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  1. Fulltext 1,10-Phenanthrolin-1-ium hydrogen d,l-tartrate dihydrate
    Cheng SF, Ng SW
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jun 01;67(Pt 6):o1306.
    PMID: 21754708 DOI: 10.1107/S1600536811015972
    In the title hydrated molecular salt, C(12)H(9)N(2) (+)·C(4)H(5)O(6) (-)·2H(2)O, the cation is almost planar (r.m.s. deviation = 0.014 Å); the carbon skeleton of the anion assumes a trans conformation [C-C-C-C torsion angle = -179.86 (14)°]. The carboxyl end of one hydrogen tartrate anion forms a short hydrogen bond to the carboxyl-ate end of another anion [O⋯O = 2.508 (2) Å] in a head-to-tail manner, forming a chain; the chains and water mol-ecules inter-act, generating an O-H⋯O hydrogen-bonded layer. The cation binds to the layer by an N-H⋯O hydrogen bond.
  2. A combined microwave pretreatment/solvent extraction process for the production of oil from palm fruit: optimisation, oil quality and effect of prolonged exposure
    Tan JC, Chuah CH, Cheng SF
    J Sci Food Agric, 2017 Apr;97(6):1784-1789.
    PMID: 27470073 DOI: 10.1002/jsfa.7975
    BACKGROUND: Conventional palm oil milling involves multiple stages after fruit collection; in particular, oil clarification introduces water into the pressed oil, which results in a large quantity of wastewater.

    RESULTS: A combined process of microwave pretreatment and solvent extraction to mill crude palm oil, without introducing water or steam, is described. An excellent yield (up to 30%) of oil was obtained with pretreatment in a 42 L, 1000 W and 2450 MHz microwave oven followed by hexane extraction. The optimum conditions (10 min microwave pretreatment and 12 h solvent extraction) yielded an oil with a low free fatty acid content (<1.0%) and an acceptable anisidine value (<3.0 meq kg(-1) ). The oil had a fatty acid composition not resembling those of conventional crude palm oil and crude palm kernel oil. In the pretreatment, the leached oil had 6.3% lauric acid whereas the solvent extracted oil had only 1.5% lauric acid. Among the factors affecting the oil quality, microwave pretreatment affected the oil quality significantly; however, an optimised duration that would ensure high efficiency in solvent extraction also resulted in ruptured fruitlets, although not to the extent of causing excessive oxidation. In fact, microwave pretreatment should exceed 12 min; after only 15 min, the oil had 1-methylcyclopentanol (12.96%), 1-tetradecanol (9.44%), 1-nonadecene (7.22%), nonanal (7.13%) and 1-tridecene (5.09%), which probably arose from the degradation of fibres.

    CONCLUSION: Microwave pretreatment represents an alternative milling process for crude palm oil compared with conventional processes in the omission of wet treatment with steam. © 2016 Society of Chemical Industry.

  3. Fulltext Enzymatic synthesis of structured lipids with behenic acid at the sn-1, 3 positions of triacylglycerols
    Kok WM, Chuah CH, Cheng SF
    Food Sci Biotechnol, 2018 Apr;27(2):353-366.
    PMID: 30263758 DOI: 10.1007/s10068-017-0271-3
    A long chain saturated fatty acid (SFA), behenic acid, is incorporated into the sn-1, 3 positions of triacylglycerols in palm olein (POo) and high-oleic sunflower oil (HOS) by solvent-free interesterification catalyzed by Lipozyme RM IM. The enzymatic interesterified HOS (EIE-HOS) yielded 76.5% of BOO and BOB as compared to 45.6% in POo (EIE-POo). The sn-2 position of EIE-HOS displayed 5.3 mol% of SFA which is significantly lower compared to 13.5 mol% in EIE-POo (P 
  4. Stearic acids at sn-1, 3 positions of TAG are more efficient at limiting fat deposition than palmitic and oleic acids in C57BL/6 mice
    Gouk SW, Cheng SF, Ong AS, Chuah CH
    Br J Nutr, 2014 Apr 14;111(7):1174-80.
