropropene (1,3-D), a major soil fumigant nematicide, is genotoxic in many types of assays, leading to its classification as possibly carcinogenic in humans. This study tests in three steps the hypothesis that 1,3-D is a promutagen activated by epoxidation and further reaction of the 1,3-D-epoxides. Stereospecific epoxidation of 1,3-D (examined as the cis/trans mixture and as individual isomers) to the corresponding cis- and trans-1,3-D-epoxides is demonstrated here for the first time, both in vitro in a mouse liver microsome-NADPH system and in vivo in the liver of ip-treated mice, using GC/MS for product identification and quantitation. The cis epoxide is observed in higher yield than the trans epoxide, both in vitro and in vivo, and the cis isomer also reacts slower than the trans isomer with GSH alone or catalyzed by GSH S-transferase. cis- and trans-1,3-D-Epoxides are stable in acetone or chloroform but degrade completely in Me2SO exclusively to 2-chloroacrolein (30 min at 40 degrees C). Epoxide decomposition is slower in pH 7.4 phosphate buffer (t1/2 = 116 and 64 min for cis and trans, respectively, at 41 degrees C) with a >99% yield of 3-chloro-2-hydroxypropanal (and its dimer) and <0.5% formation of 2-chloroacrolein (for which the t1/2 is 248 min at 41 degrees C). Mutagenicity assays in Salmonella typhimurium TA100 (standard plate incorporation) establish high potencies of 37, 17, and 150 revertants/nmol for cis- and trans-1, 3-D-epoxides and 2-chloroacrolein, respectively. The mutagenicity of the epoxides is due either to their direct action or to a degradation product formed at physiological pH, i.e., 3-chloro-2-hydroxypropanal or its dehydrochlorination products. The candidate mutagens methylglyoxal and glycidaldehyde are not detected as breakdown products of 3-chloro-2-hydroxypropanal at pH 7.4 and also have low mutagenic activity in TA100. It is therefore proposed that the penultimate and ultimate mutagens of 1,3-D metabolism are the corresponding epoxides and their direct hydrolysis product 3-chloro-2-hydroxypropanal, respectively.

Allyl Compounds↗
PubMed2004

Treatment of hyperphosphatemia in hemodialysis patients: The Calcium Acetate Renagel Evaluation (CARE Study).

BACKGROUND: Hyperphosphatemia underlies development of hyperparathyroidism, osteodystrophy, extraosseous calcification, and is associated with increased mortality in hemodialysis patients. METHODS: To determine whether calcium acetate or sevelamer hydrochloride best achieves recently recommended treatment goals of phosphorus </=5.5 mg/dL and Ca x P product </=55 mg(2)/dL(2), we conducted an 8-week randomized, double-blind study in 100 hemodialysis patients. RESULTS: Comparisons of time-averaged concentrations (weeks 1 to 8) demonstrated that calcium acetate recipients had lower serum phosphorus (1.08 mg/dL difference, P= 0.0006), higher serum calcium (0.63 mg/dL difference, P < 0.0001), and lower Ca x P (6.1 mg(2)/dL(2) difference, P= 0.022) than sevelamer recipients. At each week, calcium acetate recipients were 20% to 24% more likely to attain goal phosphorus [odds ratio (OR) 2.37, 95% CI 1.28-4.37, P= 0.0058], and 15% to 20% more likely to attain goal Ca x P (OR 2.16, 95% CI 1.20-3.86, P= 0.0097). Transient hypercalcemia occurred in 8 of 48 (16.7%) calcium acetate recipients, all of whom received concomitant intravenous vitamin D. By regression analysis hypercalcemia was more likely with calcium acetate (OR 6.1, 95% CI 2.8-13.3, P < 0.0001). Week 8 intact PTH levels were not significantly different. Serum bicarbonate levels were significantly lower with sevelamer hydrochloride treatment (P < 0.0001). CONCLUSION: Calcium acetate controls serum phosphorus and calcium-phosphate product more effectively than sevelamer hydrochloride. Cost-benefit analysis indicates that in the absence of hypercalcemia, calcium acetate should remain the treatment of choice for hyperphosphatemia in hemodialysis patients.

Acetates↗
PubMed2001

Inhibition of RXR and PPARgamma ameliorates diet-induced obesity and type 2 diabetes.

