Displaying publications 1 - 20 of 47 in total

Abstract:
Sort:
  1. Rahman FA, Abdullah SS, Manan WZWA, Tan LT, Neoh CF, Ming LC, et al.
    Front Pharmacol, 2018;9:238.
    PMID: 29970999 DOI: 10.3389/fphar.2018.00238
    There are various studies that have addressed the use of Cyclosporine among patients with acute myocardial infarction (AMI). However, to date there is hardly any concise and systematically structured evidence that debate on the efficacy and safety of Cyclosporine in AMI patients. The aim of this review is to systematically summarize the overall evidence from published trials, and to conduct a meta-analysis in order to determine the efficacy and safety of Cyclosporine vs. placebo or control among patients with AMI. All randomized control trial (RCT) published in English language from January 2000 to August 2017 were included for the systematic review and meta-analysis. A total of six RCTs met the inclusion and were hence included in the systematic review and meta-analysis. Based on the performed meta-analysis, no significant difference was found between Cyclosporine and placebo in terms of left ventricular ejection fraction (LVEF) improvement (mean difference 1.88; 95% CI -0.99 to 4.74; P = 0.2), mortality rate (OR 1.01; 95% Cl 0.60 to 1.67, P = 0.98) and recurrent MI occurrence (OR 0.65; 95% Cl 0.29 to 1.45, P = 0.29), with no evidence of heterogeneity, when given to patients with AMI. Cyclosporine also did not significantly lessen the rate of rehospitalisation in AMI patients when compared to placebo (OR 0.91; 95% Cl 0.58 to 1.42, P = 0.68), with moderate heterogeneity (I2 = 46%). There was also no significant improvement in heart failure events between Cyclosporine and placebo in AMI patients (OR 0.63; 95% Cl 0.31 to 1.29, P = 0.21; I2 = 80%). No serious adverse events were reported in Cyclosporine group across all studies suggesting that Cyclosporine is well tolerated when given to patients with AMI. The use of Cyclosporine in this group of patients, however, did not result in better clinical outcomes vs. placebo at improving LVEF, mortality rate, recurrent MI, rehospitalisation and heart failure event.
  2. Hng SY, Thinakaran AS, Ooi CJ, Eg KP, Thong MK, Tae SK, et al.
    Singapore Med J, 2023 Sep 19.
    PMID: 37870036 DOI: 10.4103/singaporemedj.SMJ-2022-093
    INTRODUCTION: : Asian children with cystic fibrosis (CF) managed in Malaysia have significant morbidity with limited access to life-sustaining treatments. We determined the morbidity and treatment cost of CF in a resource-limited country.

    METHODS: This cross-sectional study included all children diagnosed with CF in our centre. Data on clinical presentation, genetic mutation, serial spirometry results and complications were collected. Out-of-pocket (OOP) and healthcare costs over 1 year were retrieved for patients who were alive. Cohen's d and odds ratio (OR) were used to determine the effect size.

    RESULTS: Twenty-four patients were diagnosed with CF. Five patients died at a median (range) age of 18 (0.3-22) years. F508deletion (c. 1521_1523delCTT) was found in 20% of the alleles, while 89% of the variants were detected in nine patients. Body mass index (BMI) Z score was >-1.96 in 70.6% of patients. Two thirds (68%) were colonised with Pseudomonas aeruginosa, and this was associated with lower weight (P = 0.009) and BMI (P = 0.02) Z scores. Only 18% had FEV1 Z scores >-1.96. Early symptom onset (d = 0.74), delayed diagnosis (d = 2.07), a low FEF25-75 Z score (d = 0.82) and a high sweat conductance (d = 1.19) were associated with death. Inpatient cost was mainly from diagnostic tests, while medications contributed to half of the outpatient cost.

    Healthcare utilisation cost was catastrophic, amounting to 20% of the total income.

    CONCLUSION: Asian children with CF suffer significant complications such as low weight, low lung function and shortened lifespan. P. aeruginosa colonisation was frequent and associated with poor growth. Healthcare cost to parents was catastrophic.

