Bleaching augments lipid peroxidation products in pistachio oil and its cytotoxicity

Pistachio consumption is associated with reductions in serum cholesterol and oxidative stress due to their constituents of unsaturated fats, phytosterols, fiber, and antioxidants. Bleaching has been applied to whiten nut shells for antifungal and cosmetic purposes. However, the impact of bleaching on nutritional quality and safety of pistachios remains to be examined. In this study, we investigated whether bleaching would increase malondialdehyde (MDA) or 7‐keto‐sitosterol and decrease phytosterols in pistachio oil, as well as cause cytotoxicity of modeled Hepa1c1c7 cells. Bleaching increased MDA by more than 32% from 0.23 µg/g in raw oil, with the largest increase noted with the bleach containing H₂O₂ and Fe²⁺ (P ≤ 0.05). Bleached pistachio oil had larger than 12.6% decrease in β‐sitosterol and total phytosterols as compared to the raw oil (P ≤ 0.05). Bleaching with Fe²⁺ significantly increase 7‐keto‐sitosterol compared to bleaching alone. Hepatic cell viability was decreased the most by the oil of the pistachios treated with bleach containing Fe²⁺ (P ≤ 0.05), and lactate dehydrogenase activity in medium was elevated by >18‐folds (P ≤ 0.05). Compared to natural pistachios, the bleaching treatment had detrimental effects on nutritional quality and expected health benefits of pistachios by increasing lipid peroxidation, decreasing phytosterol content, and causing cytotoxicity. Practical applications: Bleaching has been applied to whiten the nut shell for antifungal and cosmetic purposes. However, the results of this study indicate that bleaching treatment has a detrimental impact on nutritional quality and expected health benefits of pistachios. Particularly, treatment with a bleach formula with hydrogen peroxide and transit metals increases formation of lipid peroxidation products and decreases phytosterol content. The resulting pistachio oil causes cell toxicity. Thus, bleaching practice for whitening pistachios is strongly discouraged.     

Inhibition of lipid peroxidation by anthocyanins,anthocyanidins and their phenolic degradation products

Food components that delay or prevent biomolecule oxidation may be relevant in shelf life extension as well as disease prevention. Anthocyanins are a potentially important group of compounds, but they are prone to degradation both in vitro and in vivo, producing simple phenols. In this study, eight structurally related (poly)phenols [anthocyan(id)ins and phenolic acids] were examined for their ability to inhibit lipid oxidation at physiologically relevant concentrations (100–1000 nM) using the Cu²⁺‐mediated low‐density lipoprotein oxidation model. Interaction between each (poly)phenol and Cu²⁺ ions was also investigated. (Poly)phenols with an ortho‐dihydroxy group arrangement, i.e. cyanidin‐3‐glucoside, cyanidin and protocatechuic acid, were the most effective within their class, extending the lag phase to oxidation by 137, 255 and 402%, respectively (at 1000 nM). At the same concentration, trihydroxy‐substituted compounds (delphinidin and gallic acid) were of intermediate efficacy, extending the lag phase by 175 and 38%, respectively. Compounds with the 4'‐hydroxy‐3',5'‐methoxy arrangement (i.e. malvidin‐3‐glucoside and malvidin) were the least effective (3 and 58% extension, respectively), while syringic acid (4‐hydroxy‐3,5‐dihydroxy benzoic acid) was pro‐oxidant (lag phase shortened by 31%). (Poly)phenols with the ortho‐dihydroxy arrangement chelated Cu²⁺ ions, which in part explains their greater efficacy over the other (poly)phenols in this model oxidation system. However, differences in their hydrogen‐donating properties and their partitioning between lipid and hydrophilic phases are also relevant in explaining these structure‐activity relationships.     

