Displaying publications 41 - 60 of 151 in total

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  1. Brief Challenges on Medicinal Plants: An Eye-Opening Look at Ageing-Related Disorders
    Bjørklund G, Dadar M, Martins N, Chirumbolo S, Goh BH, Smetanina K, et al.
    Basic Clin Pharmacol Toxicol, 2018 Jun;122(6):539-558.
    PMID: 29369521 DOI: 10.1111/bcpt.12972
    Several studies have reported that nature-derived antioxidants may prevent free radicals over-production and therefore control the onset and prevent the exacerbation of different kinds of diseases caused by oxidative stress and redox-derived stressors, including ageing, fundamentally by suppressing the oxidative by-products-mediated degradation. Naturally derived antioxidants exert their anti-ageing action via a panoply of signalling systems, many of which engaging reactive oxygen and nitrogen species scavenging, with the Nrf2/Keap1-ARE system and improving the many survival genes and functions (such as the pathway mTOR/Foxo/SIRT1) able to slow cellular senescence. Most of the research in this field has evaluated the regulative effects and even pathways of herbal extracts with antioxidant property in the ageing process, and various age-related disorders such as cardiovascular disease, ischaemia-reperfusion injury, coronary and myocardial circulatory perfusion, peripheral vascular resistance, and even neurodegenerative disorders are prevented plant phytochemicals often via their antioxidant potential. A much more complex ability to interact with survival functions makes these compounds successfully active in preventing ageing-related disorders. This report aimed to discuss in more detail some selected medicinal plants including Allium sativum, Aloe vera, Crataegus spp., Cynara scolymus, Eleutherococcus senticosus, Ginkgo biloba, Hippophae rhamnoides, Panax ginseng, Rosmarinus officinalis, Schizandra chinensis, Vitis vinifera and seaweeds in the prevention of ageing-related pathologies. A systematic overview of the relevant information in the antioxidant function of the many herbal products reviewed here for the control of the ageing process is proposed, to provide a new horizon on the design of anti-ageing herbal medicines.
  2. Microenvironment-tailored nanoassemblies for the diagnosis and therapy of neurodegenerative diseases
    Low LE, Wang Q, Chen Y, Lin P, Yang S, Gong L, et al.
    Nanoscale, 2021 Jun 17;13(23):10197-10238.
    PMID: 34027535 DOI: 10.1039/d1nr02127c
    Neurodegenerative disorder is an illness involving neural dysfunction/death attributed to complex pathological processes, which eventually lead to the mortality of the host. It is generally recognized through features such as mitochondrial dysfunction, protein aggregation, oxidative stress, metal ions dyshomeostasis, membrane potential change, neuroinflammation and neurotransmitter impairment. The aforementioned neuronal dysregulations result in the formation of a complex neurodegenerative microenvironment (NME), and may interact with each other, hindering the performance of therapeutics for neurodegenerative disease (ND). Recently, smart nanoassemblies prepared from functional nanoparticles, which possess the ability to interfere with different NME factors, have shown great promise to enhance the diagnostic and therapeutic efficacy of NDs. Herein, this review highlights the recent advances of stimuli-responsive nanoassemblies that can effectively combat the NME for the management of ND. The first section outlined the NME properties and their interrelations that are exploitable for nanoscale targeting. The discussion is then extended to the controlled assembly of functional nanoparticles for the construction of stimuli-responsive nanoassemblies. Further, the applications of stimuli-responsive nanoassemblies for the enhanced diagnosis and therapy of ND are introduced. Finally, perspectives on the future development of NME-tailored nanomedicines are given.
  3. Tumor-responsive dynamic nanoassemblies for targeted imaging, therapy and microenvironment manipulation
    Low LE, Wu J, Lee J, Tey BT, Goh BH, Gao J, et al.
    J Control Release, 2020 Aug 10;324:69-103.