  3. Isa H, Luthert P, Rose G, Verity D, Pusey C, Tomkins-Netzer O, et al.
    Ophthalmology, 2015 Oct;122(10):2140-2.
    PMID: 26116342 DOI: 10.1016/j.ophtha.2015.04.016
  4. Lo CH, Chai XY, Ting SSW, Ang SC, Chin X, Tan LT, et al.
    Cancer Med, 2020 05;9(9):3244-3251.
    PMID: 32130790 DOI: 10.1002/cam4.2821
    BACKGROUND: Breast cancer is the leading cause of death among women worldwide. Studies have identified breast density as a controversial risk factor of breast cancer. Moreover, studies found that breast density reduction through Tamoxifen could reduce risk of breast cancer significantly. To date, no study on the association between breast density and breast cancer has been carried out in Malaysia. If breast density is proven to be a risk factor of breast cancer, intervention could be carried out to reduce breast cancer risk through breast density reduction.

    PURPOSE: To determine if density of breast is an independent risk factor which will contribute to development of breast cancer.

    MATERIALS AND METHODS: A prospective cohort study is carried out in two hospitals targeting adult female patients who presented to the Breast Clinic with symptoms suspicious of breast cancer. Participants recruited were investigated for breast cancer based on their symptoms. Breast density assessed from mammogram was correlated with tissue biopsy results and final diagnosis of benign or malignant breast disease.

    RESULTS: Participants with dense breasts showed 29% increased risk of breast cancer when compared to those with almost entirely fatty breasts (odds ratio [OR] 1.29, 95% CI 0.38-4.44, P = .683). Among the postmenopausal women, those with dense breasts were 3.1 times more likely to develop breast cancer compared with those with fatty breasts (OR 3.125, 95% CI 0.72-13.64, P = .13). Moreover, the chance of developing breast cancer increases with age (OR 1.046, 95% CI 1.003-1.090, P 

