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Synthesis and Staphylococcus aureus biofilm inhibitory activity of indolenine-substituted pyrazole and pyrimido[1,2-b]indazole derivatives

Yap CH, Ramle AQ, Lim SK, Rames A, Tay ST, Chin SP, et al.

Bioorg Med Chem, 2023 Nov 15;95:117485.
PMID: 37812886 DOI: 10.1016/j.bmc.2023.117485

Staphylococcus aureus is a highly adaptable opportunistic pathogen that can form biofilms and generate persister cells, leading to life-threatening infections that are difficult to treat with antibiotics alone. Therefore, there is a need for an effective S. aureus biofilm inhibitor to combat this public health threat. In this study, a small library of indolenine-substituted pyrazoles and pyrimido[1,2-b]indazole derivatives were synthesised, of which the hit compound exhibited promising antibiofilm activities against methicillin-susceptible S. aureus (MSSA ATCC 29213) and methicillin-resistant S. aureus (MRSA ATCC 33591) at concentrations significantly lower than the planktonic growth inhibition. The hit compound could prevent biofilm formation and eradicate mature biofilms of MSSA and MRSA, with a minimum biofilm inhibitory concentration (MBIC50) value as low as 1.56 µg/mL and a minimum biofilm eradication concentration (MBEC50) value as low as 6.25 µg/mL. The minimum inhibitory concentration (MIC) values of the hit compound against MSSA and MRSA were 50 µg/mL and 25 µg/mL, respectively, while the minimum bactericidal concentration (MBC) values against MSSA and MRSA were > 100 µg/mL. Preliminary structure-activity relationship analysis reveals that the fused benzene ring and COOH group of the hit compound are crucial for the antibiofilm activity. Additionally, the compound was not cytotoxic to human alveolar A549 cells, thus highlighting its potential as a suitable candidate for further development as a S. aureus biofilm inhibitor.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Fulltext Campylobacter enteritis in children: clinical and laboratory findings in 137 cases

Puthucheary SD, Parasakthi N, Liew ST, Chee YW

Singapore Med J, 1994 Oct;35(5):453-6.
PMID: 7701360

One hundred and thirty-seven children with Campylobacter diarrhoea were reviewed. The predominant species was C. jejuni. Ninety-five percent of the children were below 5 years of age with 61% of these being 2-12 months old. A slight male preponderance was noted. About half the cases presented with fever and bloody diarrhoea; vomiting was seen in 28% and abdominal colic in only 8%. Moderate to severe diarrhoea was present in 48% of the children. Thirty-seven percent had a history of recent or concurrent illness. Other bacterial enteropathogens together with Campylobacter were isolated in 15% of the children. Erythromycin, the most useful drug, when indicated for Campylobacter infections, had an MIC90 of 2 mg/l with 96.2% of the strains being sensitive.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Antimicrobial Efficacy of Extemporaneously Prepared Herbal Mouthwashes

Dua K, Sheshala R, Al-Waeli HA, Gupta G, Chellappan DK

Recent Pat Drug Deliv Formul, 2015;9(3):257-61.
PMID: 26051152

Natural products like plants and its components have been in use for treatment and cure of diseases all around the globe from ancient times much before the discovery of the current modern drugs. These substances from the nature are well known to contain components which have therapeutic properties and can also behave as precursors for the synthesis of potential drugs. The beneficial results from herbal drugs are well reported where their popularity in usage has increased across the globe. Subsequently developing countries are now recognizing the many positive advantages from their use which has engaged the expansion of R & D from herbal research. The flow on effect from this expansion has increased the awareness to develop new herbal products and the processes, throughout the entire world. Mouth washes and mouth rinses which have plant oils, plant components or extracts have generated particular attention. High prevalence of gingival inflammation and periodontal diseases, suggests majority of the patients practice inadequate plaque control. Of the currently available mouthwashes in the market, Chlorhexidine gluconate (CHX) has been investigated on a larger scale with much detail. CHX is associated with side effects like staining of teeth when used daily as well as the bitter taste of the mouthwash which leads to patient incompliance. The present research encompasses the antibacterial activity of extemporaneously prepared herbal mouthwash using natural herbs and therefore allows for the potential commercialization with in the herbal and pharmaceutical industries. Also, the present research article reviewed details of various existing patents of herbal mouthwashes which shows the trend of existing market and significance of emerging mouthwashes in both pharmaceutical and herbal industries. The antimicrobial activity of prepared mouthwashes was found to be effective against various strains of bacteria. It also suggests that the prepared herbal mouthwashes may provide an alternative to those containing chemical entities, with enhanced antimicrobial properties and better patient compliance.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Fulltext Phenotypic and genotypic characterization of methicillin-resistant Staphylococcus aureus (MRSA) isolated from dogs and cats at University Veterinary Hospital, Universiti Putra Malaysia

