Displaying publications 21 - 38 of 38 in total

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  1. Chua LS, Abdullah FI, Lim TK, Lin Q
    Food Chem, 2024 Jan 30;432:137261.
    PMID: 37651783 DOI: 10.1016/j.foodchem.2023.137261
    This study was aimed to extract bioactive peptides from the white and purple flower varieties of Orthosiphon aristatus leaves. The herb is well known for its pharmacological importance, possibly attributed to its plant proteins. Phenol based extraction was used to extract plant proteins, and then hydrolysed by proteolytic enzymes such as trypsin (serine protease) and pepsin (aspartic protease). MS/MS analysis revealed that 145 and 125 proteins were detected from the white and purple flower varieties, respectively. Trypsin hydrolysates were showed to have a higher degree of hydrolysis (24-33%), resulting in higher antioxidant and antibacterial activities. The white flower of trypsin hydrolysates showed a higher radical scavenging activity which could be attributed to its higher content of stress proteins (19%). However, trypsin hydrolysates from the purple flower showed higher ferric reducing power and bacterial growth inhibition. The performance of hydrolysates was better than ampicillin in inhibiting Acinetobacter baumanni and Staphylococcus aureus.
  2. Choong SS, Balan SN, Chua LS, Say YH
    Nutr Res Pract, 2012 Jun;6(3):238-45.
    PMID: 22808349 DOI: 10.4162/nrp.2012.6.3.238
    This study investigated the preference and intake frequency of a list of 15 commonly available high sodium Malaysian foods/dishes, discretionary salt use, and their possible association with demographics, blood pressures and anthropometric measurements among 300 Malaysian university students (114 males, 186 females; 259 ethnic Chinese, 41 Indians; 220 lean, 80 overweight). French fries and instant soup noodle were found to be the most preferred and most frequently consumed salty food, respectively, while salted fish was least preferred and least frequently consumed. Males had a significantly higher intake frequency of at least 6 of the salty foods, but the preference of most salty foods was not significantly different between genders. Ethnic Chinese significantly preferred more and took more frequently traditional and conventional Malaysian foods like asam laksa (a Malaysian salty-sour-spicy noodle in fish stock), salted biscuits and salted vegetable, while Indians have more affinity and frequency towards eating salty Western foods. Body Mass Index was significantly negatively correlated with the intake frequency of canned/packet soup and salted fish while waist circumference was significantly positively correlated with the preference of instant noodle. Also, an increased preference of potato chips and intake frequency of salted biscuits seemed to lead to a decreased WHR. Other than these, all the other overweight/obesity indicators did not seem to fully correlate with the salty food preference and intake frequency. Nevertheless, the preference and intake frequency of asam laksa seemed to be significant negative predictors for blood pressures. Finally, increased preference and intake frequency of high sodium shrimp paste (belacan)-based foods like asam laksa and belacan fried rice seemed to discourage discretionary salt use. In conclusion, the preference and intake frequency of the high sodium belacan-based dish asam laksa seems to be a good predictor for ethnic difference, discretionary salt use and blood pressures.
  3. Wasman SQ, Mahmood AA, Chua LS, Alshawsh MA, Hamdan S
    Indian J Exp Biol, 2011 Oct;49(10):767-72.
    PMID: 22013743
    Antioxidant and gastroprotective activities of aqueous and ethanolic extract of Andrographis paniculata leaves in rats have been reported. Sprague Dawley rats, 6 per group were used and rats in groups 1 to 6 were pretreated with (0.25% w/v) carboxymethyl cellulose (negative control, 5 ml/kg), 20 mg/kg omeprazole (positive control), (250 mg/kg and 500 mg/kg) of aqueous leaf extracts (APLAE) and (250 and 500 mg/kg) of ethanol leaf extracts (APLEE) respectively. Animals were orally administered with 95% ethanol (5 ml/kg) 60 min after their pretreatments. Rats were sacrificed 1 h after treatment and gastric contents were collected to measure pH and mucous weight. Stomach was analyzed for gross and histological changes. Ulcer control group showed extensive lesions of gastric mucosal layer, whereas rats pretreated with omeprazole, 250 and 500 mg/kg of APLAE showed significant and dose dependent reduction in gastric lesions with increased pH and mucus content of stomach. Rats pretreated with 250 or 500 mg/kg of APLEE showed significantly better inhibition of gastric mucosal lesions. Further, the in vitro antioxidant studies using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay showed that ethanol extracts have superior free radical scavenging activity with IC50 value = 10.9 than aqueous extracts with IC50 value = 24.65. Results of this study showed that pretreatment with ethonolic extract of A. paniculata ethanolic provided significant protection against gastric ulcer by regulating of pH, mucous production and antioxidant property.
