Antibacterial Assay Research Articles

Biodiversity and Bioprospecting of Fungal Endophytes from Houttuynia cordata Thunb. as a Potential Antibacterial and Anticancer Agent.

Endophytic fungi are considered a new source of bioactive compounds that have important applications in agriculture and medicine. This study aims to investigate the biodiversity and potential of endophytic fungi isolated from Houttuynia cordata Thunb. as antimicrobials and anticancer agents. Out of ten isolated endophytes, four species have never been reported to be associated with H. cordata: Ceratobasidium sp., Cladosporium sp., Phomopsis sp., and Fusarium sp. The antibacterial activity assay revealed that the ethyl acetate extract of Ceratobasidium sp. HCS-3 possessed most potent antibacterial activity against Escherichia coli and Staphylococcus aureus. In addition, its cytotoxic activity test showed the promising anticancer activity on lung cancer A549, osteosarcoma MG-63, and cervical cancer HeLa cells with IC50 of 4.55 ±1.16, 32.14 ±2.78, and 1.54 ±0.66 ppm, respectively. Furthermore, metabolite profiling identified 66 compounds suggesting that benzoic acid, farnesol, and cyclopeptides may contribute to the antibacterial activity, while 4-methoxycinnamic acid may have anticancer potential.

Antibacterial Activity Assay on Escherichia coli of The Active Fraction Matoa Seeds (Pometia Pinnata J.R Forst & G. Forst.)

One of the plants had been used as a medicinal plant in Papua is Pometia Pinnata J.R Forst & G. Forst or the Matoa plant. The aim of this study is to determine the antibacterial activity of the active fraction of Matoa seeds against Escherichia coli bacteria. The positive control and negative control used were ciprofloxacin and dimethyl sulfoxide, respectively. 96% ethanol solvent was used to extract the simplicia of Matoa seeds. Fractionation was carried out using n-hexane, ethyl acetate and water as solvents. The Kirby Bauer diffusion method was used in the antibacterial activity assay at concentrations of 100 mg/mL, 200 mg/mL, 300 mg/mL, 400 mg/mL, and 500 mg/mL. Overall, the inhibition zones obtained from the sequential concentrations above were 8.89 mm, 10.18 mm, 10.34 mm, 10.84 mm, and 11.76 mm respectively. Further, data analysis was performed with One Way ANOVA and the results showed significant differences between concentrations. Data analysis was then continued with the post hoc Tukey HSD test and a concentration of 500 mg/mL was concluded as the optimum concentration.

Hydroxyapatite layer evolution on silica-based (45S10P) bioactive glass-ceramic nanoparticles doped with Zn2+ ions: Augmentation of in vitro bioactivity, antibacterial activity and textural modification for bone regeneration

Zinc-incorporated bioactive glasses (BG) and bioactive glass-ceramic (BGC) nanoparticles (BGC-NPs) represent highly adaptable, biodegradable, and bioactive materials in tissue engineering and regenerative medicine. This study delves into the synthesis, characterization and biomedical implications of Zn2+ ions-doped 45S10P spherical BGC-NPs, employing analytical techniques and in vitro assays. The resulting (Zn2++ 45S10P) BGC-NPs, prepared using a modified Strober's method, exhibited spherical morphology with excellent dispersion, as verified by TEM, FE-SEM, and DLS analyses. XRD, FTIR, and FESEM analysis revealed an augmented hydroxyapatite (HAp) layer formation with increasing zinc content. Zeta potential analysis showcased a shift from negative to positive values after immersion in simulated body fluid (SBF), indicating the bioactive potential of the developed BGC-NPs. Hemocompatibility assays indicated the biocompatibility of all BGC-NPs, demonstrating minimal hemolytic effects with incorporating Zn2+ ions below a standard threshold (<5 % lysis). Further, the migration assay revealed the potentiality of the BGC-NPs to stimulate the migration of HeLa cells. Cell viability assays employing MG-63 osteoblast-like cells highlighted enhanced cell viability over time, underscoring their non-toxic nature and potential for tissue regeneration. Antibacterial assays displayed significant inhibitory effects against Gram-negative compared to Gram-positive bacteria, underscoring their potential for anti-infection applications. Overall, the results affirm the promising prospects of Zinc incorporation into 45S10P BGC-NPs for bone tissue regeneration applications.

