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Concept: Ester


BACKGROUND: Microalgae have attracted major interest as a sustainable source for biodiesel production on commercial scale. This paper describes the screening of six microalgal species, Scenedesmus quadricauda, Scenedesmus acuminatus, Nannochloropsis sp., Anabaena sp., Chlorella sp. and Oscillatoria sp., isolated from fresh and marine water resources of southern Pakistan for biodiesel production and the GC-MS/MS analysis of their fatty acid methyl esters (FAMEs). RESULTS: Growth rate, biomass productivity and oil content of each algal species have been investigated under autotrophic condition. Biodiesel was produced from algal oil by acid catalyzed transesterification reaction and resulting fatty acid methyl esters (FAMEs) content was analyzed by GC/MS. Fatty acid profiling of the biodiesel, obtained from various microalgal oils showed high content of C-16:0, C-18:0, cis-Delta9C-18:1, cis-Delta11C-18:1 (except Scenedesmus quadricauda) and 10-hydroxyoctadecanoic (except Scenedesmus acuminatus). Absolute amount of C-14:0, C-16:0 and C-18:0 by a validated GC-MS/MS method were found to be 1.5-1.7, 15.0-42.5 and 4.2-18.4 mg/g, respectively, in biodiesel obtained from various microalgal oils. Biodiesel was also characterized in terms of cetane number, kinematic viscosity, density and higher heating value and compared with the standard values. CONCLUSION: Six microalgae of local origin were screened for biodiesel production. A method for absolute quantification of three important saturated fatty acid methyl esters (C-14, C-16 and C-18) by gas chromatography-tandem mass spectrometry (GC-MS/MS), using multiple reactions monitoring (MRM) mode, was employed for the identification and quantification of biodiesels obtained from various microalgal oils. The results suggested that locally found microalgae can be sustainably harvested for the production of biodiesel. This offers the tremendous economic opportunity for an energy-deficient nation.

Concepts: Fatty acid, Water, Fat, Liquid, Ester, Saturated fat, Biodiesel, Biodiesel production


An overview of the metabolic diversity in ripe fruits of a collection of 32 diverse pepper (Capsicum sp.) accessions was obtained by measuring the composition of both semi-polar and volatile metabolites in fruit pericarp, using untargeted LC-MS and headspace GC-MS platforms, respectively. Accessions represented C. annuum, C. chinense, C. frutescens and C. baccatum species, which were selected based on variation in morphological characters, pungency and geographic origin. Genotypic analysis using AFLP markers confirmed the phylogenetic clustering of accessions according to Capsicum species and separated C. baccatum from the C. annuum-C. chinense-C. frutescens complex. Species-specific clustering was also observed when accessions were grouped based on their semi-polar metabolite profiles. In total 88 semi-polar metabolites could be putatively identified. A large proportion of these metabolites represented conjugates of the main pepper flavonoids (quercetin, apigenin and luteolin) decorated with different sugar groups at different positions along the aglycone. In addition, a large group of acyclic diterpenoid glycosides, called capsianosides, was found to be highly abundant in all C. annuum genotypes. In contrast to the variation in semi-polar metabolites, the variation in volatiles corresponded well to the differences in pungency between the accessions. This was particularly true for branched fatty acid esters present in pungent accessions, which may reflect the activity through the acyl branch of the metabolic pathway leading to capsaicinoids. In addition, large genetic variation was observed for many well-established pepper aroma compounds. These profiling data can be used in breeding programs aimed at improving metabolite-based quality traits such as flavour and health-related metabolites in pepper fruits. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-012-0432-6) contains supplementary material, which is available to authorized users.

Concepts: DNA, Genetics, Evolution, Metabolism, Nutrition, Ester, Metabolomics, Capsicum


Rapeseed oil methyl ester (RME) and (bio)ethylene are converted into biofuel with an evenly rising boiling point curve, which fulfills the strict boiling specifications prescribed by the fuel standard EN 590 for modern (petro)diesel engines. Catalyzed by a Pd/Ru system, RME undergoes isomerizing metathesis in a stream of ethylene gas, leading to a defined olefin, monoester, and diester blend. This innovative refining concept requires negligible energy input (60°C) and no solvents and does not produce waste. It demonstrates that the pressing challenge of increasing the fraction of renewables in engine fuel may be addressed purely chemically rather than by motor engineering.

