Displaying publications 1 - 20 of 73 in total

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  1. Ha ZY, Ong HC, Oo CW, Yeong KY
    Curr Alzheimer Res, 2020;17(13):1177-1185.
    PMID: 33602088 DOI: 10.2174/1567205018666210218151228
    BACKGROUND: Benzimidazole is an interesting pharmacophore which has been extensively studied in medicinal chemistry due to its high affinity towards various enzymes and receptors. Its derivatives have been previously shown to possess a wide range of biological activities including anthelmintic, antihypertensive, antiulcer, as well as anticholinesterase activity.

    OBJECTIVE: The objective of this study is to search for more potent benzimidazole-based cholinesterase inhibitors, through the modification of the 1- and 2-positions of the benzimidazole core.

    METHODS: Synthesis of compounds were carried out via a 4-step reaction scheme following a previously reported protocol. Structure-activity relationship of the compounds are established through in vitro cholinesterase assays and in silico docking studies. Furthermore, cytotoxicity and blood brain barrier (BBB) permeability of the compounds were also investigated.

    RESULTS: Among the synthesised compounds, three of them (5IIa, 5IIb, and 5IIc) exhibited potent selective butyrylcholinesterase inhibition at low micromolar level. The compounds did not show any significant cytotoxicity when tested against a panel of human cell lines. Moreover, the most active compound, 5IIc, was highly permeable across the blood brain barrier.

    CONCLUSION: In total 10 benzimidazole derivatives were synthesized and screened for their AChE and BuChE inhibitory activities. Lead compound 5Iic, represents a valuable compound for further development as potential AD therapeutics.

  2. Wang CT, Huang YS, Sangeetha T, Chen YM, Chong WT, Ong HC, et al.
    Bioresour Technol, 2018 May;255:83-87.
    PMID: 29414177 DOI: 10.1016/j.biortech.2018.01.086
    Photosynthetic microbial fuel cells (PMFCs) are novel bioelectrochemical transducers that employ microalgae to generate oxygen, organic metabolites and electrons. Conventional PMFCs employ non-eco-friendly membranes, catalysts and phosphate buffer solution. Eliminating the membrane, buffer and catalyst can make the MFC a practical possibility. Therefore, single chambered (SPMFC) were constructed and operated at different recirculation flow rates (0, 40 and 240 ml/min) under bufferless conditions. Furthermore, maximum power density of 4.06 mW/m2, current density of 46.34 mA/m2 and open circuit potential of 0.43 V and low internal resistance of 611.8 Ω were obtained at 40 ml/min. Based on the results it was decided that SPMFC was better for operation at 40 ml/min. Therefore, these findings provided progressive insights for future pilot and industrial scale studies of PMFCs.
  3. Yong AL, Ooh KF, Ong HC, Chai TT, Wong FC
    Food Chem, 2015 Nov 1;186:32-6.
    PMID: 25976788 DOI: 10.1016/j.foodchem.2014.11.103
    In this paper, we investigated the antibacterial mechanism and potential therapeutic targets of three antibacterial medicinal plants. Upon treatment with the plant extracts, bacterial proteins were extracted and resolved using denaturing gel electrophoresis. Differentially-expressed bacterial proteins were excised from the gels and subjected to sequence analysis by MALDI TOF-TOF mass spectrometry. From our study, seven differentially expressed bacterial proteins (triacylglycerol lipase, N-acetylmuramoyl-L-alanine amidase, flagellin, outer membrane protein A, stringent starvation protein A, 30S ribosomal protein s1 and 60 kDa chaperonin) were identified. Additionally, scanning electron microscope study indicated morphological damages induced on bacterial cell surfaces. To the best of our knowledge, this represents the first time these bacterial proteins are being reported, following treatments with the antibacterial plant extracts. Further studies in this direction could lead to the detailed understanding of their inhibition mechanism and discovery of target-specific antibacterial agents.
  4. Chai TT, Kwek MT, Ong HC, Wong FC
    Food Chem, 2015 Nov 1;186:26-31.
    PMID: 25976787 DOI: 10.1016/j.foodchem.2014.12.099
    This study aimed to isolate a potent antiglucosidase and antioxidant fraction from Stenochlaena palustris. Extraction was performed with hexane, chloroform, ethyl acetate, methanol, and water. Antiglucosidase, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and ferric reducing antioxidant power (FRAP) assays found methanol extract (ME) to be the most active. Water fraction (WF) of ME was a stronger α-glucosidase inhibitor (EC50 2.9 μg/mL) than quercetin, with weak antiamylase activity. WF was a competitive α-glucosidase inhibitor. DPPH scavenging activity of WF (EC50 7.7 μg/mL) was weaker than quercetin. WF (EC50 364 μg/mL) was a stronger hydrogen peroxide scavenger than gallic acid (EC50 838 μg/mL) and was equally strong as quercetin in scavenging superoxide. WF possessed moderate copper chelating activity. WF was enriched in total phenolics (TP) and hydroxycinnamic acids (THC). TP correlated with antioxidant activity (R(2) > 0.76). Only THC correlated with antiglucosidase activity (R(2) = 0.86). Overall, WF demonstrated concurrent, potent antiglucosidase and antioxidant activities.
  5. Tan ST, Ong HC, Chai TT, Wong FC
    Pharmacogn Mag, 2018 04 10;14(54):227-230.
    PMID: 29720836 DOI: 10.4103/pm.pm_282_17
    Background: Medicinal fern species represent a potentially important source for both food and medicinal applications. Previously, two underutilized tropical fern species (Blechnum orientale and Phymatopteris triloba) were reported with cytotoxic activities against selected cancer cell lines. However, the exact mechanism remains elusive.

