Displaying publications 281 - 300 of 951 in total

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  1. Fulltext Unravelling the genome of long chain N-acylhomoserine lactone-producing Acinetobacter sp. strain GG2 and identification of its quorum sensing synthase gene
    How KY, Hong KW, Sam CK, Koh CL, Yin WF, Chan KG
    Front Microbiol, 2015;6:240.
    PMID: 25926817 DOI: 10.3389/fmicb.2015.00240
    Myriad proteobacteria use N-acyl homoserine lactone (AHL) molecules as quorum sensing (QS) signals to regulate different physiological functions, including virulence, antibiotic production, and biofilm formation. Many of these proteobacteria possess LuxI/LuxR system as the QS mechanism. Recently, we reported the 3.89 Mb genome of Acinetobacter sp. strain GG2. In this work, the genome of this long chain AHL-producing bacterium was unravelled which led to the molecular characterization of luxI homologue, designated as aciI. This 552 bp gene was cloned and overexpressed in Escherichia coli BL21(DE3). The purified protein was ∼20.5 kDa and is highly similar to several autoinducer proteins of LuxI family among Acinetobacter species. To verify the AHL synthesis activity of this protein, high-resolution liquid chromatography-mass spectrometry analysis revealed the production of 3-oxo-dodecanoyl-homoserine lactone and 3-hydroxy-dodecanoyl-homoserine lactone from induced E. coli harboring the recombinant AciI. Our data show for the first time, the cloning and characterization of the luxI homologue from Acinetobacter sp. strain GG2, and confirmation of its AHLs production. These data are of great significance as the annotated genome of strain GG2 has provided a valuable insight in the study of autoinducer molecules and its roles in QS mechanism of the bacterium.
    Matched MeSH terms: Mass Spectrometry
  2. Feasibility study of biodiesel production using lipids of Hermetia illucens larva fed with organic waste
    Leong SY, Kutty SR, Malakahmad A, Tan CK
    Waste Manag, 2016 Jan;47(Pt A):84-90.
    PMID: 25872864 DOI: 10.1016/j.wasman.2015.03.030
    Hermetia illucens larvae by nature are a decomposer which fed on organic wastes. This study explores the potential of producing biodiesel using lipids from H. illucens larvae. Three types of organic wastes (sewage sludge, fruit waste and palm decanter cake from oil palm mill) were selected based on considerable generation and disposal concern in the area of study as well as lack of investigations as feed for Hermetia illucens larvae in current literatures. Growth rate of the larvae was determined with studying the changes in the biomass per day. H. illucens larvae fed with fruit waste and palm decanter cake have shown growth rates of 0.52±0.02 and 0.23±0.09 g d(-1), respectively. No positive sign of growth were observed in the larvae fed with treated sewage sludge (-0.04±0.01 g d(-1)). Biodiesel as fatty acid methyl ester (FAME) was synthesized by transesterification of the larvae lipid using sulphuric acid as catalyst in methanol. FAME produced was ascertained using ATR-FTIR spectroscopy and GC-MS. The main compositions of fatty acid were found to be C12:0, C16:0 and C18:1n9c. Fatty acid composition of C12:0 fed with fruit waste, sewage sludge and palm decanter was found to be most abundant in the larvae lipid. The amount of C12:0 obtained was 76.13%, 58.31% and 48.06%, respectively. In addition, fatty acid of C16:0 was attained at 16.48% and 25.48% fed with sewage sludge and palm decanter, respectively. Based on the findings, FAME derived from larvae lipids is feasible to be used for biodiesel production.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  3. Biotic inactivation of the Pseudomonas aeruginosa quinolone signal molecule
    Soh EY, Chhabra SR, Halliday N, Heeb S, Müller C, Birmes FS, et al.
    Environ Microbiol, 2015 Nov;17(11):4352-65.