    PMID: 24286356 DOI: 10.1017/S0007114513003668
    In the present study, we investigated the effect of long-acyl chain SFA, namely palmitic acid (16:0) and stearic acid (18:0), at sn-1, 3 positions of TAG on obesity. Throughout the 15 weeks of the experimental period, C57BL/6 mice were fed diets fortified with cocoa butter, sal stearin (SAL), palm mid fraction (PMF) and high-oleic sunflower oil (HOS). The sn-1, 3 positions were varied by 16:0, 18:0 and 18:1, whilst the sn-2 position was preserved with 18:1. The HOS-enriched diet was found to lead to the highest fat deposition. This was in accordance with our previous postulation. Upon normalisation of total fat deposited with food intake to obtain the fat:feed ratio, interestingly, mice fed the SAL-enriched diet exhibited significantly lower visceral fat/feed and total fat/feed compared with those fed the PMF-enriched diet, despite their similarity in SFA-unsaturated fatty acid-SFA profile. That long-chain SFA at sn-1, 3 positions concomitantly with an unsaturated FA at the sn-2 position exert an obesity-reducing effect was further validated. The present study is the first of its kind to demonstrate that SFA of different chain lengths at sn-1, 3 positions exert profound effects on fat accretion.
  5. Biological properties of sodium alkyl methyl ester sulfonate/alkyltrimethylammonium bromide surfactant mixtures
    Wong SP, Lim WH, Cheng SF, Chuah CH
    Colloids Surf B Biointerfaces, 2012 Jan 1;89:48-52.
    PMID: 21937202 DOI: 10.1016/j.colsurfb.2011.08.021
    Quaternary ammonium compounds (QACs) are commonly used as disinfectant in medical care, food industry, detergents and glue industries. This is due to a small concentration of QACs is sufficient to inhibit the growth of various bacteria strains. In this work, the inhibitive power of cationic surfactants, alkyltrimethylammonium bromide (C(n)TAB) in the presence of anionic surfactants, sodium alkyl methyl ester α-sulfonate (C(n)MES) was studied. The growth inhibition test with gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria were used to determine the toxicity of single and mixed surfactants. Results from this work showed that certain mixed surfactants have lower minimum inhibition concentration (MIC) as compared to the single C(n)TAB surfactants. Besides that, it was also found that alkyl chain length and the mixing ratios of the surfactants play a significant role in determining the mixture inhibitive power.
  6. Long-chain SFA at the sn-1, 3 positions of TAG reduce body fat deposition in C57BL/6 mice
    Gouk SW, Cheng SF, Mok JS, Ong AS, Chuah CH
    Br J Nutr, 2013 Dec 14;110(11):1987-95.
    PMID: 23756564 DOI: 10.1017/S0007114513001475
    The present study aimed to determine the effect of positional distribution of long-chain SFA in TAG, especially at the sn-1, 3 positions, on fat deposition using the C57BL/6 mouse model. Throughout the 15 weeks of the study, mice were fed with diets fortified with palm olein (POo), chemically interesterified POo (IPOo) and soyabean oil (SOY). Mice receiving the SOY-enriched diet gained significantly higher amounts of subcutaneous fat (P= 0·011) and total fat (P= 0·013) compared with the POo group, despite similar body mass gain being recorded. During normalisation with food consumption to obtain the fat:feed ratio, mice fed with the POo-enriched diet exhibited significantly lower visceral (P= 0·044), subcutaneous (P= 0·006) and total (P= 0·003) fat:feed than those fed with the SOY-enriched diet. It is noteworthy that mice fed with the IPOo-enriched diet gained 14·3 % more fat per food consumed when compared with the POo group (P= 0·013), despite their identical total fatty acid compositions. This was mainly attributed to the higher content of long-chain SFA at the sn-1, 3 positions of TAG in POo, which results in delayed absorption after deacylation as evidenced by the higher amounts of long-chain SFA excreted in the faeces of mice fed with the POo-enriched diet. Negative correlations were found between the subcutaneous, visceral as well as total fat accretion per food consumption and the total SFA content at the sn-1, 3 positions, while no relationships were found for MUFA and PUFA. The present results show that the positional distribution of long-chain SFA exerts a more profound effect on body fat accretion than the total SFA content.