  5. Ma DSL, Tan LT, Chan KG, Yap WH, Pusparajah P, Chuah LH, et al.
    Front Pharmacol, 2018;9:102.
    PMID: 29515440 DOI: 10.3389/fphar.2018.00102
    Bacterial foodborne pathogens are a significant health burden and the recent emergence of pathogenic resistant strains due to the excessive use of antibiotics makes it more difficult to effectively treat infections as a result of contaminated food. Awareness of this impending health crisis has spurred the search for alternative antimicrobials with natural plant antimicrobials being among the more promising candidates as these substances have good acceptability and likely low toxicity levels as they have long been used in traditional medicines. Resveratrol (3,5,4'-trihydroxystilbene) is a naturally occurring stilbenoid which has been gaining considerable attention in medical field due to its diverse biological activities - it has been reported to exhibit antioxidant, cardioprotective, anti-diabetic, anticancer, and antiaging properties. Given that resveratrol is phytoalexin, with increased synthesis in response to infection by phytopathogens, there has been interest in exploring its antimicrobial activity. This review aims to provide an overview of the published data on the antibacterial activity of resveratrol against foodborne pathogens, its mechanisms of action as well as its possible applications in food packing and processing; in addition we also summarize the current data on its potential synergism with known antibacterials and future research and applications.
  6. Loo KY, Letchumanan V, Ser HL, Teoh SL, Law JW, Tan LT, et al.
    Microorganisms, 2021 Mar 15;9(3).
    PMID: 33804162 DOI: 10.3390/microorganisms9030605
    People around the world ushered in the new year 2021 with a fear of COVID-19, as family members have lost their loved ones to the disease. Millions of people have been infected, and the livelihood of many has been jeopardized due to the pandemic. Pharmaceutical companies are racing against time to develop an effective vaccine to protect against COVID-19. Researchers have developed various types of candidate vaccines with the release of the genetic sequence of the SARS-CoV-2 virus in January. These include inactivated viral vaccines, protein subunit vaccines, mRNA vaccines, and recombinant viral vector vaccines. To date, several vaccines have been authorized for emergency use and they have been administered in countries across the globe. Meanwhile, there are also vaccine candidates in Phase III clinical trials awaiting results and approval from authorities. These candidates have shown positive results in the previous stages of the trials, whereby they could induce an immune response with minimal side effects in the participants. This review aims to discuss the different vaccine platforms and the clinical trials of the candidate vaccines.
  7. Ang WS, Law JW, Letchumanan V, Hong KW, Wong SH, Ab Mutalib NS, et al.
    Foods, 2023 Jun 26;12(13).
    PMID: 37444223 DOI: 10.3390/foods12132485
    A new next-generation probiotic, Christensenella minuta was first discovered in 2012 from healthy human stool and described under the phylum Firmicutes. C. minuta is a subdominant commensal bacterium with highly heritable properties that exhibits mutual interactions with other heritable microbiomes, and its relative abundance is positively correlated with the lean host phenotype associated with a low BMI index. It has been the subject of numerous studies, owing to its potential health benefits. This article reviews the evidence from various studies of C. minuta interventions using animal models for managing metabolic diseases, such as obesity, inflammatory bowel disease, and type 2 diabetes, characterized by gut microbiota dysbiosis and disruption of host metabolism. Notably, more studies have presented the complex interaction between C. minuta and host metabolism when it comes to metabolic health. Therefore, C. minuta could be a potential candidate for innovative microbiome-based biotherapy via fecal microbiota transplantation or oral administration. However, the detailed underlying mechanism of action requires further investigation.
  8. Chee PY, Mang M, Lau ES, Tan LT, He YW, Lee WL, et al.
    Front Microbiol, 2019;10:2631.
    PMID: 31824449 DOI: 10.3389/fmicb.2019.02631
    Epinecidin-1 is an antimicrobial peptide derived from the orange-spotted grouper (Epinephelus coioides). The mature epinecidin-1 peptide is predicted to have an amphipathic α-helical structure and a non-helical hydrophilic domain at the C-terminal RRRH. The majority of work studying the potential pharmacological activities of epinecidin-1, utilize synthesized epinecidin-1 (Epi-1), which is made up of 21 amino acids, from the amino acid sequence of 22-42 residues of Epi-1-GFIFHIIKGLFHAGKMIHGLV. The synthetized Epi-1 peptide has been demonstrated to possess diverse pharmacological activities, including antimicrobial, immunomodulatory, anticancer, and wound healing properties. It has also been utilized in different clinical and agricultural fields, including topical applications in wound healing therapy as well as the enhancement of fish immunity in aquaculture. Hence, the present work aims to consolidate the current knowledge and findings on the characteristics and pharmacological properties of epinecidin-1 and its potential applications.
  9. Ser HL, Tan LT, Law JW, Chan KG, Duangjai A, Saokaew S, et al.
    Front Microbiol, 2017;8:2065.
    PMID: 29163380 DOI: 10.3389/fmicb.2017.02065
    Human life expectancy is rapidly increasing with an associated increasing burden of chronic diseases, such as neurodegenerative diseases and cancer. However, there is limited progress in finding effective treatment for these conditions. For this reason, members of the genus Streptomyces have been explored extensively over the past decades as these filamentous bacteria are highly efficient in producing bioactive compounds with human health benefits. Being ubiquitous in nature, streptomycetes can be found in both terrestrial and marine environments. Previously, two Streptomyces strains (MUSC 137T and MUM 256) isolated from mangrove sediments in Peninsular Malaysia demonstrated potent antioxidant and cytotoxic activities against several human cancer cell lines on bioactivity screening. These results illustrate the importance of streptomycetes from underexplored regions aside from the terrestrial ecosystem. Here we provide the insights and significance of Streptomyces species in the search of anticancer and/or chemopreventive agents and highlight the impact of next generation sequencing on drug discovery from the Streptomyces arsenal.
