Displaying publications 21 - 33 of 33 in total

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  1. Fulltext Sources and relative stabilities of acylated and nonacylated anthocyanins in beverage systems
    Vidana Gamage GC, Lim YY, Choo WS
    J Food Sci Technol, 2022 Mar;59(3):831-845.
    PMID: 35185195 DOI: 10.1007/s13197-021-05054-z
    Anthocyanins are considered as the largest group of water-soluble pigments found in the vacuole of plant cells, displaying range of colors from pink, orange, red, purple and blue. They belong to flavonoids, a polyphenolic subgroup. Application of anthocyanins in food systems as natural food colourants is limited due to the lack of stability under different environmental conditions such as light, pH, heat etc. Anthocyanins esterified with one or more acid groups are referred as acylated anthocyanins. Based on the presence or absence of acyl group, anthocyanins are categorized as acylated and nonacylated anthocyanins. Acylated anthocyanins are further classified as mono, di, tri, tetra acylated anthocyanins according to the number of acyl groups present in the anthocyanin. This review classifies common anthocyanin sources into non-acylated, mono-, di-, tri- and tetra-acylated anthocyanins based on the major anthocyanins present in these sources. The relative stabilities of these anthocyanins with respect to thermal, pH and photo stress in beverage systems are specifically discussed. Common anthocyanin sources such as elderberry, blackberry, and blackcurrant mainly contain nonacylated anthocyanins. Red radish, purple corn, black carrot also mainly contain mono acylated anthocyanins. Red cabbage and purple sweet potato have both mono and diacylated anthocyanins. Poly acylated anthocyanins show relatively higher stability compared with nonacylated and monoacylated anthocyanins. Several techniques such as addition of sweeteners, co-pigmentation and acylation techniques could enhance the stability of nonacylated anthocyanins. Flowers are main sources of polyacylated anthocyanins having higher stability, yet they have not been commercially exploited for their anthocyanins.
  2. Cannabis as antivirals
    Sea YL, Gee YJ, Lal SK, Choo WS
    J Appl Microbiol, 2023 Jan 23;134(1).
    PMID: 36626776 DOI: 10.1093/jambio/lxac036
    Cannabis is a plant notorious for its psychoactive effect, but when used correctly, it provides a plethora of medicinal benefits. With more than 400 active compounds that have therapeutic properties, cannabis has been accepted widely as a medical treatment and for recreational purposes in several countries. The compounds exhibit various clinical benefits, which include, but are not limited to, anticancer, antimicrobial, and antioxidant properties. Among the vast range of compounds, multiple research papers have shown that cannabinoids, such as cannabidiol and delta-9-tetrahydrocannabinol, have antiviral effects. Recently, scientists found that both compounds can reduce severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) viral infection by downregulating ACE2 transcript levels and by exerting anti-inflammatory properties. These compounds also act as the SARS-CoV-2 main protease inhibitors that block viral replication. Apart from cannabinoids, terpenes in cannabis plants have also been widely explored for their antiviral properties. With particular emphasis on four different viruses, SARS-CoV-2, human immunodeficiency virus, hepatitis C virus, and herpes simplex virus-1, this review discussed the role of cannabis compounds in combating viral infections and the potential of both cannabinoids and terpenes as novel antiviral therapeutics.
  3. Fulltext The convergent evolution of influenza A virus: Implications, therapeutic strategies and what we need to know
    Low ZY, Wong KH, Wen Yip AJ, Choo WS
    Curr Res Microb Sci, 2023;5:100202.
