Publications by authors named "Cheang Khoo"

The challenges of the COVID-19 pandemic have highlighted an increasing clinical demand for safe and effective treatment options against an overzealous immune defence response, also known as the "cytokine storm". Andrographolide is a naturally derived bioactive compound with promising anti-inflammatory activity in many clinical studies. However, its cytokine-inhibiting activity, in direct comparison to commonly used nonsteroidal anti-inflammatory drugs (NSAIDs), has not been extensively investigated in existing literature.

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(Blume and T. Nees) Torrend is a traditionally well-known mushroom that is used for the treatment of cancer. In order to evaluate the pharmacological activities of polysaccharides, the mushroom powder was subjected to hot water extraction and pure polysaccharides (ARPs) were isolated by gel-filtration method.

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Houtt is an important anti-skin pigmentation herb used in traditional Chinese medicine. However, the molecular basis for this activity is complex and not fully understood. In this study, water and ethanol extracts and polysaccharide extract from (LJPs) were analyzed by LC-MS/MS and HPLC-DAD separately.

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Arimisia annua L. is an important anticancer herb used in traditional Chinese medicine. The molecular basis underpinning the anticancer activity is complex and not fully understood, but the herbal polysaccharides, broadly recognised as having immunomodulatory, antioxidant and anticancer activities, are potential key active agents.

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(also known as Goji berry) is used in traditional Chinese medicine (TCM) with claimed benefits, including eye and liver protection, immune system fortification and blood glucose control. The commercially available product comes from either the or species, with the former dominating the marketplace due to its better taste profile. The main objective of this study was to develop a validated LC-ESI-MS/MS method to quantify multiple key bio-active analytes in commercially available berries and to qualitatively assess these samples using a principal component analysis (PCA).

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Background-The quality control (QC) for commercial herbal formulations is sparse due to a lack of well-developed HPLC-ESI-MS/MS methods. Objective-This study reports the quantification of nine selected analytes for a commercial eight-herb formulation known as Qi Ju Di Huang Wan (QJDHW) used to relieve hypertension. Methods-An HPLC-ESI/MS method for the quantitation of analytes selected using the Herbal Chemical Marker Ranking System (Herb MaRS) was developed.

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The Naoxinqing (NXQ) tablet is a standardised proprietary herbal product containing an extract of persimmon leaves () for the management of cardio- and cerebrovascular diseases. Although previous reports suggested that the efficacy of NXQ is at least partly mediated by its anti-oxidative property, the anti-oxidative effect of the major components of NXQ has not been studied systematically. For quality control purposes, only analytical methods limited to 3 marker analytes have been reported, the extent to which the other components affect efficacy has not been explored.

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There is a need for increased QC of complex herbal medicine formulations to ensure product consistency, efficacy, and safety. This study reports an HPLC with photodiode array and electrospray ionization-tandem MS method for quantifying selected analytes in a seven-herb formulation. Fourteen analytes were selected for quantification based on the criteria available from the Herbal Chemical Marker Ranking System, which takes into account the bioavailability, reported bioactivity, and physiological action related to its intended use, as well as commercial availability of the standard.

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Background: The anti-inflammatory activity of Andrographis paniculata (Acanthaceae), a traditional medicine widely used in Asia, is commonly attributed to andrographolide, its main secondary metabolite. Commercial A. paniculata extracts are standardised to andrographolide content.

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Background: Pattern-oriented chemical profiling is increasingly being used to characterize the phytochemical composition of herbal medicines for quality control purposes. Ideally, a fingerprint of the biological effects should complement the chemical fingerprint. For ethical and practical reasons it is not possible to test each herbal extract in laboratory animals or humans.

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A number of mushrooms are known to possess pharmacological activities. In this study, the phenolic and flavonoid contents of extracts of exo- and endopolysaccharide fractions obtained from submerged mycelia cultures of 7 edible or medicinal mushroom species, as well as their antioxidant and immunomodulatory properties, were evaluated. The exo- and endopolysaccharide yields were 0.