Kinetic study on peroxidation of benzaldehyde by polymer‐immobilized cobalt‐EDTA complex

Polymer‐immobilized cobalt‐EDTA complex was prepared by grafted copolymerization of methacrylic acid (MAA) and acrylonitrile (AN initiated by redox initiation of EDTA‐2Na (Ethylenediamine tetraacetic acid disodium salt) with ceric ion (Ce²⁺)). High yield and selectivity for peroxidation of benzaldehyde were obtained when using the polymer‐immobilized cobalt‐EDTA complex as a catalyst. With the concentration of benzaldehyde increasing, the concentration of perbenzoic acid was increased from 0.38M to 0.98M, but yield of perbenzoic acid decreased from 0.76M to 0.65M. With the amount of the polymer support increased, the yield of perbenzoic acid increased from 70% to 82%. The selectivity remained about 82% in the various amounts of the polymer support. The activation energy of peroxidation of benzaldehyde was 43.4 KJ/mole. The expression of the reaction rate was: r_i = k[RCHO][polymer support]^0.5. A mechanism for peroxidation of benzaldhyde catalysed by polymer‐immobilized cobalt‐EDTA complex was proposed in this investigation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3248–3257, 2001     

The ɛ‐Amino Group of Protein Lysine Residues Is Highly Susceptible to Nonenzymatic Acylation by Several Physiological Acyl‐CoA Thioesters

Mitochondrial enzymes implicated in the pathophysiology of diabetes, cancer, and metabolic syndrome are highly regulated by acetylation. However, mitochondrial acetyltransferases have not been identified. Here, we show that acetylation and also other acylations are spontaneous processes that depend on pH value, acyl‐CoA concentration and the chemical nature of the acyl residue. In the case of a peptide derived from carbamoyl phosphate synthetase 1, the rates of succinylation and glutarylation were up to 150 times than for acetylation. These results were confirmed by using the protein substrate cyclophilin A (CypA). Deacylation experiments revealed that SIRT3 exhibits deacetylase activity but is not able to remove any of the succinyl groups from CypA, whereas SIRT5 is an effective protein desuccinylase. Thus, the acylation landscape on lysine residues might largely depend on the enzymatic activity of specific sirtuins, and the availability and reactivity of acyl‐CoA compounds.     

Preparation of diacylglycerol‐enriched palm olein by phospholipase A1‐catalyzed partial hydrolysis

Partial hydrolysis of palm olein catalyzed by phospholipase A₁ (Lecitase Ultra) in a solvent‐free system was carried out to produce diacylglycerol (DAG)‐enriched palm olein (DEPO). Four reaction parameters, namely, reaction time (2–10 h), water content (20–60 wt‐% of the oil mass), enzyme load (10–50 U/g of the oil mass), and reaction temperature (30–60 °C), were investigated. The optimal conditions for partial hydrolysis of palm olein catalyzed by Lecitase Ultra were obtained by an orthogonal experiment as follows: 45 °C reaction temperature, 44 wt‐% water content, 8 h reaction time, and an enzyme load of 34 U/g. The upper oil layer of the reaction mixture with an acid value of 54.26 ± 0.86 mg KOH/g was first molecularly distilled at 150 °C to yield a DEPO with 35.51 wt‐% of DAG. The DEPO was distilled again at 250 °C to obtain a DAG oil with 74.52 wt‐% of DAG. The composition of the acylglycerols of palm olein and the DEPO were analyzed and identified by high‐performance liquid chromatography (HPLC) and HPLC/electrospray ionization/mass spectrometry. The released fatty acids from the partial hydrolysis of palm olein catalyzed by phospholipase A₁ showed a higher saturated fatty acid content than that of the raw material.     

Low‐density lipoprotein is oxidized by phospholipase A2 and lipoxygenase in xanthoma lesions