    PMID: 37700857 DOI: 10.1016/j.crmicr.2023.100202
    Influenza virus infection, more commonly known as the 'cold flu', is an etiological agent that gives rise to recurrent annual flu and many pandemics. Dated back to the 1918- Spanish Flu, the influenza infection has caused the loss of many human lives and significantly impacted the economy and daily lives. Influenza virus can be classified into four different genera: influenza A-D, with the former two, influenza A and B, relevant to humans. The capacity of antigenic drift and shift in Influenza A has given rise to many novel variants, rendering vaccines and antiviral therapies useless. In light of the emergence of a novel betacoronavirus, the SARS-CoV-2, unravelling the underpinning mechanisms that support the recurrent influenza epidemics and pandemics is essential. Given the symptom similarities between influenza and covid infection, it is crucial to reiterate what we know about the influenza infection. This review aims to describe the origin and evolution of influenza infection. Apart from that, the risk factors entail the implication of co-infections, especially regarding the COVID-19 pandemic is further discussed. In addition, antiviral strategies, including the potential of drug repositioning, are discussed in this context. The diagnostic approach is also critically discussed in an effort to understand better and prepare for upcoming variants and potential influenza pandemics in the future. Lastly, this review encapsulates the challenges in curbing the influenza spread and provides insights for future directions in influenza management.
  4. Fulltext Metabolic perturbations and key pathways associated with the bacteriostatic activity of Clitoria ternatea flower anthocyanin fraction against Escherichia coli
    Jeyaraj EJ, Han ML, Li J, Choo WS
    Access Microbiol, 2023;5(6).
    PMID: 37424541 DOI: 10.1099/acmi.0.000535.v5
    Clitoria ternatea flowers are rich in anthocyanins and possess various biological activities. Specifically, the antibacterial mechanism of action of C. ternatea anthocyanins remains unknown and was investigated in Escherichia coli . A time-kill assay was used to assess the antibacterial activity and the metabolic perturbations in E. coli were investigated utilizing liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. Pathway analyses were carried out for metabolites showing ≥2-fold changes. The anthocyanin fraction remarkably reduced the growth of E. coli at 4 h by 95.8 and 99.9 % at minimum inhibitory concentration (MIC) and 2× MIC, respectively. The anthocyanin fraction (MIC) had a bacteriostatic effect and was shown to have perturbed glycerophospholipids (1-acyl-sn-glycero-3-phosphoethanolamine, phosphatidylglycerol, diacylglycerol and cardiolipin), amino acids (valine, tyrosine and isoleucine) and energy (ubiquinone and NAD) metabolites at 1 and 4 h. This study demonstrated significant metabolic perturbations of the glycerophospholipid, amino acid and energy metabolism, with these being the key pathways involved in the bacteriostatic activity of anthocyanins from C. ternatea, which may have promise as bacteriostatic agents for E. coli -related infections.
  5. Fulltext Antiviral activity of betacyanins from red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius) against dengue virus type 2 (GenBank accession no. MH488959)
    Chang YJ, Pong LY, Hassan SS, Choo WS
    Access Microbiol, 2020;2(1):acmi000073.
    PMID: 33062932 DOI: 10.1099/acmi.0.000073
    This study investigated the antiviral activity of betacyanins from red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius) against dengue virus type 2 (DENV-2). The pulp of red pitahaya and the leaves of red spinach were extracted using methanol followed by sub-fractionation and Amberlite XAD16N column chromatography to obtain betacyanin fractions. The half maximum cytotoxicity concentration for betacyanin fractions from red pitahaya and red spinach on Vero cells were 4.346 and 2.287 mg ml-1, respectively. The half-maximal inhibitory concentration (IC50) of betacyanin fraction from red pitahaya was 125.8 μg ml-1 with selectivity index (SI) of 5.8. For betacyanin fraction from red spinach, the IC50 value was 14.62 µg ml-1 with SI of 28.51. Using the maximum non-toxic betacyanin concentration, direct virucidal effect against DENV-2 was obtained from betacyanin fraction from red pitahaya (IC50 of 126.70 μg ml-1; 95.0 % virus inhibition) and red spinach (IC50 value of 106.80 μg ml-1; 65.9 % of virus inhibition). Betacyanin fractions from red pitahaya and red spinach inhibited DENV-2 in vitro.