  4. Qader SW, Abdulla MA, Chua LS, Sirat HM, Hamdan S
    Int J Mol Sci, 2012;13(2):1481-96.
    PMID: 22408403 DOI: 10.3390/ijms13021481
    The leaves of Polygonum minus were fractionated using an eluting solvent to evaluate the pharmacological mechanisms underlying the anti-ulcerogenic activity of P. minus. Different P. minus fractions were obtained and evaluated for their ulcer preventing capabilities using the ethanol induction method. In this study, Sprague Dawley rats weighing 150-200 g were used. Different parameters were estimated to identify the active fraction underlying the mechanism of the gastroprotective action of P. minus: the gastric mucus barrier, as well as superoxide dismutase, total hexosamine, and prostaglandin synthesis. Amongst the five fractions from the ethanolic extract of P. minus, the ethyl acetate:methanol 1:1 v/v fraction (F2) significantly (p < 0.005) exhibited better inhibition of ulcer lesions in a dose-dependent manner. In addition, rats pre-treated with F2 showed a significant elevation in superoxide dismutase (SOD), hexosamine and PGE2 levels in the stomach wall mucosa in a dose-dependent matter. Based on these results, the ethyl acetate:methanol 1:1 v/v fraction was considered to be the best fraction for mucous protection in the ethanol induction model. The mechanisms underlying this protection were attributed to the synthesis of antioxidants and PGE2.
  5. Qader SW, Abdulla MA, Chua LS, Najim N, Zain MM, Hamdan S
    Molecules, 2011 Apr 21;16(4):3433-43.
    PMID: 21512451 DOI: 10.3390/molecules16043433
    Aqueous and ethanol extracts of different traditional Malaysian plants (Polygonum minus, Andrographis paniculata, Curcuma xanthorrhiza, Momordica charantia and Strobilanthes crispus) were evaluated for their antioxidant properties, total phenolic content and cytotoxic activity. Antioxidant activity was evaluated by using 1,1-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The results showed that ethanol extracts contain high antioxidant activities compared to aqueous extracts. The findings exhibited a strong correlation between antioxidant activity and the total phenol contents. In addition, all the plant extracts showed non-toxic effects against a normal human lung fibroblast cell line (Hs888Lu). Although traditionally aqueous extracts are used, we determined that ethanol extracts usually achieved better activity in the assays.
  6. Chua LS, Latiff NA, Lee SY, Lee CT, Sarmidi MR, Aziz RA
    Food Chem, 2011 Aug 1;127(3):1186-92.
    PMID: 25214112 DOI: 10.1016/j.foodchem.2011.01.122
    Both total phenolic content (TPC) and total flavonoid content (TFC) of Labisia pumila extracts were determined spectrophotometrically. L. pumila leaves extracted in 60% methanol (MeOH) were fractionated on C18 cartridge and the antioxidant property of each fraction was determined by measuring free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity. The 40% MeOH fraction exhibited the highest scavenging activity. Nine flavonols (quercetin, myricetin and kaempferol), two flavanols (catechin and epigallocatechin) and nine phenolic acids were identified from this active fraction by UPLC-ESI-MS/MS, and confirmed by comparison with the mass spectra of standard aglycones, theoretical fragments generated from MS Fragmenter software, and literature values.
  7. Mustafa SM, Chua LS, El-Enshasy HA, Abd Majid FA, Hanapi SZ, Abdul Malik R
    J Food Biochem, 2019 04;43(4):e12805.
