Displaying publications 361 - 380 of 1723 in total

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  1. Analysis of dog meat adulteration in beef meatballs using non-targeted UHPLC-Orbitrap HRMS metabolomics and chemometrics for halal authentication study
    Windarsih A, Bakar NKA, Rohman A, Erwanto Y
    Anal Sci, 2024 Mar;40(3):385-397.
    PMID: 38095741 DOI: 10.1007/s44211-023-00470-x
    Due to the different price and high quality, halal meat such as beef can be adulterated with non-halal meat with low price to get an economical price. The objective of this research was to develop an analytical method for halal authentication testing of beef meatballs (BM) from dog meat (DM) using a non-targeted metabolomics approach employing liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and chemometrics. The differentiation of authentic BM from that adulterated with DM was successfully performed using partial least square-discriminant analysis (PLS-DA) with high accuracy (R2X = 0.980, and R2Y = 0.980) and good predictivity (Q2 = 0.517). In addition, partial least square (PLS) and orthogonal PLS (OPLS) were successfully used to predict the DM added (% w/w) in BM with high accuracy (R2 > 0.990). A number of metabolites, potential for biomarker candidates, were identified to differentiate BM and that adulterated with DM. It showed that the combination of a non-targeted LC-HRMS Orbitrap metabolomics and chemometrics could detect up to 0.1% w/w of DM adulteration. The developed method was successfully applied for analysis of commercial meatball samples (n = 28). Moreover, pathway analysis revealed that beta-alanine, histidine, and ether lipid metabolism were significantly affected by dog meat adulteration. In summary, this developed method has great potential to be developed and used as an alternative method for analysis of non-halal meats in halal meat products.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  2. Dietary exposure to acrylamide among the Malaysian adult population
    Nur Hidayah J, Abdul Razis AF, Jambari NN, Chai LC, You L, Sanny M
    Food Chem Toxicol, 2024 Mar;185:114502.
    PMID: 38346572 DOI: 10.1016/j.fct.2024.114502
    This study aimed to estimate the Malaysian adult population's current dietary exposure and margin of exposure (MOE) to the carcinogenic processing contaminant, acrylamide. A total of 448 samples from 11 types of processed foods were collected randomly throughout Malaysia in the year 2015 and 2016. Acrylamide was analysed in samples using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) with a limit of detection (LOD) of 10 μg/kg and a limit of quantification (LOQ) of 25 μg/kg. The highest average level of acrylamide (772 ± 752 μg/kg) was found in potato crisps, followed by French fries (415 ± 914 μg/kg) and biscuits (245 ± 195 μg/kg). The total acrylamide exposure for the adult Malaysian was 0.229 and 1.77 μg/kg body weight per day for average and high consumers, respectively. The MOE were 741 and 1875 for the average consumer based on cancer and non-cancer effects of acrylamide, respectively. Meanwhile, for high consumers, the MOE is 96 for cancer and 243 for non-cancer effects. These findings indicate potential carcinogenic risks from acrylamide exposure among Malaysian adults, especially in Malay and other Bumiputra groups compared to Chinese, Indian, and other ethnic groups, while non-cancer effects appeared less concerning.
    Matched MeSH terms: Chromatography, Liquid
  3. Exploring the binding mechanisms of thermally and ultrasonically induced molten globule-like β-lactoglobulin with heptanal as revealed by multi-spectroscopic techniques and molecular simulation
    Han C, Zheng Y, Huang S, Xu L, Zhou C, Sun Y, et al.
    Int J Biol Macromol, 2024 Apr;263(Pt 1):130300.
    PMID: 38395276 DOI: 10.1016/j.ijbiomac.2024.130300
    This work employed the model protein β-lactoglobulin (BLG) to investigate the contribution of microstructural changes to regulating the interaction patterns between protein and flavor compounds through employing computer simulation and multi-spectroscopic techniques. The formation of molten globule (MG) state-like protein during the conformational evolution of BLG, in response to ultrasonic (UC) and heat (HT) treatments, was revealed through multi-spectroscopic characterization. Differential MG structures were distinguished by variations in surface hydrophobicity and the microenvironment of tryptophan residues. Fluorescence quenching measurements indicated that the formation of MG enhanced the binding affinity of heptanal to protein. LC-MS/MS and NMR revealed the covalent bonding between heptanal and BLG formed by Michael addition and Schiff-base reactions, and MG-like BLG exhibited fewer chemical shift residues. Molecular docking and molecular dynamics simulation confirmed the synergistic involvement of hydrophobic interactions and hydrogen bonds in shaping BLG-heptanal complexes thus promoting the stability of BLG structures. These findings indicated that the production of BLG-heptanal complexes was driven synergistically by non-covalent and covalent bonds, and their interaction processes were influenced by processes-induced formation of MG potentially tuning the release and retention behaviors of flavor compounds.
