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Cold plasma inactivation of chronic wound bacteria

Mohd Nasir N, Lee BK, Yap SS, Thong KL, Yap SL

Arch Biochem Biophys, 2016 09 01;605:76-85.
PMID: 27046340 DOI: 10.1016/j.abb.2016.03.033

Cold plasma is partly ionized non-thermal plasma generated at atmospheric pressure. It has been recognized as an alternative approach in medicine for sterilization of wounds, promotion of wound healing, topical treatment of skin diseases with microbial involvement and treatment of cancer. Cold plasma used in wound therapy inhibits microbes in chronic wound due to its antiseptic effects, while promoting healing by stimulation of cell proliferation and migration of wound relating skin cells. In this study, two types of plasma systems are employed to generate cold plasma: a parallel plate dielectric barrier discharge and a capillary-guided corona discharge. Parameters such as applied voltage, discharge frequency, treatment time and the flow of the carrier gas influence the cold plasma chemistry and therefore change the composition and concentration of plasma species that react with the target sample. Chronic wound that fails to heal often infected by multidrug resistant organisms makes them recalcitrant to healing. Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (Pseudomonas aeruginosa) are two common bacteria in infected and clinically non-infected wounds. The efficacies of the cold plasma generated by the two designs on the inactivation of three different isolates of MRSA and four isolates of P. aeruginosa are reported here.

Matched MeSH terms: Methicillin/chemistry
Flemingin-Type Prenylated Chalcones from the Sarawak Rainforest Plant Desmodium congestum

Rees KA, Bermudez C, Edwards DJ, Elliott AG, Ripen JE, Seta C, et al.

J Nat Prod, 2015 Aug 28;78(8):2141-4.
PMID: 26284978 DOI: 10.1021/acs.jnatprod.5b00410

In an ongoing program to identify new anti-infective leads, an extract derived from whole plant material of Desmodium congestum collected in the Sarawak rainforest was found to have anti-MRSA activity. Bioassay-guided isolation led to the isolation of two new prenylated chalcones, 5'-O-methyl-3-hydroxyflemingin A (1) and 5'-O-methylflemingin C (2), which were closely related to the flemingins previously isolated from various Flemingia species. Chalcones 1 and 2, which were determined to be 4:6 enantiomeric mixtures by chiral HPLC, exhibited moderate activity against a panel of Gram-positive bacteria and were also cytotoxic to the HEK293 human embryonic kidney cell line.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects
A major methicillin-resistant Staphylococcus aureus clone predominates in Malaysian hospitals

Norazah A, Lim VK, Rohani MY, Alfizah H, Koh YT, Kamel AG

Epidemiol Infect, 2003 Jun;130(3):407-11.
PMID: 12825724

This study was conducted to determine the molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Malaysian hospitals. A total of 264 MRSA isolates from eight hospitals were subjected to typing by pulsed-field gel electrophoresis (PFGE) of SmaI restricted DNA. Antibiotic disk susceptibility testing was also carried out to determine their resistance patterns. Thirty-one PFGE pattern types were identified. Three major pattern types A, ZC and K were found with type A the predominant profile in c. 80% of strains and present in all hospitals. Unlike type A, other DNA pattern types were unique to the hospitals in which they were isolated. PFGE type A also consisted of strains that were multiply antibiotic resistant. The presence of a single predominant PFGE type in Malaysian hospitals is an important finding which suggests that inter-hospital spread of MRSA had occurred frequently and regularly.