  7. Fulltext Bioethanol production from agarophyte red seaweed, Gelidium elegans, using a novel sample preparation method for analysing bioethanol content by gas chromatography
    Hessami MJ, Cheng SF, Ambati RR, Yin YH, Phang SM
    3 Biotech, 2019 Jan;9(1):25.
    PMID: 30622863 DOI: 10.1007/s13205-018-1549-8
    In this study, Gelidium elegans is investigated for ethanol production. A combination of factors including different temperatures, acid concentration and incubation time was evaluated to determine the suitable saccharification conditions. The combination of 2.5% (w/v) H2SO4 at 120 °C for 40 min was selected for hydrolysis of the seaweed biomass, followed by purification, and fermentation to yield ethanol. The galactose and glucose were dominant reducing sugars in the G. elegans hydrolysate and under optimum condition of dilute acid hydrolysis, 39.42% of reducing sugars was produced and fermentation resulted in ethanol concentration of 13.27 ± 0.47 g/L. A modified method was evaluated for sample preparation for gas chromatography (GC) analysis of the ethanol content. A solvent mixture of acetonitrile and iso-butanol precipitated dissolved organic residues and reduced water content in GC samples at least by 90%. Results showed that this method could be successfully used for bioethanol production from seaweed.
  8. Fulltext Production of Biodegradable Palm Oil-Based Polyurethane as Potential Biomaterial for Biomedical Applications
    Yeoh FH, Lee CS, Kang YB, Wong SF, Cheng SF, Ng WS
    Polymers (Basel), 2020 Aug 17;12(8).
    PMID: 32824514 DOI: 10.3390/polym12081842
    Being biodegradable and biocompatible are crucial characteristics for biomaterial used for medical and biomedical applications. Vegetable oil-based polyols are known to contribute both the biodegradability and biocompatibility of polyurethanes; however, petrochemical-based polyols were often incorporated to improve the thermal and mechanical properties of polyurethane. In this work, palm oil-based polyester polyol (PPP) derived from epoxidized palm olein and glutaric acid was reacted with isophorone diisocyanate to produce an aliphatic polyurethane, without the incorporation of any commercial petrochemical-based polyol. The effects of water content and isocyanate index were investigated. The polyurethanes produced consisted of > 90% porosity with interconnected micropores and macropores (37-1700 µm) and PU 1.0 possessed tensile strength and compression stress of 111 kPa and 64 kPa. The polyurethanes with comparable thermal stability, yet susceptible to enzymatic degradation with 7-59% of mass loss after 4 weeks of treatment. The polyurethanes demonstrated superior water uptake (up to 450%) and did not induce significant changes in pH of the medium. The chemical changes of the polyurethanes after enzymatic degradation were evaluated by FTIR and TGA analyses. The polyurethanes showed cell viability of 53.43% and 80.37% after 1 and 10 day(s) of cytotoxicity test; and cell adhesion and proliferation in cell adhesion test. The polyurethanes produced demonstrated its potential as biomaterial for soft tissue engineering applications.
  9. Fulltext Light-responsive polyurethanes: classification of light-responsive moieties, light-responsive reactions, and their applications
    Lam KY, Lee CS, Pichika MR, Cheng SF, Hang Tan RY
    RSC Adv, 2022 May 17;12(24):15261-15283.