    PMID: 25809238 DOI: 10.1111/1462-2920.12857
    In Pseudomonas aeruginosa, quorum sensing (QS) regulates the production of secondary metabolites, many of which are antimicrobials that impact on polymicrobial community composition. Consequently, quenching QS modulates the environmental impact of P. aeruginosa. To identify bacteria capable of inactivating the QS signal molecule 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), a minimal medium containing PQS as the sole carbon source was used to enrich a Malaysian rainforest soil sample. This yielded an Achromobacter xylosoxidans strain (Q19) that inactivated PQS, yielding a new fluorescent compound (I-PQS) confirmed as PQS-derived using deuterated PQS. The I-PQS structure was elucidated using mass spectrometry and nuclear magnetic resonance spectroscopy as 2-heptyl-2-hydroxy-1,2-dihydroquinoline-3,4-dione (HHQD). Achromobacter xylosoxidans Q19 oxidized PQS congeners with alkyl chains ranging from C1 to C5 and also N-methyl PQS, yielding the corresponding 2-hydroxy-1,2-dihydroquinoline-3,4-diones, but was unable to inactivate the PQS precursor HHQ. This indicates that the hydroxyl group at position 3 in PQS is essential and that A. xylosoxidans inactivates PQS via a pathway involving the incorporation of oxygen at C2 of the heterocyclic ring. The conversion of PQS to HHQD also occurred on incubation with 12/17 A. xylosoxidans strains recovered from cystic fibrosis patients, with P. aeruginosa and with Arthrobacter, suggesting that formation of hydroxylated PQS may be a common mechanism of inactivation.
    Matched MeSH terms: Mass Spectrometry
  4. Quantitative application of fecal sterols using gas chromatography-mass spectrometry to investigate fecal pollution in tropical waters: western Malaysia and Mekong Delta, Vietnam
    Isobe KO, Tarao M, Zakaria MP, Chiem NH, Minh le Y, Takada H
    Environ Sci Technol, 2002 Nov 1;36(21):4497-507.
    PMID: 12433157
    This is the first report on fecal pollution using molecular markers in Southeast Asia where serious sewage pollution has occurred. A simple and sensitive analytical method using gas chromatography-mass spectrometry for 10 sterols in various environmental samples was developed to monitor extensive areas of tropical Asia. First, the method was applied to wastewater to confirm that >95% of sterols existed in the particulate phase. Then the approach was applied to a tropical Asian region, Malaysia and Vietnam, with a selection of 59 sampling stations in total. River water and sediment samples were collected and analyzed for chemical markers (coprostanol and other sterols) and microbiological markers (fecal coliforms and fecal streptococci). Particulate coprostanol concentrations ranged from <0.0001 to 13.47 microg/L in tropical river and estuarine waters, indicating severe fecal pollution in populous areas. Coprostanol concentrations in the sediments ranged from 0.005 to 15.5 microg/g-dry. The sedimentary coprostanol concentrations were lower than those reported in some urban areas of industrialized countries. This is probably because frequent heavy rain induces intensive input of eroded soil, which dilutes fecal material in river sediments. The relationship between the concentrations of fecal sterols and bacterial indicators was examined in an attempt to develop public health criteria for coprostanol levels applicable to the tropical region. Coprostanol concentrations of 30-100 ng/L or percent coprostanol levels of 2% corresponded to approximately 1000 fecal coliforms per 100 mL, which is set for secondary contact limit in many countries. These coprostanol concentrations were lower than those proposed as criteria in temperate countries, probably owing to greater survival of bacteria in warmer tropical waters. On the basis of these criteria, extensive monitoring of sediments suggests that poor sanitary conditions exist in most of the urbanized area of Malaysia and in several urban and rural sites in Vietnam.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  5. Distribution of oil and grease and petroleum hydrocarbons in the Straits of Johor, peninsular Malaysia
    Abdullah AR, Woon WC, Bakar RA
    Bull Environ Contam Toxicol, 1996 Jul;57(1):155-62.
    PMID: 8661474
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  6. Simple and rapid LC-MS/MS method for simultaneous determination of flavoxate and 3-methyl-flavone-8-carboxylic acid in human plasma: Application to a bioequivalence study
    Loh GOK, Wong EYL, Tan YTF, Wee HC, Ng RS, Lee CY, et al.
    J Pharm Biomed Anal, 2021 Feb 05;194:113758.