Design, Synthesis, and Evaluation of Triazoline Schiff Bases as Potential Antibacterial Agents Against Methicillin-Resistant Staphylococcus aureus (MRSA): A Comprehensive Computational and Experimental Study

In this study, a series of novel triazoline Schiff bases are designed and synthesized on a triazole-based AADHR_1 hypothesis pharmacophore model tailored to meet structural requirements for antibacterial activity. FT-IR, 1H-NMR, and 13C-NMR spectroscopy techniques confirmed molecular structures. Assessment of ADMET properties utilizing the pkCSM online tool unveiled encouraging pharmacokinetic profiles. Detailed Density Functional Theory (DFT) calculations showed significant electronic properties, delineating certain compounds as potent electron donors or acceptors. Docking studies unveil that, the compound 1-((1-(p-tolyl)piperidin-4-yl)methyl)-1H-1,2,3-triazole-4-carboxylic acid (2b) binded into the active site of the Penicillin-binding protein (PBP2a) of Methicillin-resistant Staphylococcus aureus (MRSA) with the docking score of -8.0 kcal/mol. Molecular dynamics simulations further corroborated the stability of the protein-ligand complex, emphasizing the compound 2b is enduring interaction at the MRSA protein's active site. Antibacterial assays against MRSA showed selective compounds exhibiting minimum inhibitory concentrations (MICs) of 20µg/mL and Zone of inhibition up to 14mm, highlighting their potential as effective antimicrobial agents against antibiotic-resistant bacteria. These findings collectively suggest the promising therapeutic prospects of the synthesized triazoline Schiff bases in combatting MRSA infections.

Bio-synthesized AGS@AgNPs for wound healing, antioxidant support, antibacterial defense, and anticancer intervention

Slow wound healing and wound infections are significant challenges for burn patients. Biosynthesis of nanoparticles (NPs) using plant extracts offers a rapid, facile, and safe method for producing biocompatible NPs. In this study, Anethum graveolens seed (AGS) extract served as a masking and reducing agent for the synthesis of silver nanoparticles (AGS@AgNPs). Initially, the parameters influencing AGS@AgNPs synthesis, including silver nitrate concentration, reaction time, temperature, and pH, were optimized. Subsequently, AGS@AgNPs structural and biological characteristics were evaluated. Observation of the surface plasmon resonance (SPR) of the AGS@AgNPs at approximately 420 nm, accompanied by a color change of the suspension to dark brown, confirmed AGS@AgNPs synthesis. Analysis via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), zeta potential, and transmission electron microscopy (TEM) confirmed the production of pure, homogeneous, spherical, and stable silver NPs with sizes ranging from 20 to 40 nm using Anethum graveolens extract. Antibacterial assays revealed significant activity against both Gram-positive and Gram-negative bacterial strains. Antioxidant assessments demonstrated that AGS@AgNPs at a concentration of 250 μg/ml exhibited 92% inhibition of DPPH free radicals and in FRAP test, A. graveolens seed extract and AGS@AgNPs reduced Fe3+ ions to Fe2+ by 48.7% and 73.1%, respectively. Investigation of anticancer properties against the lung cancer cell line (A-549) revealed an IC50 value of 242 μg/ml. The results of the flow cytometry test and lactate dehydrogenase (LDH) assay demonstrated the death of cancer cells. Moreover, wound healing assays demonstrated a significant acceleration in burn wound closure rates in rats on days 3, 7, and 14 following treatments with AGS@AgNPs. Overall, these findings highlight the favorable biological activities of AGS@AgNPs, suggesting their potential utility in nanomedicine applications.

Computational and in vitro analyses of the antibacterial effect of the ethanolic extract of Pluchea indica L. leaves.