    PMID: 32423874 DOI: 10.1016/j.jconrel.2020.05.014
    The recent designs of dynamic nanoassemblies exploiting the tumor-targeting properties have received increasing attention for tumor imaging and therapy due to their tumor-specific delivery and enhanced antitumor efficacy. However, these designs are mainly focused on the macroscopic tumor therapeutic effect, while the nano-bio interactions in the tumor microenvironment (TME) remain poorly understood. This review aims to provide an overview of the development of tumor-responsive nanoassemblies towards the imaging, therapy and TME modulation in the tumor site. The tumor biology leading to TME formation and the potential TME properties for the practicable design of tumor-targeting nanoassemblies has been outlined. Furthermore, the various approaches for TME modification and the realization via dynamic nanoassemblies for enhanced tumor therapy were reviewed. Lastly, the prospects of these methods were briefly discussed. These strategies may inspire the development of new combinational cancer therapeutics.
  4. Fulltext Cisplatin-Resistance in Oral Squamous Cell Carcinoma: Regulation by Tumor Cell-Derived Extracellular Vesicles
    Khoo XH, Paterson IC, Goh BH, Lee WL
    Cancers (Basel), 2019 Aug 14;11(8).
    PMID: 31416147 DOI: 10.3390/cancers11081166
    Drug resistance remains a severe problem in most chemotherapy regimes. Recently, it has been suggested that cancer cell-derived extracellular vesicles (EVs) could mediate drug resistance. In this study, the role of EVs in mediating the response of oral squamous cell carcinoma (OSCC) cells to cisplatin was investigated. We isolated and characterized EVs from OSCC cell lines showing differential sensitivities to cisplatin. Increased EV production was observed in both de novo (H314) and adaptive (H103/cisD2) resistant lines compared to sensitive H103 cells. The protein profiles of these EVs were then analyzed. Differences in the proteome of EVs secreted by H103 and H103/cisD2 indicated that adaptation to cisplatin treatment caused significant changes in the secreted nanovesicles. Intriguingly, both resistant H103/cisD2 and H314 cells shared a highly similar EV protein profile including downregulation of the metal ion transporter, ATP1B3, in the EVs implicating altered drug delivery. ICP-MS analysis revealed that less cisplatin accumulated in the resistant cells, but higher levels were detected in their EVs. Therefore, we inhibited EV secretion from the cells using a proton pump inhibitor and observed an increased drug sensitivity in cisplatin-resistant H314 cells. This finding suggests that control of EV secretion could be a potential strategy to enhance the efficacy of cancer treatment.
  5. Fulltext Detection of Prostate Cancer via IR Spectroscopic Analysis of Urinary Extracellular Vesicles: A Pilot Study
    Yap XL, Wood B, Ong TA, Lim J, Goh BH, Lee WL
    Membranes (Basel), 2021 Jul 31;11(8).
    PMID: 34436354 DOI: 10.3390/membranes11080591
    Extracellular vesicles (EVs) are membranous nanoparticles naturally released from living cells which can be found in all types of body fluids. Recent studies found that cancer cells secreted EVs containing the unique set of biomolecules, which give rise to a distinctive absorbance spectrum representing its cancer type. In this study, we aimed to detect the medium EVs (200-300 nm) from the urine of prostate cancer patients using Fourier transform infrared (FTIR) spectroscopy and determine their association with cancer progression. EVs extracted from 53 urine samples from patients suspected of prostate cancer were analyzed and their FTIR spectra were preprocessed for analysis. Characterization of morphology, particle size and marker proteins confirmed that EVs were successfully isolated from urine samples. Principal component analysis (PCA) of the EV's spectra showed the model could discriminate prostate cancer with a sensitivity of 59% and a specificity of 81%. The area under curve (AUC) of FTIR PCA model for prostate cancer detection in the cases with 4-20 ng/mL PSA was 0.7, while the AUC for PSA alone was 0.437, suggesting the analysis of urinary EVs described in this study may offer a novel strategy for the development of a noninvasive additional test for prostate cancer screening.