    Objective: In this paper, we reported the identification of six differentially expressed proteins isolated from cancer cells, following exposure to the cytotoxic fern extracts.

    Materials and Methods: The identities of these cancer proteins were determined by matrix-assisted laser desorption ionization time-of-flight protein sequencing.

    Results: The cancer proteins were identified as follows: elongation factor 1-γ, glyceraldehydes-3-phosphate dehydrogenase, heat shock protein 90-β, heterogeneous nuclear ribonucleoprotein-A2/B1, truncated nucleolar phosphoprotein B23, and tubulin-β chain. To the best of our knowledge, this paper represents the first time these cancer proteins are being reported, following exposure to the aforementioned cytotoxic fern extracts.

    Conclusion: It is hoped that further efforts in this direction could lead to the identification and development of target-specific chemotherapeutic agents.

    SUMMARY: Cytotoxic fern extracts were tested in anti-cancer proteomic works.Six differentially-expressed cancer proteins were identified.Potential anti-cancer protein targets were reported. Abbreviations used: EF: Elongation factor; HRP: Horseradish peroxidase; HSP: Heat shock protein; MALDI: Matrix-assisted laser desorption/ionization.

  6. Chai TT, Elamparuthi S, Yong AL, Quah Y, Ong HC, Wong FC
    Bot Stud, 2013 Dec;54(1):55.
    PMID: 28510890 DOI: 10.1186/1999-3110-54-55
    BACKGROUND: Ferns contain natural products with potential therapeutic applications. Current knowledge of the pharmacological properties of ferns, specifically those growing at high altitudes, is limited. This study aimed to evaluate the phytochemical contents as well as antibacterial, anti-glucosidase, and antioxidant activities of four highland ferns in Malaysia.