    PMID: 31353583 DOI: 10.1111/jfbc.12805
    This study was focused on the effects of fermentation temperature and pH on the quality of Punica granatum juice probioticated with Lactobacillus species: Lactobacillus plantarum, Lactobacillus casei, Lactobacillus bulgaricus, and Lactobacillus salivarius. The whole fruit juice of P. granatum which is rich with phytonutrients appeared to be a good probiotic carrier. The probiotication was carried out for 24 hr at 30, 35, and 37°C and pH 2.5, 4.0, and 5.5 under microaerophilic conditions. The results found that P. granatum juice cultivated with L. casei had a better growth profile with a higher biomass density at 37°C around pH 3.5-4.0. Probiotication could maintain the scavenging activity of P. granatum juice cultivated with L. casei. The scavenging activity achieved up to 90% inhibition at the concentration of 5 mg/ml. The whole fruit-squeezed P. granatum juice was suitable for the growth of Lactobacillus species even without supplementation during cultivation. PRACTICAL APPLICATIONS: The findings of this study presented the potential of P. granatum juice (whole fruit) to be used as a good probiotic carrier, particularly for Lactobacillus species without supplementation. High nutritious P. granatum juice catered the need of probiotic bacteria during fermentation. Probiotication could maintain the antioxidant capacity of the juice in term of its radical scavenging activity. The antioxidant capacity was mainly attributed to the metabolites such as phenolic acids (romarinic acid and caftaric acid) and flavonoids (quercetin, quercetin 3-glucoside, rutin and kaempferol rutinoside). With the optimized temperature (37°C) and pH (4.00), probiotic bacteria could growth well up to a cell viability of 2.46 × 1010  cfu/ml. This offers P. granatum to be developed into functional food to cater to the needs of the consumers who are lactose intolerant to dairy products.
  8. Tarmizi AAA, Wagiran A, Mohd Salleh F, Chua LS, Abdullah FI, Hasham R, et al.
    Plants (Basel), 2021 Apr 07;10(4).
    PMID: 33917172 DOI: 10.3390/plants10040717
    Labisia pumila is a precious herb in Southeast Asia that is traditionally used as a health supplement and has been extensively commercialized due to its claimed therapeutic properties in boosting a healthy female reproductive system. Indigenous people used these plants by boiling the leaves; however, in recent years it has been marketed as powdered or capsuled products. Accordingly, accuracy in determination of the authenticity of these modern herbal products has faced great challenges. Lack of authenticity is a public health risk because incorrectly used herbal species can cause adverse effects. Hence, any measures that may aid product authentication would be beneficial. Given the widespread use of Labisia herbal products, the current study focuses on authenticity testing via an integral approach of DNA barcoding and qualitative analysis using HPLC. This study successfully generated DNA reference barcodes (ITS2 and rbcL) for L. pumila var. alata and pumila. The DNA barcode that was generated was then used to identify species of Labisia pumila in herbal medicinal products, while HPLC was utilized to determine their quality. The findings through the synergistic approach (DNA barcode and HPLC) implemented in this study indicate the importance of both methods in providing the strong evidence required for the identification of true species and to examine the authenticity of such herbal medicinal products.
  9. Chan GF, Rashid NA, Chua LS, Ab llah N, Nasiri R, Ikubar MR
    Bioresour Technol, 2012 Feb;105:48-59.
    PMID: 22182471 DOI: 10.1016/j.biortech.2011.11.094
    A novel bacterial consortium, NAR-2 which consists of Citrobacter freundii A1, Enterococcus casseliflavus C1 and Enterobacter cloacae L17 was investigated for biodegradation of Amaranth azo dye under sequential microaerophilic-aerobic condition. The NAR-2 bacterial consortium with E. casseliflavus C1 as the dominant strain enhanced the decolorization process resulting in reduction of Amaranth in 30 min. Further aerobic biodegradation, which was dominated by C. freundii A1 and E. cloacae L17, allowed biotransformation of azo reduction intermediates and mineralization via metabolic pathways including benzoyl-CoA, protocatechuate, salicylate, gentisate, catechol and cinnamic acid. The presence of autoxidation products which could be metabolized to 2-oxopentenoate was elucidated. The biodegradation mechanism of Amaranth by NAR-2 bacterial consortium was predicted to follow the steps of azo reduction, deamination, desulfonation and aromatic ring cleavage. This is for the first time the comprehensive microaerophilic-aerobic biotransformation pathways of Amaranth dye intermediates by bacterial consortium are being proposed.