Oxidized LDL has been obtained by incubation with copper ions (Cu‐LDL) or various kinds of cells. LDL incubated with xanthoma tissues (x‐LDL) is considered a model of in vivo oxidized LDL that has extravasated into xanthoma lesions. To investigate the mechanism of x‐LDL formation, we studied the effects of various enzyme inhibitors or antioxidants on the oxidation process of LDL. Thiobarbituric acid‐reactive substance (TBARS) levels, electrophoretic mobility and spectrophotometric pattern of the oxidized LDL were examined. Antioxidants suppressed TBARS formation in both x‐LDL and Cu‐LDL. Enzyme inhibitors inhibited TBARS levels in x‐LDL, but not in Cu‐LDL. All the enzyme inhibitors and antioxidants, except for the cyclooxygenase inhibitor, inhibited the anodic electrophoretic mobility of x‐LDL. The anodic electrophoretic mobility of Cu‐LDL was suppressed only with antioxidants. Spectrophotometry indicated that an increase in the absorbance at 240 nm was observed in Cu‐LDL, but not in x‐LDL. x‐LDL oxidation is primarily catalyzed by phospholipase A₂, and subsequently generated polyunsaturated free fatty acids propagate the peroxidation. Fatty acid hydroperoxides conjugated with dienes are not synthesized in x‐LDL. On the other hand, non‐enzymatic oxidants, such as superoxide anion and hydroxyl radicals generate Cu‐LDL with diene‐conjugated fatty acid hydroperoxides.     

Inhibition of Human α‐Methylacyl CoA Racemase (AMACR): a Target for Prostate Cancer

The enzyme α‐methylacyl CoA racemase (AMACR) is involved in the metabolism of branched‐chain fatty acids and has been identified as a promising therapeutic target for prostate cancer. By using the recently available human AMACR from HEK293 kidney cell cultures, we tested a series of new rationally designed inhibitors to determine the structural requirements in the acyl component. An N‐methylthiocarbamate (K_i=98 nM ), designed to mimic the proposed enzyme‐bound enolate, was found to be the most potent AMACR inhibitor reported to date.     

Palladium‐Catalyzed,Chelation‐Assisted Stereo‐ and Regioselective Synthesis of Tetrasubstituted Olefins by Oxidative Heck Arylation

An efficient synthesis of tetrasubstituted olefins was achieved via a palladium‐catalyzed, chelation‐assisted oxidative Heck arylation protocol from trisubstituted olefins bearing a tether with a directing group in a completely stereo‐ and regioselective manner. The stereo‐ and regioselectivity as well as excellent yields of tetrasubstituted olefins originated from the stabilization of a palladium intermediate by chelation between the palladium center and a directing group.     

Fluorine‐Containing 6,7‐Dialkoxybiaryl‐Based Inhibitors for Phosphodiesterase 10 A: Synthesis and in vitro Evaluation of Inhibitory Potency,Selectivity, and Metabolism

Based on the potent phosphodiesterase 10 A (PDE10A) inhibitor PQ‐10, we synthesized 32 derivatives to determine relationships between their molecular structure and binding properties. Their roles as potential positron emission tomography (PET) ligands were evaluated, as well as their inhibitory potency toward PDE10A and other PDEs, and their metabolic stability was determined in vitro. According to our findings, halo‐alkyl substituents at position 2 of the quinazoline moiety and/or halo‐alkyloxy substituents at positions 6 or 7 affect not only the compounds′ affinity, but also their selectivity toward PDE10A. As a result of substituting the methoxy group for a monofluoroethoxy or difluoroethoxy group at position 6 of the quinazoline ring, the selectivity for PDE10A over PDE3A increased. The same result was obtained by 6,7‐difluoride substitution on the quinoxaline moiety. Finally, fluorinated compounds (R)‐7‐(fluoromethoxy)‐6‐methoxy‐4‐(3‐(quinoxaline‐2‐yloxy)pyrrolidine‐1‐yl)quinazoline ( 16 a ), 19 a – d , (R)‐tert‐butyl‐3‐(6‐fluoroquinoxalin‐2‐yloxy)pyrrolidine‐1‐carboxylate ( 29 ), and 35 (IC₅₀ PDE10A 11–65 nM ) showed the highest inhibitory potential. Further, fluoroethoxy substitution at position 7 of the quinazoline ring improved metabolic stability over that of the lead structure PQ‐10.     