Matched MeSH terms: Methicillin Resistance/genetics*
Comparison of methicillin-resistant and methicillin-sensitive Staphylococcus aureus strains isolated from a tertiary hospital in Terengganu, Malaysia

Lim KT, Yeo CC, Suhaili Z, Thong KL

Jpn J Infect Dis, 2012;65(6):502-9.
PMID: 23183202

Staphylococcus aureus is a persistent human pathogen responsible for a variety of infections ranging from soft-tissue infections to bacteremia. The objective of this study was to determine genetic relatedness between methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) strains. We isolated 35 MRSA and 21 MSSA strains from sporadic cases at the main tertiary hospital in Terengganu, Malaysia, screening them for the presence of virulence genes. Their genetic relatedness was determined by accessory gene regulator (agr) types, PCR-restriction fragment length polymorphism (RFLP) of the coa gene, pulsed-field gel electrophoresis (PFGE), S. aureus protein A (spa), and multilocus-sequence typing (MLST). We found that 57% of MRSA and 43% of MSSA strains harbored enterotoxin genes. The majority (87.5%) of the strains were agr type I. PCR-RFLP and PFGE genotyping of the coa gene revealed that MRSA strains were genetically related, whereas MSSA strains had higher heterogeneity. The combined genotype, MLST-spa type ST239-t037, was shared among MRSA and MSSA strains, indicating that MRSA strains could have evolved from MSSA strains. Two combined MLST-spa types were present in MRSA strains, whereas 7 different MLST-spa types were detected in MSSA strains, including 2 combined types (ST779-t878 and ST1179-t267) that have not been reported in Malaysia. In conclusion, enterotoxin genes were more prevalent in MRSA than in MSSA strains in the Terengganu hospital. The MSSA strains were genetically more diverse than the MRSA strains.

Matched MeSH terms: Methicillin Resistance*
Fulltext Scedosporium apiospermum: A Rare Cause of Aggressive Orbital Apex Syndrome

Loh UL, Tai PY, Hussein A, A Qamarruddin F

Cureus, 2018 Dec 17;10(12):e3743.
PMID: 30800553 DOI: 10.7759/cureus.3743

Orbital apex syndrome (OAS) is a localized orbital cellulitis at the orbital apex that can cause vision loss from optic neuropathy and ophthalmoplegia involving multiple cranial nerves. Herein, we report a rare and rapidly progressive case of OAS secondary to fungal pansinusitis caused by Scedosporiumapiospermum in an immunocompromised patient following the extraction of abscessed teeth. A 48-year-old man with diabetes mellitus who had failed to adhere to his treatment presented with complaints of a right-sided headache and toothache for two weeks, with nausea and vomiting for two days prior to presentation. The patient was treated for septic shock secondary to the dental abscesses. Non-contrast brain computed tomography (CT) showed no significant intracranial abnormalities other than pansinusitis. Four days later, dental extraction was performed. The patient reported progressive painless blurring of the vision in his right eye following the dental extractions and was referred to the ophthalmology department. Subsequent examinations revealed decreased optic nerve function and ophthalmoplegia in his right eye and dental caries in the upper molars, with a mucopurulent discharge from the right sphenoid region. The clinical diagnosis was OAS. Pus near the orbital apex was drained surgically. Methicillin-resistant Staphylococcus aureus was isolated from the pus and a nasal swab. Tissue culture from the septal wall yielded S.apiospermum. The patient's condition deteriorated, despite intensive antibiotic and antifungal treatment and repeated surgical debridement. The disease progressed rapidly to his left eye. Sixty-seven days after the inital presentation, his visual acuity (VA) of both eyes was classified as no perception of light (NPL). The patient discharged himself from the hospital (at own risk discharge) and subsequently failed to attend a scheduled appointment in the ophthalmology clinic. If immunocompromised patients present with OAS, fungal infections should be ruled out. Prompt and aggressive treatment using a multidisciplinary approach is mandatory in cases of potentially life-threatening and vision-threatening fungal infections.