  6. Attenuating influenza a virus infection by heparin binding EGF-like growth factor
    Lai KM, Goh BH, Lee WL
    Growth Factors, 2021 03 15;38(3-4):167-176.
    PMID: 33719806 DOI: 10.1080/08977194.2021.1895144
    Cell entry of influenza A virus (IAV) was reported to be promoted by epidermal growth factor receptor (EGFR). On the other hand, binding of heparin-binding EGF-like growth factor (HB-EGF) to EGFR leads to internalisation and degradation of the receptors. This study aimed to testify whether or not HB-EGF-induced downregulation of EGFR could attenuate IAV cell entry and subsequently diminish the infection. Immunoblotting and plaque assay revealed that HB-EGF-induced degradation of EGFR led to reduction of viral matrix 1 protein level and suppressed virion production. In addition, immunoblotting and imaging flow cytometric analysis demonstrated that IAV-induced phosphorylation of STAT1 and its localisation to nucleus in the early stage of infection were inhibited by HB-EGF treatment. This suggested the potential of HB-EGF in modulating uncontrolled and exaggerated inflammatory response caused by IAV infection. Together these findings attest the potential of HB-EGF mediated endocytosis and degradation of EGFR as a novel anti-IAV strategy.
  7. Bacterial extracellular vesicles in biofluids as potential diagnostic biomarkers
    Su KY, Koh Kok JY, Chua YW, Ong SD, Ser HL, Pusparajah P, et al.
    Expert Rev Mol Diagn, 2022 Dec;22(12):1057-1062.
    PMID: 36629056 DOI: 10.1080/14737159.2022.2166403
    INTRODUCTION: Extracellular vesicles (EVs) are spherical membrane-derived lipid bilayers released by cells. The human microbiota consists of trillions of microorganisms, with bacteria being the largest group secreting microbial EVs. The discovery of bacterial EVs (BEVs) has garnered interest among researchers as potential diagnostic markers, given that the microbiota is known to be associated with various diseases and EVs carry important macromolecular cargo for intercellular interaction.

    AREAS COVERED: The differential bacterial composition identified from BEVs isolated from biofluids between patients and healthy controls may be valuable for detecting diseases. Therefore, BEVs may serve as novel diagnostic markers. Literature search on PubMed and Google Scholar databases was conducted. In this special report, we outline the commonly used approach for investigating BEVs in biofluids, the 16S ribosomal RNA gene sequencing of V3-V4 hypervariable regions, and the recent studies exploring the potential of BEVs as biomarkers for various diseases.

    EXPERT OPINION: The emerging field of BEVs offers new possibilities for the diagnosis of various types of diseases, although there remain issues that need to be resolved in this research area to implement BEVs in clinical applications. Hence, it is important for future studies to take these challenges into consideration when investigating the diagnostic value of BEVs.

  8. Fulltext Evaluation of Antioxidative and Cytotoxic Activities of Streptomyces pluripotens MUSC 137 Isolated from Mangrove Soil in Malaysia
    Ser HL, Ab Mutalib NS, Yin WF, Chan KG, Goh BH, Lee LH
    Front Microbiol, 2015;6:1398.
    PMID: 26733951 DOI: 10.3389/fmicb.2015.01398
    Streptomyces pluripotens MUSC 137 was isolated from mangrove soil obtained from Tanjung Lumpur, Pahang, Malaysia. We investigated the phylogenetic, genomic, biochemical, and phenotypic characteristics of this strain. Uniquely adapted microorganisms from mangrove habitats have previously yielded compounds of biopharmaceutical interest. In order to examine the bioactivities possessed by the strain, fermentation extract was prepared through solvent extraction method prior to bioactivities screenings. Antioxidant activity was examined via DPPH assay while the cytotoxic effect was assessed by means of examining the activity of the extract against selected human cancer cell lines, namely colon cancer cells (HCT-116, Caco-2, SW480, and HT-29), breast cancer cell (MCF-7), lung cancer cell (A549), prostate cancer cell (DU145), and cervical cancer cell (Ca Ski). The results revealed MUSC 137 possesses significant antioxidant activity and demonstrates cytotoxic effect against several cancer cell lines tested. The results indicated MCF-7 cells were most susceptible to the extract with the lowest IC50 (61.33 ± 17.10 μg/mL), followed by HCT-116 and A549. Additionally, selective index (SI) showed that MUSC 137 extract was less toxic against normal cell lines when compared to MCF-7 and HCT-116 cells. The extract was further subjected to chemical analysis using GC-MS and revealed the presence of deferoxamine and pyrrolizidines related compounds which may account for the antioxidant and cytotoxic properties observed.