    Matched MeSH terms: Chromatography, Liquid
  4. Fulltext Rho-Kinase II Inhibitory Potential of Eurycoma longifolia New Isolate for the Management of Erectile Dysfunction
    Ezzat SM, Okba MM, Ezzat MI, Aborehab NM, Mohamed SO
    Evid Based Complement Alternat Med, 2019;2019:4341592.
    PMID: 31223329 DOI: 10.1155/2019/4341592
    Background. Eurycoma longifolia Jack (Fam.: Simaroubaceae), known as Tongkat Ali (TA), has been known as a symbol of virility and sexual power. The aim of the study was to screen E. longifolia aqueous extract (AE) and isolates for ROCK-II inhibition. Results. The AE (1-10 μg/ml) showed a significant inhibition for ROCK-II activity (62.8-81%) at P < 0.001 with an IC50 (651.1 ± 32.9 ng/ml) compared to Y-27632 ([(+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide dihydrochloride]) (68.15-89.9 %) at same concentrations with an IC50 (192 ± 8.37 ng/ml). Chromatographic purification of the aqueous extract (AE) allowed the isolation of eight compounds; stigmasterol T1, trans-coniferyl aldehyde T2, scopoletin T3, eurycomalactone T4, 6α- hydroxyeurycomalactone T5, eurycomanone T6, eurycomanol T7, and eurycomanol-2-O-β-D-glucopyranoside T8. This is the first report for the isolation of T1 and T3 from E. longifolia and for the isolation of T2 from genus Eurycoma. The isolates (at 10 μg/ml) exhibited maximum inhibition % of ROCK-II 82.1 ± 0.63 (T2), 78.3 ± 0.38 (T6), 77.1 ± 0.11 (T3), 76.2 ± 3.53 (T4), 74.5 ± 1.27 (T5), 74.1 ± 2.97 (T7), 71.4 ± 2.54 (T8), and 60.3 ± 0.14 (T1), where the newly isolated compound trans-coniferyl aldehyde T2 showed the highest inhibitory activity among the tested isolated compounds and even higher than the total extract AE. The standard Y-27632 (10 μg/ml) showed 89.9 ± 0.42 % inhibition for ROCK-II activity when compared to control at P < 0.0001. Conclusion. The traditional use of E. longifolia as aphrodisiac and for male sexual disorders might be in part due to the ROCK-II inhibitory potential.
    Matched MeSH terms: Chromatography
  5. Fulltext Phytochemicals and Antioxidant Capacity from Nypa fruticans Wurmb. Fruit
    Prasad N, Yang B, Kong KW, Khoo HE, Sun J, Azlan A, et al.
    Evid Based Complement Alternat Med, 2013;2013:154606.
    PMID: 23710209 DOI: 10.1155/2013/154606
    Nypa fruticans Wurmb. is one of the important underutilized fruit of Malaysia, which lacks scientific attention. Total phenolics, flavonoid content, and antioxidant capacities from endosperm extracts of Nypa fruticans (unripe and ripe fruits) were evaluated. Endosperm extract of unripe fruits (EEU) exhibited the highest phenolics (135.6 ± 4.5 mg GAE/g), flavonoid content (68.6 ± 3.1 RE/g), and antioxidant capacity. Free radical scavenging capacity of EEU as assessed by 2-2'-azino-bis (3-ethylbenz-thiazoline-6-sulfonic acid (ABTS) and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radicals showed inhibitory activity of 78 ± 1.2% and 85 ± 2.6%, respectively. Beta carotene bleaching coefficient of EEU was higher (2550 ± 123), when compared to endosperm extract of ripe fruits (1729 ± 172). Additionally, EEU exhibited high antioxidant capacity by phosphomolybdenum method and ferric reducing antioxidant power values. Eight phenolic compounds from Nypa fruticans endosperm extracts were identified and quantified by ultra-high-performance liquid chromatography. Chlorogenic acid, protocatechuic acid, and kaempferol were the major phenolic compounds. Thus this fruit could be used as a potential source of natural antioxidant.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  6. Fulltext Physicochemical and antioxidant properties of Apis cerana honey from Lombok and Bali Islands
    Huyop F, Ullah S, Abdul Wahab R, Huda N, Sujana IGA, Saloko S, et al.