Aklilu E, Zunita Z, Hassan L, Chen HC

Trop Biomed, 2010 Dec;27(3):483-92.
PMID: 21399590

Methicillin-resistant Staphylococcus aureus (MRSA) is known to cause nosocomial infections and is now becoming an emerging problem in veterinary medicine. The objective of the study was to determine the presence of MRSA in 100 cats and dogs sampled between November 2007 and April 2008 at the University Veterinary Hospital, Universiti Putra Malaysia. MRSA was detected in 8% of pets sampled. Ten percent (5/50) and 6% (3/50) of the isolates were from dogs and cats, respectively. All MRSA isolates possessed the mecA gene and were found to be resistant to at least three antimicrobials with a minimum of Oxacillin MIC of 8 μg/mL. One isolate (CT04) had an extremely high MIC of >256 μg/mL. The MLST type ST59 found in this study have been reported earlier from Singapore and other countries as a strain from animal and community-associated MRSA respectively. Pulsed-field gel electrophoresis revealed five pulsotypes. Two isolates from cats (CT27 and CT33) and three isolates from dogs (DG16, DG20, and DG49) were respectively assigned to pulsotypes B and D. The study suggests that cats and dogs in Malaysia are potential reservoirs for MRSA.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Development of the PVA/CS nanofibers containing silk protein sericin as a wound dressing: In vitro and in vivo assessment

Bakhsheshi-Rad HR, Ismail AF, Aziz M, Akbari M, Hadisi Z, Omidi M, et al.

Int J Biol Macromol, 2020 Apr 15;149:513-521.
PMID: 31954780 DOI: 10.1016/j.ijbiomac.2020.01.139

Skin and soft tissue infections are major concerns with respect to wound repair. Recently, anti-bacterial wound dressings have been emerging as promising candidates to reduce infection, thus accelerating the wound healing process. This paper presents our work to develop and characterize poly(vinyl alcohol) (PVA)/chitosan (CS)/silk sericin (SS)/tetracycline (TCN) porous nanofibers, with diameters varying from 305 to 425 nm, both in vitro and in vivo for potential applications as wound dressings. The fabricated nanofibers possess a considerable capacity to take up water through swelling (~325-650%). Sericin addition leads to increased hydrophilicity and elongation at break while decreasing fiber diameter and mechanical strength. Moreover, fibroblasts (L929) cultured on the nanofibers with low sericin content (PVA/CS/1-2SS) displayed greater proliferation compared to those on nanofibers without sericin (PVA/CS). Nanofibers loaded with high sericin and tetracycline content significantly inhibited the growth of Escherichia coli and Staphylococcus aureus. In vivo examination revealed that PVA/CS/2SS-TCN nanofibers enhance wound healing, re-epithelialization, and collagen deposition compared to traditional gauze and nanofibers without sericin. The results of this study demonstrate that the PVA/CS/2SS-TCN nanofiber creates a promising alternative to traditional wound dressing materials.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Co-incorporation of graphene oxide/silver nanoparticle into poly-L-lactic acid fibrous: A route toward the development of cytocompatible and antibacterial coating layer on magnesium implants

Bakhsheshi-Rad HR, Ismail AF, Aziz M, Akbari M, Hadisi Z, Khoshnava SM, et al.