  10. Sari E, Mahira KF, Patel DN, Chua LS, Pratami DK, Sahlan M
    Heliyon, 2021 May;7(5):e06912.
    PMID: 34013079 DOI: 10.1016/j.heliyon.2021.e06912
    Royal jellies (RJs) possess moisturizing, emulsifying, and stabilizing properties, and several pharmacological activities have also been found to be present, which make them an ideal component for cosmetic and skin care products. However, despite the abundant efficacies, there is a lack of studies that explore the chemical composition of RJ using metabolome analysis. Furthermore, an evaluation of the chemical composition of Indonesian RJs collected from different regions has yet to be carried out. Therefore, the main objective of this study was to identify any differences in the chemical composition of such RJs. Chemical profiling was also carried out to enable more targeted utilization based on the actual compositions. Chemical profiling is also important given the rich Indonesian biodiversity and the high dependence of the RJ compositions on the botanical source. In this research, ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was used as part of an untargeted metabolomics approach. From the chemical profiling, >30 compounds were identified across four RJ samples. The major constituents of the samples were found to be oligosaccharides, fatty acids, and adenosine monophosphate derivatives. Meanwhile, sucrose and planteose were found to be highest in the samples from Banjarnegara and Kediri, whereas dimethyloctanoic acid was found to be unique to the sample from Banjarnegara. It was also discovered that the RJs from Demak and Tuban contained more organic fatty acids and oligosaccharides than the other samples. Although the sample from Demak demonstrated good potential for use in the cosmetic, skin care, and bio-supplement industries, the higher abundance of fatty acids and oligosaccharides in the sample from Tuban indicated that it is perhaps the most suitable RJ for use in this field.
  11. Fan YV, Lee CT, Klemeš JJ, Chua LS, Sarmidi MR, Leow CW
    J Environ Manage, 2018 Jun 15;216:41-48.
    PMID: 28427880 DOI: 10.1016/j.jenvman.2017.04.019
    Home composting can be an effective way to reduce the volume of municipal solid waste. The aim of this study is to evaluate the effect of Effective Microorganism™ (EM) for the home scale co-composting of food waste, rice bran and dried leaves. A general consensus is lacking regarding the efficiency of inoculation composting. Home scale composting was carried out with and without EM (control) to identify the roles of EM. The composting parameters for both trials showed a similar trend of changes during the decomposition. As assayed by Fourier Transform Infrared Spectroscopy (FTIR), the functional group of humic acid was initially dominated by aliphatic structure but was dominated by the aromatic in the final compost. The EM compost has a sharper peak of aromatic CC bond presenting a better degree of humification. Compost with EM achieved a slightly higher temperature at the early stage, with foul odour suppressed, enhanced humification process and a greater fat reduction (73%). No significant difference was found for the final composts inoculated with and without EM. The properties included pH (∼7), electric conductivity (∼2), carbon-to-nitrogen ratio (C: N 100%), humic acid content (4.5-4.8%) and pathogen content (no Salmonella, <1000 Most Probable Number/g E. coli). All samples were well matured within 2 months. The potassium and phosphate contents in both cases were similar however the EM compost has a higher nitrogen content (+1.5%). The overall results suggested the positive effect provided by EM notably in odour control and humification.
  12. Chua LS, Lau CH, Chew CY, Ismail NIM, Soontorngun N
    Phytomedicine, 2018 Jan 15;39:49-55.