    PLoS One, 2024;19(4):e0301213.
    PMID: 38578814 DOI: 10.1371/journal.pone.0301213
    Limited honey production worldwide leads to higher market prices, thus making it prone to adulteration. Therefore, regular physicochemical analysis is imperative for ensuring authenticity and safety. This study describes the physicochemical and antioxidant properties of Apis cerana honey sourced from the islands of Lombok and Bali, showing their unique regional traits. A comparative analysis was conducted on honey samples from Lombok and Bali as well as honey variety from Malaysia. Moisture content was found slightly above 20% in raw honey samples from Lombok and Bali, adhering to the national standard (SNI 8664:2018) of not exceeding 22%. Both honey types displayed pH values within the acceptable range (3.40-6.10), ensuring favorable conditions for long-term storage. However, Lombok honey exhibited higher free acidity (78.5±2.14 meq/kg) than Bali honey (76.0±1.14 meq/kg), surpassing Codex Alimentarius recommendations (≤50 meq/kg). The ash content, reflective of inorganic mineral composition, was notably lower in Lombok (0.21±0.02 g/100) and Bali honey (0.14±0.01 g/100) compared to Tualang honey (1.3±0.02 g/100). Electric conductivity, indicative of mineral content, revealed Lombok and Bali honey with lower but comparable values than Tualang honey. Hydroxymethylfurfural (HMF) concentrations in Lombok (14.4±0.11 mg/kg) and Bali (17.6±0.25 mg/kg) were slightly elevated compared to Tualang honey (6.4±0.11 mg/kg), suggesting potential processing-related changes. Sugar analysis revealed Lombok honey with the highest sucrose content (2.39±0.01g/100g) and Bali honey with the highest total sugar content (75.21±0.11 g/100g). Both honeys exhibited lower glucose than fructose content, aligning with Codex Alimentarius guidelines. The phenolic content, flavonoids, and antioxidant activity were significantly higher in Lombok and Bali honey compared to Tualang honey, suggesting potential health benefits. Further analysis by LC-MS/MS-QTOF targeted analysis identified various flavonoids/flavanols and polyphenolic/phenolic acid compounds in Lombok and Bali honey. The study marks the importance of characterizing the unique composition of honey from different regions, ensuring quality and authenticity in the honey industry.
    Matched MeSH terms: Chromatography, Liquid
  7. Fulltext Crystallization and preliminary crystallographic studies of the hypothetical protein BPSL1038 from Burkholderia pseudomallei
    Shaibullah S, Mohd-Sharif N, Ho KL, Firdaus-Raih M, Nathan S, Mohamed R, et al.
    Acta Crystallogr F Struct Biol Commun, 2014 Dec 01;70(Pt 12):1697-700.
    PMID: 25484229 DOI: 10.1107/S2053230X14025278
    Melioidosis is an infectious disease caused by the pathogenic bacterium Burkholderia pseudomallei. Whole-genome sequencing revealed that the B. pseudomallei genome includes 5855 coding DNA sequences (CDSs), of which ∼25% encode hypothetical proteins. A pathogen-associated hypothetical protein, BPSL1038, was overexpressed in Escherichia coli, purified and crystallized using vapour-diffusion methods. A BPSL1038 protein crystal that grew using sodium formate as precipitant diffracted to 1.55 Å resolution. It belonged to space group C2221, with unit-cell parameters a = 85.36, b = 115.63, c = 46.73 Å. The calculated Matthews coefficient (VM) suggests that there are two molecules per asymmetric unit, with a solvent content of 48.8%.