Mater Sci Eng C Mater Biol Appl, 2020 Jun;111:110812.
PMID: 32279830 DOI: 10.1016/j.msec.2020.110812

Magnesium (Mg) alloys present great potential for the development of orthopedic implants, whereas, their high degradation rate and poor antibacterial performance have restricted orthopedic applications. In this work, PLLA/GO-AgNP (poly-L-lactic acid/graphene oxide- silver nanoparticle) with different concentration of GO-AgNPs were deposited on Mg alloy via electrospinning method for enhancement of corrosion resistance and antibacterial performance. The result revealed that incorporation of GO into PLLA fibrous considerably slowed down the degradation rate of Mg alloy substrate and reduced the H2 release rate from the substrate. Also, co-incorporation of GO and AgNPs into PLLA fibrous resulted in substantial escalate in compressive strength after immersion in simulated body fluid (SBF). Antibacterial activity test exhibited that Mg alloy and neat PLLA fibrous presented minimal inhibition area toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In contrast, using PLLA/GO-AgNPs fibrous improved antibacterial performance against both bacteria. Cytocompatibility results indicated that PLLA/GO-AgNPs fibrous with a low amount of GO-AgNPs enhanced cell proliferation and growth while high co-incorporation of GO-AgNPs showed a negative effect on cell proliferation. Taken together, PLLA/1GO-AgNPs fibrous coating shows suitable corrosion resistance, cytocompatibility, and antibacterial function for use in orthopedic applications.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) among veterinary students and personnel at a veterinary hospital in Malaysia

Aklilu E, Zunita Z, Hassan L, Cheng CH

Vet Microbiol, 2013 Jun 28;164(3-4):352-8.
PMID: 23523336 DOI: 10.1016/j.vetmic.2013.02.030

In this study, we report the molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) among veterinary students and personnel in Malaysia. Nasal and oral swabs were collected from 103 veterinary medicine students and 28 personnel from a veterinary hospital. Antibiotic sensitivity test (AST), minimum inhibitory concentration (MIC) test, and PCR amplifications of nucA and mecA gene were performed. Molecular characterization of the isolates was conducted using multilocus sequence typing (MLST), staphylococcal protein A gene (spa) typing, and pulsed-field gel electrophoresis (PFGE). Results from MLST show the presence of the pandemic and widespread MRSA clones, ST5 and ST59. Spa gene typing revealed spa type t267 which has a wide geographical distribution. A new spa type, t5697 was found in this study. Fingerprint analysis by using PFGE show heterogeneity of the isolates. These findings affirm the importance of MRSA in veterinary settings and underscore the need for further extensive research to devise contextual control and prevention strategies.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Tigecycline and inducible clindamycin resistance in clinical isolates of methicillin-resistant Staphylococcus aureus from Terengganu, Malaysia

Che Hamzah AM, Yeo CC, Puah SM, Chua KH, A Rahman NI, Abdullah FH, et al.

J Med Microbiol, 2019 Sep;68(9):1299-1305.
PMID: 31140965 DOI: 10.1099/jmm.0.000993

The spread of multidrug-resistant Staphylococcus aureus is a public health concern. The inducible macrolide-lincosamide-streptogrammin B (iMLSB ) phenotype (or inducible clindamycin resistance) is associated with false clindamycin susceptibility in routine laboratory testing and may lead to treatment failure. Tigecycline resistance remains rare in S. aureus worldwide. This study aims to determine the antimicrobial susceptibility profiles of clinical isolates of S. aureus obtained from the main tertiary hospital in Terengganu state, Malaysia, from July 2016 to June 2017. The antimicrobial susceptibilities of 90 methicillin-resistant S. aureus (MRSA) and 109 methicillin-susceptible S. aureus (MSSA) isolates were determined by disc diffusion with the iMLSB phenotype determined by D-test. Multidrug resistance (MDR) and the iMLSB phenotype were more prevalent in MRSA (84.4 and 46.7 %, respectively) compared to MSSA isolates. All five tigecycline-resistant isolates were MRSA. The high incidence of MDR and the iMLSB phenotype and the emergence of tigecycline resistance in the Terengganu S. aureus isolates warrants continuous vigilance.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
New integron gene arrays from multiresistant clinical isolates of members of the Enterobacteriaceae and Pseudomonas aeruginosa from hospitals in Malaysia