    PMID: 33248861 DOI: 10.1016/j.jpba.2020.113758
    A simple, rapid, sensitive, and reproducible LC-MS/MS method was developed for simultaneous quantification of flavoxate and 3-methyl-flavone-8-carboxylic (MFCA) in human plasma, using diphenhydramine HCl as internal standard (IS). The chromatographic separation was achieved using Agilent Poroshell 120 EC-C18 - Fast LC column (100 × 2.1mmID, 2.7 μm) fitted with UHPLC Guard Poroshell 120 EC-C18 (5 × 2.1 mmID, 2.7 μm). The mobile phase consisted of 0.1 % v/v formic acid and acetonitrile (30:70, v/v) run at a flow rate of 0.40 mL/min. The standard calibration curve was linear over the concentration range of 2.00 - 2,000.31 ng/mL and 240.00 - 24,000.04 ng/mL for flavoxate and MFCA. For flavoxate and MFCA, the within-run precision was 0.81-6.67 % and 1.68-4.37 %, while accuracy was 100.21-108.25 % and 103.99-110.28 %. The between-run precision was 2.01-9.14 % and 2.31-11.11 %, and accuracy was 96.09-103.33 % and 102.37-109.52 %. The extended run precision was 7.78-11.04 % and 2.22-3.33 %, while accuracy was 100.72-101.88 % and 102.34-105.60 %. Flavoxate and MFCA in plasma were stable 4 h at bench top (short term), 24 h in autosampler and instrumentation room (post-preparative), after 7 freeze-thaw cycles, and 89 days in the freezer. Both analytes and IS stock solutions were stable for 31 days when kept at room temperature (25 ± 4 °C) and refrigerated (2-8 °C). The validated method was successfully applied to a bioequivalence study of two flavoxate formulations involving 24 healthy volunteers.
    Matched MeSH terms: Tandem Mass Spectrometry
  7. Fulltext Optimization of headspace solid phase microextraction (HS-SPME) for the extraction of volatile organic compounds (VOCs) in MD2 pineapple
    Syaidatul Faraha Zainuddin, Siti Raihan Zakaria, Norashikin Saim, Rossuriati Dol Hamid, Rozita Osman
    Science Letters, 2020;14(2):58-70.
    MyJurnal
    Headspace solid phase microextraction (HS-SPME) was employed for the extraction of volatile organic compounds (VOCs) in MD2 pineapple (Ananas comosus L. var. comosus cv. MD2). Optimisation of HS-SPME operating parameters was conducted using three-factor, three-level Box–Behnken response surface experimental design to evaluate the interactive effects of temperature (30 – 50 ºC), extraction time (10 – 30 min) and salting effect (1 – 3 g of salt addition) on the amount of selected VOCs. Determination of VOCs was done using gas chromatography with spectrometry detector (GC-MSD). Extraction temperature was found to be significant (p < 0.05) in increasing the amount of selected VOCs (ethyl acetate, methyl isobutyrate and butanoic acid methyl ester). Based on the maximum amount of these VOCs, the optimum operating extraction conditions for HS-SPME were set up at temperature of 30 °C, time of 29 min and salt addition of 1 g. The optimized HS-SPME conditions were employed for the extraction of VOCs from pineapple of different varieties.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  8. Fulltext Antinociceptive activity of methanolic extract of melastoma malabathricum l.leaves and mechanisms of action in experimentalanimals
    Erman Shah Jaios, Suzanah Abdul Rahman, Mooi, Ching Siew, Arifah Abdul Kadir, Mohd Nasir Mohd Desa, Zainul Amirudin Zakaria
    International Journal of Allied Health Sciences, 2017;1(1):1-1.
    MyJurnal
    Objectives/Research Problem:Melastoma malabathricum L., (Melastomaceae) is a medicinally important plant known as “Senduduk”. Traditionally, the leaves are used to relieve diverse pain-related ailments. Present study aims to examine the antinociceptive activity of methanolic extract of M. malabathricum (MEMM) leaves and its fractions via in vivo models of nociception.