    Matched MeSH terms: Chromatography, Gel
  8. Chemical composition, acetylcholinesterase inhibition and molecular docking studies of essential oil from Knema hookeriana Warb. (Myristicaceae)
    Salihu AS, Salleh WMNHW, Ogunwa TH
    Nat Prod Res, 2024 Jul;38(14):2516-2521.
    PMID: 36855270 DOI: 10.1080/14786419.2023.2184359
    The genus Knema Lour. is distributed mainly in Southeast Asian and widely used in folk medicine for treating diseases such as jaundice, chronic fever, and inflammation. The chemical composition, acetylcholinesterase inhibition, and molecular docking studies of essential oil from Knema hookeriana Warb. were investigated in this study. The essential oil was achieved through hydrodistillation and was characterised using gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The acetylcholinesterase inhibitory activity was evaluated using Ellman method while molecular docking studies were carried out using Autodock v.4.3.2. The results revealed that the essential oil examined consisted mainly of β-caryophyllene (26.2%), germacrene D (12.5%), δ-cadinene (9.2%), germacrene B (8.8%) and bicyclogermacrene (5.5%). The essential oil showed acetylcholinesterase activity with IC50 value of 70.5 µg/mL. The enzyme-ligand molecular docking study showed that β-caryophyllene and δ-cadinene exhibited good binding affinities towards AChE with docking scores -8.1 kcal/mol and -8.3 kcal/mol, respectively.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  9. The antioxidant and antimicrobial activity of ethanolic extract in roots, stems, and leaves of three commercial Cymbopogon species
    Wahyuni DK, Kharisma VD, Murtadlo AAA, Rahmawati CT, Syukriya AJ, Prasongsuk S, et al.
    BMC Complement Med Ther, 2024 Jul 18;24(1):272.
    PMID: 39026301 DOI: 10.1186/s12906-024-04573-4
    BACKGROUND: Cymbopogon is a member of the family Poaceae and has been explored for its phytochemicals and bioactivities. Although the antimicrobial activities of Cymbopogon spp. extracts have been extensively studied, comprehensive analyses are required to identify promising compounds for the treatment of antimicrobial resistance. Therefore, this study investigated the antioxidant and antimicrobial properties of Cymbopogon spp. ethanolic extracts in every single organ.

    METHODS: Ethanolic extracts were obtained from three Indonesian commercial species of Cymbopogon spp., namely Cymbopogon citratus (L.) Rendle, Cymbopogon nardus (DC.) Spatf., and Cymbopogon winterianus Jowitt. The leaf, stem, and root extracts were evaluated via metabolite profiling using gas chromatography-mass spectrometry (GC-MS). In silico and in vitro analyses were used to evaluate the antioxidant and antimicrobial properties of the Cymbopogon spp. ethanolic extracts. In addition, bioactivity was measured using cytotoxicity assays. Antioxidant assays were performed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis [3-ethylbenzothiazoline-6-sulfonic acid (ABTS) to determine toxicity to Huh7it-1 cells using a tetrazolium bromide (MTT) assay. Finally, the antimicrobial activity of these extracts was evaluated against Candida albicans, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli using a well diffusion assay.

    RESULTS: GC-MS analysis revealed 53 metabolites. Of these, 2,5-bis(1,1-dimethylethyl)- phenol (27.87%), alpha-cadinol (26.76%), and 1,2-dimethoxy-4-(1-propenyl)-benzene (20.56%) were the predominant compounds. C. winterianus and C. nardus leaves exhibited the highest antioxidant activity against DPPH and ABTS, respectively. Contrastingly, the MTT assay showed low cytotoxicity. C. nardus leaf extract exhibited the highest antimicrobial activity against E. coli and S. aureus, whereas C. winterianus stem extract showed the highest activity against B. substilis. Furthermore, computational pathway analysis predicted that antimicrobial activity mechanisms were related to antioxidant activity.

    CONCLUSIONS: These findings demonstrate that the leaves had strong antioxidant activity, whereas both the leaves and stems showed great antimicrobial activity. Furthermore, all Cymbopogon spp. ethanolic extracts showed low toxicity. These findings provide a foundation for future studies that assess the clinical safety of Cymbopogon spp. as novel drug candidates.