Concepts: Acetic acid, Carboxylic acid, Ester, Distillation, Methyl acetate, Internal combustion engine, Biodiesel, Banana


Parabens (p-hydroxybenzoic acid esters), bisphenols, benzophenone-type UV filters, triclosan, and triclocarban are used in a variety of consumer products, including baby teethers. Nevertheless, the exposure of infants to these chemicals through the use of teethers is still unknown. In this study, 59 teethers, encompassing three types, namely solid plastic, gel-filled, and water-filled (most labeled “bisphenol A-free”), were collected from the U.S. market and analyzed for 26 potential endocrine-disrupting chemicals (EDCs) from intact surfaces through migration/leaching tests performed with Milli-Q water and methanol. The total amount of the sum of six parent parabens (Σ6 Parabens) leached from teethers ranged from 2.0 to 1990 ng, whereas that of their four transformation products (Σ4 Parabens) ranged from 0.47 to 839 ng. The total amount of the sum of nine bisphenols (Σ9 bisphenols) and 5 benzophenones (Σ5 benzophenones) leached from teethers ranged from 1.93 to 213 ng and 0.59 to 297 ng, respectively. Triclosan and triclocarban were found in the extracts of teethers at approximately 10-fold less amounts than were bisphenols and benzophenones. Based on the amount leached into Milli-Q water, daily intake of these chemicals was estimated from the use of teethers by infants at 12 months of age. This is the first study to document the occurrence and migration of a wide range EDCs from intact surfaces of baby teethers.

Concepts: Infant, Summation, Infant mortality, Ester, Approximation, Phenols, Endocrine disruptor, Paraben


PURPOSE: The aim of this study was to investigate the effects of 1 day and 7 days ingestion of a green tea extract (GTE) on whole body fat oxidation during moderate-intensity exercise. METHODS: Thirty one males completed two exercise trials (60 min cycle 50% Wmax). Following the baseline trial (Day 0) subjects were randomly assigned to one of three conditions involving a week supplementation of; 1) 7 days placebo (PLA); 2) 6 days of PLA followed by 1 day of GTE (GTE1); 3) 7 days of GTE ingestion (GTE7). The morning after the supplementation week, subjects consumed an additional supplement and completed a second exercise trial (Day 8). VO2 and VCO2 measurements were taken during exercise to calculate whole body fat oxidation rates. Blood samples, for analysis of plasma fatty acids (FAs), glycerol and epigallocatechin gallate (EGCG), were collected at rest and during exercise. RESULTS: On Day 8 the plasma kinetics and maximal plasma concentrations of EGCG were similar in the GTE1 and GTE7 group (206 ± 28 and 216 ± 25 ng·mL-1 respectively). One day of GTE ingestion did not affect markers of lipolysis during the exercise bout. Seven days of GTE ingestion significantly increased plasma glycerol during exercise (P=0.045) and plasma FAs during exercise (P=0.020) as well as at rest (P= 0.046). However, fat oxidation did not change in any of the groups. CONCLUSIONS: There was no effect of 1 day GTE ingestion on markers of lipolysis or fat oxidation during exercise. Seven days of GTE ingestion increased lipolysis, indicated by increased plasma FA and glycerol concentrations, but did not result in significant changes in fat oxidation.

Concepts: Fatty acid, Triglyceride, Fat, Ester, Green tea, Glycerol, Epigallocatechin gallate, Green tea extract


ABSTRACT A comprehensive analysis of 175 Xanthomonas axonopodis pv. dieffenbachiae strains isolated from 10 Araceae hosts was done to identify pathogen variation. The strains were subjected to repetitive extragenic palindromic sequence polymerase chain reaction and four major phylogenetic clusters were generated. A subset of 40 strains isolated from Anthurium, Dieffenbachia, and Syngonium was further defined by amplified fragment length polymorphism and fatty acid methyl ester analysis and the same four phylogenetic clusters were observed. Comparison of representative strains in the first three clusters using DNA-DNA hybridization and multilocus sequence analysis supports the previous reclassification of strains in cluster I, including the X. axonopodis pv. dieffenbachiae pathovar reference strain (LMG695), to X. citri. Our research findings indicate that strains in cluster I, isolated primarily from anthurium, probably represent an undescribed pathovar. Other phylogenetic subclusters consisting primarily of strains isolated from xanthosoma and philodendron in clusters III and IV, respectively, may yet represent other undescribed species or pathovars of Xanthomonas.

Concepts: DNA, Polymerase chain reaction, Molecular biology, Fatty acid, Carboxylic acid, Ester, Araceae, Araceae genera


A novel isotope labeling reagent d(0)-/d(6)-2, 4-dimethoxy-6-piperazin-1-yl pyrimidine (DMPP) has been developed for derivatization toward the carboxyl group based on carbodiimide chemistry for mass spectrometry (MS) analysis. The strengths of this derivatization strategy involve fast labeling (15s), low chemical background and general access to most carboxylic analytes. This has been demonstrated using a series of compounds containing carboxylic acids, including peptides and proteins. To enhance the MS response of the derivatized analytes, the design of DMPP has been based on integration of the theoretical consideration of high gas-phase hydrogenation capacity and hydrophobicity. In addition, the high abundance product ions at m/z 225 and m/z 231 from d(0)-/d(6)-DMPP labeled carboxylic acids indicate high efficiency of the gas-phase cleavage induced by the labeling reagent. Quantitative determination of these ions can also be used in single reaction monitoring to achieve extremely high sensitivity toward the target analytes. This has subsequently been used to determine trace free fatty acids in human urine. Furthermore, the DMPP labeled peptides also provide additional sequence information in MALDI-MS/MS because of the formation of sequence-related isotope fragment ions. This DMPP-oriented labeling technique is expected to be a promising tool for the MS detection of many varieties of compounds containing carboxyl groups.