PPARgamma is a ligand-activated transcription factor and functions as a heterodimer with a retinoid X receptor (RXR). Supraphysiological activation of PPARgamma by thiazolidinediones can reduce insulin resistance and hyperglycemia in type 2 diabetes, but these drugs can also cause weight gain. Quite unexpectedly, a moderate reduction of PPARgamma activity observed in heterozygous PPARgamma-deficient mice or the Pro12Ala polymorphism in human PPARgamma, has been shown to prevent insulin resistance and obesity induced by a high-fat diet. In this study, we investigated whether functional antagonism toward PPARgamma/RXR could be used to treat obesity and type 2 diabetes. We show herein that an RXR antagonist and a PPARgamma antagonist decrease triglyceride (TG) content in white adipose tissue, skeletal muscle, and liver. These inhibitors potentiated leptin's effects and increased fatty acid combustion and energy dissipation, thereby ameliorating HF diet-induced obesity and insulin resistance. Paradoxically, treatment of heterozygous PPARgamma-deficient mice with an RXR antagonist or a PPARgamma antagonist depletes white adipose tissue and markedly decreases leptin levels and energy dissipation, which increases TG content in skeletal muscle and the liver, thereby leading to the re-emergence of insulin resistance. Our data suggested that appropriate functional antagonism of PPARgamma/RXR may be a logical approach to protection against obesity and related diseases such as type 2 diabetes.

3T3 Cells↗
PubMed2003

Phosphate binder usage in kidney failure patients.

Phosphorus binders are used in patients with kidney failure because of the incomplete removal of phosphorus with dialysis and the inability to exclude phosphorus from the diet. Aluminium was the initial phosphorus binder used, but was replaced by calcium-containing binders because of the development of aluminium toxicity. Calcium-based binders have been the mainstay of therapy for many years, but recent investigations have pointed to increased rates of vascular calcification in patients taking calcium-containing binders. For this reason, alternative agents have been developed. Sevelamer (Renagel), GelTex Pharmaceuticals Inc.) is a polymer which has been found to effectively bind phosphorus. It has resulted in a decreased rate of vascular calcification compared to calcium-containing binders. Other agents under development include lanthanum carbonate and iron-complex preparations. Further research will likely concentrate on identifying binders that bind phosphate more efficiently, have minimal gastrointestinal side effects and provide other benefits to dialysis patients.

Acetates↗
PubMed2005

[Simulation of migration from a multi-layer laminated film intended for retort foods].

Migration from multi-layer laminated film pouches intended for retort foods was investigated through HPLC analysis with a fluorescence detector, and measurements of residue on evaporation, consumption of potassium permanganate and total organic carbon. HPLC analysis revealed that the levels of migrants in oil and the water which were heated in the pouches (121 degrees C, 30 min) were ten times of those in the corresponding official simulants under the official conditions; n-heptane (25 degrees C, 60 min), and water (95 degrees C, 30 min). Bisphenol A diglycidyl ether and related compounds were found in the oil and the water heated in the pouches, as well as in the simulants. These compounds were thought to have been present in the adhesive between the laminated films, and migrated through the food-contact film of the package. Consumption of potassium permanganate and residue on evaporation of the heated water were ten times of those of the water simulant, while the total organic carbon level of the heated water was several-hold greater than that of the water simulant. In addition, migrant levels per surface area of the pouch were one-fourth of the concentrations per content volume of the pouch. Since compliance with the legal limits is evaluated based on the concentration per surface area, real migration into foods would be underestimated by a factor of another four.

Benzhydryl Compounds↗
PubMedDate not supplied

Sensitive and rapid reversed-phase liquid chromatography-fluorescence method for determining bisphenol A diglycidyl ether in aqueous-based food simulants.

A method has been developed for determination of bisphenol A diglycidyl ether (BADGE) in 3 aqueous-based food simulants: water, 15% (v/v) ethanol, and 3% (w/v) acetic acid. BADGE is extracted with C18 cartridges and the extract is concentrated under a stream of nitrogen. BADGE is quantitated by reversed-phase liquid chromatography with fluorescence detection. Relative precision at 200 micrograms/L was 3.4%, the detection limit of the method was 0.1 micrograms/L, and recoveries of spiking concentrations from 1 to 8 micrograms/L were nearly 100%. Relative standard deviations for the method ranged from 3.5 to 5.9%, depending on the identity of the spiked aqueous-based food simulant.