  9. Fulltext Streptomyces malaysiense sp. nov.: A novel Malaysian mangrove soil actinobacterium with antioxidative activity and cytotoxic potential against human cancer cell lines
    Ser HL, Palanisamy UD, Yin WF, Chan KG, Goh BH, Lee LH
    Sci Rep, 2016 Apr 13;6:24247.
    PMID: 27072394 DOI: 10.1038/srep24247
    Actinobacteria from the unique intertidal ecosystem of the mangroves are known to produce novel, bioactive secondary metabolites. A novel strain known as MUSC 136(T) (=DSM 100712(T) = MCCC 1K01246(T)) which was isolated from Malaysian mangrove forest soil has proven to be no exception. Assessed by a polyphasic approach, its taxonomy showed a range of phylogenetic and chemotaxonomic properties consistent with the genus of Streptomyces. Phylogenetically, highest similarity was to Streptomyces misionensis NBRC 13063(T) (99.6%) along with two other strains (>98.9% sequence similarities). The DNA-DNA relatedness between MUSC 136(T) and these type strains ranged from 22.7 ± 0.5% to 46.5 ± 0.2%. Overall, polyphasic approach studies indicated this strain represents a novel species, for which the name Streptomyces malaysiense sp. nov. is proposed. The potential bioactivities of this strain were explored by means of antioxidant and cytotoxic assays. Intriguingly, MUSC 136(T) exhibited strong antioxidative activities as evaluated by a panel of antioxidant assays. It was also found to possess high cytotoxic effect against HCT-116 cells, which probably mediated through altering p53 protein and intracellular glutathione levels. Chemical analysis of the extract using GC-MS further affirms that the strain produces chemopreventive related metabolites.
  10. Streptomyces gilvigriseus sp. nov., a novel actinobacterium isolated from mangrove forest soil
    Ser HL, Zainal N, Palanisamy UD, Goh BH, Yin WF, Chan KG, et al.
    Antonie Van Leeuwenhoek, 2015 Jun;107(6):1369-78.
    PMID: 25863667 DOI: 10.1007/s10482-015-0431-5
    A novel Streptomyces, strain MUSC 26(T), was isolated from mangrove soil at Tanjung Lumpur, Malaysia. The bacterium was observed to be Gram-positive and to form grayish yellow aerial and substrate mycelium on ISP 7 agar. A polyphasic approach was used to study the taxonomy of strain MUSC 26(T), which shows a range 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 (H8) and MK-9(H6). The polar lipids detected were identified as diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylmethylethanolamine and hydroxyphosphatidylmethylethanolamine. The predominant cellular fatty acids (>10.0 %) were identified as anteiso-C15:0 (31.4 %), iso-C16:0 (16.3 %), iso-C15:0 (13.9 %) and anteiso-C17:0 (12.6 %). The cell wall sugars were found to be galactose, glucose, mannose, ribose and rhamnose. These results suggest that MUSC 26(T) should be placed within the genus Streptomyces. Phylogenetic analysis indicated that closely related strains include Streptomyces qinglanensis 172205(T) (96.5 % sequence similarity), S. sodiiphilus YIM 80305(T) (96.5 %) and S. rimosus subsp. rimosus ATCC 10970(T) (96.4 %). DNA-DNA relatedness values between MUSC 26(T) and closely related type strains ranged from 17.0 ± 2.2 to 33.2 ± 5.3 %. Comparison of BOX-PCR fingerprints indicated MUSC 26(T) presents a unique DNA profile. The DNA G+C content was determined to be 74.6 mol%. Based on this polyphasic study of MUSC 26(T), it is concluded that this strain represents a novel species, for which the name Streptomyces gilvigriseus sp. nov. is proposed. The type strain is MUSC 26(T) (=DSMZ 42173(T) = MCCC 1K00504(T)).