    RESULTS: Aqueous extracts of the leaves and rhizomes of Cyathea latebrosa, Dicranopteris curranii, Gleichenia truncata, and Phymatopteris triloba were analysed. P. triloba leaf extract had the highest contents of total flavonoids (118.6 mg/g dry matter), hydroxycinnamic acids (69.7 mg/g dry matter), and proanthocyanidins (29.4 mg/g dry matter). P. triloba leaf and rhizome extracts as well as G. truncata leaf extract inhibited the growth of both Gram-positive and Gram-negative bacteria. P. triloba leaf extract produced a minimum inhibitory concentration (MIC) value of 0.78 mg dry matter/mL when tested against Pseudomonas aeruginosa, which is 2.5-fold higher than that of ampicillin. Among all extracts, P. triloba leaf extract had the highest anti-glucosidase activity (EC50 = 56 μg dry matter/mL) and also the highest antioxidant potential based on DPPH radical scavenging and Ferric Reducing Antioxidant Power assays. Antioxidant activities of both the leaf and rhizome extracts correlated positively with total flavonoid and hydroxycinnamic acid contents (R(2) = 0.80-0.95). On the other hand, anti-glucosidase activity correlated with total proanthocyanidin contents in both the leaf and rhizome extracts (R(2) = 0.62-0.84).

    CONCLUSIONS: In conclusion, highland ferns are potential sources of antibacterial agents, glucosidase inhibitors, and antioxidants.

  7. Milano J, Ong HC, Masjuki HH, Silitonga AS, Kusumo F, Dharma S, et al.
    Waste Manag, 2018 Oct;80:435-449.
    PMID: 30455026 DOI: 10.1016/j.wasman.2018.09.005
    Recycling waste cooking vegetable oils by reclaiming and using these oils as biodiesel feedstocks is one of the promising solutions to address global energy demands. However, producing these biodiesels poses a significant challenge because of their poor physicochemical properties due the high free fatty acid content and impurities present in the feedstock, which will reduce the biodiesel yields. Hence, this study implemented the following strategy in order to address this issue: (1) 70 vol% of waste cooking vegetable oil blended with 30 vol% of Calophyllum inophyllum oil named as WC70CI30 used to alter its properties, (2) a three-stage process (degumming, esterification, and transesterification) was conducted which reduces the free fatty acid content and presence of impurities, and (3) the transesterification process parameters (methanol/oil ratio, reaction temperature, reaction time, and catalyst concentration) were optimized using response surface methodology in order to increase the biodiesel conversion yield. The results show that the WC70CI30 biodiesel has favourable physicochemical properties, good cold flow properties, and high oxidation stability (22.4 h), which fulfil the fuel specifications stated in the ASTM D6751 and EN 14214 standards. It found that the WC70CI30 biodiesel has great potential as a diesel substitute without the need for antioxidants and pour point depressants.
  8. Su G, Ong HC, Fattah IMR, Ok YS, Jang JH, Wang CT
    Sci Total Environ, 2022 Feb 25;809:151170.
    PMID: 34699825 DOI: 10.1016/j.scitotenv.2021.151170
    The continuous growth of population and the steady improvement of people's living standards have accelerated the generation of massive food waste. Untreated food waste has great potential to harm the environment and human health due to bad odor release, bacterial leaching, and virus transmission. However, the application of traditional disposal techniques like composting, landfilling, animal feeding, and anaerobic digestion are difficult to ease the environmental burdens because of problems such as large land occupation, virus transmission, hazardous gas emissions, and poor efficiency. Pyrolysis is a practical and promising route to reduce the environmental burden by converting food waste into bioenergy. This paper aims to analyze the characteristics of food waste, introduce the production of biofuels from conventional and advanced pyrolysis of food waste, and provide a basis for scientific disposal and sustainable management of food waste. The review shows that co-pyrolysis and catalytic pyrolysis significantly impact the pyrolysis process and product characteristics. The addition of tire waste promotes the synthesis of hydrocarbons and inhibits the formation of oxygenated compounds efficiently. The application of calcium oxide (CaO) exhibits good performance in the increment of bio-oil yield and hydrocarbon content. Based on this literature review, pyrolysis can be considered as the optimal technique for dealing with food waste and producing valuable products.
  9. Ong HC, Ibrahim N, Wahab S
    PMID: 27574475 DOI: 10.2147/PRBM.S112129
    Nowadays, family members are gradually taking on the role of full-time caregivers for patients suffering from schizophrenia. The increasing burden and tasks of caretaking can cause them psychological distress such as depression or anxiety. The aim of this study was to measure the correlation between perceived stigma and coping, and psychological distress as well as determine the predictors of psychological distress among the caregivers. Results showed that 31.5% of the caregivers experienced psychological distress. "Community rejection" was found to be positively associated with psychological distress. In case of coping subscales, psychological distress had a positive correlation with substance use, use of emotional support, behavioral disengagement, venting, and self-blame, while it was negatively correlated with "positive reframing". Behavioral disengagement was the best predictor of psychological distress among caregivers of patients with schizophrenia, followed by positive reframing, use of emotional support, self-blame, and venting. Health practitioners can use adaptive coping strategies instead of maladaptive for caregivers to help ease their distress and prevent further deterioration of psychological disorders.
    Study site: Psychiatric Clinic, Hospital Canselor Tuanku Muhriz (Pusat Perubatan Universiti Kebangsaan Malaysia, PPUKM)
    Scales & Questionnaire: Kessler’s K10
    Psychological Distress Scale; Devaluation of Consumer Scale (DCS); Devaluation of Consumer Families Scale (DCFS); Brief COPE
  10. Ibrahim N, Ong HC, Wahab S
    Malays J Med Sci, 2017 May;24(3):83-91.
    PMID: 28814936 MyJurnal DOI: 10.21315/mjms2017.24.3.10
    INTRODUCTION: Caregivers often experience stressful situations while in the midst of the caregiving process. Thus, various methods of coping have been widely applied and studied in previous researches. The aim of this study was to develop a novel questionnaire to assess the coping strategies employed by those who provide care to patients, and to further validate it among caregivers of schizophrenia patients in Malaysia.