Matched MeSH terms: Methicillin; Methicillin-Resistant Staphylococcus aureus
Fulltext Gold Nanoparticle-Conjugated Cinnamic Acid Exhibits Antiacanthamoebic and Antibacterial Properties

Anwar A, Siddiqui R, Shah MR, Khan NA

Antimicrob Agents Chemother, 2018 09;62(9).
PMID: 29967024 DOI: 10.1128/AAC.00630-18

trans-Cinnamic acid (CA) is a natural organic compound. Using amoebicidal assays, for the first time we showed that CA affected the viability of the protist pathogen Acanthamoeba castellanii Conjugation with gold nanoparticles (AuNPs) enhanced the antiamoebic effects of CA. CA-coated AuNPs (CA-AuNPs) also exhibited significant excystation and encystation activity, compared to CA and AuNPs alone. Pretreatment of amoebae with CA-AuNPs inhibited A. castellanii-mediated host cell cytotoxicity. Moreover, CA-AuNPs exhibited potent effects against methicillin-resistant Staphylococcus aureus and neuropathogenic Escherichia coli K1 and protected host cells against bacteria-mediated host cell death.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects
Synergistic Antibacterial Activity Between 1,4-Naphthoquinone and β-Lactam Antibiotics Against Methicillin-Resistant Staphylococcus aureus

Yap JKY, Tan SYY, Tang SQ, Thien VK, Chan EWL

Microb Drug Resist, 2021 Feb;27(2):234-240.
PMID: 32589487 DOI: 10.1089/mdr.2020.0178

Aims: Currently, limited antibiotics are available to treat methicillin-resistant Staphylococcus aureus (MRSA) infections. One approach is the use of adjuvants in antibiotic therapy. 1,4-Naphthoquinones are naturally occurring alkaloids shown to have antibacterial properties. The objective of this study is to investigate the synergy between 1,4-naphthoquinone and selected β-lactam antibiotics and to evaluate the potential use of 1,4-naphthoquinone as an adjuvant in antibiotic treatment against MRSA infections. Methods: The antibacterial activity of 1,4-naphthoquinone and plumbagin was tested against nine pathogenic bacterial strains using the microdilution broth method. The interactions between 1,4-naphthoquinone and three antibiotics (cefuroxime, cefotaxime, and imipenem) were estimated by calculating the fractional inhibitory concentration of the combination. Results: The compounds 1,4-naphthoquinone and plumbagin exhibited a broad range of bacteriostatic and bactericidal effects against both Gram-positive and Gram-negative bacteria. The interaction between 1,4-naphthoquinone and imipenem, cefuroxime, and cefotaxime was synergistic against methicillin-sensitive Staphylococcus aureus and MRSA clinical strains. Against ATCC-cultured MRSA, a synergistic effect was observed between 1,4-naphthoquinone and cefotaxime. However, combination with imipenem only produced an additive effect, and an antagonistic action was observed between 1,4-naphthoquinone and cefuroxime. Conclusions: Although individually less potent than common antibiotics, 1,4-naphthoquinone acts synergistically with imipenem, cefuroxime, and cefotaxime against MRSA clinical strains and could potentially be used in adjuvant-antibiotic therapy against multidrug resistant bacteria.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects*
Smoothing a discrete hazard function for the number of patients colonized with Methicillin-resistant Staphylococcus Aureus in an intensive care unit

Ismail NA, Pettitt AN

Stat Med, 2004 Apr 30;23(8):1247-58.
PMID: 15083481

A new method for estimating the time to colonization of Methicillin-resistant Staphylococcus Aureus (MRSA) patients is developed in this paper. The time to colonization of MRSA is modelled using a Bayesian smoothing approach for the hazard function. There are two prior models discussed in this paper: the first difference prior and the second difference prior. The second difference prior model gives smoother estimates of the hazard functions and, when applied to data from an intensive care unit (ICU), clearly shows increasing hazard up to day 13, then a decreasing hazard. The results clearly demonstrate that the hazard is not constant and provide a useful quantification of the effect of length of stay on the risk of MRSA colonization which provides useful insight.

