Displaying publications 1 - 20 of 77 in total

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  1. Gan CY
    Med J Malaysia, 1981 Jun;36(2):70-5.
    PMID: 7343821
    In the outbreak of cholera in Perak in 1978, a study on 179 cholera patients (cases) from 8 health districts in the state indicated that those afflicted with the disease were from the rural areas, belonged to the lower socio-economic class and had little or no formal education. Under such conditions, it is expected that personal hygiene may not be satisfactory and person to person contact could play an important role in the transmission of the disease especially among those living in close contact. 34.2 percent of the 164 households of the cholera patients contained injected household contacts. From 1 to 6 infected household contacts per household were found for household size ranging from 2 to 18. Ninetyjive (8.6 percent) of the total 1101 household contacts were injected. Only 8 of these 95 infected household contacts developed clinical symptoms giving a ratio of 1:12 symptomatic to inapparent injections. While most of the contacts probably acquired their infection from the patient who constitutes the index case, the role of the asymptomatic carrier in the transmission ofinjection cannot be underestimated.
  2. Gan CY
    PMID: 8629063
    A survey was conducted to document and bring attention to the use of smokeless tobacco among rural Kadazan women in Sabah, East Malaysia. Of the 472 women interviewed, 59.5% had used tobacco among the ingredients that they habitually chewed. Women with low education were more likely to be chewers. The chewing habit was usually acquired during the teenage years and the practice was perceived mainly as a cultural norm. 73.3% of these smokeless tobacco users were unaware of any adverse health effect of this type of tobacco use as compared to 53.9% of the non-tobacco users. The high prevalence of smokeless tobacco use is easily maintained as tobacco is cheap, locally produced and its use is socially accepted. The low level educational status of the women compounds the problem and intervention programs to curb this form of tobacco use is warranted.
  3. Gan CY
    PMID: 10437972
    As part of a larger study to bring attention to smoking and smokeless tobacco use among the indigenous people of Sabah State in Malaysia, the Bajaus were interviewed in a cross-sectional survey. 74.4% of the men smoked compared to 3.3% of the women and 77% of women used smokeless tobacco compared to 4.3% of men. Local handrolled cigarettes called kirais were popular and smokeless tobacco was used as an ingredient in the ritual of betel-quid chewing. Tobacco was also used because it was thought to have medicinal effects. The prevalence of smokeless tobacco use was significantly lower among the better educated women but for smoking, education had no relation with prevalence. Both habits could be easily maintained as they were cheap practices which were socially and culturally accepted. Awareness of the adverse effects of such tobacco habits was poor and intervention programs to curb tobacco use is required.
  4. Kamarudin F, Gan CY
    Int J Biol Macromol, 2016 Jul;88:280-7.
    PMID: 27044345 DOI: 10.1016/j.ijbiomac.2016.04.003
    Pinto bean pod polysaccharide (PBPP) was successfully extracted with yield of 38.5g/100g and the PBPP gave total carbohydrate and uronic acid contents of 286.2mg maltose equivalent/g and 374.3mgGal/g, respectively. The Mw of PBPP was 270.6kDa with intrinsic viscosity of 0.262dm(3)/g, which composed of mannose (2.5%), galacturonic acid (15.0%), rhamnose (4.0%), glucose (9.0%), galactose (62.2%), xylose (2.9%) and arabinose (4.3%) with trace amount of ribose and fucose. The result suggested that PBPP has a spherical conformation with a highly branched structure. Fourier Transform Infrared analysis showed that PBPP has a similar structure as commercial pectin with an esterification degree of 59.9%, whereas scanning electron microscopy study showed that the crude polysaccharide formed a thin layer of film that was made of multiple micro strands of fibre. PBPP exhibited substantial free radical scavenging activity (7.7%), metal reducing capability (2.04mmol/dm(3)) and α-amylase inhibitory activity (97.6%) at a total amount of 1mg. PBPP also exhibited high water- and oil-holding capacities (3.6g/g and 2.8g/g, respectively). At a low concentration, PBPP exhibited emulsifying activity of 39.6% with stability of 38.6%. Apart from that, PBPP was able to show thickening capability at low concentration (0.005kg/dm(3)).
  5. Gan CY, Yusof K
    PMID: 8266233
    A survey conducted to assess the extent which the urban poor in rapidly expanding Kuala Lumpur utilize maternal and child health services available to them. The sample consisted of 1,380 households with children below 6 years and yielded 1,233 children below 6 years of age. 74% of the children had been delivered in government hospitals and 86% of the pregnancies had antenatal care in governmental establishments. 89.2% had BCG immunization before they were 1 year old but 13.3% had not received DPT by that age. Immunization was mainly done in government clinics. The overall immunization coverage for the whole of Kuala Lumpur is expected to be higher than these figures limited to the urban poor. Health planners should increase health facilities in the city to accommodate the expanding population. There is a need to continually campaign for immunization to improve coverage among the urban poor.