  10. Tan LT, Davagnanam I, Isa H, Taylor SR, Rose GE, Verity DH, et al.
    Ophthalmology, 2014 Jun;121(6):1304-9.
    PMID: 24560566 DOI: 10.1016/j.ophtha.2013.12.003
    Granulomatosis with polyangiitis (GPA), previously Wegener's granulomatosis, requires prompt diagnosis and systemic review to exclude life-threatening disease. However, early diagnosis of orbital GPA may be difficult because anti-neutrophil cytoplasmic antibody (ANCA) and anti-PR3 antibody screening can be negative at presentation and orbital biopsies taken for diagnosis may not show the classic features of GPA. This study was designed to compare GPA with other causes of orbital inflammation and to identify the presenting clinical and imaging features most likely to predict GPA and its systemic spread.
  11. Goonewardene ST, Tang C, Tan LT, Chan KG, Lingham P, Lee LH, et al.
    Front Pediatr, 2019;7:339.
    PMID: 31456997 DOI: 10.3389/fped.2019.00339
    Nephrotic syndrome affects both children and adults. Idiopathic nephrotic syndrome is reported to be one of the most frequent renal pathologies in childhood. Nephrotic children are at high risk for severe pneumococcal infections as one of the life-threatening complications of nephrotic syndrome due to involvement of the immunosuppressive regimen and the acquired immune deficiency induced by nephrotic syndrome including decreased plasma IgG and low complement system components. Aiming to prevent pneumococcal infection is of paramount importance especially in this era of ever-increasing pneumococcal resistance to penicillins and cephalosporins. The pneumococcal vaccines currently available are inactivated vaccines-the two main forms in use are polysaccharide vaccines and conjugated vaccines. However, the data supporting the use of these vaccines and to guide the timing and dosage recommendations is still limited for nephrotic children. Thus, this review discusses the evidences of immunogenicity and safety profile of both vaccinations on nephrotic patients as well as the effect of nephrotic syndrome treatment on vaccine seroresponses.
  12. Tay KC, Tan LT, Chan CK, Hong SL, Chan KG, Yap WH, et al.
    Front Pharmacol, 2019;10:820.
    PMID: 31402861 DOI: 10.3389/fphar.2019.00820
    Cancer, a complex yet common disease, is caused by uncontrolled cell division and abnormal cell growth due to a variety of gene mutations. Seeking effective treatments for cancer is a major research focus, as the incidence of cancer is on the rise and drug resistance to existing anti-cancer drugs is major concern. Natural products have the potential to yield unique molecules and combinations of substances that may be effective against cancer with relatively low toxicity/better side effect profile compared to standard anticancer therapy. Drug discovery work with natural products has demonstrated that natural compounds display a wide range of biological activities correlating to anticancer effects. In this review, we discuss formononetin (C16H12O4), which originates mainly from red clovers and the Chinese herb Astragalus membranaceus. The compound comes from a class of 7-hydroisoflavones with a substitution of methoxy group at position 4. Formononetin elicits antitumorigenic properties in vitro and in vivo by modulating numerous signaling pathways to induce cell apoptosis (by intrinsic pathway involving Bax, Bcl-2, and caspase-3 proteins) and cell cycle arrest (by regulating mediators like cyclin A, cyclin B1, and cyclin D1), suppress cell proliferation [by signal transducer and activator of transcription (STAT) activation, phosphatidylinositol 3-kinase/protein kinase-B (PI3K/AKT), and mitogen-activated protein kinase (MAPK) signaling pathway], and inhibit cell invasion [by regulating growth factors vascular endothelial growth factor (VEGF) and Fibroblast growth factor 2 (FGF2), and matrix metalloproteinase (MMP)-2 and MMP-9 proteins]. Co-treatment with other chemotherapy drugs such as bortezomib, LY2940002, U0126, sunitinib, epirubicin, doxorubicin, temozolomide, and metformin enhances the anticancer potential of both formononetin and the respective drugs through synergistic effect. Compiling the evidence thus far highlights the potential of formononetin to be a promising candidate for chemoprevention and chemotherapy.
  13. Mangzira Kemung H, Tan LT, Chan KG, Ser HL, Law JW, Lee LH, et al.
    Molecules, 2020 Aug 03;25(15).
    PMID: 32756432 DOI: 10.3390/molecules25153545
    There is an urgent need to search for new antibiotics to counter the growing number of antibiotic-resistant bacterial strains, one of which is methicillin-resistant Staphylococcus aureus (MRSA). Herein, we report a Streptomyces sp. strain MUSC 125 from mangrove soil in Malaysia which was identified using 16S rRNA phylogenetic and phenotypic analysis. The methanolic extract of strain MUSC 125 showed anti-MRSA, anti-biofilm and antioxidant activities. Strain MUSC 125 was further screened for the presence of secondary metabolite biosynthetic genes. Our results indicated that both polyketide synthase (pks) gene clusters, pksI and pksII, were detected in strain MUSC 125 by PCR amplification. In addition, gas chromatography-mass spectroscopy (GC-MS) detected the presence of different chemicals in the methanolic extract. Based on the GC-MS analysis, eight known compounds were detected suggesting their contribution towards the anti-MRSA and anti-biofilm activities observed. Overall, the study bolsters the potential of strain MUSC 125 as a promising source of anti-MRSA and antibiofilm compounds and warrants further investigation.
  14. Tan LT, Nathan AM, Jayanath S, Eg KP, Thavagnanam S, Lum LCS, et al.
    Pediatr Pulmonol, 2020 12;55(12):3477-3486.
    PMID: 33002341 DOI: 10.1002/ppul.25083
    BACKGROUND: Provision of home mechanical ventilation (HMV) to children with chronic respiratory insufficiency enhances growth and quality of life. The hypothesis was that health-related quality of life (HRQoL) and the development of these children were poorer than in healthy children.