    PMID: 35693222 DOI: 10.1039/d2ra01506d
    Stimuli responsiveness has been an attractive feature of smart material design, wherein the chemical and physical properties of the material can be varied in response to small environmental change. Polyurethane (PU), a widely used synthetic polymer can be upgraded into a light-responsive smart polymer by introducing a light-sensitive moiety into the polymer matrix. For instance, azobenzene, spiropyran, and coumarin result in reversible light-induced reactions, while o-nitrobenzyl can result in irreversible light-induced reactions. These variations of light-stimulus properties endow PU with wide ranges of physical, mechanical, and chemical changes upon exposure to different wavelengths of light. PU responsiveness has rarely been reviewed even though it is known to be one of the most versatile polymers with diverse ranges of applications in household, automotive, electronic, construction, medical, and biomedical industries. This review focuses on the classes of light-responsive moieties used in PU systems, their synthesis, and the response mechanism of light-responsive PU-based materials, which also include dual- or multi-responsive light-responsive PU systems. The advantages and limitations of light-responsive PU are reviewed and challenges in the development of light-responsive PU are discussed.
  10. Enhanced assembly stability for amine-based cationic glycolipid
    Aravindan D, Alagan AA, Heidelberg T, Cheng SF, Duali Hussen RS
    Carbohydr Res, 2024 Jul 29;543:109224.
    PMID: 39084163 DOI: 10.1016/j.carres.2024.109224
    Glycolipids incorporating positive charges, mediated by an imidazolium cation, have shown potential for effective formulation of vesicular drug carriers, reflecting repulsive electrostatic forces, promoting the formation of nanosized assemblies and preventing unwanted Oswald ripening (Goh et al. (2019), ACS Omega 4, 17,039). Our continuous development of an assembly-based drug delivery system prompted us to investigate a pH-sensitive analogue, leading to the synthesis of a 6-amino-Guerbet glycoside. However, in contrast to the imidazolium counterpart, the amine-mediated charge increased the intermolecular cohesions, furnishing bigger assemblies instead, which further increased upon introduction of acid. Moreover, assemblies exhibited a significantly reduced positive charge density. It is concluded that strong proton-initiated hydrogen bonding between amino groups provide cohesive head group interactions overcompensating possible repulsive charge interactions. While this behavior invalidates the application of the amino-glucoside as dispersing agent for the formulation of small vesicles, it potentially paves a route towards enhanced vesicle stability.
  11. Fulltext Dietary supplements: usage and opinions among health sciences students
    Teng CL, Tey KK, Lim PH, Cheng SF, Nordin MS, Ng CM, et al.
    International e-Journal of Science, Medicine & Education, 2008;2(2):30-32.
    MyJurnal
    This is a questionnaire survey of dietary supplement usage among students in the International Medical University. Just over two-fifths of these students reported using dietary supplements daily. This high usage of dietary supplements is in contrast their expressed ambivalence about these products.
  12. The Outcome of the Elderly Living Kidney Donors in a Single Tertiary Center in Malaysia
    Goh ET, Jalalonmuhali M, Ng KP, Wan Md Adnan AH, Hing Wong A, Cheng SF, et al.
    Transplant Proc, 2022 Feb 04.