    Materials and Method: Extracts (100, 250, 500 mg/kg) were administered orally 60 minutes prior to subjection to the respective test, n=6/group. Evaluation of MEMM antinociceptive activity; chemically (acetic acid-induced abdominal constriction; ACT, formalin-induced paw licking test; FT) and thermally (hot plate test; HT) models of nociception and elucidation of mechanisms of action involved; role of opioid, vanilloid receptors, glutamatergic system and NO/cGMP pathway were determined. Continuously, MEMM, partitioned into three fractions: petroleum ether (PEMM), ethyl acetate (EAMM), and aqueous (AQMM) extracts and determine the most potent fraction. Therefore, experiment ED50 and its 95% confidence intervals (CI) values were conducted, and ACT was used to screen. Calculation, obtained, PEMM, the most effective was further used to assess the antinociceptive properties. Phytochemical screening, HPLC and GC-MS analysis were performed.

    Results and Discussion: First stage, MEMM exhibited significant (P
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  9. Fulltext Inhibition of Quorum Sensing and Biofilm Formation in Chromobacterium violaceum by Fruit Extracts of Passiflora edulis
    Venkatramanan M, Sankar Ganesh P, Senthil R, Akshay J, Veera Ravi A, Langeswaran K, et al.
    ACS Omega, 2020 Oct 13;5(40):25605-25616.
    PMID: 33073086 DOI: 10.1021/acsomega.0c02483
    Chromobacterium violaceum (C. violaceum) is a Gram-negative, rod-shaped facultatively anaerobic bacterium implicated with recalcitrant human infections. Here, we evaluated the anti-QS and antibiofilm activities of ethyl acetate extracts of Passiflora edulis (P. edulis) on the likely inactivation of acyl-homoserine lactone (AHL)-regulated molecules in C. violaceum both by in vitro and in silico analyses. Our investigations showed that the sub-MIC levels were 2, 1, and 0.5 mg/mL, and the concentrations showed a marked reduction in violacein pigment production by 75.8, 64.6, and 35.2%. AHL quantification showed 72.5, 52.2, and 35.9% inhibitions, inhibitions of EPS production (72.8, 36.5, and 25.9%), and reductions in biofilm formation (90.7, 69.4, and 51.8%) as compared to a control. Light microscopy and CLSM analysis revealed dramatic reduction in the treated biofilm group as compared to the control. GC-MS analysis showed 20 major peaks whose chemical structures were docked as the CviR ligand. The highest docking score was observed for hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester bonds in the active site of CviR with a binding energy of -8.825 kcal/mol. Together, we found that hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester remarkably interacted with CviR to inhibit the QS system. Hence, we concluded that hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester of P. edulis could likely be evaluated for treating C. violaceum infections.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  10. Fulltext Dual bioactivities of laurus nobilis essential oil
    Nur Afiqah Saparin, Mohd Muzamir Mahat, Muhd Fauzi Safian, Shahrul Hisham Zainal Ariffin, Nor Azah Mohamad Ali, Zaidah Zainal Ariffin
    Science Letters, 2020;14(1):62-67.
    MyJurnal
    The evolution of cosmetic products results in the growing demands for cosmetics that are preservatives free. Plant essential oils were found to be a promising antimicrobial and also antioxidant agent. In this study, Cymbopogon citratus (lemongrass), Laurus nobilis (bay leaf) and Backhousia citriodora (lemon myrtle) essential oils were selected and evaluated for their antimicrobial properties. It was found that Laurus nobilis exhibited strong antimicrobial activity against the selected bacteria Streptococcus saprophyticus (ATCC 49619), Streptococcus aureus (ATCC 22923), Streptococcus pyogenes (ATCC 29436), Pseudomonas aeruginosa (ATCC 13048), Klebsiella pneumoniae (ATCC 700603), Escherichia coli (ATCC 22922) with MIC ranging between 7.8 ug/mL to 250 μg/mL. The antioxidant activity of selected essential oils was determined by antioxidant assays which were 1,1-Diphenyl-2-picrylhydrazyl assay (DPPH), determination of ferric reducing antioxidant power assay (FRAP) and β-Carotene/linoleic acid bleaching assay. Backhousia citriodora and Laurus nobilis showed the highest antioxidant activity.
    n-Octanal and β-Selinene were identified to be the major components with peak area of 26.37 % and 13.92 % respectively in secondary metabolites analysis by Gas Chromatography-Mass Spectrometry (GCMS).
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  11. Fulltext Microbial Biodegradation of Paraffin Wax in Malaysian Crude Oil Mediated by Degradative Enzymes
    Adlan NA, Sabri S, Masomian M, Ali MSM, Rahman RNZRA
    Front Microbiol, 2020;11:565608.