    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  10. Preliminary studies on the effect of excretory secretory (ES) Ascaris lumbricoides antigens on colorectal cell line viability
    Ab Talib NN, Nisha M, Ramasamy R, Pang JC
    Trop Biomed, 2024 Jun 01;41(2):160-165.
    PMID: 39154268 DOI: 10.47665/tb.41.2.005
    Helminth parasites are a group of complex metazoans from various taxonomic families. Excretory secretory (ES) by-products, secreted by living parasites from the surface, appeared to modulate the host immunological response towards helminth infection. This study aims to investigate the effect of ES antigen from helminth parasite on colorectal cell viability. Worm were cultured in phosphate-buffered saline (PBS x1) at 37°C for 24 hours after being rinsed in sterile PBS. Using a mortar and pestle, the worm was crushed vigorously using PBS. The obtained excretory secretory (ES) antigens were extracted and filtered using a 0.22 µM filter and stored at -20°C for further assay. For LCMS, 100 µl of the extract was analysed using Agilent ZORBAX Eclipse Plus C18 Rapid Resolution HT. The extraction of ES antigen (10 µg/ml and 20 µg/ml) was used for cell viability studies using CRC cell line HCT 116. Cell viability and MTT assay were conducted as per the protocol mentioned in the MTT kit. The liquid chromatography and mass spectrometry (LCMS) data indicated that the ES antigen contained metabolic compounds, namely fatty acid, amino alcohol, indoles, sterols, glycosides, and sphingoids. For the Ascaris lumbricoides LCMS analyses, around 405 metabolic peaks were detected. Out of which, 58 were detected via the database were identified, while several compounds detected have anticancer properties. The MTT assay indicated that after 24 hours and 48 hours of exposure, all treated cells showed a decrease in cell viability compared to the control group. The preliminary studies demonstrated that the ES antigen from Ascaris lumbricoides has some ability to decrease the cell viability of the HCT116 CRC cell line. Further studies are needed to examine the cell cycle arrest and apoptosis effect of the ES antigen towards the CRC cell line.
    Matched MeSH terms: Chromatography, Liquid
  11. Development and validation of a selective, sensitive and stability indicating UPLC-MS/MS method for rapid, simultaneous determination of six process related impurities in darunavir drug substance
    A VBR, Yusop Z, Jaafar J, Aris AB, Majid ZA, Umar K, et al.
    J Pharm Biomed Anal, 2016 Sep 05;128:141-148.
    PMID: 27262107 DOI: 10.1016/j.jpba.2016.05.026
    In this study a sensitive and selective gradient reverse phase UPLC-MS/MS method was developed for the simultaneous determination of six process related impurities viz., Imp-I, Imp-II, Imp-III, Imp-IV, Imp-V and Imp-VI in darunavir. The chromatographic separation was performed on Acquity UPLC BEH C18 (50 mm×2.1mm, 1.7μm) column using gradient elution of acetonitrile-methanol (80:20, v/v) and 5.0mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4mL/min. Both negative and positive electrospray ionization (ESI) modes were operated simultaneously using multiple reaction monitoring (MRM) for the quantification of all six impurities in darunavir. The developed method was fully validated following ICH guidelines with respect to specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, robustness and sample solution stability. The method was able to quantitate Imp-I, Imp-IV, Imp-V at 0.3ppm and Imp-II, Imp-III, and Imp-VI at 0.2ppm with respect to 5.0mg/mL of darunavir. The calibration curves showed good linearity over the concentration range of LOQ to 250% for all six impurities. The correlation coefficient obtained was >0.9989 in all the cases. The accuracy of the method lies between 89.90% and 104.60% for all six impurities. Finally, the method has been successfully applied for three formulation batches of darunavir to determine the above mentioned impurities, however no impurity was found beyond the LOQ. This method is a good quality control tool for the trace level quantification of six process related impurities in darunavir during its synthesis.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods
  12. Chemometric approach to the optimization of HS-SPME/GC-MS for the determination of multiclass pesticide residues in fruits and vegetables
    Abdulra'uf LB, Tan GH
    Food Chem, 2015 Jun 15;177:267-73.
