Displaying publications 21 - 40 of 933 in total

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  1. Prioritization of natural extracts by LC-MS-PCA for the identification of new photosensitizers for photodynamic therapy
    Samat N, Tan PJ, Shaari K, Abas F, Lee HB
    Anal Chem, 2014 Feb 4;86(3):1324-31.
    PMID: 24405504 DOI: 10.1021/ac403709a
    Photodynamic therapy (PDT) is an alternative treatment for cancer that involves administration of a photosensitive drug or photosensitizer that localizes at the tumor tissue followed by in situ excitation at an appropriate wavelength of light. Tumour tissues are then killed by cytotoxic reactive oxygen species generated by the photosensitizer. Targeted excitation and photokilling of affected tissues is achieved through focal light irradiation, thereby minimizing systemic side effects to the normal healthy tissues. Currently, there are only a small number of photosensitizers that are in the clinic and many of these share the same structural core based on cyclic tetrapyrroles. This paper describes how metabolic tools are utilized to prioritize natural extracts to search for structurally new photosensitizers from Malaysian biodiversity. As proof of concept, we analyzed 278 photocytotoxic extracts using a hyphenated technique of liquid chromatography-mass spectrometry coupled with principal component analysis (LC-MS-PCA) and prioritized 27 extracts that potentially contained new photosensitizers for chemical dereplication using an in-house UPLC-PDA-MS-Photocytotoxic assay platform. This led to the identification of 2 new photosensitizers with cyclic tetrapyrrolic structures, thereby demonstrating the feasibility of the metabolic approach.
    Matched MeSH terms: Mass Spectrometry*
  2. Label-Free Time-of-Flight Secondary Ion Mass Spectrometry Imaging of Sulfur-Producing Enzymes inside Microglia Cells following Exposure to Silver Nanowires
    Leo BF, Fearn S, Gonzalez-Cater D, Theodorou I, Ruenraroengsak P, Goode AE, et al.
    Anal Chem, 2019 Sep 03;91(17):11098-11107.
    PMID: 31310103 DOI: 10.1021/acs.analchem.9b01704
    There are no methods sensitive enough to detect enzymes within cells, without the use of analyte labeling. Here we show that it is possible to detect protein ion signals of three different H2S-synthesizing enzymes inside microglia after pretreatment with silver nanowires (AgNW) using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Protein fragment ions, including the fragment of amino acid (C4H8N+ = 70 amu), fragments of the sulfur-producing cystathionine-containing enzymes, and the Ag+ ion signal could be detected without the use of any labels; the cells were mapped using the C4H8N+ amino acid fragment. Scanning electron microscopy imaging and energy-dispersive X-ray chemical analysis showed that the AgNWs were inside the same cells imaged by TOF-SIMS and transformed chemically into crystalline Ag2S within cells in which the sulfur-producing proteins were detected. The presence of these sulfur-producing cystathionine-containing enzymes within the cells was confirmed by Western blots and confocal microscopy images of fluorescently labeled antibodies against the sulfur-producing enzymes. Label-free TOF-SIMS is very promising for the label-free identification of H2S-contributing enzymes and their cellular localization in biological systems. The technique could in the future be used to identify which of these enzymes are most contributory.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  3. Sequential Hybrid Three-Dimensional Gas Chromatography with Accurate Mass Spectrometry: A Novel Tool for High-Resolution Characterization of Multicomponent Samples
    Yan D, Wong YF, Whittock SP, Koutoulis A, Shellie RA, Marriott PJ
    Anal Chem, 2018 04 17;90(8):5264-5271.