  6. Siow HL, Gan CY
    Food Chem, 2013 Dec 15;141(4):3435-42.
    PMID: 23993504 DOI: 10.1016/j.foodchem.2013.06.030
    Antioxidative and antihypertensive bioactive peptides were successfully derived from Parkia speciosa seed using alcalase. The effects of temperature (25 and 50 °C), substrate-to-enzyme ratio (S/E ratio, 20 and 50), and incubation time (0.5, 1, 2 and 5h) were evaluated based on 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and angiotensin-converting enzyme (ACE) assays. Bioactive peptide extracted at a hydrolysis condition of: temperature=50 °C, S/E ratio=50 and incubation time=2h, exhibited the highest DPPH radical scavenging activity (2.9 mg GAE/g), reducing power (11.7 mM) and %ACE-inhibitory activity (80.2%). The sample was subsequently subjected to fractionation and the peptide fraction of <10 kDa showed the strongest bioactivities. A total of 29 peptide sequences from peptide fraction of <10 kDa were identified as the most potent contributors to the bioactivities. These novel bioactive peptides were suggested to be beneficial to nutraceutical and food industries.
  7. Tan HF, Gan CY
    Int J Biol Macromol, 2016 Apr;85:487-96.
    PMID: 26778156 DOI: 10.1016/j.ijbiomac.2016.01.023
    Functional polysaccharide was isolated from Momordica charantia, with a yield of 36% (w/w). M. charantia bioactive polysaccharide (MCBP) was an acidic and branched heteropolysaccharide with a molecular weight of 92 kDa. Fourier transform infrared spectroscopic analysis indicated that MCBP was a pectin-like polysaccharide with an esterification degree of 53% and it contains numerous monosaccharides, predominantly glucose, galactose, and galaturonic acid. The results also showed that MCBP exhibited free radical scavenging activity (31.9%), ferric reducing antioxidant power (0.95 mM), α-amylase inhibition (89.1%), and angiotensin-converting enzyme inhibition (94.1%). In the terms of functionality, MCBP showed a lower water-holding capacity but higher in oil-holding capacity, emulsifying activity and foaming capacity compared to citrus pectin. Scanning electron microscopy images demonstrated that MCBP formed gels with a porous structure, and flow analysis showed that the gel solution exhibited pseudoplastic shear-thinning behavior. These findings indicated that MCBP is a promising functional macromolecular carbohydrate for the food and nutraceutical industries.
  8. Ngoh YY, Gan CY
    Food Chem, 2016 Jan 1;190:331-7.
    PMID: 26212978 DOI: 10.1016/j.foodchem.2015.05.120
    Antioxidant and α-amylase inhibitor peptides were successfully extracted from Pinto bean protein isolate (PBPI) using Protamex. A factorial design experiment was conducted and the effects of extraction time, pH and temperature were studied. pH 7.5, extraction time of 1h, S/E ratio of 10 (w/w) and temperature of 50 °C gave the highest antioxidant activities (i.e., ABTS scavenging activity (53.3%) and FRAP value (3.71 mM)), whereas pH 6.5 with the same extraction time, S/E ratio and temperature, gave the highest α-amylase inhibitory activity (57.5%). It was then fractioned using membrane ultrafiltration with molecular weight cutoffs of 100, 50, 30, 10 and 3 kDa. Peptide fraction <3 kDa, which exhibited the highest antioxidant activities (i.e., ABTS (42.2%) and FRAP (0.81 mM)) and α-amylase inhibitory activity (62.1%), was then subjected to LCMS and MS/MS analyses. Six sequences were identified for antioxidant peptides, whereas seven peptides for α-amylase inhibitor.
  9. Yap PG, Gan CY
    Foods, 2021 Mar 22;10(3).