    METHODS: This study, which involved the caregivers of schizophrenia patients from a hospital in Kuala Lumpur, Malaysia, was comprised of three parts, namely in-depth interviews, a pilot study, and the validation of the developed questionnaire, known as Caregiver Cope (CgCopeTM).

    RESULTS: Part A originally consisted of eight themes, and it was later modified to seven themes with four items each after discussions with some experts. Part B initially had 28 items derived from the seven themes in Part A, which were then reduced to six components after a factor analysis. Part C of the questionnaire consisted of 19 items, with six components (Distraction, Caring for patient, Venting, Religion, Recreation, and Social support) having a moderate to high reliability ranging from a Cronbach's alpha coefficient of 0.54 to 0.82. A factor analysis showed that the six factors of coping accounted for 62.36% of the total variance.

    CONCLUSION: The CgCOPETM questionnaire is suitable for use among caregivers of schizophrenia patients. There is a need to further validate the instrument among caregivers of other patient populations.

  11. Ong HC, Teo SP
    Med J Malaysia, 1976 Sep;31(1):42-5.
    PMID: 1023012
  12. Ong HC, Soo KL
    Med J Malaysia, 2006 Dec;61(5):616-20.
    PMID: 17623964 MyJurnal
    It has been almost two decades ago since the first AIDS case was reported in Malaysia. It has also been approximately eight years ago when the method of backcalculation was used to estimate the past HIV infection rate from the AIDS incidence data and an estimate of the incubation period distribution. This method is used because it makes use of the Malaysian AIDS incidence which is fairly reliable and reflects the trend of the epidemic as compared to the HIV infection rate recorded. The latest results generated show a slowdown in the increase of the number of estimated infected HIV+ cases in the late 1990s and this trend is supported by a slowdown in the increase of the number of AIDS cases recorded.
  13. Lai NM, Yap AQY, Ong HC, Wai SX, Yeo JHH, Koo CYE, et al.
    Neonatology, 2021;118(3):259-263.
    PMID: 33780936 DOI: 10.1159/000514402
    INTRODUCTION: Composite outcomes are used to increase the power of a study by combining event rates. Many composite outcomes in adult clinical trials have components that differ substantially in patient importance, event rate, and effect size, making interpretation challenging. Little is known about the use of composite outcomes in neonatal randomized controlled trials (RCTs).