  6. Fulltext Anthocyanins From Clitoria ternatea Flower: Biosynthesis, Extraction, Stability, Antioxidant Activity, and Applications
    Vidana Gamage GC, Lim YY, Choo WS
    Front Plant Sci, 2021;12:792303.
    PMID: 34975979 DOI: 10.3389/fpls.2021.792303
    Clitoria ternatea plant is commonly grown as an ornamental plant and possesses great medicinal value. Its flower is edible and also known as blue pea or butterfly pea flower. The unique feature of anthocyanins present in blue pea flowers is the high abundance of polyacylated anthocyanins known as ternatins. Ternatins are polyacylated derivatives of delphinidin 3,3',5'-triglucoside. This review covers the biosynthesis, extraction, stability, antioxidant activity, and applications of anthocyanins from Clitoria ternatea flower. Hot water extraction of dried or fresh petals of blue pea flower could be employed successfully to extract anthocyanins from blue pea flower for food application. Blue pea flower anthocyanins showed good thermal and storage stability, but less photostability. Blue pea flower anthocyanins also showed an intense blue colour in acidic pH between pH 3.2 to pH 5.2. Blue pea flower anthocyanin extracts demonstrate significant in vitro and cellular antioxidant activities. Blue pea flower anthocyanins could be used as a blue food colourant in acidic and neutral foods. The incorporation of blue pea flower anthocyanins in food increased the functional properties of food such as antioxidant and antimicrobial properties. Blue pea flower anthocyanins have also been used in intelligent packaging. A comparison of blue pea flower anthocyanins with two other natural blue colouring agents used in the food industry, spirulina or phycocyanin and genipin-derived pigments is also covered. Anthocyanins from blue pea flowers are promising natural blue food colouring agent.
  7. 14-3-3 Family of Proteins: Biological Implications, Molecular Interactions, and Potential Intervention in Cancer, Virus and Neurodegeneration Disorders
    Low ZY, Yip AJW, Chan AML, Choo WS
    J Cell Biochem, 2024 Jul;125(7):e30624.
    PMID: 38946063 DOI: 10.1002/jcb.30624
    The 14-3-3 family of proteins are highly conserved acidic eukaryotic proteins (25-32 kDa) abundantly present in the body. Through numerous binding partners, the 14-3-3 is responsible for many essential cellular pathways, such as cell cycle regulation and gene transcription control. Hence, its dysregulation has been linked to the onset of critical illnesses such as cancers, neurodegenerative diseases and viral infections. Interestingly, explorative studies have revealed an inverse correlation of 14-3-3 protein in cancer and neurodegenerative diseases, and the direct manipulation of 14-3-3 by virus to enhance infection capacity has dramatically extended its significance. Of these, COVID-19 has been linked to the 14-3-3 proteins by the interference of the SARS-CoV-2 nucleocapsid (N) protein during virion assembly. Given its predisposition towards multiple essential host signalling pathways, it is vital to understand the holistic interactions between the 14-3-3 protein to unravel its potential therapeutic unit in the future. As such, the general structure and properties of the 14-3-3 family of proteins, as well as their known biological functions and implications in cancer, neurodegeneration, and viruses, were covered in this review. Furthermore, the potential therapeutic target of 14-3-3 proteins in the associated diseases was discussed.
  8. Fulltext Acute stroke patients with high BMI are less likely to have severe disability at initial presentation
    Choo WS, Foo S, Tan E, Thayaparan FS, Chung YY, Raman S, et al.
    Med J Malaysia, 2009 Mar;64(1):34-6.