    PMID: 33810046 DOI: 10.3390/foods10030675
    Nature-derived tyrosinase inhibitors are of great industrial interest. Three monophenolase inhibitor peptides (MIPs) and three diphenolase inhibitor peptides (DIPs) from a previous study were investigated for their in vitro tyrosinase inhibitory effects, mode of inhibition, copper-chelating activity, sun protection factor (SPF) and antioxidant activities. DIP1 was found to be the most potent tyrosinase inhibitor (IC50 = 3.04 ± 0.39 mM), which could be due to the binding interactions between its aromatic amino acid residues (Y2 and D7) with tyrosinase hotspots (H85, V248, H258, H263, F264, R268, V283 and E322) and its ability to chelate copper ion within the substrate-binding pocket. The conjugated planar rings of tyrosine and tryptophan may interact with histidine within the active site to provide stability upon enzyme-peptide binding. This postulation was later confirmed as the Lineweaver-Burk analysis had identified DIP1 as a competitive inhibitor and DIP1 also showed 36.27 ± 1.17% of copper chelating activity. In addition, DIP1 provided the highest SPF value (11.9 ± 0.04) as well as ferric reducing antioxidant power (FRAP) (5.09 ± 0.13 mM FeSO4), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) (11.34 ± 0.90%) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (29.14 ± 1.36%) free radical scavenging activities compared to other peptides. These results demonstrated that DIP1 could be a multifunctional anti-tyrosinase agent with pharmaceutical and cosmeceutical applications.
  10. Ngoh YY, Gan CY
    Food Chem, 2018 Nov 30;267:124-131.
    PMID: 29934146 DOI: 10.1016/j.foodchem.2017.04.166
    Five Pinto bean peptides with α-amylase and angiotensin converting enzyme (ACE) inhibitory activities were successfully identified using the integrated bioinformatics approach. By using PEAKS studio, 511 peptide sequences were first shortlisted based on their de novo sequence property and average local confidence (ALC) yield of ≥60%. Subsequently, only five peptides were found to have high potential (score ≥0.80) for contributing bioactivy. The important sites which were potentially bound by the peptides: (a) Trp58, Trp59, Tyr 62, Asp96, Arg195, Asp197, Glu233, His299, Asp300 and His305 for α-amylase; (b) His353, Ala354, His383, Glu384, His387, Glu411, Lys511, His513, Tyr520 and Tyr523 for ACE had corresponded to the catalytic and substrate binding sites of the two enzymes. A validation assay was then conducted and IC50 values were determined. The range of the values for α-amylase inhibitory activity was 10.03-23.33mM, whereas the values for ACE inhibitory activity were of 1.52-31.88μM.
  11. Shafie MH, Gan CY
    Int J Biol Macromol, 2020 Apr 15;149:835-843.
    PMID: 32027904 DOI: 10.1016/j.ijbiomac.2020.02.013
    The deep eutectic solvents (DESs), which were made from different molar ratios (3:1, 2:1, 1:1, 1:2, 1:3) of choline chloride and citric acid monohydrate, were used as media for the pectic polysaccharide extraction from Averrhoa bilmbi (ABP). The physico-chemical, structural, functional and antioxidant properties of ABP were subsequently determined. The ABP was found to be xylogalacturonan. Moreover, results showed that different structures (i.e. linearity of pectin and branch size) of ABP were obtained, hence, affecting the solubility and functional properties due to the surface availability and steric effect. In addition, when increasing the molar ratio of citric acid monohydrate in DES, lower pH and higher TPC values were observed. These values were correlated with antioxidant activities (i.e. free radical scavenging activity and ferric reducing antioxidant power) of ABP. In conclusion, the molar ratio of the DES components plays an important role in extracting ABP with the aforementioned properties.
  12. Olalere OA, Gan CY
    Food Chem, 2023 May 30;409:135224.
    PMID: 36577323 DOI: 10.1016/j.foodchem.2022.135224
    This is the first study to provide a preliminary investigation into the recovery of protein from wheat germ and the prediction of their extraction conditions in microwave cavity using a novel DES solvent. The response surface methodology was used to predict the microwaved protein extraction conditions of the DWG. The effects of DES buffer-concentration (X1: 0.01-1.00 g/mL), microwave power (X2: 50-250 W), irradiation time (X3: 1-5 min) and sample-to-buffer ratio (X4: 1:10-1:50) were tested using a single factor and Box-Behnken experimental design. Under the optimized conditions (X1 = 0.52 g/mL, X2 = 186 W, X3 = 3.28 min, and X4 = 1:39) protein yield and absorbed microwave were obtained at the optimal value of 33.00 % and 677 J/min, respectively with no denaturation of the protein as validated from the SDS-PAGE gel electrophoresis profile. Consequently, this investigation provides a practical approach for the extraction of bioactive protein from DWG using a novel deep eutectic solvent.
  13. Yap PG, Gan CY
    Biochim Biophys Acta Gen Subj, 2024 Jan;1868(1):130503.