    METHODS: We assessed the use of composite outcomes in neonatal RCTs included in Cochrane Neonatal reviews published till November 2017. Two authors reviewed the components of the composite outcomes to compare their patient importance and computed the ratios of effect sizes and event rates between the components, with an a priori threshold of 1.5, indicating a substantial difference. Descriptive statistics were presented.

    RESULTS: We extracted 7,766 outcomes in 2,134 RCTs in 312 systematic reviews. Among them, 55 composite outcomes (0.7%) were identified in 46 RCTs. The vast majority (92.7%) of composite outcomes had 2 components, with death being the most common component (included 51 times [92.7%]). The components in nearly three-quarters of the composite outcomes (n = 40 [72.7%]) had different patient importance, while the effect sizes and event rates differed substantially between the components in 27 (49.1%) and 35 (63.6%) outcomes, respectively, with up to 43-fold difference in the event rates observed.

    CONCLUSIONS: The majority of composite outcomes in neonatal RCTs had different patient importance with contrasting effect sizes and event rates between the components. In patient communication, clinicians should highlight individual components, rather than the composites, with explanation on the relationship between the components, to avoid misleading impression on the effect of the intervention. Future trials should report the estimates of all individual components alongside the composite outcomes presented.

  14. Chan YS, Cheah YH, Chong PZ, Khor HL, Teh WS, Khoo KS, et al.
    Pak J Pharm Sci, 2018 Jan;31(1):119-127.
    PMID: 29348093
    This study was conducted to investigate the antifungal potential and cytotoxicity of selected medicinal plants from Malaysia. The extracts from the stem of Cissus quadrangularis and the leaves of Asplenium nidus, Pereskia bleo, Persicaria odorata and Sauropus androgynus were assayed against six fungi using p-iodonitrotetrazolium-based on colorimetric broth microdilution method. All the plant extracts were found to be fungicidal against at least one type of fungus. The strongest fungicidal activity (minimum fungicidal concentration=0.16 mg/mL) were exhibited by the hexane extract of C. quadrangularis, the hexane, chloroform, ethanol and methanol extracts of P. bleo, the hexane and ethyl acetate extracts of P. odorata, and the water extract of A. nidus. In terms of cytotoxicity on the African monkey kidney epithelial (Vero) cells, the chloroform extract of P. odorata produced the lowest 50% cytotoxic concentration (100.3 ± 4.2 μ g/mL). In contrast, none of the water extracts from the studied plants caused significant toxicity on the cells. The water extract of A. nidus warrants further investigation since it showed the strongest fungicidal activity and the highest total activity (179.22 L/g) against Issatchenkia orientalis, and did not cause any toxicity to the Vero cells.
  15. Ong HC, Chan WF, Sinnathuray TA
    Med J Malaysia, 1978 Mar;32(3):217-9.
    PMID: 683046
  16. Ong HC, White JC, Sinnathuray TA
    Acta Haematol., 1977;58(4):229-33.
    PMID: 410224 DOI: 10.1159/000207832
    A case of haemoglobin H (HbH) disease associated with pregnancy is presented and discussed in the light of reports in the literature. The variable symptomatology is commented upon, although mild to moderate chronic haemolytic anaemia seems to be a constant feature. The roles of folic acid supplements and of splenectomy; the avoidance of oxidant drugs, and the mode of inheritance in HbH disease are briefly commented upon. Available reports indicate that HbH disease probably has no adverse effect on pregnancy. However, the association of the two conditions is uncommon, and reports are too few, therefore, to allow definite conclusions on the outcome in all instances.
  17. Damanik N, Ong HC, Tong CW, Mahlia TMI, Silitonga AS
    Environ Sci Pollut Res Int, 2018 Jun;25(16):15307-15325.
    PMID: 29721797 DOI: 10.1007/s11356-018-2098-8
    Biodiesels have gained much popularity because they are cleaner alternative fuels and they can be used directly in diesel engines without modifications. In this paper, a brief review of the key studies pertaining to the engine performance and exhaust emission characteristics of diesel engines fueled with biodiesel blends, exhaust aftertreatment systems, and low-temperature combustion technology is presented. In general, most biodiesel blends result in a significant decrease in carbon monoxide and total unburned hydrocarbon emissions. There is also a decrease in carbon monoxide, nitrogen oxide, and total unburned hydrocarbon emissions while the engine performance increases for diesel engines fueled with biodiesels blended with nano-additives. The development of automotive technologies, such as exhaust gas recirculation systems and low-temperature combustion technology, also improves the thermal efficiency of diesel engines and reduces nitrogen oxide and particulate matter emissions.
  18. Khoo KS, Chew KW, Ooi CW, Ong HC, Ling TC, Show PL
    Bioresour Technol, 2019 Oct;290:121794.
    PMID: 31319214 DOI: 10.1016/j.biortech.2019.121794
    This work aimed to study the application of liquid biphasic flotation (LBF) for the efficient and rapid recovery of astaxanthin from H. pluvialis microalgae. The performance of LBF for the extraction of astaxanthin was studied comprehensively under different operating conditions, including types and concentrations of food-grade alcohol and salt, volume ratio, addition of neutral salt, flotation period, and mass of dried H. pluvialis biomass powder. The maximum recovery, extraction efficiency and partition coefficient of astaxanthin obtained from the optimum LBF system were 95.11 ± 1.35%, 99.84 ± 0.05% and 385.16 ± 3.87, respectively. A scaled-up LBF system was also performed, demonstrating the feasibility of extracting natural astaxanthin from microalgae at a larger scale. This exploration of LBF system opens a promising avenue to the extraction of astaxanthin at lower cost and shorter processing time.
  19. Phwan CK, Chew KW, Sebayang AH, Ong HC, Ling TC, Malek MA, et al.
    Biotechnol Biofuels, 2019;12:191.
    PMID: 31384298 DOI: 10.1186/s13068-019-1533-5
    Background: Microalgae are one of the promising feedstock that consists of high carbohydrate content which can be converted into bioethanol. Pre-treatment is one of the critical steps required to release fermentable sugars to be used in the microbial fermentation process. In this study, the reducing sugar concentration of Chlorella species was investigated by pre-treating the biomass with dilute sulfuric acid and acetic acid at different concentrations 1%, 3%, 5%, 7%, and 9% (v/v).