    PMID: 19852318 MyJurnal
    This is a prospective study to determine the severity of disability and prognosis of acute stroke patients related to their Body Mass index (BMI). A total of 79 consecutive CT-scan-proven acute stroke patients who were admitted to Hospital Tuanku Ja'afar, Seremban between November 2006 and April 2007 were recruited (male:female 49:30; mean age 62.7 years; ischemic stroke 70, intracerebral bleed 9). The patients were divided according to BMI less than 25 (Group A) and equal or greater than 25 (Group B). Severity of disability was measured between 24-48 hours by modified Rankin's score. Patients were followed up after one month. Thirty-seven patients had severe disability (Rankin Score 5). Twenty-nine patients had adverse outcomes including 11 deaths and 18 rehospitalizations or prolonged hospital/nursing home stay. 34.3% of Group B had severe disability compared to 56.8% of Group A (chi2 P = 0.046). Conversely 42.9% of Group B had adverse events at one month compared to 31.8% of Group A (chi2 P = 0.312). There were no statistical differences between high- and low-BMI groups for gender ratio, smoking, hypertension, diabetes, prior cardiovascular disease, mean age, mean lipid profile and blood pressure. When comparing patients with Rankin Score 1-4 versus 5, age and BMI were statistically significant between the two groups. By multivariate analysis only age is independent predictor for severe disability (P < 0.05). The results of this pilot study should be confirmed in larger prospective multicentre trial.
  9. Current vaccine approaches and emerging strategies against herpes simplex virus (HSV)
    Wijesinghe VN, Farouk IA, Zabidi NZ, Puniyamurti A, Choo WS, Lal SK
    Expert Rev Vaccines, 2021 Sep;20(9):1077-1096.
    PMID: 34296960 DOI: 10.1080/14760584.2021.1960162
    Introduction: Vaccine development for the disease caused by the herpes simplex virus (HSV) has been challenging over the years and is always in dire need of novel approaches for prevention and cure. To date, the HSV disease remains incurable and challenging to prevent. The disease is extremely widespread due to its high infection rate, resulting in millions of infection cases worldwide.Areas covered: This review first explains the diverse forms of HSV-related disease presentations and reports past vaccine history for the disease. Next, this review examines current and novel HSV vaccine approaches being studied and tested for efficacy and safety as well as vaccines in clinical trial phases I to III. Modern approaches to vaccine design using bioinformatics are described. Finally, we discuss measures to enhance new vaccine development pipelines for HSV.Expert opinion: Modernized approaches using in silico analysis and bioinformatics are emerging methods that exhibit potential for producing vaccines with enhanced targets and formulations. Although not yet fully established for HSV disease, we describe current studies using these approaches for HSV vaccine design to shed light on these methods. In addition, we provide up-to-date requirements of immunogenicity, adjuvant selection, and routes of administration.
  10. Unprecedented Acid-Promoted Polymerization and Gelation of Acrylamide: A Serendipitous Discovery
    Chan SY, Goh SS, Dou Q, Chan BQY, Choo WS, Young DJ, et al.
    Chem Asian J, 2018 Jun 20.
    PMID: 29924504 DOI: 10.1002/asia.201800552
    Dilute acid polymerizes degassed, aqueous acrylamide with concomitant gelation, without the need for added free radical initiator or cross-linking agent. This reaction is accelerated by sonication or UV irradiation, but inhibited by adventitious oxygen or the addition of a free radical inhibitor, suggesting an acid-accelerated free radical process. The resulting hydrogels are thixotropic in nature and partially disrupted by the addition of chaotropic agents, indicating the importance of hydrogen bonding to the 3D network. This discovery was made while trying to prepare pectin-polyacrylamide hydrogels. We observed that pectin initiated the gelation of acrylamide, but only if the aqueous pectin samples had a pH lower than ca. 5.
  11. Betacyanins from red pitahaya (Hylocereus polyrhizus) exhibit antiviral response against influenza A virus
    Lim CM, Lal SK, Isa NM, Omar AR, Choo WS
    Heliyon, 2024 Jun 30;10(12):e33049.