    PMID: 37923180 DOI: 10.1016/j.bbagen.2023.130503
    BACKGROUND: Bioactive peptides have gained attention as potential alternatives to chemical-based skin lightening agents. Based on literature search, the reported articles focused mainly on the sources and preparation methods of tyrosinase inhibitory peptides and there is lacking information regarding the structure-activity relationship (SAR) between peptide property and tyrosinase inhibition. It was hypothesized that peptide properties such as hydrophobicity/hydrophilicity and the amino acid type and position/arrangement at the terminal positions could affect peptide mode of binding hence result in various degrees of tyrosinase inhibition.

    METHODS: In this study, the sequences of 128 tyrosinase inhibitory peptides were collected from peer-reviewed articles. The hydrophobicity/hydrophilicity property and the amino acid profile of peptides at the N- and C-terminals were analyzed using bioinformatics tools. Molecular docking analysis was employed to further elucidate the roles of reactive amino acids in tyrosinase-peptide binding interactions. The peptide-regulated intracellular melanogenesis pathways were also compiled and discussed.

    RESULTS: It was found that hydrophobic and/or polar neutral properties may facilitate or stabilize peptide binding with tyrosinase. Moreover, short peptides featuring a cysteine and tyrosine at the N- and C- terminal ultimate positions tend to bind to the active site of tyrosinase whereas positively charged amino acid such as arginine at the N-terminal does not favor peptide binding to tyrosinase.

    CONCLUSIONS: These findings provide detailed explanation on how peptide/amino acid structures are related and what function they play in tyrosinase inhibition. It could also inspire researchers to account for tyrosinase-peptide SAR and the underlying anti-melanogenesis mechanisms in formulating peptide-based treatments or strategies against skin hyperpigmentation.

  14. Gan CY, Chan MK
    PMID: 8160073
    A survey was conducted to document the blood pressures of two indigenous groups (Kadazans and Bajaus) who reside in rural Sabah in East Malaysia. Their health knowledge status is also recorded. Fifty percent of those surveyed were unable to associate high blood pressure with a risk factor and as high as 38% were unaware of the consequences of high blood pressure. A total of 16.2% had blood pressures > or = 140/or 90mm Hg while 3.9% had blood pressures > or = 160/or 95mm Hg. While these figures are low compared to those of developed countries, lifestyle changes associated with rapid urbanization in Malaysia may be expected to increase hypertension prevalence. The strengthening of health education programs is timely as health knowledge is limited and many hypertensives default treatment.
  15. Khor GL, Gan CY
    Asia Pac J Clin Nutr, 1992 Sep;1(3):159-68.
    PMID: 24323170
    Non-communicable diseases with dietary implications, ischaemic heart disease, diabetes mellitus and cancers of the breast and colon are discussed in relation to their prevalence and mortality rates in peninsular Malaysia during the past few decades. The mortality rate due to diseases of the circulatory system has more than doubled since 1970, deaths due to ischaemic heart disease being the major cause. The prevalence of diabetes mellitus has risen from 0.65% in 1960 to about 4% currently. The mortality risk for both ischaemic heart disease and diabetes is highest in the Indian compared to Malay and Chinese populations. The Chinese show the highest mortality rate for cancers of the breast and colon. This could reflect, partly, because more people especially in the urban areas are seeking treatment and improved diagnosis. Empirical dietary data indicate an increase in the prevalence of hypercholesterolaemia among urban adults and overweight among urban and rural adults. Aggregate data from food balance sheets indicate increased availability of energy intake from fats and oils, sugar, and animal products, with concomitant decline in available energy from plant products. Continued public health education on the important linkage between diet and disease is called for.
  16. Low YY, Gan CY, Kam TS
    J Nat Prod, 2014 Jun 27;77(6):1532-5.
    PMID: 24832351 DOI: 10.1021/np500289t
    Racemic andransinine (1), an indole alkaloid derivative obtained during isolation of alkaloids from Alstonia angustiloba and Kopsia pauciflora, was found to undergo spontaneous resolution when crystallized in EtOAc, forming racemic conglomerates (an equimolar mechanical mixture of enantiomerically pure individual crystals). X-ray analyses of the enantiomers (obtained from crystals from EtOAc solution and from chiral-phase HPLC) provided the absolute configuration of each enantiomer as (15R,16S,21R)-(+)-andransinine (1a or I+) and (15S,16R,21S)-(-)-andransinine (1b or I-).
  17. Tan ES, Ying-Yuan N, Gan CY
    Food Chem, 2014;152:447-55.