  11. Fulltext Diversity of Streptomyces spp. from mangrove forest of Sarawak (Malaysia) and screening of their antioxidant and cytotoxic activities
    Law JW, Chan KG, He YW, Khan TM, Ab Mutalib NS, Goh BH, et al.
    Sci Rep, 2019 12 03;9(1):15262.
    PMID: 31792235 DOI: 10.1038/s41598-019-51622-x
    Streptomycetes have been the center of attraction within scientific community owing to their capability to produce various bioactive compounds, for instance, with different antimicrobial, anticancer, and antioxidant properties. The search for novel Streptomyces spp. from underexplored area such as mangrove environment has been gaining attention since these microorganisms could produce pharmaceutically important metabolites. The aim of this study is to discover the diversity of Streptomyces spp. from mangrove in Sarawak and their bioactive potentials - in relation to antioxidant and cytotoxic activities. A total of 88 Streptomyces isolates were successfully recovered from the mangrove soil in Kuching, state of Sarawak, Malaysia. Phylogenetic analysis of all the isolates and their closely related type strains using 16S rRNA gene sequences resulted in 7 major clades in the phylogenetic tree reconstructed based on neighbour-joining algorithm. Of the 88 isolates, 18 isolates could be considered as potentially novel species according to the 16S rRNA gene sequence and phylogenetic analyses. Preliminary bioactivity screening conducted on the potential novel Streptomyces isolates revealed significant antioxidant activity and notable cytotoxic effect against tested colon cancer cell lines (HCT-116, HT-29, Caco-2, and SW480), with greater cytotoxicity towards SW480 and HT-29 cells. This study highlighted that the Sarawak mangrove environment is a rich reservoir containing streptomycetes that could produce novel secondary metabolites with antioxidant and cytotoxic activities.
  12. Fulltext Targeting Gut Microbial Biofilms-A Key to Hinder Colon Carcinogenesis?
    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.
  13. Fulltext Genome Sequence of Vibrio parahaemolyticus VP152 Strain Isolated from Penaeus indicus in Malaysia
    Letchumanan V, Ser HL, Tan WS, Ab Mutalib NS, Goh BH, Chan KG, et al.
    Front Microbiol, 2016;7:1410.
    PMID: 27656174 DOI: 10.3389/fmicb.2016.01410
  14. Fulltext Streptomyces antioxidans sp. nov., a Novel Mangrove Soil Actinobacterium with Antioxidative and Neuroprotective Potentials
    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.
  15. Genome Sequence of Vibrio parahaemolyticus VP103 Strain Isolated from Shrimp in Malaysia
    Letchumanan V, Ser HL, Chan KG, Goh BH, Lee LH
    Front Microbiol, 2016;7:1496.
    PMID: 27708636
  16. Fulltext Bile Sensing: The Activation of Vibrio parahaemolyticus Virulence
    Letchumanan V, Chan KG, Khan TM, Bukhari SI, Ab Mutalib NS, Goh BH, et al.
    Front Microbiol, 2017;8:728.