Kor SB, Choo QC, Chew CH

J Med Microbiol, 2013 Mar;62(Pt 3):412-420.
PMID: 23180481 DOI: 10.1099/jmm.0.053645-0

This study investigated 147 multidrug-resistant Enterobacteriaceae and Pseudomonas aeruginosa isolates from hospitalized patients in Malaysia. Class 1 integrons were the most dominant class identified (45.6%). Three isolates were shown to contain class 2 integrons (2.0%), whilst one isolate harboured both class 1 and 2 integrons. No class 3 integrons were detected in this study. In addition, the sul1 gene was amplified in 35% of isolates and was significantly associated with the presence of integrase genes in an integron structure. RFLP and DNA sequencing analyses revealed the presence of 19 different cassette arrays among the detected integrons. The most common gene cassettes were those encoding resistance towards aminoglycosides (aad) and trimethoprim (dfr). As far as is known, this study is the first to identify integron-carrying cassette arrays such as aadA2-linF, aacC3-cmlA5 and aacA4-catB8-aadA1 in the Malaysian population. Patients' age was demonstrated as a significant risk factor for the acquisition of integrons (P=0.028). Epidemiological typing using PFGE also demonstrated a clonal relationship among isolates carrying identical gene cassettes in Klebsiella pneumoniae and P. aeruginosa but not in Escherichia coli isolates.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Fulltext FabV/Triclosan Is an Antibiotic-Free and Cost-Effective Selection System for Efficient Maintenance of High and Medium-Copy Number Plasmids in Escherichia coli

Ali SA, Chew YW

PLoS One, 2015;10(6):e0129547.
PMID: 26057251 DOI: 10.1371/journal.pone.0129547

Antibiotic resistance genes and antibiotics are frequently used to maintain plasmid vectors in bacterial hosts such as Escherichia coli. Due to the risk of spread of antibiotic resistance, the regulatory authorities discourage the use of antibiotic resistance genes/antibiotics for the maintenance of plasmid vectors in certain biotechnology applications. Overexpression of E. coli endogenous fabI gene and subsequent selection on Triclosan has been proposed as a practical alternative to traditional antibiotic selection systems. Unfortunately, overexpression of fabI cannot be used to select medium-copy number plasmids, typically used for the expression of heterologous proteins in E. coli. Here we report that Vibrio cholera FabV, a functional homologue of E. coli FabI, can be used as a suitable marker for the selection and maintenance of both high and medium-copy number plasmid vectors in E. coli.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Lactoferrin modulates the biofilm formation and bap gene expression of methicillin-resistant Staphylococcus epidermidis

Khanum R, Chung PY, Clarke SC, Chin BY

Can J Microbiol, 2023 Feb 01;69(2):117-122.
PMID: 36265186 DOI: 10.1139/cjm-2022-0135

Lactoferrin is an innate glycoprotein with broad antibacterial and antibiofilm properties. The autonomous antibiofilm activity of lactoferrin against Gram-positive bacteria is postulated to involve the cell wall and biofilm components. Thus, the prevention of biomass formation and eradication of preformed biofilms by lactoferrin was investigated using a methicillin-resistant Staphylococcus epidermidis (MRSE) strain. Additionally, the ability of lactoferrin to modulate the expression of the biofilm-associated protein gene (bap) was studied. The bap gene regulates the production of biofilm-associated proteins responsible for bacterial adhesion and aggregation. In the in vitro biofilm assays, lactoferrin prevented biofilm formation and eradicated established biofilms for up to 24 and 72 h, respectively. Extensive eradication of MRSE biofilm biomass was accompanied by the significant upregulation of bap gene expression. These data suggest the interaction of lactoferrin with the biofilm components and cell wall of MRSE, including the biofilm-associated protein.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Fulltext The Skeletal Effects of Short-Term Triple Therapy in a Rat Model of Gastric Ulcer Induced by Helicobacter pylori Infection

Ekeuku SO, Thong BKS, Quraisiah A, Annuar F, Hanafiah A, Nur Azlina MF, et al.