    PMID: 25660885 DOI: 10.1016/j.foodchem.2015.01.031
    An HS-SPME method was developed using multivariate experimental designs, which was conducted in two stages. The significance of each factor was estimated using the Plackett-Burman (P-B) design, for the identification of significant factors, followed by the optimization of the significant factors using central composite design (CCD). The multivariate experiment involved the use of Minitab® statistical software for the generation of a 2(7-4) P-B design and CCD matrices. The method performance evaluated with internal standard calibration method produced good analytical figures of merit with linearity ranging from 1 to 500 μg/kg with correlation coefficient greater than 0.99, LOD and LOQ were found between 0.35 and 8.33 μg/kg and 1.15 and 27.76 μg/kg respectively. The average recovery was between 73% and 118% with relative standard deviation (RSD=1.5-14%) for all the investigated pesticides. The multivariate method helps to reduce optimization time and improve analytical throughput.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  13. Assessment of dispersive liquid-liquid microextraction conditions for gas chromatography time-of-flight mass spectrometry identification of organic compounds in honey
    Moniruzzaman M, Rodríguez I, Rodríguez-Cabo T, Cela R, Sulaiman SA, Gan SH
    J Chromatogr A, 2014 Nov 14;1368:26-36.
    PMID: 25441341 DOI: 10.1016/j.chroma.2014.09.057
    The suitability of the dispersive liquid-liquid microextraction (DLLME) technique for gas chromatography (GC) characterization of minor organic compounds in honey samples is evaluated. Under optimized conditions, samples were pre-treated by liquid-liquid extraction with acetonitrile followed by DLLME using carbon tetrachloride (CCl4, 0.075 mL) as extractant. The yielded settled phase was analyzed by GC using high resolution time-of-flight (TOF) mass spectrometry (MS). The whole sample preparation process is completed in approximately 10 min, with a total consumption of organic solvents below 4 mL, relative standard deviations lower than 12% and with more than 70 organic compounds, displaying linear retention index in the range from 990 to 2900, identified in the obtained extracts. In comparison with HS SPME extraction, higher peak intensities were attained for most volatile and semi-volatile compounds amenable to both extraction techniques. Furthermore, other species such as highly polar and water soluble benzene acids, long chain fatty acids, esters and flavonoids, which are difficult to concentrate by HS SPME, could be identified in DLLME extracts. Some of the compounds identified in DLLME extracts have been proposed as useful for samples classification and/or they are recognized as markers of honeys from certain geographic areas.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  14. Fulltext Rapid and simultaneous quantification of levetiracetam and its carboxylic metabolite in human plasma by liquid chromatography tandem mass spectrometry
    Yeap LL, Lo YL
    PLoS One, 2014;9(11):e111544.
    PMID: 25375249 DOI: 10.1371/journal.pone.0111544
    A simple liquid chromatography tandem mass spectrometry method was developed and validated according to the guidelines of the US Food and Drug Administration and the European Medicines Agency for a simultaneous quantification of levetiracetam (LEV) and its metabolite, UCB L057 in the plasma of patients. A 0.050 mL plasma sample was prepared by a simple and direct protein precipitation with 0.450 mL acetonitrile (ACN) containing 1 µg/mL of internal standard (IS, diphenhydramine), then vortex mixed and centrifuged. A 0.100 mL of the clear supernatant was diluted with 0.400 mL water and well mixed. A 0.010 mL of the resultant solution was injected into an Agilent Zorbax SB-C18 (2.1 mm×100 mm, 3.5 µm) column with an isocratic elution at 0.5 mL/min using a mixture of 0.1% formic acid in water and ACN (40:60 v/v). Detection was performed using an AB Sciex API 3000 triple quadrupole mass spectrometer, equipped with a Turbo Ion Spray source, operating in a positive mode: LEV at transition 171.1>154.1, UCB L057 at 172.5>126.1, and IS at 256.3>167.3; with an assay run time of 2 minutes. The lower limit of quantification (LLOQ) for both LEV and UCB L057 was validated at 0.5 µg/mL, while their lower limit of detection (LOD) was 0.25 µg/mL. The calibration curves were linear between 0.5 and 100 µg/mL for both analytes. The inaccuracy and imprecision of both intra-assay and inter-assay were less than 10%. Matrix effects were consistent between sources of plasma and the recoveries of all compounds were between 100% and 110%. Stability was established under various storage and processing conditions. The carryovers from both LEV and UCB L057 were less than 6% of the LLOQ and 0.13% of the IS. This assay method has been successfully applied to a population pharmacokinetic study of LEV in patients with epilepsy.