Highly Ligand Efficient and Selective N‐2‐(Thioethyl)picolinamide Histone Deacetylase Inhibitors Inspired by the Natural Product Psammaplin A

Novel picolinamide‐based histone deacetylase (HDAC) inhibitors were developed, drawing inspiration from the natural product psammaplin A. We found that the HDAC potency and isoform selectivity provided by the oxime unit of psammaplin A could be reproduced by using carefully chosen heterocyclic frameworks. The resulting (hetero)aromatic amide based compounds displayed very high potency and isoform selectivity among the HDAC family, in addition to excellent ligand efficiency relative to previously reported HDAC inhibitors. In particular, the high HDAC1 isoform selectivity provided by the chloropyridine motif represents a valuable design criterion for the development of new lead compounds and chemical probes that target HDAC1.     

Chelation properties of poly(β‐diketone) polymer and its oxime toward heavy metal ions

The chelation behavior of poly(β‐diketone), polymer I, and poly(β‐diketone) oxime, polymer II, toward the divalent metal ions, Cu²⁺, Zn²⁺, Ni²⁺, and Cd²⁺, and the trivalent lanthanide metal ions, La³⁺, Nd³⁺, Sm³⁺, Gd³⁺, and Tb³⁺ was investigated by a batch equilibration technique as a function of contact time, pH, and counter ion. Polymer II exhibited improved chelation characteristics toward lanthanide metal ions in comparison with polymer I and the metal‐ion uptake follows the order Tb³⁺ ≈ Gd³⁺ ≈ Sm³⁺ > Nd³⁺ ≈ La³⁺. On the other hand, polymer I showed relatively higher capacity than polymer II, toward the investigated divalent metal ions, where the metal‐ion uptake follows the order Cu²⁺ > Cd²⁺ ≈ Zn²⁺ > Ni²⁺. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

壳聚糖及其衍生物去除金属离子的研究进展

壳聚糖具有来源广泛、无毒无害、功能基团丰富、化学活性强等特点,广泛应用于化工、环保、医药、食品等领域.围绕壳聚糖分子链上活性基团对金属离子的吸附能力,综述了壳聚糖及其衍生物在去除溶液中金属离子方面的研究工作及进展.介绍了对壳聚糖单体进行官能团置换或重组的化学改性法和改变壳聚糖物理形态的物理改性法,详细阐述了交联改性法、接枝改性法、磁化改性法、分子印迹法的基本原理、应用效果和优缺点,并对壳聚糖微球、壳聚糖膜的制备方法和材料性能进行了归纳.结合壳聚糖及其衍生物在制备和应用过程中存在的问题,提出了将化学改性和物理改性相结合制备新型印迹壳聚糖基聚合物,从而实现高效和选择性去除金属离子的研究方向.     

Antibody Epitope of Human α‐Galactosidase A Revealed by Affinity Mass Spectrometry: A Basis for Reversing Immunoreactivity in Enzyme Replacement Therapy of Fabry Disease

α‐Galactosidase (αGal) is a lysosomal enzyme that hydrolyses the terminal α‐galactosyl moiety from glycosphingolipids. Mutations in the encoding genes for αGal lead to defective or misfolded enzyme, which results in substrate accumulation and subsequent organ dysfunction. The metabolic disease caused by a deficiency of human α‐galactosidase A is known as Fabry disease or Fabry–Anderson disease, and it belongs to a larger group known as lysosomal storage diseases. An effective treatment for Fabry disease has been developed by enzyme replacement therapy (ERT), which involves infusions of purified recombinant enzyme in order to increase enzyme levels and decrease the amounts of accumulated substrate. However, immunoreactivity and IgG antibody formation are major, therapy‐limiting, and eventually life‐threatening complications of ERT. The present study focused on the epitope determination of human α‐galactosidase A against its antibody formed. Here we report the identification of the epitope of human αGal(309–332) recognized by a human monoclonal anti‐αGal antibody, using a combination of proteolytic excision of the immobilized immune complex and surface plasmon resonance biosensing mass spectrometry. The epitope peptide, αGal(309–332), was synthesized by solid‐phase peptide synthesis. Determination of its affinity by surface plasmon resonance analysis revealed a high binding affinity for the antibody (K_D=39×10^?9 m ), which is nearly identical to that of the full‐length enzyme (K_D=16×10^?9 m ). The proteolytic excision affinity mass spectrometry method is shown here to be an efficient tool for epitope identification of an immunogenic lysosomal enzyme. Because the full‐length αGal and the antibody epitope showed similar binding affinities, this provides a basis for reversing immunogenicity upon ERT by: 1) treatment of patients with the epitope peptide to neutralize antibodies, or 2) removal of antibodies by apheresis, and thus significantly improving the response to ERT.     