Matched MeSH terms: Methicillin Resistance*
Community-acquired necrotising pneumonia caused by Panton-Valentine leucocidin-producing methicillin-resistant Staphylococcus aureus

Leong CL, Norazah A, Azureen A, Lingam R

Med J Malaysia, 2017 12;72(6):378-379.
PMID: 29308781

A 61-year-old male presented with community-onset pneumonia not responding to treatment despite given appropriate antibiotics. Computed tomography scan of the thorax showed large multiloculated pleural effusion with multiple cavitating foci within collapsed segments; lesions which were suggestive of necrotising pneumonia. Drainage of the effusion and culture revealed methicillin-resistant Staphylococcus aureus, which had the same antibiotic profile with the blood isolate and PVL gene positive.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/metabolism*
Fulltext Clinical characteristics and outcomes of paediatric orbital cellulitis in Hospital Universiti Sains Malaysia: a five-year review

Mohd-Ilham I, Muhd-Syafi AB, Khairy-Shamel ST, Shatriah I

Singapore Med J, 2020 Jun;61(6):312-319.
PMID: 31598730 DOI: 10.11622/smedj.2019121

INTRODUCTION: Limited data is available on paediatric orbital cellulitis in Asia. We aimed to describe demographic data, clinical presentation, predisposing factors, identified microorganisms, choice of antibiotics and management in children with orbital cellulitis treated in a tertiary care centre in Malaysia.
METHODS: A retrospective review was performed on children with orbital cellulitis aged below 18 years who were admitted to Hospital Universiti Sains Malaysia, Kelantan, Malaysia, between January 2013 and December 2017.
RESULTS: A total of 14 paediatric patients fulfilling the diagnostic criteria for orbital cellulitis were included. Their mean age was 6.5 ± 1.2 years. Boys were more likely to have orbital cellulitis than girls (71.4% vs. 28.6%). Involvement of both eyes was observed in 14.3% of the patients. Sinusitis (28.6%) and upper respiratory tract infection (21.4%) were the most common predisposing causes. Staphylococcus aureus (28.6%) was the leading pathogen. Longer duration of hospitalisation was observed in those infected with methicillin-resistant Staphylococcus aureus and Burkholderia pseudomallei. 10 (71.4%) patients were treated with a combination of two or three antibiotics. In this series, 42.9% had surgical interventions.
CONCLUSION: Young boys were found to be more commonly affected by orbital cellulitis than young girls. Staphylococcus aureus was the most common isolated microorganism. Methicillin-resistant Staphylococcus aureus and Burkholderia pseudomallei caused severe infection. Sinusitis and upper respiratory tract infection were the most common predisposing factors. A majority of the children improved with medical treatment alone. Our findings are in slight disagreement with other published reports on paediatric orbital cellulitis, especially from the Asian region.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/isolation & purification
Fulltext Bioactive 2-(Methyldithio)Pyridine-3-Carbonitrile from Persian Shallot (Allium stipitatum Regel.) Exerts Broad-Spectrum Antimicrobial Activity

Karunanidhi A, Ghaznavi-Rad E, Jeevajothi Nathan J, Joseph N, Chigurupati S, Mohd Fauzi F, et al.

Molecules, 2019 Mar 13;24(6).
PMID: 30871159 DOI: 10.3390/molecules24061003

Antibiotic resistance is a problem that continues to challenge the healthcare sector, especially in clinically significant pathogens like methicillin-resistant Staphylococcus aureus (MRSA). Herein is described the isolation and structure elucidation of a bioactive compound from Allium stipitatum with antimicrobial activity. Crude Allium stipitatum dichloromethane extract (ASDE) was subjected to systematic purification by chromatographic procedures to afford various bioactive fractions. A fraction that exhibited anti-MRSA activity (4 µg·mL-1) was further characterized to determine the structure. The structure of the compound was elucidated as 2-(methyldithio)pyridine-3-carbonitrile (2-Medpy-3-CN). The 2-Medpy-3-CN compound, which was screened for antimicrobial activity, exhibited minimum inhibitory concentrations (MICs) in the range of 0.5 to >64 µg·mL-1 for tested bacterial species and 0.25 to 2 µg·mL-1 for Candida spp. Further studies are important to confirm the drug target and mechanism of action.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects*
Low levels of meticillin-resistant Staphylococcus aureus in pigs in Malaysia

Khalid KA, Zakaria Z, Toung OP, McOrist S

Vet Rec, 2009 May 16;164(20):626-7.
PMID: 19448256
Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/isolation & purification*
Fulltext Single-molecule sequencing reveals the molecular basis of multidrug-resistance in ST772 methicillin-resistant Staphylococcus aureus

Steinig EJ, Andersson P, Harris SR, Sarovich DS, Manoharan A, Coupland P, et al.