    PMID: 29433683 DOI: 10.1016/j.phymed.2017.12.015
    BACKGROUND: Orthosiphon aristatus (Blume) Miq. is a medicinal herb which is traditionally used for the treatment of diabetes and kidney diseases in South East Asia. Previous studies reported higher concentration of antioxidative phytochemicals, especially rosmarinic acid (ester of caffeic acid) and other caffeic acid derivatives in this plant extract than the other herbs such as rosemary and sage which are usually used as raw materials to produce rosmarinic acid supplement in the market.

    PURPOSE: The phytochemical profile of O. aristatus was investigated at different storage durations for quality comparison.

    METHODS: The phytochemicals were extracted from the leaves and stems of O. aristatus using a reflux reactor. The extracts were examined for total phenolic and flavonoid contents, as well as their antioxidant capacities, in terms of radical scavenging, metal chelating and reducing power. The phytochemical profiles were also analyzed by unsupervised principal component analysis and hierarchical cluster analysis, in relation to the factor of storage at 4 °C for 5 weeks.

    RESULTS: The leaf extract was likely to have more phytochemicals than stem extract, particularly caffeic acid derivatives including glycosylated and alkylated caffeic acids. This explains higher ratio of total phenolic content to total flavonoid content with higher antioxidant capacities for the leaf extracts. Rosmarinic acid dimer and salvianolic acid B appeared to be the major constituents, possibly contributing to the previously reported pharmacological properties. However, the phytochemical profiles were found changing, even though the extracts were stored in the refrigerator (4 °C). The change was significantly observed at the fifth week based on the statistical pattern recognition technique.

    CONCLUSION: O. aristatus could be a promising source of rosmarinic acid and its dimer, as well as salvianolic acid B with remarkably antioxidant properties. The phytochemical profile was at least stable for a month stored at 4 °C. It is likely to be a good choice of herbal tea with comparable radical scavenging activity, but lower caffeine content than other tea samples.

  13. Li F, Lv Z, Zhong Z, Mao L, Chua LS, Xu L, et al.
    Foods, 2023 Jan 28;12(3).
    PMID: 36766095 DOI: 10.3390/foods12030567
    Aspergillus niger is one of the major pathogenic fungi causing postharvest grape decay. The development of antifungal agents is beneficial to reduce the loss of grapes during storage. The aim of this study was to investigate the antifungal mechanism of cyclosporin A (CsA). It was indicated that the rot development on grapes caused by A. niger was almost completely inhibited with CsA in vivo at a concentration of 200 mg/L. The transcriptomic analysis revealed that the expression levels of genes involved in rRNA processing and ribosome biogenesis were down-regulated, whereas those related to β-glucosidases and chitinases were up-regulated. The results implied that CsA may disturb rRNA and ribosome formation to obstruct protein synthesis, accelerate chitin and glucan degradation to destruct cell walls, and ultimately reduce postharvest decay caused by A. niger in grapes. This study evaluated the potential of CsA as a grape preservative and provided new insights into the mechanisms underlying the molecular response in A. niger with the treatment of CsA.
  14. Chua LS, Rahaman NL, Adnan NA, Eddie Tan TT
    J Anal Methods Chem, 2013;2013:313798.
    PMID: 24027653 DOI: 10.1155/2013/313798
    The antioxidant activities based on the free radical scavenging, reducing power, and bleaching inhibition were investigated for the three commonly used honeys in Malaysia, namely, tualang, gelam, and acacia honey. The antioxidant capacity of the honey samples was correlated with their biochemical constituents such as total phenol, total flavonoid content, and total water-soluble vitamins (vitamin B1, B2, B3, B9, B12, and vitamin C). The total flavonoid content of honey samples was strongly correlated with the three antioxidative processes (r = 0.9276-0.9910). In contrast, the total water-soluble vitamins was found to be well correlated with the free radical scavenging activity (r = 0.8226). Vitamin B3 was likely to be in the highest concentration, which covered for 69-80% of the total vitamin content. A number of five phenolic acids, three flavonoids, and two organic acids had also been detected from the honey samples using UPLC-MS/MS, without sugar-removal procedure.
  15. Tnah LH, Lee CT, Lee SL, Ng KK, Ng CH, Nurul-Farhanah Z, et al.
    Am J Bot, 2012 Nov;99(11):e431-3.