    PMID: 24444960 DOI: 10.1016/j.foodchem.2013.12.008
    Optimisation of protein extraction yield from pinto bean was investigated using response surface methodology. The maximum protein yield of 54.8 mg/g was obtained with the optimal conditions of: temperature=25 °C, time=1 h and buffer-to-sample ratio=20 ml/g. PBPI was found to obtain high amount of essential amino acids such as leucine, lysine, and phenylalanine compared to SPI. The predominant proteins of PBPI were vicilin and phytohemagglutinins whereas the predominant proteins of SPI were glycinin and conglycinins. Significantly higher emulsifying capacity was found in PBPI (84.8%) compared to SPI (61.9%). Different isoelectric points were found in both PBPI (4.0-5.5) and SPI (4.0-5.0). Also, it was found that PBPI obtained a much higher denaturation temperature of 110.2 °C compared to SPI (92.5 °C). Other properties such as structural information, gelling capacity, water- and oil-holding capacities, emulsion stability as well as digestibility were also reported.
  18. Lew LC, Liong MT, Gan CY
    J Appl Microbiol, 2013 Feb;114(2):526-35.
    PMID: 23082775 DOI: 10.1111/jam.12044
    AIMS: The study aimed to optimize the growth and evaluate the production of putative dermal bioactives from Lactobacillus rhamnosus FTDC 8313 using response surface methodology, in the presence of divalent metal ions, namely manganese and magnesium.
    METHODS AND RESULTS: A central composite design matrix (alpha value of ± 1.414) was generated with two independent factors, namely manganese sulphate (MnSO(4) ) and magnesium sulphate (MgSO(4) ). The second-order regression model indicated that the quadratic model was significant (P < 0.01), suggesting that the model accurately represented the data in the experimental region. Three-dimensional response surfaces predicted an optimum point with maximum growth of 10.59 log(10) CFU ml(-1) . The combination that produced the optimum point was 0.80 mg ml(-1) MnSO(4) and 1.09 mg ml(-1) MgSO(4) . A validation experiment was performed, and data obtained showed a deviation of 0.30% from the predicted value, ascertaining the predictions and the reliability of the regression model used. Effects of divalent metal ions on the production of putative dermal bioactives, namely hyaluronic acid, diacetyl, peptidoglycan, lipoteichoic acid and organic acids in the region of optimized growth, were evaluated using 3D response surfaces generated. Evaluation based on the individual and interaction effects showed that both manganese and magnesium played an important role in the production of these putative bioactives.
    CONCLUSIONS: Optimum growth of Lact. rhamnosus FTDC 8313 in reconstituted skimmed milk was achieved at 10.59 log(10) CFU ml(-1) in the presence of MnSO(4) (0.80 mg ml(-1) ) and MgSO(4) (1.09 mg ml(-1) ). Production of putative dermal bioactive and inhibitory compounds including hyaluronic acid, diacetyl, peptidoglycan, lipoteichoic acid and organic acids at the regions of optimized growth showed potential dermal applications.
    SIGNIFICANT AND IMPACT OF THE STUDY: This research can serve as a fundamental study to further evaluate the potential of Lactobacillus strains in non-gut-related roles such as dermal applications.
  19. Gan CY, Cheng LH, Easa AM
    J Food Sci, 2009 Mar;74(2):C141-6.
    PMID: 19323728 DOI: 10.1111/j.1750-3841.2009.01053.x
    Soy protein isolate (SPI) gels were produced using single cross-linking agents (SCLA) of microbial transglutaminase (MTG) via incubation for 5 or 24 h (SCLA-MTG). When powdered SCLA-MTG gels were heated for 2 h with ribose (R2) (2 g/100 mL), dark brown gels were formed, and these were designated as combined cross-linking agent (CCLA) gels: MTG5(R2) and MTG24(R2). The results showed that the levels of Maillard-derived browning and cross-links of MTG5(R2) and MTG24(R2) gels were significantly (P < 0.05) lower than a control gel produced without MTG (SCLA-R2) even though the percentage of ribose remaining after heating of these gels was similar, indicating that a similar amount of ribose was consumed during heating. epsilon-(gamma-glutamyl)lysine bonds formed during incubation of SPI with MTG may have reduced the free amino group of SPI to take part in the Maillard reaction; nevertheless, ribose took part in the Maillard reaction and initiated the Maillard cross-linkings within the CCLA gels.
  20. Uma Deavi Ayyamani, Gan CY, Ooi GS
    Med J Malaysia, 1986 Jun;41(2):108-15.
    PMID: 3821605
    A KAP study on dengue/dengue haemorrhagic fever (DF/DHF) was carried out in three areas in the Federal Territory. The three areas were selected based on their ethnic group composition and were Jinjang North (Chinese), Kampung Bahru (Malays) and Sentul (Indians). Houses were selected by a systematic sampling method and house-to-house interviews were carried out with a pre-tested, predesigned questionnaire. 546 (87.62%) of the households responded.
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