BMC Genomics, 2015;16:388.
PMID: 25981586 DOI: 10.1186/s12864-015-1599-9

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-associated infection, but there is growing awareness of the emergence of multidrug-resistant lineages in community settings around the world. One such lineage is ST772-MRSA-V, which has disseminated globally and is increasingly prevalent in India. Here, we present the complete genome sequence of DAR4145, a strain of the ST772-MRSA-V lineage from India, and investigate its genomic characteristics in regards to antibiotic resistance and virulence factors.
RESULTS: Sequencing using single-molecule real-time technology resulted in the assembly of a single continuous chromosomal sequence, which was error-corrected, annotated and compared to nine draft genome assemblies of ST772-MRSA-V from Australia, Malaysia and India. We discovered numerous and redundant resistance genes associated with mobile genetic elements (MGEs) and known core genome mutations that explain the highly antibiotic resistant phenotype of DAR4145. Staphylococcal toxins and superantigens, including the leukotoxin Panton-Valentinin Leukocidin, were predominantly associated with genomic islands and the phage φ-IND772PVL. Some of these mobile resistance and virulence factors were variably present in other strains of the ST772-MRSA-V lineage.
CONCLUSIONS: The genomic characteristics presented here emphasize the contribution of MGEs to the emergence of multidrug-resistant and highly virulent strains of community-associated MRSA. Antibiotic resistance was further augmented by chromosomal mutations and redundancy of resistance genes. The complete genome of DAR4145 provides a valuable resource for future investigations into the global dissemination and phylogeography of ST772-MRSA-V.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/genetics*
Fulltext Indonesian Mangrove Sonneratia caseolaris Leaves Ethanol Extract Is a Potential Super Antioxidant and Anti Methicillin-Resistant Staphylococcus aureus Drug

Audah KA, Ettin J, Darmadi J, Azizah NN, Anisa AS, Hermawan TDF, et al.

Molecules, 2022 Nov 30;27(23).
PMID: 36500458 DOI: 10.3390/molecules27238369

Methicillin-resistant Staphylococcus aureus (MRSA) is an S. aureus strain that has developed resistance against ß-lactam antibiotics, resulting in a scarcity of a potent cure for treating Staphylococcus infections. In this study, the anti-MRSA and antioxidant activity of the Indonesian mangrove species Sonneratia caseolaris, Avicennia marina, Rhizophora mucronata, and Rhizophora apiculata were studied. Disk diffusion, DPPH, a brine shrimp lethality test, and total phenolic and flavonoid assays were conducted. Results showed that among the tested mangroves, ethanol solvent-based S. caseolaris leaves extract had the highest antioxidant and anti-MRSA activities. An antioxidant activity assay showed comparable activity when compared to ascorbic acid, with an IC50 value of 4.2499 ± 3.0506 ppm and 5.2456 ± 0.5937 ppm, respectively, classifying the extract as a super-antioxidant. Moreover, S. caseolaris leaves extract showed the highest content of strongly associated antioxidative and antibacterial polyphenols, with 12.4% consisting of nontoxic flavonoids with the minimum inhibitory concentration of the ethanol-based S. caseolaris leaves extract being approximately 5000 ppm. LC-MS/MS results showed that phenolic compounds such as azelaic acid and aspirin were found, as well as flavonoid glucosides such as isovitexin and quercitrin. This strongly suggested that these compounds greatly contributed to antibacterial and antioxidant activity. Further research is needed to elucidate the interaction of the main compounds in S. caseolaris leaves extract in order to confirm their potential either as single or two or more compounds that synergistically function as a nontoxic antioxidant and antibacterial against MRSA.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus*
In vitro activities of 28 antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA) from a clinical setting in Malaysia