    OBJECTIVES: To determine the HRQoL and developmental outcome of children on HMV.

    METHODS: This cross-sectional study used the TNO-AZL Preschool children's Quality Of Life (TAPQOL; <5 years old) and Health Utilities Index (HUI) 2/3 (≥5 years old) to assess the quality of life and the Schedule of Growing Skills-II to assess development. Instruments were used on children currently or previously on HMV (≥3 months) and compared with age and sex-matched controls.

    RESULTS: Sixty-five patients and 130 controls were recruited. Patients' median (interquartile range) age was 3.12 (1.65, 5.81) years. Patients had significantly lower TAPQOL scores in the domains of lung, liveliness, positive mood, social functioning, motor functioning, and communication, and lower HUI 2/3 scores in hearing, sensation, pain, speech, mobility, ambulatory, dexterity, and self-care domains. The developmental outcome of patients was poorer in all domains. However, patients had fewer behavioral problems. Those with respiratory tract disease and without comorbidities had better HRQoL and developmental scores. Having a parent as the primary caregiver was associated with better speech and language skills.

    CONCLUSIONS: HRQoL and the developmental outcome are lower in children on HMV compared to controls. Children with respiratory tract disease and without comorbidities have a better outcome. Parents play a crucial role in the acquisition of speech.

  15. Kemung HM, Tan LT, Chan KG, Ser HL, Law JW, Lee LH, et al.
    Biomed Res Int, 2020;2020:6402607.
    PMID: 32258133 DOI: 10.1155/2020/6402607
    The mangrove ecosystem of Malaysia remains yet to be fully explored for potential microbes that produce biologically active metabolites. In the present study, a mangrove-derived Streptomyces sp. strain MUSC 14 previously isolated from the state of Pahang, Malaysia Peninsula, was studied for its potential in producing antioxidant metabolites. The identity of Streptomyces sp. strain MUSC14 was consistent with the genotypic and phenotypic characteristics of the Streptomyces genus. The antioxidant potential of Streptomyces sp. strain MUSC 14 was determined through screening of its methanolic extract against sets of antioxidant assays. The results were indicative of Streptomyces sp. strain MUSC 14 displaying strong antioxidant activity against ABTS, DPPH free radicals and metal chelating activity of 62.71 ± 3.30%, 24.71 ± 2.22%, and 55.82 ± 2.35%, respectively. The result of ferric reducing activity measured in terms of dose was equivalent to 2.35-2.45 μg of positive control ascorbic acid. Furthermore, there was a high correlation between the total phenolic content and the antioxidant activities with r = 0.979, r = 0.858, and r = 0.983 representing ABTS, DPPH, and metal chelation, respectively. Overall, the present study suggests that Streptomyces sp. strain MUSC 14 from mangrove forest soil has potential to produce antioxidant metabolites that can be further exploited for therapeutic application.
  16. Chew SS, Tan LT, Law JW, Pusparajah P, Goh BH, Ab Mutalib NS, et al.
    Cancers (Basel), 2020 Aug 13;12(8).
    PMID: 32823729 DOI: 10.3390/cancers12082272
    Colorectal cancer (CRC) is a global public health issue which poses a substantial humanistic and economic burden on patients, healthcare systems and society. In recent years, intestinal dysbiosis has been suggested to be involved in the pathogenesis of CRC, with specific pathogens exhibiting oncogenic potentials such as Fusobacterium nucleatum, Escherichia coli and enterotoxigenic Bacteroides fragilis having been found to contribute to CRC development. More recently, it has been shown that initiation of CRC development by these microorganisms requires the formation of biofilms. Gut microbial biofilm forms in the inner colonic mucus layer and is composed of polymicrobial communities. Biofilm results in the redistribution of colonic epithelial cell E-cadherin, increases permeability of the gut and causes a loss of function of the intestinal barrier, all of which enhance intestinal dysbiosis. This literature review aims to compile the various strategies that target these pathogenic biofilms and could potentially play a role in the prevention of CRC. We explore the potential use of natural products, silver nanoparticles, upconverting nanoparticles, thiosalicylate complexes, anti-rheumatic agent (Auranofin), probiotics and quorum-sensing inhibitors as strategies to hinder colon carcinogenesis via targeting colon-associated biofilms.