    PMID: 33013795 DOI: 10.3389/fmicb.2020.565608
    The deposition of paraffin wax in crude oil is a problem faced by the oil and gas industry during extraction, transportation, and refining of crude oil. Most of the commercialized chemical additives to prevent wax are expensive and toxic. As an environmentally friendly alternative, this study aims to find a novel thermophilic bacterial strain capable of degrading paraffin wax in crude oil to control wax deposition. To achieve this, the biodegradation of crude oil paraffin wax by 11 bacteria isolated from seawater and oil-contaminated soil samples was investigated at 70°C. The bacteria were identified as Geobacillus kaustophilus N3A7, NFA23, DFY1, Geobacillus jurassicus MK7, Geobacillus thermocatenulatus T7, Parageobacillus caldoxylosilyticus DFY3 and AZ72, Anoxybacillus geothermalis D9, Geobacillus stearothermophilus SA36, AD11, and AD24. The GCMS analysis showed that strains N3A7, MK7, DFY1, AD11, and AD24 achieved more than 70% biodegradation efficiency of crude oil in a short period (3 days). Notably, most of the strains could completely degrade C37-C40 and increase the ratio of C14-C18, especially during the initial 2 days incubation. In addition, the degradation of crude oil also resulted in changes in the pH of the medium. The degradation of crude oil is associated with the production of degradative enzymes such as alkane monooxygenase, alcohol dehydrogenase, lipase, and esterase. Among the 11 strains, the highest activities of alkane monooxygenase were recorded in strain AD24. A comparatively higher overall alcohol dehydrogenase, lipase, and esterase activities were observed in strains N3A7, MK7, DFY1, AD11, and AD24. Thus, there is a potential to use these strains in oil reservoirs, crude oil processing, and recovery to control wax deposition. Their ability to withstand high temperature and produce degradative enzymes for long-chain hydrocarbon degradation led to an increase in the short-chain hydrocarbon ratio, and subsequently, improving the quality of the oil.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  12. High Throughput Residue Analysis of Indaziflam and its Metabolites in Palm Oil Using Liquid Chromatography-Tandem Mass Spectrometry
    Halim N, Kuntom A, Shinde R, Banerjee K
    J AOAC Int, 2020 Sep 01;103(5):1237-1242.
    PMID: 33241391 DOI: 10.1093/jaoacint/qsaa041
    BACKGROUND: Indaziflam (IND) is a herbicide that is used in palm oil plantations for broad spectrum management of weeds. Until now, no validated method has been available for residue estimation of this herbicide in palm oil products.

    OBJECTIVE: In this study, we report a rapid method for the residue analysis of IND and its metabolites, viz., IND-carboxylic acid, diaminotriazine, and triazine indanone in a wide range of palm oil matrices using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

    METHOD: The optimized sample preparation workflows included two options: (1) acetonitrile extraction (QuEChERS workflow), followed by freezing at -80°C and (2) acetonitrile extraction, followed by cleanup through a C18 solid phase extraction (SPE) cartridge. The optimized LC runtime was 7 min. All these analytes were estimated by LC-MS/MS multiple reaction monitoring.

    RESULTS: Both sample preparation methods provided similar method performance and acceptable results. The limit of quantification (LOQ) of IND, IND-carboxylic acid, and triazine indanone was 0.001 mg/kg. For diaminotriazine, the LOQ was 0.005 mg/kg. The method accuracy and precision complied with the SANTE/12682/2019 guidelines of analytical quality control.

    CONCLUSIONS: The potentiality of the method lies in a high throughput analysis of IND and its metabolites in a single chromatographic run with high selectivity and sensitivity. Considering its fit-for-purpose performance, the method can be implemented in regulatory testing of IND residues in a wide range of palm oil matrices that are consumed and traded worldwide.

    HIGHLIGHTS: This work has provided a validated method for simultaneous residue analysis of indaziflam and its metabolites in crude palm oil and its derived matrices with high sensitivity, selectivity, and throughput.