    PMID: 29575899 DOI: 10.1021/acs.analchem.8b00142
    A novel sequential three-dimensional gas chromatography-high-resolution time-of-flight mass spectrometry (3D GC-accTOFMS) approach for profiling secondary metabolites in complex plant extracts is described. This integrated system incorporates a nonpolar first-dimension (1Dnp) separation step, prior to a microfluidic heart-cut (H/C) of a targeted region(s) to a cryogenic trapping device, directly followed by the rapid reinjection of a trapped solute into a polar second-dimension (2DPEG) column for multidimensional separation (GCnp-GCPEG). For additional separation, the effluent from 2DPEG can then be modulated according to a comprehensive 2D GC process (GC×GC), using an ionic liquid phase as a third-dimension (3DIL) column, to produce a sequential GCnp-GCPEG×GCIL separation. Thus, the unresolved or poorly resolved components, or regions that require further separation, can be precisely selected and rapidly transferred for additional separation on 2D or 3D columns, based on the greater separation realized by these steps. The described integrated system can be used in a number of modes, but one useful approach is to target specific classes of compounds for improved resolution. This is demonstrated through the separation and detection of the oxygenated sesquiterpenes in hop ( Humulus lupulus L.) essential oil and agarwood ( Aquilaria malaccensis) oleoresin. Improved resolution and peak capacity were illustrated through the progressive comparison of the tentatively identified components for GCnp-GCPEG and GCnp-GCPEG×GCIL methods. Relative standard deviations of intraday retentions (1 tR, 2 tR,, and 3 tR) and peak areas of ≤0.01, 0.07, 0.71, and 7.5% were achieved. This analytical approach comprising three GC column selectivities, hyphenated with high-resolution TOFMS detection, should be a valuable adjunct for the improved characterization of complex plant samples, particularly in the area of plant metabolomics.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  4. iSegMSI: An Interactive Strategy to Improve Spatial Segmentation of Mass Spectrometry Imaging Data
    Guo L, Liu X, Zhao C, Hu Z, Xu X, Cheng KK, et al.
    Anal Chem, 2022 Oct 25;94(42):14522-14529.
    PMID: 36223650 DOI: 10.1021/acs.analchem.2c01456
    Spatial segmentation is a critical procedure in mass spectrometry imaging (MSI)-based biochemical analysis. However, the commonly used unsupervised MSI segmentation methods may lead to inappropriate segmentation results as the MSI data is characterized by high dimensionality and low signal-to-noise ratio. This process can be improved by the incorporation of precise prior knowledge, which is hard to obtain in most cases. In this study, we show that the incorporation of partial or coarse prior knowledge from different sources such as reference images or biological knowledge may also help to improve MSI segmentation results. Here, we propose a novel interactive segmentation strategy for MSI data called iSegMSI, which incorporates prior information in the form of scribble-regularization of the unsupervised model to fine-tune the segmentation results. By using two typical MSI data sets (including a whole-body mouse fetus and human thyroid cancer), the present results demonstrate the effectiveness of the iSegMSI strategy in improving the MSI segmentations. Specifically, the method can be used to subdivide a region into several subregions specified by the user-defined scribbles or to merge several subregions into a single region. Additionally, these fine-tuned results are highly tolerant to the imprecision of the scribbles. Our results suggest that the proposed iSegMSI method may be an effective preprocessing strategy to facilitate the analysis of MSI data.
    Matched MeSH terms: Mass Spectrometry
  5. Electrokinetic Extraction of Doxorubicin from Biological Fluids by Polymer Inclusion Membrane Sampling Probe
    Tey HY, Breadmore MC, See HH
    Anal Chem, 2023 Jan 31;95(4):2134-2139.
    PMID: 36649064 DOI: 10.1021/acs.analchem.2c02937
    A polymer inclusion membrane (PIM) based sampling probe was developed for electrokinetic extraction of drugs from biological fluids. The probe was fabricated by dip-coating a nonconductive glass capillary tube in a homogeneous PIM solution for three cycles. The PIM solution comprised cellulose triacetate (CTA), 2-nitrophenyl octyl ether (NPOE), and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [EMIM][NTf2] in a ratio of 5:4:2. The developed probe electrokinetically extracted doxorubicin from human plasma, human serum, and dried blood spot (DBS). The practicability and reliability of the electrokinetic extraction were evaluated by LC-MS/MS to quantify the desorption of extracted doxorubicin. Under the optimized conditions, a quantification limit of 0.2-2 ng/mL was achieved for the three biological samples. The probe was further integrated into a portable battery-powered device for safe low-voltage (36 V) electrokinetic extraction. The developed technique is envisioned to provide a more efficient analytical workflow in the laboratory.