Drug Des Devel Ther, 2020;14:5359-5366.
PMID: 33324037 DOI: 10.2147/DDDT.S287239

Purpose: Triple therapy is the standard therapy to eradicate Helicobacter pylori (H.pylori) infection. Chronic use of proton pump inhibitors (PPIs), a component of triple therapy, is associated with osteoporosis. However, the skeletal effects of short-term triple therapy containing PPI remain elusive. This study aims to determine the skeletal effect of short-term triple therapy in a rat model of gastric ulcer induced by H. pylori.
Methods: Three-month-old male Sprague Dawley rats were assigned to normal control, H. pylori-inoculated group (negative control) and H. pylori-inoculated group receiving triple therapy consisting of omeprazole [2.035 mg/kg body weight (b.w)], amoxicillin (102.80 mg/kg b.w) and clarithromycin (51.37 mg/kg b.w) (n=6/group). H. pylori infection developed for four weeks after inoculation, followed by two-week triple therapy. At the end of the treatment period, femoral bones of the rats were harvested for analysis. Bone mineral density and content of the femurs were determined using dual-energy X-ray absorptiometry, while bone strength was measured with a universal mechanical tester.
Results: Bone mineral content was significantly lower in the negative control group compared to the triple therapy group (p=0.014). Triple therapy decreased strain (vs negative control, p=0.002) and displacement of the femur (vs normal control, p=0.004; vs untreated control, p=0.005). No significant difference was observed in other parameters among the study groups (p>0.05).
Conclusion: Short-term triple therapy increases bone mineral content but decreases bone strength of rats. Skeletal prophylaxis should be considered for patients on short-term triple therapy containing PPI.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Fabrication of biodegradable Zn-Al-Mg alloy: Mechanical properties, corrosion behavior, cytotoxicity and antibacterial activities

Bakhsheshi-Rad HR, Hamzah E, Low HT, Kasiri-Asgarani M, Farahany S, Akbari E, et al.

Mater Sci Eng C Mater Biol Appl, 2017 Apr 01;73:215-219.
PMID: 28183601 DOI: 10.1016/j.msec.2016.11.138

In this work, binary Zn-0.5Al and ternary Zn-0.5Al-xMg alloys with various Mg contents were investigated as biodegradable materials for implant applications. Compared with Zn-0.5Al (single phase), Zn-0.5Al-xMg alloys consisted of the α-Zn and Mg2(Zn, Al)11 with a fine lamellar structure. The results also revealed that ternary Zn-Al-Mg alloys presented higher micro-hardness value, tensile strength and corrosion resistance compared to the binary Zn-Al alloy. In addition, the tensile strength and corrosion resistance increased with increasing the Mg content in ternary alloys. The immersion tests also indicated that the corrosion rates in the following order Zn-0.5Al-0.5Mg

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
The Antibacterial Agent Identified from Acidocella spp. in the Fluid of Nepenthes gracilis Against Multidrug-Resistant Klebsiella pneumoniae: A Functional Metagenomic Approach

Chan EWL, Chin MY, Low YH, Tan HY, Ooi YS, Chong CW

Microb Drug Resist, 2021 Aug;27(8):1018-1028.
PMID: 33325795 DOI: 10.1089/mdr.2020.0311