    PMID: 39021953 DOI: 10.1016/j.heliyon.2024.e33049
    Seasonal influenza affects millions of lives worldwide, with the influenza A virus (IAV) responsible for pandemics and annual epidemics, causing the most severe illnesses resulting in patient hospitalizations or death. With IAV threatening the next global influenza pandemic, it is a race against time to search for antiviral drugs. Betacyanins are unique nitrogen-containing and water-soluble reddish-violet pigments that have been reported to possess antiviral properties against the dengue virus. This study aimed to examine the antiviral effect of betacyanins from red pitahaya (Hylocereus polyrhizus) on IAV-infected lung epithelial A549 cells. HPLC and LC-MS analysis of extracted betacyanin showed four betacyanins in the betacyanin fraction: phyllocactin, hylocerenin, betanin, and isobetanin. Cytotoxicity assay showed that betacyanin fractions were not cytotoxic to A549 cells at concentrations below 100 μg/mL. Betacyanin fraction concentrations of 12.5, 25.0, and 50.0 μg/mL prevented the formation of viral cytopathic effect and reduced virus titer in IAV-infected cells up to 72 h. A downregulation of protein and mRNA nucleoprotein expression levels was observed after treatment with 25.0 and 50.0 μg/mL of betacyanin fraction after 24 h, thereby providing evidence for the antiviral activity of betacyanin from red pitahaya against IAV in vitro.
  12. Assessing the impact of temperature, pH, light and chemical oxidation on fucoxanthin colour changes, antioxidant activity and the resulting metabolites
    Yusof Z, Lim V, Khong NMH, Choo WS, Foo SC
    J Sci Food Agric, 2025 Jan 15;105(1):93-108.
    PMID: 39177277 DOI: 10.1002/jsfa.13807
    BACKGROUND: The present study evaluated the effects of temperature, pH, light and chemical oxidation on fucoxanthin changes in terms of colour, antioxidant activity and metabolomic profile. Additionally, the correlation between antioxidant activity and identified metabolites was analysed.

    RESULTS: It was found that colour change was significantly reduced at elevated heat (100 °C, *∆E = 0.81 ± 0.05), reduced pH (pH 3, *∆E = 0.59 ± 0.04) and length of light exposure (*∆E = 3.16 ± 0.04). Antioxidant activity decreased under all treatments. Among the temperatures tested, fucoxanthin exhibited the highest activity at 60 °C, ranging from 0.92 to 3.04 mg Trolox equivalents (TE) g-1. Significant activity reductions (P 

  13. Fulltext Electrospun Pectin-Polyhydroxybutyrate Nanofibers for Retinal Tissue Engineering
    Chan SY, Chan BQY, Liu Z, Parikh BH, Zhang K, Lin Q, et al.
    ACS Omega, 2017 Dec 31;2(12):8959-8968.
    PMID: 30023596 DOI: 10.1021/acsomega.7b01604
    Natural polysaccharide pectin has for the first time been grafted with polyhydroxybutyrate (PHB) via ring-opening polymerization of β-butyrolactone. This copolymer, pectin-polyhydroxybutyrate (pec-PHB), was blended with PHB in various proportions and electrospun to produce nanofibers that exhibited uniform and bead-free nanostructures, suggesting the miscibility of PHB and pec-PHB. These nanofiber blends exhibited reduced fiber diameters from 499 to 336-426 nm and water contact angles from 123.8 to 88.2° on incorporation of pec-PHB. They also displayed 39-335% enhancement of elongation at break relative to pristine PHB nanofibers. pec-PHB nanofibers were found to be noncytotoxic and biocompatible. Human retinal pigmented epithelium (ARPE-19) cells were seeded onto pristine PHB and pec-PHB nanofibers as scaffold and showed good proliferation. Higher proportions of pec-PHB (pec-PHB10 and pec-PHB20) yielded higher densities of cells with similar characteristics to normal RPE cells. We propose, therefore, that nanofibers of pec-PHB have significant potential as retinal tissue engineering scaffold materials.
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