    Matched MeSH terms: Chromatography, Liquid*
  15. Novel lipase purification methods - a review of the latest developments
    Tan CH, Show PL, Ooi CW, Ng EP, Lan JC, Ling TC
    Biotechnol J, 2015 Jan;10(1):31-44.
    PMID: 25273633 DOI: 10.1002/biot.201400301
    Microbial lipases are popular biocatalysts due to their ability to catalyse diverse reactions such as hydrolysis, esterification, and acidolysis. Lipases function efficiently on various substrates in aqueous and non-aqueous media. Lipases are chemo-, regio-, and enantio-specific, and are useful in various industries, including those manufacturing food, detergents, and pharmaceuticals. A large number of lipases from fungal and bacterial sources have been isolated and purified to homogeneity. This success is attributed to the development of both conventional and novel purification techniques. This review highlights the use of these techniques in lipase purification, including conventional techniques such as: (i) ammonium sulphate fractionation; (ii) ion-exchange; (iii) gel filtration and affinity chromatography; as well as novel techniques such as (iv) reverse micellar system; (v) membrane processes; (vi) immunopurification; (vi) aqueous two-phase system; and (vii) aqueous two-phase floatation. A summary of the purification schemes for various bacterial and fungal lipases are also provided.
    Matched MeSH terms: Chromatography/methods*
  16. Co-solvent selection for supercritical fluid extraction of astaxanthin and other carotenoids from Penaeus monodon waste
    Radzali SA, Baharin BS, Othman R, Markom M, Rahman RA
    J Oleo Sci, 2014;63(8):769-77.
    PMID: 25007745
    In recent years, astaxanthin is claimed to have a 10 times higher antioxidant activity than that of other carotenoids such as lutein, zeaxanthin, canthaxanthin, and β-carotene; the antioxidant activity of astaxanthin is 100 times higher than that of α-tocopherol. Penaeus monodon (tiger shrimp) is the largest commercially available shrimp species and its waste is a rich source of carotenoids such as astaxanthin and its esters. The efficient and environment-friendly recovery of astaxanthins was accomplished by using a supercritical fluid extraction (SFE) technique. The effects of different co-solvents and their concentrations on the yield and composition of the extract were investigated. The following co-solvents were studied prior to the optimization of the SFE technique: ethanol, water, methanol, 50% (v/v) ethanol in water, 50% (v/v) methanol in water, 70% (v/v) ethanol in water, and 70% (v/v) methanol in water. The ethanol extract produced the highest carotenoid yield (84.02 ± 0.8 μg/g) dry weight (DW) with 97.1% recovery. The ethanol extract also produced the highest amount of the extracted astaxanthin complex (58.03 ± 0.1 μg/g DW) and the free astaxanthin content (12.25 ± 0.9 μg/g DW) in the extract. Lutein and β-carotene were the other carotenoids identified. Therefore, ethanol was chosen for further optimization studies.
    Matched MeSH terms: Chromatography, Supercritical Fluid/methods*
  17. Fulltext Antimicrobial compounds from leaf extracts of Jatropha curcas, Psidium guajava, and Andrographis paniculata
    Rahman MM, Ahmad SH, Mohamed MT, Ab Rahman MZ
    ScientificWorldJournal, 2014;2014:635240.
    PMID: 25250382 DOI: 10.1155/2014/635240
    The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts of Jatropha curcas and Andrographis paniculata and ethanolic leaf extract of Psidium guajava and the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified in J. curcas, P. guajava, and A. paniculata leaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing the P. guajava and A. paniculata leaf extracts at 15 mg/L. Moreover, solution with leaf extracts of A. paniculata had the lowest bacterial count compared to P. guajava and J. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods
  18. UPLC method for the determination of vitamin E homologues and derivatives in vegetable oils, margarines and supplement capsules using pentafluorophenyl column
    Wong YF, Makahleh A, Saad B, Ibrahim MN, Rahim AA, Brosse N
    Talanta, 2014 Dec;130:299-306.