Aims: The fluid of Nepenthes gracilis harbors diverse bacterial taxa that could serve as a gene pool for the discovery of the new genre of antimicrobial agents against multidrug-resistant Klebsiella pneumoniae. The aim of this study was to explore the presence of antibacterial genes in the fluids of N. gracilis growing in the wild. Methods: Using functional metagenomic approach, fosmid clones were isolated and screened for antibacterial activity against three strains of K. pneumoniae. A clone that exhibited the most potent antibacterial activity was sent for sequencing to identify the genes responsible for the observed activity. The secondary metabolites secreted by the selected clone was sequentially extracted using hexane, chloroform, and ethyl acetate. The chemical profiles of a clone (C6) hexane extract were determined by gas chromatography/mass spectrometry (GC-MS). Results: Fosmid clone C6 from the fluid of pitcher plant that exhibited antibacterial activity against three strains of K. pneumoniae was isolated using functional metagenome approach. A majority of the open reading frames detected from C6 were affiliated with the largely understudied Acidocella genus. Among them, the gene that encodes for coproporphyrinogen III oxidase in the heme biosynthesis pathway could be involved in the observed antibacterial activity. Based on the GC-MS analysis, the identities of the putative bioactive compounds were 2,5-di-tert-butylphenol and 1-ethyl-2-methyl cyclododecane. Conclusions: The gene that encodes for coproporphyrinogen III oxidase in the heme biosynthesis pathway as well as the secondary metabolites, namely 2,5-di-tert-butylphenol and 1-ethyl-2-methyl cyclododecane could be the potential antibacterial molecules responsible for the antibacterial activity of C6.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Social demographics determinants for resistome and microbiome variation of a multiethnic community in Southern Malaysia

Dwiyanto J, Huët MAL, Hussain MH, Su TT, Tan JBL, Toh KY, et al.

NPJ Biofilms Microbiomes, 2023 Aug 12;9(1):55.
PMID: 37573460 DOI: 10.1038/s41522-023-00425-0

The prevalence of antibiotic-resistant bacteria in Southeast Asia is a significant concern, yet there is limited research on the gut resistome and its correlation with lifestyle and environmental factors in the region. This study aimed to profile the gut resistome of 200 individuals in Malaysia using shotgun metagenomic sequencing and investigate its association with questionnaire data comprising demographic and lifestyle variables. A total of 1038 antibiotic resistance genes from 26 classes were detected with a mean carriage rate of 1.74 ± 1.18 gene copies per cell per person. Correlation analysis identified 14 environmental factors, including hygiene habits, health parameters, and intestinal colonization, that were significantly associated with the resistome (adjusted multivariate PERMANOVA, p

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Ganoderma boninense mycelia for phytochemicals and secondary metabolites with antibacterial activity

Abdullah S, Jang SE, Kwak MK, Chong K

J Microbiol, 2020 Dec;58(12):1054-1064.
PMID: 33263896 DOI: 10.1007/s12275-020-0208-z

Antiplasmodial nortriterpenes with 3,4-seco-27-norlanostane skeletons, almost entirely obtained from fruiting bodies, represent the main evidential source for bioactive secondary metabolites derived from a relatively unexplored phytopathogenic fungus, Ganoderma boninense. Currently lacking is convincing evidence for antimicrobial secondary metabolites in this pathogen, excluding that obtained from commonly observed phytochemicals in the plants. Herein, we aimed to demonstrate an efficient analytical approach for the production of antibacterial secondary metabolites using the mycelial extract of G. boninense. Three experimental cultures were prepared from fruiting bodies (GBFB), mycelium cultured on potato dextrose agar (PDA) media (GBMA), and liquid broth (GBMB). Through solvent extraction, culture type-dependent phytochemical distributions were diversely exhibited. Water-extracted GBMB produced the highest yield (31.21 ± 0.61%, p < 0.05), but both GBFB and GBMA elicited remarkably higher yields than GBMB when polar-organic solvent extraction was employed. Greater quantities of phytochemicals were also obtained from GBFB and GBMA, in sharp contrast to those gleaned from GBMB. However, the highest antibacterial activity was observed in chloroform-extracted GBMA against all tested bacteria. From liquid-liquid extractions (LLE), it was seen that mycelia extraction with combined chloroform-methanol-water at a ratio of 1:1:1 was superior at detecting antibacterial activities with the most significant quantities of antibacterial compounds. The data demonstrate a novel means of assessing antibacterial compounds with mycelia by LLE which avoids the shortcomings of standardized methodologies. Additionally, the antibacterial extract from the mycelia demonstrate that previously unknown bioactive secondary metabolites of the less studied subsets of Ganoderma may serve as active and potent antimicrobial compounds.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Fulltext Biophysical characterization of antibacterial compounds derived from pathogenic fungi Ganoderma boninense