Neela V, Sasikumar M, Ghaznavi GR, Zamberi S, Mariana S

Southeast Asian J Trop Med Public Health, 2008 Sep;39(5):885-92.
PMID: 19058585

Methicillin-resistant Staphylococcus aureus (MRSA), an established nosocomial and emerging community pathogen associated with many fatalities due to its hyper-virulence and multiple drug resistant properties, is on the continuous rise. To update the current status on the susceptibility of local MRSA isolates to various classes of antibiotics and to identify the most potent antibiotics, thirty-two clinical isolates comprised of hospital acquired (HA) and community acquired (CA) infections were investigated by disk diffusion test. Of the 32 MRSA isolates, 14 (43.75%) and 18 (56.25%) were community and hospital acquired MRSA, respectively. All isolates were multiple drug resistant to more than 3 classes of antibiotics despite the source or specimen from which it was isolated. The oxacillin MICs for all isolates ranged from 2 to > or = 256 microg/ml. Twenty-five of 26 erythromycin-resistant MRSA isolates exhibited an inducible MLS(B) resistance phenotype while one showed an MS phenotype. More than half the isolates (68.75%) were resistant to at least one of the six aminoglycosides tested, with netilmicin as the most susceptible. The most effective antistaphylococcal agents were linezolid, vancomycin, teicoplanin and quinupristin/dalfopristin exhibited 100% susceptibility. Since MRSA is under continuous pressure of acquiring multiple drug resistance, it is imperative to focus routine surveillance on HA and CA-MRSA strains to monitor and limit the spread of this organism.

Matched MeSH terms: Methicillin Resistance*
Fulltext Discovery of potential anti-infectives against Staphylococcus aureus using a Caenorhabditis elegans infection model

Kong C, Yehye WA, Abd Rahman N, Tan MW, Nathan S

BMC Complement Altern Med, 2014;14:4.
PMID: 24393217 DOI: 10.1186/1472-6882-14-4

The limited antibiotic options for effective control of methicillin-resistant Staphylococcus aureus infections has led to calls for new therapeutic approaches to combat this human pathogen. An alternative approach to control MRSA is through the use of anti-infective agents that selectively disrupt virulence-mediated pathways without affecting microbial cell viability or by modulating the host natural immune defenses to combat the pathogen.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects; Methicillin-Resistant Staphylococcus aureus/pathogenicity
Fulltext Gut bacteria of Cuora amboinensis (turtle) produce broad-spectrum antibacterial molecules

Akbar N, Khan NA, Sagathevan K, Iqbal M, Tawab A, Siddiqui R

Sci Rep, 2019 11 18;9(1):17012.
PMID: 31740685 DOI: 10.1038/s41598-019-52738-w

Antimicrobial resistance is a major threat to human health, hence there is an urgent need to discover antibacterial molecule(s). Previously, we hypothesized that microbial gut flora of animals are a potential source of antibacterial molecules. Among various animals, Cuora amboinensis (turtle) represents an important reptile species living in diverse ecological environments and feed on organic waste and terrestrial organisms and have been used in folk medicine. The purpose of this study was to mine turtle's gut bacteria for potential antibacterial molecule(s). Several bacteria were isolated from the turtle gut and their conditioned media were prepared. Conditioned media showed potent antibacterial activity against several Gram-positive (Bacillus cereus, Streptococcus pyogenes and methicillin-resistant Staphylococcus aureus) and Gram-negative (neuropathogenic Escherichia coli K1, Serratia marcescens, Pseudomonas aeruginosa, Salmonella enterica and Klebsiella pneumoniae) pathogenic bacteria. Conditioned media-mediated bactericidal activity was heat-resistant when treated at 95°C for 10 min. By measuring Lactate dehydrogenase release, the results showed that conditioned media had no effect on human cell viability. Tandem Mass Spectrometric analysis revealed the presence of various secondary metabolites, i.e., a series of known as well as novel N-acyl-homoserine lactones, several homologues of 4-hydroxy-2-alkylquinolines, and rhamnolipids, which are the signature metabolites of Pseudomonas species. These findings are significant and provide the basis for rational development of therapeutic interventions against bacterial infections.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects; Methicillin-Resistant Staphylococcus aureus/physiology
Fulltext Streptomyces sp. Strain MUSC 125 from Mangrove Soil in Malaysia with Anti-MRSA, Anti-Biofilm and Antioxidant Activities