    PMID: 25159413 DOI: 10.1016/j.talanta.2014.07.021
    A sensitive and rapid reversed-phase ultra performance liquid chromatographic (UPLC) method for the simultaneous determination of tocopherols (α-, β-, γ-, δ-), tocotrienols (α-, β-, γ-, δ-), α-tocopherol acetate and α-tocopherol nicotinate is described. The separation was achieved using a Kinetex pentafluorophenyl (PFP) column (150 × 2.1mm, 2.6 µm) with both photodiode array (PDA) and fluorescence (FL) detectors that were connected in series. Column was thermostated at 42°C. Under a gradient system consisting of methanol and water at a constant flow rate of 0.38 mL min(-1), all the ten analytes were well separated in less than 9.5 min. The method was validated in terms of linearity, limits of detection and quantitation, precision and recoveries. Calibration curves of the ten compounds were well correlated (r(2)>0.999) within the range of 100 to 25,000 μg L(-1) for α-tocopherol acetate and α-tocopherol nicotinate, 10 to 25,000 μg L(-1) for α-tocotrienol and 5 to 25,000 μg L(-1) for the other components. The method is simple and sensitive with detection limits (S/N, 3) of 1.0 to 3.0 μg L(-1) (FL detection) and 30 to 74 μg L(-1) (PDA detection). Relative standard deviations for intra- and inter-day retention times (<1%) and peak areas (≤ 4%) were obtained. The method was successfully applied to the determination of vitamin E in vegetable oils (extra virgin olive, virgin olive, pomace olive, blended virgin and refined olive, sunflower, soybean, palm olein, carotino, crude palm, walnut, rice bran and grape seed), margarines and supplements.
    Matched MeSH terms: Chromatography, Liquid; Chromatography, Reverse-Phase
  19. Phytosterols and their extraction from various plant matrices using supercritical carbon dioxide: a review
    Uddin MS, Sarker MZ, Ferdosh S, Akanda MJ, Easmin MS, Bt Shamsudin SH, et al.
    J Sci Food Agric, 2015 May;95(7):1385-94.
    PMID: 25048690 DOI: 10.1002/jsfa.6833
    Phytosterols provide important health benefits: in particular, the lowering of cholesterol. From environmental and commercial points of view, the most appropriate technique has been searched for extracting phytosterols from plant matrices. As a green technology, supercritical fluid extraction (SFE) using carbon dioxide (CO2) is widely used to extract bioactive compounds from different plant matrices. Several studies have been performed to extract phytosterols using supercritical CO2 (SC-CO2) and this technology has clearly offered potential advantages over conventional extraction methods. However, the efficiency of SFE technology fully relies on the processing parameters, chemistry of interest compounds, nature of the plant matrices and expertise of handling. This review covers SFE technology with particular reference to phytosterol extraction using SC-CO2. Moreover, the chemistry of phytosterols, properties of supercritical fluids (SFs) and the applied experimental designs have been discussed for better understanding of phytosterol solubility in SC-CO2.
    Matched MeSH terms: Chromatography, Supercritical Fluid/methods*
  20. Fulltext Detection of quorum sensing activity in the multidrug-resistant clinical isolate Pseudomonas aeruginosa strain GB11
    Cheng HJ, Ee R, Cheong YM, Tan WS, Yin WF, Chan KG
    Sensors (Basel), 2014;14(7):12511-22.
    PMID: 25019635 DOI: 10.3390/s140712511
    A multidrug-resistant clinical bacteria strain GB11 was isolated from a wound swab on the leg of a patient. Identity of stain GB11 as Pseudomonas aeruginosa was validated by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Detection of the production of signaling molecules, N-acylhomoserine lactones (AHLs), was conducted using three different bacterial biosensors. A total of four different AHLs were found to be produced by strain GB11, namely N-butyryl homoserine lactone (C4-HSL), N-hexanoylhomoserine lactone (C6-HSL), N-octanoyl homoserine lactone (C8-HSL) and N-3-oxo-dodecanoylhomoserine lactone (3-oxo-C12-HSL) using high resolution liquid chromatography tandem mass spectrometry (LC-MS/MS). Of these detected AHLs, 3-oxo-C12-HSL was found to be the most abundant AHL produced by P. aeruginosa GB11.
    Matched MeSH terms: Chromatography, Liquid/methods
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