Abdullah S, Oh YS, Kwak MK, Chong K

J Microbiol, 2021 Feb;59(2):164-174.
PMID: 33355891 DOI: 10.1007/s12275-021-0551-8

There have been relatively few studies which support a link between Ganoderma boninense, a phytopathogenic fungus that is particularly cytotoxic and pathogenic to plant tissues and roots, and antimicrobial compounds. We previously observed that liquid-liquid extraction (LLE) using chloroformmethanol-water at a ratio (1:1:1) was superior at detecting antibacterial activities and significant quantities of antibacterial compounds. Herein, we demonstrate that antibacterial secondary metabolites are produced from G. boninense mycelia. Antibacterial compounds were monitored in concurrent biochemical and biophysical experiments. The combined methods included high performance thin-layer chromatography (HPTLC), gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopy. The antibacterial compounds derived from mycelia with chloroform-methanol extraction through LLE were isolated via a gradient solvent elution system using HPTLC. The antibacterial activity of the isolated compounds was observed to be the most potent against Staphylococcus aureus ATCC 25923 and multidrug-resistant S. aureus NCTC 11939. GC-MS, HPLC, and FTIR analysis confirmed two antibacterial compounds, which were identified as 4,4,14α-trimethylcholestane (m/z = 414.75; lanostane, C30H54) and ergosta-5,7,22-trien-3β-ol (m/z = 396.65; ergosterol, C28H44O). With the aid of spectroscopic evaluations, ganoboninketal (m/z = 498.66, C30H42O6), which belongs to the 3,4-seco-27-norlanostane triterpene family, was additionally characterized by 2D-NMR analysis. Despite the lack of antibacterial potential exhibited by lanostane; both ergosterol and ganoboninketal displayed significant antibacterial activities against bacterial pathogens. Results provide evidence for the existence of bioactive compounds in the mycelia of the relatively unexplored phytopathogenic G. boninense, together with a robust method for estimating the corresponding potent antibacterial secondary metabolites.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Elucidating the structural, catalytic, and antibacterial traits of Ficus carica and Azadirachta indica leaf extract-mediated synthesis of the Ag/CuO/rGO nanocomposite

Fayyaz Z, Farrukh MA, Ul-Hamid A, Chong KK

Microsc Res Tech, 2024 May;87(5):957-976.
PMID: 38174385 DOI: 10.1002/jemt.24487

The present exploration demonstrates the efficient, sustainable, cost-effective, and environment-friendly green approach for the synthesis of silver (Ag)-doped copper oxide (CuO) embedded with reduced graphene oxide (rGO) nanocomposite using the green one-pot method and the green deposition method. Leaf extracts of Ficus carica and Azadirachta indica were used for both methods as reducing and capping agents. The effect of methodology and plant extract was analyzed through different characterization techniques such as UV-visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM). The lowest band gap of 3.0 eV was observed for the Ag/CuO/rGO prepared by the green one-pot method using F. carica. The reduction of graphene oxide (GO) and the formation of metal oxide was confirmed through functional group detection using FT-IR. Calculation of thermodynamic parameters showed that all reactions involved were nonspontaneous and endothermic which shows the stability of nanocomposites. XRD studies revealed the crystallinity, phase purity and small average crystallite size of 32.67 nm. SEM images disclosed that the morphology of the nanocomposites was spherical with agglomeration and rough texture. The particle size of the nanocomposites calculated through HRTEM was found in agreement with the XRD results. The numerous properties of the synthesized nanocomposites enhanced their potential against the degradation of methylene blue, rhodamine B, and ciprofloxacin. The highest percentage degradation of Ag/CuO/rGO was found to be 97%, synthesized using the green one-pot method with F. carica against ciprofloxacin, which might be due to the lowest band gap, delayed electron-hole pair recombination, and large surface area available. The nanocomposites were also tested against the Gram-positive and Gram-negative bacteria. RESEARCH HIGHLIGHTS: Facile synthesis of Ag/CuO/rGO nanocomposite using a green one-pot method and the green deposition method. The lowest band gap of 3.0 eV was observed for nanocomposite prepared by a green one-pot method using Ficus carica. Least average crystallite size of 32.67 nm was found for nanocomposite prepared by a green one-pot method using F. carica. Highest antibacterial and catalytic activity (97%) was obtained against ciprofloxacin with nanocomposite prepared through green one-pot method using F. carica. A mechanism of green synthesis is proposed.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology
Phytochemical constituents from Cassia alata with inhibition against methicillin-resistant Staphylococcus aureus (MRSA)