    Matched MeSH terms: Tandem Mass Spectrometry
  13. Optimization of metabolite extraction protocols for untargeted metabolite profiling of mycoparasitic scytalidium parasiticum using lc-tof-ms
    Lim CK, Nurul Fadhilah Marzuki, Goh YK, You KG, Kah JG, Rafidah Ahmad, et al.
    Sains Malaysiana, 2018;47:3061-3068.
    Basal stem rot disease of oil palm caused by Ganoderma boninense is one of the most devastating diseases in oil palm
    plantation resulting in low yield, loss of palm stands and shorter replanting cycle. To-date, there is no effective treatment
    for Ganoderma infected palms. Control measures, either chemical or cultural approaches, show varying degrees of
    effectiveness. The application of biological control agents which is environmental-friendly could be an attractive solution
    to overcome the problem. Earlier, we had isolated a mycoparasite, Scytalidium parasiticum, from the basidiomata of
    Ganoderma boninense. In vitro assay and nursery experiment showed that this fungus could suppress Ganoderma infection
    and reduce disease severity. However, metabolites which might contribute to the antagonistic or mycoparasitic effect
    remain unknown. In the current study, optimization of fungal sample processing, extraction, and analytical procedures
    were conducted to obtain metabolites from the maize substrate colonized by mycoparasitic ascomycetous Scytalidium
    parasiticum. This technique capable of producing sexual spores in sac-like organs. Untargeted metabolomics profiling
    was carried out by using Liquid Chromatography Time of Flight Mass Spectrometry (LC-ToF-MS). We found that
    S. parasiticum in both liquid- and solid-state cultivation gave higher metabolite when extracted with 60% methanol with
    1% formic acid in combination with homogenisation methods such as ultrasonication and grinding. The findings from
    this study are useful for optimisation of metabolite extraction from other fungi-Ganoderma-plant interactions.
    Matched MeSH terms: Mass Spectrometry
  14. Fulltext Classification of different pineapple varieties grown in Malaysia based on volatile fingerprinting and sensory analysis
    Lasekan O, Hussein FK
    Chem Cent J, 2018 Dec 19;12(1):140.
    PMID: 30569201 DOI: 10.1186/s13065-018-0505-3
    BACKGROUND: Pineapple is highly relished for its attractive sweet flavour and it is widely consumed in both fresh and canned forms. Pineapple flavour is a blend of a number of volatile and non-volatile compounds that are present in small amounts and in complex mixtures. The aroma compounds composition may be used for purposes of quality control as well as for authentication and classification of pineapple varieties.

    RESULTS: The key volatile compounds and aroma profile of six pineapple varieties grown in Malaysia were investigated by gas chromatography-olfactometry (GC-O), gas-chromatography-mass spectrometry and qualitative descriptive sensory analysis. A total of 59 compounds were determined by GC-O and aroma extract dilution analysis. Among these compounds, methyl-2-methylbutanoate, methyl hexanoate, methyl-3-(methylthiol)-propanoate, methyl octanoate, 2,5-dimethyl-4-methoxy-3(2H)-furanone, δ-octalactone, 2-methoxy-4-vinyl phenol, and δ-undecalactone contributed greatly to the aroma quality of the pineapple varieties, due to their high flavour dilution factor. The aroma of the pineapples was described by seven sensory terms as sweet, floral, fruity, fresh, green, woody and apple-like.

    CONCLUSION: Inter-relationship between the aroma-active compounds and the pineapples revealed that 'Moris' and 'MD2' covaried majorly with the fruity esters, and the other varieties correlated with lesser numbers of the fruity esters. Hierarchical cluster analysis (HCA) was used to establish similarities among the pineapples and the results revealed three main groups of pineapples.

    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  15. Quantification of VOCs and the development of odour wheels for rubber processing
    Kamarulzaman NH, Le-Minh N, Fisher RM, Stuetz RM
    Sci Total Environ, 2019 Mar 20;657:154-168.