  17. Ser HL, Tan LT, Palanisamy UD, Abd Malek SN, Yin WF, Chan KG, et al.
    Front Microbiol, 2016;7:899.
    PMID: 27379040 DOI: 10.3389/fmicb.2016.00899
    A novel strain, Streptomyces antioxidans MUSC 164(T) was recovered from mangrove forest soil located at Tanjung Lumpur, Malaysia. The Gram-positive bacterium forms yellowish-white aerial and brilliant greenish yellow substrate mycelium on ISP 2 agar. A polyphasic approach was used to determine the taxonomy status of strain MUSC 164(T). The strain showed a spectrum of phylogenetic and chemotaxonomic properties consistent with those of the members of the genus Streptomyces. The cell wall peptidoglycan was determined to contain LL-diaminopimelic acid. The predominant menaquinones were identified as MK-9(H6) and MK-9(H8), while the identified polar lipids consisted of aminolipid, diphosphatidylglycerol, glycolipid, hydroxyphosphatidylethanolamine, phospholipid, phosphatidylinositol, phosphatidylethanolamine, phosphatidylglycerol and lipid. The cell wall sugars consist of galactose, glucose and ribose. The predominant cellular fatty acids (>10.0%) were identified as iso-C15: 0 (34.8%) and anteiso-C15: 0(14.0%). Phylogenetic analysis identified that closely related strains for MUSC 164(T) as Streptomyces javensis NBRC 100777(T) (99.6% sequence similarity), Streptomyces yogyakartensis NBRC 100779(T) (99.6%) and Streptomyces violaceusniger NBRC 13459(T) (99.6%). The DNA-DNA relatedness values between MUSC 164(T) and closely related type strains ranged from 23.8 ± 0.3% to 53.1 ± 4.3%. BOX-PCR fingerprints comparison showed that MUSC 164(T) exhibits a unique DNA profile, with DNA G + C content determined to be 71.6 mol%. Based on the polyphasic study of MUSC 164(T), it is concluded that this strain represents a novel species, for which the name Streptomyces antioxidans sp. nov. is proposed. The type strain is MUSC 164(T) (=DSM 101523(T) = MCCC 1K01590(T)). The extract of MUSC 164(T) showed potent antioxidative and neuroprotective activities against hydrogen peroxide. The chemical analysis of the extract revealed that the strain produces pyrazines and phenolic-related compounds that could explain for the observed bioactivities.
  18. Yong YL, Tan LT, Ming LC, Chan KG, Lee LH, Goh BH, et al.
    Front Pharmacol, 2016;7:538.
    PMID: 28119613 DOI: 10.3389/fphar.2016.00538
    In particular, neuropathic pain is a major form of chronic pain. This type of pain results from dysfunction or lesions in the central and peripheral nervous system. Capsaicin has been traditionally utilized as a medicine to remedy pain. However, the effectiveness and safety of this practice is still elusive. Therefore, this systematic review aimed to investigate the effect of topical capsaicin as a pain-relieving agent that is frequently used in pain management. In brief, all the double-blinded, randomized placebo- or vehicle-controlled trials that were published in English addressing postherpetic neuralgia were included. Meta-analysis was performed using Revman(®) version 5.3. Upon application of the inclusion and exclusion criteria, only six trials fulfilled all the criteria and were included in the review for qualitative analysis. The difference in mean percentage change in numeric pain rating scale score ranges from -31 to -4.3. This demonstrated high efficacy of topical capsaicin application and implies that capsaicin could result in pain reduction. Furthermore, meta-analysis was performed on five of the included studies. All the results of studies are in favor of the treatment using capsaicin. The incidence of side effects from using topical capsaicin is consistently higher in all included studies, but the significance of safety data cannot be quantified due to a lack of p-values in the original studies. Nevertheless, topical capsaicin is a promising treatment option for specific patient groups or certain neuropathic pain conditions such as postherpetic neuralgia.