    Matched MeSH terms: Tandem Mass Spectrometry*
  6. Multimodal Image Fusion Offers Better Spatial Resolution for Mass Spectrometry Imaging
    Guo L, Zhu J, Wang K, Cheng KK, Xu J, Dong L, et al.
    Anal Chem, 2023 Jun 27;95(25):9714-9721.
    PMID: 37296503 DOI: 10.1021/acs.analchem.3c02002
    High-resolution reconstruction has attracted increasing research interest in mass spectrometry imaging (MSI), but it remains a challenging ill-posed problem. In the present study, we proposed a deep learning model to fuse multimodal images to enhance the spatial resolution of MSI data, namely, DeepFERE. Hematoxylin and eosin (H&E) stain microscopy imaging was used to pose constraints in the process of high-resolution reconstruction to alleviate the ill-posedness. A novel model architecture was designed to achieve multi-task optimization by incorporating multi-modal image registration and fusion in a mutually reinforced framework. Experimental results demonstrated that the proposed DeepFERE model is able to produce high-resolution reconstruction images with rich chemical information and a detailed structure on both visual inspection and quantitative evaluation. In addition, our method was found to be able to improve the delimitation of the boundary between cancerous and para-cancerous regions in the MSI image. Furthermore, the reconstruction of low-resolution spatial transcriptomics data demonstrated that the developed DeepFERE model may find wider applications in biomedical fields.
    Matched MeSH terms: Mass Spectrometry/methods
  7. Windows Scanning Multiomics: Integrated Metabolomics and Proteomics
    Shi J, Zhao J, Zhang Y, Wang Y, Tan CP, Xu YJ, et al.
    Anal Chem, 2023 Dec 26;95(51):18793-18802.
    PMID: 38095040 DOI: 10.1021/acs.analchem.3c03785
    Metabolomics and proteomics offer significant advantages in understanding biological mechanisms at two hierarchical levels. However, conventional single omics analysis faces challenges due to the high demand for specimens and the complexity of intrinsic associations. To obtain comprehensive and accurate system biological information, we developed a multiomics analytical method called Windows Scanning Multiomics (WSM). In this method, we performed simultaneous extraction of metabolites and proteins from the same sample, resulting in a 10% increase in the coverage of the identified biomolecules. Both metabolomics and proteomics analyses were conducted by using ultrahigh-performance liquid chromatography mass spectrometry (UPLC-MS), eliminating the need for instrument conversions. Additionally, we designed an R-based program (WSM.R) to integrate mathematical and biological correlations between metabolites and proteins into a correlation network. The network created from simultaneously extracted biomolecules was more focused and comprehensive compared to those from separate extractions. Notably, we excluded six pairs of false-positive relationships between metabolites and proteins in the network established using simultaneously extracted biomolecules. In conclusion, this study introduces a novel approach for multiomics analysis and data processing that greatly aids in bioinformation mining from multiomics results. This method is poised to play an indispensable role in systems biology research.
    Matched MeSH terms: Tandem Mass Spectrometry
  8. Metabolite profiling from different parts of tender fruit endosperm of Borassus flabellifer L. (ice apple)
    Vasudevan V, Prabaharan J, Krishnan N, K A, Gopinath SCB, Raman P
    Anal Methods, 2023 Aug 03;15(30):3735-3751.