    PMID: 28484445 DOI: 10.3389/fmicb.2017.00728
    Bacteria must develop resistance to various inhospitable conditions in order to survive in the human gastrointestinal tract. Bile, which is secreted by the liver, and plays an important role in food digestion also has antimicrobial properties and is able to disrupt cellular homeostasis. Paradoxically, although bile is one of the guts defenses, many studies have reported that bacteria such as Vibrio parahaemolyticus can sense bile and use its presence as an environmental cue to upregulate virulence genes during infection. This article aims to discuss how bile is detected by V. parahaemolyticus and its role in regulating type III secretion system 2 leading to human infection. This bile-bacteria interaction pathway gives us a clearer understanding of the biochemical and structural analysis of the bacterial receptors involved in mediating a response to bile salts which appear to be a significant environmental cue during initiation of an infection.
  17. Draft Genome Sequence of Mangrove-Derived Streptomyces sp. MUSC 125 with Antioxidant Potential
    Ser HL, Tan WS, Ab Mutalib NS, Yin WF, Chan KG, Goh BH, et al.
    Front Microbiol, 2016;7:1470.
    PMID: 27695452
  18. Fulltext Vibrio vulnificus: An Environmental and Clinical Burden
    Heng SP, Letchumanan V, Deng CY, Ab Mutalib NS, Khan TM, Chuah LH, et al.
    Front Microbiol, 2017;8:997.
    PMID: 28620366 DOI: 10.3389/fmicb.2017.00997
    Vibrio vulnificus is a Gram negative, rod shaped bacterium that belongs to the family Vibrionaceae. It is a deadly, opportunistic human pathogen which is responsible for the majority of seafood-associated deaths worldwide. V. vulnificus infection can be fatal as it may cause severe wound infections potentially requiring amputation or lead to sepsis in susceptible individuals. Treatment is increasingly challenging as V. vulnificus has begun to develop resistance against certain antibiotics due to their indiscriminate use. This article aims to provide insight into the antibiotic resistance of V. vulnificus in different parts of the world as well as an overall review of its clinical manifestations, treatment, and prevention. Understanding the organism's antibiotic resistance profile is vital in order to select appropriate treatment and initiate appropriate prevention measures to treat and control V. vulnificus infections, which should eventually help lower the mortality rate associated with this pathogen worldwide.
  19. The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae)
    Law JW, Ser HL, Khan TM, Chuah LH, Pusparajah P, Chan KG, et al.
    Front Microbiol, 2017;8:3.
    PMID: 28144236 DOI: 10.3389/fmicb.2017.00003
    Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10-30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyces bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae. The ability of various Streptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae. In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents.
  20. Fulltext Streptomyces as a Prominent Resource of Future Anti-MRSA Drugs
    Kemung HM, Tan LT, Khan TM, Chan KG, Pusparajah P, Goh BH, et al.
    Front Microbiol, 2018;9:2221.
    PMID: 30319563 DOI: 10.3389/fmicb.2018.02221
    Methicillin-resistant Staphylococcus aureus (MRSA) pose a significant health threat as they tend to cause severe infections in vulnerable populations and are difficult to treat due to a limited range of effective antibiotics and also their ability to form biofilm. These organisms were once limited to hospital acquired infections but are now widely present in the community and even in animals. Furthermore, these organisms are constantly evolving to develop resistance to more antibiotics. This results in a need for new clinically useful antibiotics and one potential source are the Streptomyces which have already been the source of several anti-MRSA drugs including vancomycin. There remain large numbers of Streptomyces potentially undiscovered in underexplored regions such as mangrove, deserts, marine, and freshwater environments as well as endophytes. Organisms from these regions also face significant challenges to survival which often result in the production of novel bioactive compounds, several of which have already shown promise in drug development. We review the various mechanisms of antibiotic resistance in MRSA and all the known compounds isolated from Streptomyces with anti-MRSA activity with a focus on those from underexplored regions. The isolation of the full array of compounds Streptomyces are potentially capable of producing in the laboratory has proven a challenge, we also review techniques that have been used to overcome this obstacle including genetic cluster analysis. Additionally, we review the in vivo work done thus far with promising compounds of Streptomyces origin as well as the animal models that could be used for this work.
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