  19. Tan LT, Chan KG, Khan TM, Bukhari SI, Saokaew S, Duangjai A, et al.
    Front Pharmacol, 2017;8:276.
    PMID: 28567016 DOI: 10.3389/fphar.2017.00276
    Reactive oxygen species and other radicals potentially cause oxidative damage to proteins, lipids, and DNA which may ultimately lead to various complications including mutations, carcinogenesis, neurodegeneration, cardiovascular disease, aging, and inflammatory disease. Recent reports demonstrate that Streptomyces bacteria produce metabolites with potent antioxidant activity that may be developed into therapeutic drugs to combat oxidative stress. This study shows that Streptomyces sp. MUM212 which was isolated from mangrove soil in Kuala Selangor, Malaysia, could be a potential source of antioxidants. Strain MUM212 was characterized and determined as belonging to the genus Streptomyces using 16S rRNA gene phylogenetic analysis. The MUM212 extract demonstrated significant antioxidant activity through DPPH, ABTS and superoxide radical scavenging assays and also metal-chelating activity of 22.03 ± 3.01%, 61.52 ± 3.13%, 37.47 ± 1.79%, and 41.98 ± 0.73% at 4 mg/mL, respectively. Moreover, MUM212 extract was demonstrated to inhibit lipid peroxidation up to 16.72 ± 2.64% at 4 mg/mL and restore survival of Vero cells from H2O2-induced oxidative damages. The antioxidant activities from the MUM212 extract correlated well with its total phenolic contents; and this in turn was in keeping with the gas chromatography-mass spectrometry analysis which revealed the presence of phenolic compounds that could be responsible for the antioxidant properties of the extract. Other chemical constituents detected included hydrocarbons, alcohols and cyclic dipeptides which may have contributed to the overall antioxidant capacity of MUM212 extract. As a whole, strain MUM212 seems to have potential as a promising source of novel molecules for future development of antioxidative therapeutic agents against oxidative stress-related diseases.
  20. Sun S, Tan LT, Fang YL, Jin ZJ, Zhou L, Goh BH, et al.
    Mol Plant Microbe Interact, 2020 Mar;33(3):488-498.
    PMID: 31710580 DOI: 10.1094/MPMI-09-19-0264-R
    Phenazine-1-carboxylic acid (PCA) is the primary active component in the newly registered, commercial biopesticide Shenqinmycin and is produced during fermentation by the engineered rhizobacterium strain Pseudomonas PA1201. Both phz1 and phz2 gene clusters contribute to PCA biosynthesis. In this study, we evaluated the role of OxyR in the regulation of PCA biosynthesis in PA1201. We first showed a functional link between oxyR expression and PCA biosynthesis. Deletion of oxyR and overexpression of oxyR both increase PCA biosynthesis. The molecular mechanisms underlying OxyR regulation of PCA production were investigated using several approaches. OxyR acts divergently in phz1 and phz2. Overexpression of oxyR activated the expression of phz1 and phz1-dependent PCA production. However, overexpression of oxyR had little effect on phz2-dependent PCA biosynthesis, while deletion of oxyR promoted phz2-dependent PCA production and exerted a negative effect on phz2 expression. Further, OxyR directly bound to the phz2 promoter region. In addition, the regulation of PCA biosynthesis by OxyR was associated with quorum sensing (QS) systems. Overexpression of OxyR positively regulated pqs QS system. Finally, transcriptomic analysis and subsequent genetic analysis revealed the small RNA phrS plays a key role in OxyR-dependent PCA accumulation. Specifically, OxyR directly binds to the phrS promoter region to positively regulate phrS expression wherein PhrS regulates the PCA positive regulator MvfR in order to control PCA biosynthesis.
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links