    PMID: 37493014 DOI: 10.1039/d3ay00704a
    Borassus flabellifer L., commonly known as Asian palmyra, is native to South and Southeast Asia. The endosperms of B. flabellifer (known as nungu in Dravidian culture) are widely consumed during the summer season. It is rich in various nutrients and helps in reducing weight, treating skin and digestive issues, lowering body temperature, and managing migraines and diabetes. This study focuses on identifying the small molecules and proteins from the two varieties of B. flabellifer tender fruit endosperms collected from districts around Chennai, Tamil Nadu, India. The collected free nuclear endosperm was subjected to direct extraction and the mesocarp and cellular endosperms were lyophilized and homogenized. Metabolites were extracted by hexane, methanol, and chloroform and investigated using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). The compounds identified were from the classes of carboxylic acids, flavonoids, amino acids, alkaloids, fatty acids, oligopeptides, vitamins, and glycosides. High-performance liquid chromatography (HPLC) technique was employed to estimate the quantity of amino acids, wherein the total amino acid in the green variety was found to be higher than in the black variety. Proteins were identified after simulating with a gastrointestinal enzyme using liquid chromatography tandem mass spectrometry (LC-MS/MS)-based peptide mass fingerprinting. The different mineral oxides present in the tender fruit endosperm were identified using X-ray diffraction studies, which confirmed the presence of mineral oxides, such as Br1.25ClO2.75Pb3.88, calcium zirconium tantalum oxide, and barium fluoroniobate. This study validates the presence of bioactive metabolites in green and black varieties of B. flabellifer tender fruit endosperm with a range of activities, such as anti-inflammatory, antibacterial, anticancer, and anti-diabetic properties.
    Matched MeSH terms: Tandem Mass Spectrometry
  9. Fulltext Flaxseed (linum usitatissimum) extract activity on human oral fibroblasts (HOrF) cell line
    Sama Naziyah Shaban, Abdelkader Elbadawy Abbas Ashour, Khairani Idah Mokhtar, Solachuddin JauhariAriefIchwan, Basma Ezzat Mustafa Alahmad
    Ann Dent, 2020;27(1):50-54.
    MyJurnal
    Natural products have demonstrated various activities beneficial to general health. Flaxseed (Linum usitatissimum) has been reported in many studies for its antimicrobial, antioxidant, and anti-inflammatory effects. Additionally, flaxseed extracts have skin wound healing activity and potential for treating oral ulcers.L. usitatissimum was extracted using 70% ethanol via soxhlet method and gas chromatography mass spectrum (GC-MS) was used to analyze the components of L. usitatissimum extract. The crude flaxseed oil were applied to human oral fibroblasts (HOrF), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to assess the cell viability after 24, 48 and 72 hours. Scratched HOrF cells were treated with crude flaxseed oil and healing was monitored per wound healing assay. GC-MS indicate that the major components present in L. usitatissimum oil extract are linolic, palmitic and oleic acid. L. usitatissimum crude oil extract showed high proliferation effect on HOrF cells at 24 and 48 hours, while the highest proliferation effect was recorded at 72 hours post-treatment. The wound healing assay results showed that healing activity of HOrF cells occurred as soon as 18 hours post-treatment when treated with L. usitatissimum crude oil extract. L. usitatissimum crude oil extract has proliferating and healing effects on HOrF cell line. Therefore, it can be considered as a potential promising oral wound healing agent.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  10. Fulltext Isolation, identification and quantification of differentially expressed proteins from cancerous and normal breast tissues
    Othman MI, Majid MI, Singh M, Man CN, Lay-Harn G
    Ann. Clin. Biochem., 2008 May;45(Pt 3):299-306.
    PMID: 18482919 DOI: 10.1258/acb.2007.007104
    Infiltrating ductal carcinoma (IDCA) is the most common type of breast cancer accounting for 85% of all invasive breast cancers.
    Matched MeSH terms: Mass Spectrometry
  11. Fulltext Simultaneous determination of tramadol and paracetamol in human plasma using LC-MS/MS and application in bioequivalence study of -fixed-dose combination
    Loh GOK, Wong EYL, Goh CZ, Tan YTF, Lee YL, Pang LH, et al.
    Ann Med, 2023;55(2):2270502.