    Results: 3,5-Dinitrosalicylic acid (DNS) method, FTIR, and GC-FID were employed to evaluate the reducing sugar concentration, functional groups of alcohol bonds and concentration of bioethanol, respectively. The two-way ANOVA results (p 

  20. Mofijur M, Ahmed SF, Rahman SMA, Arafat Siddiki SY, Islam ABMS, Shahabuddin M, et al.
    Environ Res, 2021 04;195:110857.
    PMID: 33581088 DOI: 10.1016/j.envres.2021.110857
    The nature of micro- and nanoplastics and their harmful consequences has drawn significant attention in recent years in the context of environmental protection. Therefore, this paper aims to provide an overview of the existing literature related to this evolving subject, focusing on the documented human health and marine environment impacts of micro- and nanoplastics and including a discussion of the economic challenges and strategies to mitigate this waste problem. The study highlights the micro- and nanoplastics distribution across various trophic levels of the food web, and in different organs in infected animals which is possible due to their reduced size and their lightweight, multi-coloured and abundant features. Consequently, micro- and nanoplastics pose significant risks to marine organisms and human health in the form of cytotoxicity, acute reactions, and undesirable immune responses. They affect several sectors including aquaculture, agriculture, fisheries, transportation, industrial sectors, power generation, tourism, and local authorities causing considerable economic losses. This can be minimised by identifying key sources of environmental plastic contamination and educating the public, thus reducing the transfer of micro- and nanoplastics into the environment. Furthermore, the exploitation of the potential of microorganisms, particularly those from marine origins that can degrade plastics, could offer an enhanced and environmentally sound approach to mitigate micro- and nanoplastics pollution.
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