    PMID: 35131101 DOI: 10.1016/j.transproceed.2021.12.039
    Living-kidney transplantation increases with years, however, the rate is comparatively low to support local needs. Marginal living donors like the elderly were used to increase the donor pool. We retrospectively evaluate the outcome of 25 elderly living kidney donors (eLKDs) who were ≥60 years old at the time of donation in our center. Their medical history and laboratory results were analyzed retrospectively from e-medical records. There are 16 females (64.0%) with a median age of 63 (60.5-66.0). The mean follow-up duration was 4.36 ± 2.46 years. Their mean body mass index increased from 23.70 ± 3.07 kg/m2 to 24.21 ± 2.93 kg/m2 (t[14] = -2.176, P = .047) post donation. Systolic blood pressure (SBP) increased from 133.33 ± 11.65 mm Hg to 140.56 ± 17.78 mm Hg (t[17] = -2.124, P = .049). However, the prevalence of overweight and hypertension were not significant. Only 5.56% of the eLKDs developed proteinuria post nephrectomy (P =1.000). Serum creatinine increased from 62.33 ± 14.39 mmol/L to 104.63 ± 28.53 mmol/L post 1-month donation (t[23] = -9.720, P = .000) and decreased to 99.67 ± 22.39 mmol/L post 1-year donation (t[17] = -8.415, P = .006), and latest results were 94.28 ± 20.74mmol/L (t[17] = -6.630, P = .033). Fasting blood glucose and HbA1c level recorded no significant changes post donation. We noted that 47.62% of the eLKDs had dyslipidemia pre donation, which increased to 76.20% post donation (P = .031). eLKDs with hyperuricemia increased significantly from 5.88% to 52.94%; with uric acid level from 306.12 ± 68.67 umol/L to 412.24 ± 74.14 umol/L (t[16] = -7.726, P = .000). None of the eLKDs were diagnosed with metabolic syndrome pre and post kidney donation. Postdonation kidney function of the eLKDs compensated well and were stable in the short term. We noted statistically significant increments of weight, body mass index, SBP, uric acid, and lipid levels, which did not translate to clinical significance post donation. Elderly living-kidney donation can be done safely with close monitoring post donation.
  13. The Effects of Different Induction Regimes on Serial Lymphocyte Subsets in Kidney Transplant Recipients: A Single Tertiary Center Experience
    Jalalonmuhali M, Ng KP, Lee YW, Gan CC, Hing Wong A, Wan Md Adnan WAH, et al.
    Transplant Proc, 2022 Feb 15.
    PMID: 35181166 DOI: 10.1016/j.transproceed.2022.01.004
    BACKGROUND: Immunosuppressive therapy is the backbone of kidney transplantation in preventing acute rejection. T-cell depletion after doses of thymoglobulin is dose-dependent, as are their side effects. At the same time, basiliximab and other maintenance immunosuppressive drugs act at different signals on T lymphocytes. Therefore, studying the pattern of lymphocyte subset depletion depending on the induction regime given at transplantation could be an added tool in managing post-transplant recipients.

    METHODOLOGY: This prospective observational study recruited kidney transplant recipients from August 2019 through April 2021 at the University of Malaya Medical Centre. Blood tests for lymphocyte subsets were taken at pre-transplant, 1 week, 1 month, 3 months, and 6 months post-transplantation. At transplantation, recipients received either basiliximab, low-dose thymoglobulin (cumulative dose: 1.5 mg/kg), or standard-dose thymoglobulin (cumulative dose: 5 mg/kg).

    RESULTS: A total of 39 patients were recruited: 38.5% received basiliximab (15 of 39), 15.4% received low-dose thymoglobulin (6 of 39), and 46.2% received standard-dose thymoglobulin (18 of 39). Absolute lymphocyte counts 1 week post-transplantation were 1.5 ± 0.84 × 109/L for basiliximab, 0.7 ± 0.57 × 109/L for low-dose thymoglobulin, and 0.1 ± 0.08 × 109/L for standard-dose thymoglobulin (P < .001). The CD4+ and CD8+ counts were severely depleted in the standard-dose thymoglobulin group, with a statistically significant differenceup to 6 months post-transplantation. In the low-dose thymoglobulin group, the CD4+ and CD8+ counts were depleted at 1 week post-transplantation and recovered at 1 month post-transplantation. There was no difference in allograft function and incidence of allograft rejection across groups.

    CONCLUSIONS: The effects on lymphocyte counts, CD4+ and CD8+, vary depending on the type and dose of induction immunosuppression. This could be a guiding tool in managing immunosuppression post-transplantation depending on the patient's immunologic risk.

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