    PMID: 37857359 DOI: 10.1080/07853890.2023.2270502
    The study aimed to develop a sensitive and high-throughput liquid chromatography coupled with tandem mass spectrometry method to quantify concentrations of tramadol and paracetamol simultaneously in human plasma. Sample preparation involved single-step protein precipitation using methanol and two deuterated internal standards, tramadol D6 and paracetamol D4. Agilent Poroshell 120 EC-C18 (100 × 2.1 mm, 2.1 µm) analytical column was employed to achieve chromatographic separation. Detection was in positive ion multiple reaction monitoring mode. A tailing factor (Tf) of <1.2, separation factor (K prime) of >1.5 from the column dead time and signal-to-noise (S/N) ratio >10, were obtained for analytes and internal standards. The standard curve was linear over the concentration range of 2.5-500.00 ng/mL for tramadol and 0.025-20.00 μg/mL for paracetamol. A small injection volume of 1 µL, low flow rate of 440 µL/min and short analysis time of 3.5 min reduced the solvent consumption, analysis cost and system contamination. The results of method validation parameters fulfilled the acceptance criteria of bioanalytical guidelines. The method was successfully applied to a bioequivalence study of fixed-dose combination products of tramadol and paracetamol in Malaysian healthy subjects.
    Matched MeSH terms: Tandem Mass Spectrometry/methods
  12. Gut Microbial Ecosystem in Parkinson Disease: New Clinicobiological Insights from Multi-Omics
    Tan AH, Chong CW, Lim SY, Yap IKS, Teh CSJ, Loke MF, et al.
    Ann Neurol, 2021 03;89(3):546-559.
    PMID: 33274480 DOI: 10.1002/ana.25982
    OBJECTIVE: Gut microbiome alterations in Parkinson disease (PD) have been reported repeatedly, but their functional relevance remains unclear. Fecal metabolomics, which provide a functional readout of microbial activity, have scarcely been investigated. We investigated fecal microbiome and metabolome alterations in PD, and their clinical relevance.

    METHODS: Two hundred subjects (104 patients, 96 controls) underwent extensive clinical phenotyping. Stool samples were analyzed using 16S rRNA gene sequencing. Fecal metabolomics were performed using two platforms, nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-mass spectrometry.

    RESULTS: Fecal microbiome and metabolome composition in PD was significantly different from controls, with the largest effect size seen in NMR-based metabolome. Microbiome and NMR-based metabolome compositional differences remained significant after comprehensive confounder analyses. Differentially abundant fecal metabolite features and predicted functional changes in PD versus controls included bioactive molecules with putative neuroprotective effects (eg, short chain fatty acids [SCFAs], ubiquinones, and salicylate) and other compounds increasingly implicated in neurodegeneration (eg, ceramides, sphingosine, and trimethylamine N-oxide). In the PD group, cognitive impairment, low body mass index (BMI), frailty, constipation, and low physical activity were associated with fecal metabolome compositional differences. Notably, low SCFAs in PD were significantly associated with poorer cognition and low BMI. Lower butyrate levels correlated with worse postural instability-gait disorder scores.

    INTERPRETATION: Gut microbial function is altered in PD, characterized by differentially abundant metabolic features that provide important biological insights into gut-brain pathophysiology. Their clinical relevance further supports a role for microbial metabolites as potential targets for the development of new biomarkers and therapies in PD. ANN NEUROL 2021;89:546-559.

    Matched MeSH terms: Mass Spectrometry
  13. Apoptosis induced by desmethyl-lasiodiplodin is associated with upregulation of apoptotic genes and downregulation of monocyte chemotactic protein-3
    Hazalin NA, Lim SM, Cole AL, Majeed AB, Ramasamy K
    Anticancer Drugs, 2013 Sep;24(8):852-61.