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.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects*; Methicillin-Resistant Staphylococcus aureus/physiology
Fulltext A scaffolded approach to unearth potential antibacterial components from epicarp of Malaysian Nephelium lappaceum L

Asghar A, Tan YC, Zahoor M, Zainal Abidin SA, Yow YY, Khan E, et al.

Sci Rep, 2021 Jul 05;11(1):13859.
PMID: 34226594 DOI: 10.1038/s41598-021-92622-0

The emergence and spread of antimicrobial resistance have been of serious concern to human health and the management of bacterial infectious diseases. Effective treatment of these diseases requires the development of novel therapeutics, preferably free of side effects. In this regard, natural products are frequently conceived to be potential alternative sources for novel antibacterial compounds. Herein, we have evaluated the antibacterial activity of the epicarp extracts of the Malaysian cultivar of yellow rambutan fruit (Nephelium lappaceum L.) against six pathogens namely, Bacillus subtilis, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella enterica. Among a series of solvent extracts, fractions of ethyl acetate and acetone have revealed significant activity towards all tested strains. Chemical profiling of these fractions, via HPLC, LC-MS and GC-MS, has generated a library of potentially bioactive compounds. Downstream virtual screening, pharmacological prediction, and receptor-ligand molecular dynamics simulation have eventually unveiled novel potential antibacterial compounds, which can be extracted for medicinal use. We report compounds like catechin, eplerenone and oritin-4-beta-ol to be computationally inhibiting the ATP-binding domain of the chaperone, DnaK of P. aeruginosa and MRSA. Thus, our work follows the objective to propose new antimicrobials capable of perforating the barrier of resistance posed by both the gram positives and the negatives.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects; Methicillin-Resistant Staphylococcus aureus/pathogenicity
Fulltext Volatile profiling of aromatic traditional medicinal plant, Polygonum minus in different tissues and its biological activities

Ahmad R, Baharum SN, Bunawan H, Lee M, Mohd Noor N, Rohani ER, et al.

Molecules, 2014 Nov 20;19(11):19220-42.
PMID: 25420073 DOI: 10.3390/molecules191119220

The aim of this research was to identify the volatile metabolites produced in different organs (leaves, stem and roots) of Polygonum minus, an important essential oil producing crop in Malaysia. Two methods of extraction have been applied: Solid Phase Microextraction (SPME) and hydrodistillation coupled with Gas Chromatography-Mass Spectrometry (GC-MS). Approximately, 77 metabolites have been identified and aliphatic compounds contribute significantly towards the aroma and flavour of this plant. Two main aliphatic compounds: decanal and dodecanal were found to be the major contributor. Terpenoid metabolites were identified abundantly in leaves but not in the stem and root of this plant. Further studies on antioxidant, total phenolic content, anticholinesterase and antimicrobial activities were determined in the essential oil and five different extracts. The plant showed the highest DPPH radical scavenging activity in polar (ethanol) extract for all the tissues tested. For anti-acetylcholinesterase activity, leaf in aqueous extract and methanol extract showed the best acetylcholinesterase inhibitory activities. However, in microbial activity, the non-polar extracts (n-hexane) showed high antimicrobial activity against Methicillin-resistant Staphylococcus aureus (MRSA) compared to polar extracts. This study could provide the first step in the phytochemical profiles of volatile compounds and explore the additional value of pharmacology properties of this essential oil producing crop Polygonum minus.

Matched MeSH terms: Methicillin-Resistant Staphylococcus aureus/drug effects

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