Acetates↗
PubMed1995

Metabolism of allylbenzene 2',3'-oxide and estragole 2',3'-oxide in the isolated perfused rat liver.

The metabolism of allylbenzene 2',3'-oxide, estragole 2',3'-oxide, allylbenzene and estragole was studied in the isolated perfused rat liver. Formation of dihydrodiol and glutathione conjugate metabolites was detected for both epoxides and the presence of dihydrodiol metabolites after perfusion of allylbenzene or estragole indicated the formation of allylic epoxide intermediates in the intact liver. A comparison of elimination kinetics for parent compounds and epoxides indicated that epoxides were relatively rapidly detoxified and probably do not accumulate on formation in vivo. Acute toxicity of epoxides, measured as the release of alanine aminotransferase activity into the perfusate, or genetic toxicity, determined as covalent binding of radiolabeled epoxide to DNA, were not observed. It was concluded that both epoxide hydrolases and glutathione S-transferases can effectively detoxify the allylic epoxides derived from either allylbenzene or estragole and effectively prevent cellular or genetic toxicity of these reactive intermediates. Epoxide hydrolases appear to play the major role in the detoxication of these epoxides in vivo.

Allyl Compounds↗
PubMed1985

Rates of hydrolysis and extents of DNA binding of 5-methylchrysene dihydrodiol epoxides.

The rates of hydrolysis in the absence and presence of native and denatured DNA, and the extents of DNA binding of five dihydrodiol epoxides derived from 5-methylchrysene (5-MeC) and chrysene have been determined. The compounds studied were: trans-1,2-dihydroxy-anti-3,4-epoxy-1,2,3,4-tetrahydro-5-MeC; trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydro-5-Mec; trans-1,2-dihydroxy-syn-3,4-epoxy-1,2,3,4-tetrahydro-5-MeC; trans-7,8-dihydroxy-syn-9,10-epoxy-7,8,9,10-tetrahydro-5-MeC; and trans-1,2-dihydroxy-anti-3,4-epoxy-1,2,3,4-tetrahydrochrysene. In the absence of DNA, at pH 7 and 37 degrees C half-lives of trans-1,2-dihydroxy-syn-3,4-epoxy-1,2,3,4-tetrahydro-5-MeC and trans-1,2-dihydroxy-anti-3,4-epoxy-1,2,3,4-tetrahydro-5-MeC were similar, t 1/2 = 62 and 59 min, while trans-7,8-dihydroxy-syn-9,10-epoxy-7,8,9,10-tetrahydro-5-MeC hydrolyzed faster than trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydro-5-MeC, t 1/2 = 5.4 versus 17.5 min; trans-1,2-dihydroxy-anti-3,4-epoxy-1,2,3,4-tetrahydrochrysene had the slowest rate of hydrolysis, t 1/2 = 104 min. Studies of the effects of native and denatured DNA on the rates of hydrolysis of the dihydrodiol epoxides indicated that native DNA remarkably accelerated these rates for all dihydrodiol epoxides, but the degree of acceleration varied for the different dihydrodiol epoxides. The acceleration of hydrolytic rates by native DNA relative to that by denatured DNA was correlated with the covalent binding of these dihydrodiol epoxides with DNA in vitro. The catalytic effect of DNA in enhancing the rates of hydrolysis of dihydrodiol epoxides and the relative extents of covalent binding of the dihydrodiol epoxides to DNA were in the following order: trans-1,2-dihydroxy-anti-3,4-epoxy-1,2,3,4-tetrahydro-5-MeC greater than trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydro-5-MeC greater than trans-1,2-dihydroxy-anti-3,4-epoxy-1,2,3,4-tetrahydrochrysene greater than trans-1,2-dihydroxy-syn-3,4-epoxy-1,2,3,4-tetrahydro-5-MeC greater than trans-7,8-dihydroxy-syn-9,10-epoxy-7,8,9,10-tetrahydro-5-MeC. The results of this study suggest that physical interactions with DNA are important in determining the relative extents of binding of these dihydrodiol epoxides to DNA in vitro.

Chromatography, High Pressure Liquid↗