    PMID: 23764760 DOI: 10.1097/CAD.0b013e3283635a47
    There is growing interest in the discovery of bioactive metabolites from endophytes as an alternative source of therapeutics. Identification of their therapeutic targets is essential in understanding the underlying mechanisms and enhancing the resultant therapeutic effects. As such, bioactive compounds produced by endophytic fungi from plants at the National Park, Pahang, Malaysia, were investigated. Five known compounds were identified using LC-UV-MS-NMR and they include trichodermol, 7-epi-brefeldin A, (3R,4S)-4-hydroxymellein, desmethyl-lasiodiplodin and cytochalasin D. The present study went on to investigate the potential anticancer effects of these compounds and the corresponding molecular mechanisms of the lead compound against human breast adenocarcinoma, MCF-7. For the preliminary screening, the cytotoxicity and apoptotic effects of these compounds against MCF-7 were examined. The compounds were also tested against noncarcinogenic hepatocytes (WRL68). The differential cytotoxicity was then determined using the MTT assay. Desmethyl-lasiodiplodin was found to suppress the growth of MCF-7, yielding an inhibitory concentration (IC50) that was seven-fold lower than that of the normal cells. The cytotoxic effect of desmethyl-lasiodiplodin was accompanied by apoptosis. Subsequent analysis demonstrated increased expression levels of caspase 3, c-myc and p53. Further, desmethyl-lasiodiplodin resulted in inhibition of monocyte chemotactic protein (MCP)-3, a cytokine involved in cell survival and metastasis. Hence, this study proposed that desmethyl-lasiodiplodin inhibited growth and survival of MCF-7 through the induction of apoptosis. This anticancer effect is mediated, in part, by upregulation of apoptotic genes and downregulation of MCP-3. As desmethyl-lasiodiplodin elicited minimal impact against normal hepatocytes, our findings also imply its potential use as a specific apoptotic agent in breast cancer treatment.
    Matched MeSH terms: Mass Spectrometry
  14. Fulltext Decoding Antioxidant and Antibacterial Potentials of Malaysian Green Seaweeds: Caulerpa racemosa and Caulerpa lentillifera
    Yap WF, Tay V, Tan SH, Yow YY, Chew J
    Antibiotics (Basel), 2019 Sep 17;8(3).
    PMID: 31533237 DOI: 10.3390/antibiotics8030152
    Seaweeds are gaining a considerable amount of attention for their antioxidant and antibacterial properties. Caulerpa racemosa and Caulerpa lentillifera, also known as 'sea grapes', are green seaweeds commonly found in different parts of the world, but the antioxidant and antibacterial potentials of Malaysian C. racemosa and C. lentillifera have not been thoroughly explored. In this study, crude extracts of the seaweeds were prepared using chloroform, methanol, and water. Total phenolic content (TPC) and total flavonoid content (TFC) were measured, followed by in vitro antioxidant activity determination using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Antibacterial activities of these extracts were tested against Methicillin-resistant Staphylococcus aureus (MRSA) and neuropathogenic Escherichia coli K1. Liquid chromatography-mass spectrometry (LCMS) analysis was then used to determine the possible compounds present in the extract with the most potent antioxidant and antibacterial activity. Results showed that C. racemosa chloroform extract had the highest TPC (13.41 ± 0.86 mg GAE/g), antioxidant effect (EC50 at 0.65 ± 0.03 mg/mL), and the strongest antibacterial effect (97.7 ± 0.30%) against MRSA. LCMS analysis proposed that the chloroform extracts of C. racemosa are mainly polyunsaturated and monounsaturated fatty acids, terpenes, and alkaloids. In conclusion, C. racemosa can be a great source of novel antioxidant and antibacterial agents, but isolation and purification of the bioactive compounds are needed to study their mechanism of action.
    Matched MeSH terms: Mass Spectrometry
  15. Fulltext Prediction of Fluoroquinolone Susceptibility Directly from Whole-Genome Sequence Data by Using Liquid Chromatography-Tandem Mass Spectrometry To Identify Mutant Genotypes
    Wan Nur Ismah WAK, Takebayashi Y, Findlay J, Heesom KJ, Jiménez-Castellanos JC, Zhang J, et al.
    Antimicrob Agents Chemother, 2018 03;62(3).
    PMID: 29263066 DOI: 10.1128/AAC.01814-17
    Fluoroquinolone resistance in Gram-negative bacteria is multifactorial, involving target site mutations, reductions in fluoroquinolone entry due to reduced porin production, increased fluoroquinolone efflux, enzymes that modify fluoroquinolones, and Qnr, a DNA mimic that protects the drug target from fluoroquinolone binding. Here we report a comprehensive analysis, using transformation and in vitro mutant selection, of the relative importance of each of these mechanisms for fluoroquinolone nonsusceptibility using Klebsiella pneumoniae as a model system. Our improved biological understanding was then used to generate 47 rules that can predict fluoroquinolone susceptibility in K. pneumoniae clinical isolates. Key to the success of this predictive process was the use of liquid chromatography-tandem mass spectrometry to measure the abundance of proteins in extracts of cultured bacteria, identifying which sequence variants seen in the whole-genome sequence data were functionally important in the context of fluoroquinolone susceptibility.