Hazni H, Ahmad N, Hitotsuyanagi Y, Takeya K, Choo CY

Planta Med, 2008 Dec;74(15):1802-5.
PMID: 18991205 DOI: 10.1055/s-0028-1088340

The methanolic extract of the leaves of CASSIA ALATA was sequentially partitioned in increasing polarity to afford the hexane, chloroform, butanol and residual extract. Crude extracts were evaluated against MRSA using the agar well diffusion assay. The butanol and chloroform extracts both exhibited inhibition against MRSA with inhibition indexes of 1.03 +/- 0.16 and 0.78 +/- 0.07 at the concentration of 50 mg/mL. The butanol extracts were further purified using silica gel and reverse phase chromatography to afford kaempferol ( 1), kaempferol 3- O-beta-glucopyranoside ( 2), kaempferol 3- O-gentiobioside ( 3) and aloe emodin ( 4). The four constituents showed varying degrees of inhibition against MRSA. Both 1 and 4 exhibited MIC (50) values of 13.0 +/- 1.5 microg/mL and 12.0 +/- 1.5 microg/mL, respectively. The kaempferol glycosides 2 and 3 were less active with MIC (50) values of 83.0 +/- 0.9 microg/mL and 560.0 +/- 1.2 microg/mL, respectively. A free hydroxyl group at C-3 of the flavonol structure is a structural requirement for the inhibition of MRSA.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*
Antimicrobial susceptibility and distribution of non-typhoidal Salmonella serovars isolated in Malaysian children

Lee WS, Puthucheary SD, Parasakthi N, Choo KE

J Trop Pediatr, 2003 Feb;49(1):37-41.
PMID: 12630719

There is widespread resistance of Salmonella species to commonly prescribed antimicrobials the world over. We aimed to determine the antimicrobial susceptibility and serovar distribution of non-typhoidal Salmonella (NTS) isolated from blood cultures of Malaysian children. Positive isolates of NTS from blood cultures obtained from children admitted to the pediatric wards of University of Malaya Medical Center (UMMC), a large urban hospital from Kuala Lumpur (1991-2001), and Hospital Kota Bharu (HKB), from the predominantly rural state of Kelantan (1991-1999), Malaysia, were reviewed retrospectively. Serovar distribution and antimicrobial susceptibility were ascertained. A total of 64 and 55 isolates of NTS were obtained from blood cultures of children admitted to UMMC and HKB, respectively. The commonest serovar isolated was Salmonella enteritidis in both centers. The NTS isolated were highly sensitive to the antimicrobials tested: ampicillin 98 per cent, chloramphenicol 98 per cent, gentamicin 97 per cent, trimethoprim-sulfamethoxazole (TMP-SMX) 98 per cent, and ceftriaxone 100 per cent in UMMC; ampicillin 100 per cent, chloramphenicol 87 per cent, kanamycin 100 per cent, streptomycin 96 per cent, TMP-SMX 93 per cent, and tetracycline 89 per cent in HKB. There were only one and five multi-resistant isolates in UMMC and HKB, respectively. In conclusion, NTS isolated from blood cultures of Malaysian children from Kuala Lumpur and Kota Bharu were highly sensitive to commonly prescribed antibiotics. We speculate that this is due to the restriction of sales of antimicrobials in Malaysia except by prescription. Continuing vigilance and frequent antmicrobial surveillance is necessary.

Matched MeSH terms: Anti-Bacterial Agents/pharmacology*

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