    PMID: 30543968 DOI: 10.1016/j.scitotenv.2018.11.451
    The impacts of rubber variations (clonal, seasonal, and pre-treatment) were investigated to assess changes in the composition of volatile organic compounds (VOCs) emitted during rubber processing. VOC emissions from 14 different rubber types were evaluated by headspace micro-chamber (μ-TEC) extraction coupled with gas chromatography-mass spectrometry (GC-MS). Headspace extracted at 120 °C, which is equivalent to the drying temperature during rubber processing, revealed a significant number of odorants in terms of concentrations as well as odorant type. Volatile fatty acids (VFAs) such as acetic, propanoic, butanoic, pentanoic and hexanoic acids, were frequently detected at concentrations greater than their odour detection thresholds. Other odorous compounds including trimethylamine, p-cresol, butanone, indole, and phenol, were also detected. Emissions collected at ambient conditions represent odorants released during material storage (or maturation) and were dominated by benzene derivatives followed by ketones, aldehydes, esters, and acids. Emission composition during storage appeared to be governed by specific rubber properties such as protein and rubber moisture content. Seasonal variations revealed greater impacts on the concentration of VOCs for all studied clones, compared to pre-treatment variations, suggesting that the VOCs composition was seasonally dependent and may represents the 'potential' emissions from rubber as they are processed. A combination of sensorial and analytical measurements were used to produce odour wheels which may be used as tool to identify key malodours in onsite rubber processing. The linking of odours and odorants can facilitate communication between receptors (the public) and plant operators inorder to minimise odour impact and develop effective abatement and on-site management practices.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  16. Proteomic analysis of stored core oil palm trunk (COPT) sap identifying proteins Related to stress, disease resistance and differential gene/protein expression
    Marhaini Mostapha, Noorhasmiera Abu Jahar, Sarani Zakaria, Sharifah Nabihah Syed Jaafar, Kamalrul Azlan Azizan, Wan Mohd Aizat
    Sains Malaysiana, 2018;47:1259-1268.
    Oil palm is the major crop grown and cultivated in various Asian countries such as Malaysia, Indonesia and Thailand.
    The core of oil palm trunk (COPT) consists of high sugar content, hence suitable for synthesis of fine chemicals and
    biofuels. Increase of sugar content was reported previously during prolonged COPT storage. However, until now, there
    has been no report on protein profiles during storage. Therefore, in this study, protein expression of the COPT during the
    storage period of one to six weeks was investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis
    (SDS-PAGE) coupled with optical density quantification and multivariate analyses for measuring differentially expressed
    proteins. Accordingly, protein bands were subjected to tryptic digestion followed by tandem mass spectrometry (nanoLCMS/MS)
    protein identification. The results from SDS-PAGE showed consistent protein bands appearing across the biological
    replicates ranging from 10.455 to 202.92 kDa molecular weight (MW) regions. The findings from the principal component
    analysis (PCA) plot illustrated the separation pattern of the proteins at weeks 4 and 5 of storage, which was influenced
    mainly by the molecular weights of 14.283, 25.543, 29.757, 30.549, 31.511, 34.585 and 84.395 kDa, respectively. The
    majority of these proteins are identified as those involved in stress- and defense-related, disease resistance, as well
    as gene/protein expression processes. Indeed, these proteins were mostly upregulated during the later storage period
    suggesting that long-term storage may influence the molecular regulation of COPT sap.
    Matched MeSH terms: Tandem Mass Spectrometry
  17. Fulltext Social Defeat Stress Decreases mRNA for Monoamine Oxidase A and Increases 5-HT Turnover in the Brain of Male Nile Tilapia (Oreochromis niloticus)
    Higuchi Y, Soga T, Parhar IS
    Front Pharmacol, 2018;9:1549.
    PMID: 30687104 DOI: 10.3389/fphar.2018.01549
    Stress induces various neurobiological responses and causes psychiatric disorders, including depression. Monoamine oxidase A (MAO-A) plays an important role in various functions of the brain, such as regulation of mood, anxiety and aggression, and dysregulation of MAO-A is observed in stress-related psychiatric disorders. This study addressed the question whether acute social stress induces changes to transcriptional and/or post-transcriptional regulation of MAO-A expression in the brain. Using male Nile tilapia (Oreochromis niloticus), we investigated whether acute social stress, induced by the presence of a dominant male fish, changes the expression of MAO-A. We measured gene expression of MAO-A by quantitative PCR, enzymatic activity of MAO-A by the luminescent method, and 5-HT and 5-HIAA levels by liquid chromatography-mass spectrometry in the brain of socially stressed and control fish. Socially stressed males showed decreased MAO-A mRNA levels, consistent MAO-A enzymatic activity, increased 5-HT turnover in the brain, and elevated plasma cortisol levels, compared to controls. Our results suggest that acute social stress suppresses the transcription of MAO-A gene, enhances 5-HT metabolism but does not affect the production of MAO-A protein.