    Matched MeSH terms: Tandem Mass Spectrometry/methods*
  16. Overexpression, purification and validation of antigenic Salmonella enterica serovar Typhi proteins identified from LC-MS/MS
    Chin CF, Teh BA, Anthony AA, Aziah I, Ismail A, Ong EB, et al.
    Appl Biochem Biotechnol, 2014 Nov;174(5):1897-906.
    PMID: 25149461 DOI: 10.1007/s12010-014-1173-y
    In our earlier study, an immunoblot analysis using sera from febrile patients revealed that a 50-kDa band from an outer membrane protein fraction of Salmonella enterica serovar Typhi was specifically recognized only by typhoid sera and not sera from other febrile illnesses. Here, we investigated the identities of the proteins contained in the immunogenic 50-kDa band to pinpoint antigens responsible for its immunogenicity. We first used LC-MS/MS for protein identification, then used the online tool ANTIGENpro for antigenicity prediction and produced recombinant proteins of the lead antigens for validation in an enzyme-linked immunosorbent assay (ELISA). We found that proteins TolC, GlpK and SucB were specific to typhoid sera but react to antibodies differently under native and denatured conditions. This difference suggests the presence of linear and conformational epitopes on these proteins.
    Matched MeSH terms: Mass Spectrometry
  17. Bacteriocin release protein-mediated secretory expression of recombinant chalcone synthase in Escherichia coli
    Zakaria II, Rahman RN, Salleh AB, Basri M
    Appl Biochem Biotechnol, 2011 Sep;165(2):737-47.
    PMID: 21633820 DOI: 10.1007/s12010-011-9292-1
    Flavonoids are secondary metabolites synthesized by plants shown to exhibit health benefits such as anti-inflammatory, antioxidant, and anti-tumor effects. Thus, due to the importance of this compound, several enzymes involved in the flavonoid pathway have been cloned and characterized in Escherichia coli. However, the formation of inclusion bodies has become a major disadvantage of this approach. As an alternative, chalcone synthase from Physcomitrella patens was secreted into the medium using a bacteriocin release protein expression vector. Secretion of P. patens chalcone synthase into the culture media was achieved by co-expression with a psW1 plasmid encoding bacteriocin release protein in E. coli Tuner (DE3) plysS. The optimized conditions, which include the incubation of cells for 20 h with 40 ng/ml mitomycin C at OD(600) induction time of 0.5 was found to be the best condition for chalcone synthase secretion.
    Matched MeSH terms: Tandem Mass Spectrometry
  18. GC-MS Analysis of Bioactive Compounds in Ethanolic Leaf Extract of Hellenia speciosa (J.Koenig) S.R. Dutta
    R R
    Appl Biochem Biotechnol, 2022 Jan;194(1):176-186.