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Aims: To compare health and science students' demographic characteristics and learning approaches across different disciplines, and to examine the relationship between learning approaches and academic performance.

Background: While there is increasing recognition of a need to foster learning approaches that improve the quality of student learning, little is known about students' learning approaches across different disciplines, and their relationships with academic performance.

Design: Prospective, correlational design.

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Background: This study aims to determine the relationship between the antioxidant and anti-inflammatory activities of the thirteen herbs and two fungi extracts, and their total phenolic and flavonoid contents.

Methods: Antioxidant activities were evaluated by four assays: an antioxidant activity assay using Saccharomyces cerevisiae, a DPPH ((2, 2-diphenyl-1-picrylhydrazyl) assay to assess free radical scavenging, an assay assessing ferrous ions or iron (II) chelating ability, and a ferric reducing antioxidant power (FRAP) assay. Total phenolic and flavonoid contents were determined using the Folin-Ciocalteu and aluminium chloride methods, respectively.

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The GenBank(®) database is perhaps one of the most important repositories of genetic information. A researcher working in the field of genomic authentication must therefore be equipped with the skills needed to competently access the required information from this database whilst ultimately contributing their own data to it. This chapter presents a practical guide to using GenBank(®) to search for sequences, search and align unknown sequences using BLAST, and uploading and maintaining your own sequences.

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A GC method was developed for the identification and quantitation of eight sympathomimetic amines in urine, i.e., amphetamine, methamphetamine, mephentermine, ephedrine, pseudoephedrine, methylenedioxyamphetamine, methylenedioxymethamphetamine, and methylenedioxyethylamphetamine.

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A validated analytical method is reported for the analysis of paeoniflorin and albiflorin in Bai Shao (Paeonia lactiflora) as a dried raw herb and commercially prepared dried aqueous extract. The samples were extracted by sonication in methanol and the extract analyzed by LC-photodiode array with identity confirmation by electrospray ionization-tandem MS. A C18 column was used with an acetonitrile-water gradient mobile phase.

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A validated analytical method is reported for the analysis of narirutin and hesperidin in Zhi Ke (Citrus aurantium L.) in the form of the dried raw herb and of the commercially prepared dried aqueous extract. The samples were extracted by sonication in methanol and the extract was analyzed by liquid chromatography-photodiode array (PDA) detection with identity confirmation by negative electrospray ionization-tandem mass spectrometry (MS).

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The determination of 6-, 8-, 10-gingerol, and 6-shogaol in dried ginger (Zingiber officinale) and in the dried aqueous extract of ginger is reported. This is the first study to report a validated method for the determination of these 4 analytes. Several extraction solvents and methods were examined, and the optimum combination was determined.

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A validated analytical method is described for the determination of honokiol and magnolol in Hou Po (Magnolia officinalis) as the dried raw herb and the commercially prepared dried aqueous extract. The samples were extracted with methanol by the Soxhlet method, and the extract was analyzed by liquid chromatography with photodiode array (LC/PDA) detection with confirmation of analyte identity by negative-ion electrospray ionization tandem mass spectrometry (ESI-MS/MS). A C18 column was used with a menthanol--0.

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A liquid chromatography (LC) method with UV detection is reported for the determination of the sulfonamide herbicide flumetsulam in soybeans. The ground soybean sample was partitioned between methanol and hexane. The hexane removed the lipids, and the methanol layer containing the analyte was further partitioned between dichloromethane and aqueous phosphate buffer at pH 7.

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An electrospray ionization-liquid chromatography-tandem mass spectrometry (ESI/LC/MS/MS) method was developed for the simultaneous determination of the beta-agonists clenbuterol, salbutamol, and cimaterol in bovine retina. The tissue was homogenized in alkaline buffer and spiked to give 10, 15, and 20 ng/g each of the 3 analytes together with the internal standards d6-salbutamol and d6-clenbuterol. The mixture was incubated with protease enzyme to release any protein-bound analytes and then made alkaline before extraction with isobutanol.

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