Concepts: Alcohol, Amino acid, Fatty acid, Mass spectrometry, Acetic acid, Carboxylic acid, Ester, Butyric acid


The present work demonstrates the application of a hydrodynamic cavitation reactor for the synthesis of biodiesel with used frying oil as a feedstock. The synthesis involved the transesterification of used frying oil (UFO) with methanol in the presence of potassium hydroxide as a catalyst. The effect of geometry and upstream pressure of a cavitating orifice plate on the rate of transesterification reaction has been studied. It is observed that the micro level turbulence created by hydrodynamic cavitation somewhat overcomes the mass transfer limitations for triphasic transesterification reaction. The significant effects of upstream pressure on the rate of formation of methyl esters have been seen. It has been observed that flow geometry of orifice plate plays a crucial role in process intensification. With an optimized plate geometry of 2mm hole diameter and 25 holes, more than 95% of triglycerides have been converted to methyl esters in 10 min of reaction time with cavitational yield of 1.28 × 10(-3) (Grams of methyl esters produced per Joule of energy supplied). The potential of UFO to produce good quality methyl esters has been demonstrated.

Concepts: Time, Alcohol, Fluid dynamics, Ester, Chemical engineering, Potassium hydroxide, Biodiesel, Transesterification


ETHNOPHARMACOLOGICAL RELEVANCE: The stem-barks of Hintonia latiflora and H. standleyana, locally known as “copalchi”, are used for treating several maladies such as diabetes and gastrointestinal complaints, including gastric ulcers. Although the antidiabetic properties have been demonstrated, the gastroprotective action remains unexplored. AIM OF THE STUDY: The main goals of this study were to establish the potential acute toxicity and the gastroprotective activity of aqueous extracts and compounds from H. latiflora and H. standleyana in order to demonstrate their preclinical efficacy for the treatment of gastric ulcers in Mexican folk medicine. MATERIALS AND METHODS: The aqueous extracts from the stem-barks (HLSB and HSSB) and leaves (HLL and HSL) from H. latiflora and H standleyana were prepared by infusion. Investigation of the acute toxicity was accomplished by the Lorke method. The gastroprotective effect was assessed by means of a conventional ethanol-induced gastric injury model in rats using carbenoxolone as positive control. 5-O-[β-D-apiofuranosyl-(1→6)-β-D-glucopyranosyl]-7-methoxy-3',4'-dihydroxy-4-phenylcoumarin (1) and chlorogenic acid (2) were also assayed. Preliminary mechanism of action of the tested compounds was analyzed using the same pharmacological models but pretreating the animals with N(G)-nitro-L-arginine methyl ester (L-NAME), N-ethylmaleimide (NEM) and indomethacin. RESULTS: Investigation of the acute toxicity revealed that infusions of the leaves and stem-barks of both Hintonia species were not toxic to mice (LD(50)>5000mg/kg in all cases). HLSB, HSSB, HLL and HSL provoked a significant gastroprotective effect [80.5±3.35% (ED(50)=184.7mg/kg), 80.26±3.96%, 75.1±7.26% % (ED(50)=109.1mg/kg), 76.85±3.17% (ED(50)=149.7mg/kg) of gastroprotection respectively]. Compounds 1 and 2, present in all the extracts, were also active [68.85±8.4% (ED(50)=15mg/kg), 74.04±4.4% (ED(50)=26mg/kg) of gastroprotection respectively] and their mode of action involved non-protein sulfhydryl endogenous (NP-SH) compounds, since only pretreatment with NEM inhibited their gastroprotective action. CONCLUSIONS: The present investigation tends to support the ethnomedical use of HLSB, HSSB for treating gastric ulceration. Since HLL and HSL were also active, the leaves could be use alternatively, which in terms of natural resources conservation is an outstanding finding, considering that the plant populations of both Hintonia are scarce and in danger of extinction. Mainly two compounds (1 and 2) are important active principles of the plants.

Concepts: Present, Toxicology, Ester, Helicobacter pylori, Acute accent, Acute toxicity, Traditional medicine, Hintonia latiflora


The dynamic kinetic resolution of α-keto esters via asymmetric transfer hydrogenation has been developed as a technique for the highly stereoselective construction of structurally diverse β-substituted-α-hydroxy carboxylic acid derivatives. Through the development of a privileged m-terphenylsulfonamide for (arene)RuCl(monosulfonamide) complexes with a high affinity for selective α-keto ester reduction, excellent levels of chemo-, diastereo-, and enantiocontrol can be realized in the reduction of β-aryl- and β-chloro-α-keto esters.

Concepts: Alcohol, Amino acid, Stereochemistry, Hydrogenation, Acetic acid, Carboxylic acid, Ester, Amide