    PMID: 34762268 DOI: 10.1007/s12010-021-03742-2
    Hellenia speciosa (J.Koenig) S.R. Dutta is a plant species belonging to the family Costaceae. It is widely distributed in China, India, Malaysia, Indonesia, tropical, and subtropical Asia. In Ayurveda, the rhizome of this plant has been extensively used to treat fever, rash, asthma, bronchitis, and intestinal worms. The objective of the present study was to investigate the phytochemical constituents of the leaf of Hellenia speciosa using gas chromatography and mass spectroscopy analysis (GC-MS). The GC-MS analysis revealed the presence of 17 phytochemical components in the ethanolic leaf extract of Hellenia speciosa. The prevailing bioactive compounds present in Hellenia speciosa were thymol (RT-10.019; 3.59%), caryophyllene (RT-11.854; 0.62%), caryophyllene oxide (RT-13.919; 1.34%), artumerone (RT-14.795; 1.35%), hexadecanoic acid methyl ester (RT-17.536; 2.77%), 9,12-octadecanoic acid methyl ester (RT-19.163; 1.35%), squalene (RT-24.980; 1.19%), piperine (RT-25.745; 3.11%), beta tocopherol (RT-26.681; 2.88%), vitamin E (RT-27.290; 2.64%), progesterone (RT-29.608; 3.18%), caparratriene (RT-29.861; 9.72%), and testosterone (RT-30.73; 5.81%). The compounds were identified by comparing their retention time and peak area with that of the literature and by interpretation of mass spectra. The results and findings of the present study suggest that the plant leaf can be used as a valuable source in the field of herbal drug discovery. The presence of bioactive compounds justifies the use of plant leaves for treating various diseases with fewer side effects and recommended the plant of pharmaceutical importance. However, further studies are needed to undertake its bioactivity and toxicity profile.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry*
  19. Identification and characterization of antibacterial compound(s) of cockroaches (Periplaneta americana)
    Ali SM, Siddiqui R, Ong SK, Shah MR, Anwar A, Heard PJ, et al.
    Appl Microbiol Biotechnol, 2017 Jan;101(1):253-286.
    PMID: 27743045 DOI: 10.1007/s00253-016-7872-2
    Infectious diseases remain a significant threat to human health, contributing to more than 17 million deaths, annually. With the worsening trends of drug resistance, there is a need for newer and more powerful antimicrobial agents. We hypothesized that animals living in polluted environments are potential sources of antimicrobials. Under polluted milieus, organisms such as cockroaches encounter different types of microbes, including superbugs. Such creatures survive the onslaught of superbugs and are able to ward off disease by producing antimicrobial substances. Here, we characterized antibacterial properties in extracts of various body organs of cockroaches (Periplaneta americana) and showed potent antibacterial activity in crude brain extract against methicillin-resistant Staphylococcus aureus and neuropathogenic Escherichia coli K1. The size-exclusion spin columns revealed that the active compound(s) are less than 10 kDa in molecular mass. Using cytotoxicity assays, it was observed that pre-treatment of bacteria with lysates inhibited bacteria-mediated host cell cytotoxicity. Using spectra obtained with LC-MS on Agilent 1290 infinity liquid chromatograph, coupled with an Agilent 6460 triple quadruple mass spectrometer, tissues lysates were analysed. Among hundreds of compounds, only a few homologous compounds were identified that contained the isoquinoline group, chromene derivatives, thiazine groups, imidazoles, pyrrole-containing analogs, sulfonamides, furanones, and flavanones and known to possess broad-spectrum antimicrobial properties and anti-inflammatory, anti-tumour, and analgesic properties. Further identification, characterization, and functional studies using individual compounds can act as a breakthrough in developing novel therapeutics against various pathogens including superbugs.
    Matched MeSH terms: Mass Spectrometry
  20. Distribution of Heavy Metals in Core Marine Sediments of Coastal East Malaysia by Instrumental Neutron Activation Analysis and Inductively Coupled Plasma Spectroscopy
    Ashraf A, Saion E, Gharibshahi E, Yap CK, Kamari HM, Elias MS, et al.
    Appl Radiat Isot, 2018 Feb;132:222-231.
    PMID: 29183762 DOI: 10.1016/j.apradiso.2017.11.012
    Fifty-five core marine sediments from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea of coastal East Malaysia were analyzed for heavy metals by instrumental neutron activation analysis and inductively coupled plasma mass spectroscopy. The enrichment factor and the modified degree of contamination were used to calculate the anthropogenic and pollution status of the elements in the samples. The enrichment factor of As, Cd, Cr, Cu, Ni, Pb, and Zn varied from 0.42-4.26, 0.50-2.34, 0.31-0.82, 0.20-0.61, 0.91-1.92, 0.23-1.52, and 0.90-1.28, respectively, with the modified degree of contamination values below 0.6. Comparative data showed that coastal East Malaysia has low levels of contamination.
    Matched MeSH terms: Mass Spectrometry
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