    PMID: 23108468 DOI: 10.3732/ajb.1200165
    Aggressive collections and trade activities in recent decades have resulted in heavy pressure on the natural stands of Aquilaria malaccensis and concerns over its long-term survival potential. To aid DNA profiling and assessment of its genetic diversity, microsatellite markers were developed for the species.
  16. Chew YH, Shia YL, Lee CT, Majid FA, Chua LS, Sarmidi MR, et al.
    Mol Cell Endocrinol, 2009 Aug 13;307(1-2):57-67.
    PMID: 19524127 DOI: 10.1016/j.mce.2009.03.005
    A mathematical model to describe the oscillatory bursting activity of pancreatic beta-cells is combined with a model of glucose regulation system in this work to study the bursting pattern under regulated extracellular glucose stimulation. The bursting electrical activity in beta-cells is crucial for the release of insulin, which acts to regulate the blood glucose level. Different types of bursting pattern have been observed experimentally in glucose-stimulated islets both in vivo and in vitro, and the variations in these patterns have been linked to changes in glucose level. The combined model in this study enables us to have a deeper understanding on the regime change of bursting pattern when glucose level changes due to hormonal regulation, especially in the postprandial state. This is especially important as the oscillatory components of electrical activity play significant physiological roles in insulin secretion and some components have been found to be lost in type 2 diabetic patients.
  17. Chew YH, Shia YL, Lee CT, Majid FA, Chua LS, Sarmidi MR, et al.
    Mol Cell Endocrinol, 2009 May 6;303(1-2):13-24.
    PMID: 19428987 DOI: 10.1016/j.mce.2009.01.018
    A model of glucose regulation system was combined with a model of insulin-signaling pathways in this study. A feedback loop was added to link the transportation of glucose into cells (by GLUT4 in the insulin-signaling pathways) and the insulin-dependent glucose uptake in the glucose regulation model using the Michaelis-Menten kinetic model. A value of K(m) for GLUT4 was estimated using Genetic Algorithm. The estimated value was found to be 25.3 mM, which was in the range of K(m) values found experimentally from in vivo and in vitro human studies. Based on the results of this study, the combined model enables us to understand the overall dynamics of glucose at the systemic level, monitor the time profile of components in the insulin-signaling pathways at the cellular level and gives a good estimate of the K(m) value of glucose transportation by GLUT4. In conclusion, metabolic modeling such as displayed in this study provides a good predictive method to study the step-by-step reactions in an organism at different levels and should be used in combination with experimental approach to increase our understanding of metabolic disorders such as type 2 diabetes.
  18. Chua LS, Amin NA, Neo JC, Lee TH, Lee CT, Sarmidi MR, et al.
    J Chromatogr B Analyt Technol Biomed Life Sci, 2011 Dec 15;879(32):3909-19.
    PMID: 22119436 DOI: 10.1016/j.jchromb.2011.11.002
    A number of three LC-MS/MS hybrid systems (QTof, TripleTof and QTrap) has been used to profile small metabolites (m/z 100-1000) and to detect the targeted metabolites such as quassinoids, alkaloids, triterpene and biphenylneolignans from the aqueous extracts of Eurycoma longifolia. The metabolite profiles of small molecules showed four significant clusters in the principle component analysis for the aqueous extracts of E. longifolia, which had been collected from different geographical terrains (Perak and Pahang) and processed at different extraction temperatures (35°C and 100°C). A small peptide of leucine (m/z 679) and a new hydroxyl methyl β-carboline propionic acid have been identified to differentiate E. longifolia extracts that prepared at 35°C and 100°C, respectively. From the targeted metabolites identification, it was found that 3,4ɛ-dihydroeurycomanone (quassinoids) and eurylene (squalene-type triterpene) could only be detected in the Pahang extract, whereas canthin-6-one-3N-oxide could only be detected in the Perak extract. Overall, quassinoids were present in the highest concentration, particularly eurycomanone and its derivatives compared to the other groups of metabolites. However, the concentration of canthin-6-one and β-carboline alkaloids was significantly increased when the roots of the plant samples were extracted at 100°C.
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