Ultra‐Performance Liquid Chromatography‐Mass Spectrometry Analysis of Free and Esterified Oxygenated Derivatives from Docosahexaenoic Acid in Rat Brain

Docosahexaenoic acid (DHA), a prominent long‐chain fatty acid of the omega‐3 family, is present at high amount in brain tissues, especially in membrane phospholipids. This polyunsaturated fatty acid is the precursor of various oxygenated lipid mediators involved in diverse physiological and pathophysiological processes. Characterization of DHA‐oxygenated metabolites is therefore crucial for better understanding the biological roles of DHA. In this study, we identified and measured, by ultrahigh‐performance liquid chromatography coupled with tandem mass spectrometry, a number of oxygenated products derived from DHA in exsanguinated and nonexsanguinated brains. These metabolites were found both in free form and esterified in phospholipids. Interestingly, both (R)‐ and (S)‐monohydroxylated fatty acid stereoisomers were observed free and esterified in phospholipids. Monohydroxylated metabolites were the main derivatives; however, measurable amounts of dihydroxylated products such as protectin DX were detected. Moreover, exsanguination allowed discriminating brain oxygenated metabolites from those generated in blood. These results obtained in healthy rats allowed an overview on the brain oxygenated metabolism of DHA, which deserves further research in pathophysiological conditions, especially in neurodegenerative diseases.     

Synthesis and Biological Evaluation of New (−)‐Englerin Analogues

We report the synthesis and biological evaluation of a series of (?)‐englerin A analogues obtained along our previously reported synthetic route based on a stereoselective gold(I) cycloaddition process. This synthetic route is a convenient platform to access analogues with broad structural diversity and has led us to the discovery of unprecedented and easier‐to‐synthesize derivatives with an unsaturation in the cyclopentyl ring between C4 and C5. We also introduce novel analogues in which the original isopropyl motif has been substituted with cyclohexyl, phenyl, and cyclopropyl moieties. The high selectivity and growth‐inhibitory activity shown by these new derivatives in renal cancer cell lines opens new ways toward the final goal of finding effective drugs for the treatment of renal cell carcinoma (RCC).     

Effect of classic sterilization on lipid oxidation in model liquid milk‐based infant and follow‐on formulas

The objective of this study was to evaluate the effect of classic sterilization on lipid oxidation of liquid infant and follow‐on formulas by analyzing formation of oxidized and dimeric TAGs. Model systems containing similar components and proportions to those normally found in manufactured samples and a mixture of high‐oleic sunflower oil, rapeseed oil, and fish oil were used to obtain a fatty acid composition profile in accordance with the EU regulations. For comparative purposes, some samples were prepared with high‐oleic sunflower or fish oil and others without the protein components and added Tween‐20. Quantification of total oxidized TAGs provided complete information of the oxidation state and showed clear advantages versus the other methods used, i.e., loss of PUFA and peroxide value. The results showed that the heat treatment used for sterilization did not lead to significant lipid oxidation, but the tocopherol concentration decreased significantly. The marked tocoherol losses found in protein‐free formulas together with the significantly lower tocopherol concentrations in infant formulas (80% whey in protein fraction) compared to follow‐on formulas (80% caseinate in protein ratio) showed the protective effect of the protein fraction, specially sodium caseinate. Practical applications: This study provides useful information on the utility of different methods used to evaluate oxidation in infant and follow‐on formulas. Quantification of total oxidized TAGs standed out because it is a direct and sensitive method and provides complete information at any stage of the oxidative process. Also, this study shows that important decreases of tocopherols may occur during formula processing and special cautions should therefore be taken during storage and commercialization to avoid additional antioxidant losses.