    Matched MeSH terms: Mass Spectrometry
  18. Differentiation of Commercially Available Kratom by Purported Country of Origin using Inductively Coupled Plasma-Mass Spectrometry
    Braley C, Hondrogiannis EM
    J Forensic Sci, 2020 Mar;65(2):428-437.
    PMID: 31560807 DOI: 10.1111/1556-4029.14201
    Kratom is a plant material exhibiting both analgesic and stimulant effects and is also forensically relevant since it is abused as a "legal high." It is regulated in several countries but not scheduled in the United States at the federal level. This study used inductively coupled plasma-mass spectrometry (ICP-MS) to measure the concentrations of 13 elements in 19 kratom samples obtained from an online distributor selling kratom, from Borneo, Malaysia, Indonesia, Thailand, and Vietnam, for the purpose of using the elements to discriminate among purported country of origin, "suborigin," and strain. Analysis of variance revealed statistical differences in concentrations of elements from each group, while discriminant function analysis (using leave-one-out classification) successfully classified kratom samples by their purported country of origin (100%), "suborigin," (100%), and strain (86%). Our method illustrates the possibility of utilizing ICP-MS for determination of commercially available kratom samples by purported origin, "subororign," or by product line.
    Matched MeSH terms: Mass Spectrometry
  19. Essential oil composition of Alseodaphne perakensis (Gamble) Kosterm from Malaysia
    Anuar MZA, Salleh WMNHW, Khamis S, Nafiah MA, Mat Said Z
    Nat Prod Res, 2021 Feb;35(3):508-511.
    PMID: 31266357 DOI: 10.1080/14786419.2019.1636245
    The chemical composition of the essential oil from the leaves of Alseodaphne perakensis (Gamble) Kosterm (Lauraceae) growing in Perak, Malaysia was investigated for the first time. The essential oil was obtained by hydrodistillation and fully characterized by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). A total of 37 components (90.9 ± 2.5%) were successfully identified in the essential oil which were characterized by high proportions of bicyclogermacrene (15.8 ± 0.5%), δ-cadinene (11.7 ± 0.2%), γ-cadinene (6.3 ± 0.4%), and aromadendrene (5.6 ± 0.5%).
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  20. Fulltext UPLC-MS-Based Metabolomics Profiling for α-Glucosidase Inhibiting Property of Parkia speciosa Pods
    Saleh MSM, Jalil J, Mustafa NH, Ramli FF, Asmadi AY, Kamisah Y
    Life (Basel), 2021 Jan 22;11(2).
    PMID: 33499128 DOI: 10.3390/life11020078
    Parkia speciosa is a food plant that grows indigenously in Southeast Asia. A great deal of interest has been paid to this plant due to its traditional uses in the treatment of several diseases. The pods contain many beneficial secondary metabolites with potential applications in medicine and cosmetics. However, studies on their phytochemical properties are still lacking. Therefore, the present study was undertaken to profile the bioactive compounds of P. speciosa pods collected from six different regions of Malaysia through ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) and α-glucosidase inhibitory potential. This study applied metabolomics to elucidate the differences between P. speciosa populations found naturally in the different locations and to characterize potential α-glucosidase inhibitors from P. speciosa pods. P. speciosa collected from different regions of Malaysia showed good α-glucosidase inhibitory activity, with a median inhibitory concentration (IC50) of 0.45-0.76 μg/mL. The samples from the northern and northeastern parts of Peninsular Malaysia showed the highest activity. Using UHPLC-QTOF-MS/MS analysis, 25 metabolites were identified in the pods of P. speciosa. The findings unveiled that the pods of P. speciosa collected from different locations exhibit different levels of α-glucosidase inhibitory activity. The pods are a natural source of potent antidiabetic bioactive compounds.
    Matched MeSH terms: Tandem Mass Spectrometry
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