The most common gram-negative, Escherichia coli, and gram-positive bacteria, Bacillus spp., have evolved different mechanisms that have caused the emergence of multi-drug resistance. As a result, drugs that block the bacterial growth cycle are needed. Here, in silico and in vitro studies were performed to assess compounds in the Pluchea indica leaf extract, a medicinal plant, that can inhibit bacterial proteins. Briefly, P. indica leaves were extracted using ethanol. The crude extract was then subjected to gas chromatography-mass spectrometry for metabolite screening. Molecular docking simulations with rhomboid protease (Rpro) (Protein data bank ID number: 3ZMI from E. coli and filamenting temperature-sensitive mutant Z (FtsZ) protein data bank ID number: 2VAM from Bacillus subtilis were performed. Moreover, the well diffusion method was used to confirm the antibacterial activity of P. indica leaf extract. A total of 10 compounds were identified in the P. indica extract and used for computational analysis. Based on drug-likeness prediction, P. indica compounds may be drug-like molecules. Binding affinity tests indicated that 10,10-Dimethyl-2,6-dimethylenebicyclo(7.2.0)undecan-5.β.-ol and 11,11-Dimethyl-4,8-dimethylenebicyclo(7.2.0)undecan-3-ol had the most negative values. Accordingly, these compounds may be potential ligands that bind to bacterial proteins. The root mean square fluctuation values was <2 Å, indicating stable fluctuation binding for the ligand-protein complex. According to in vitro antibacterial assays, a high concentration (50%) of the P. indica extract markedly inhibited E. coli and B. subtilis, with inhibitory zone diameters of 31.86±1.63 and 21.09±0.09 mm, respectively. Overall, the compounds in the P. indica leaf extract were identified as functional inhibitors of E. coli and B. subtilis proteins via in silico analysis. This may facilitate development of antibacterial agents.

Engineering a 3D network hydrogel composite membrane with Chitosan/Pluronic F127/bioactive glass for the topical administration of therapeutic agents

The primary aim of designing a topical drug delivery system is to address localized ailments by administering therapeutic agents directly to superficial areas of the body such as skin and open wounds. This study presents the engineering of a three-dimensional (3D) network hydrogel composite membrane comprising chitosan (CS), Pluronic F127 (Pl), and bioactive glass (BG) for the topical administration. In the presence of CS and Pl, glutaraldehyde forms imine bonds (Schiff base linkages) by reacting its aldehyde groups with the amino groups of the polymer chains. The hydrogel structural and chemical properties were characterized using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), revealed its unique composition and molecular structure. Field Emission Scanning electron microscopy (FESEM) was employed to image and investigate the morphology of the hydrogel, confirming its interconnected sheet like morphology with small beads structure. The hydrogels demonstrated excellent water retention ability as 32.93 %, further controlled degradation kinetics rate was systematically evaluated up to 14 days, and optimal swelling behavior makes it suitable for prolonged drug delivery applications. Moreover, hemocompatibility and cyto-compatibility assays yielded less than 1.1 % and above 60 %, confirming the hydrogel safety for blood contact and cell viability. Tube inversion tests confirmed its mechanical integrity, while antibacterial assays revealed its efficacy against pathogenic microorganisms. Co-culture studies demonstrated the capability of developed hydrogel to support cell growth and proliferation. In vitro drug release studies clearly reveal that the hydrogel provides a sustainable delivery system for piperacillin-tazobactam, demonstrating superior characteristics indicative of non-Fickian or anomalous diffusion. Furthermore, the membrane exhibited promising hemostatic properties, suggesting its potential for wound healing applications. Overall, this comprehensive strategy highlights the versatility of the engineered 3D network hydrogel composite membrane as a promising platform for delivering therapeutic agents locally in various biomedical applications.

Evaluation of the Secondary Metabolites and Bioactivity of South African Bulbine Natalensis Under Simultaneous Elevated Carbon Dioxide and Temperatures

The secondary metabolism in medicinal plants are responsible for their protection against environmental factors and the health-promoting benefits they provide to users. The purpose of this study was to assess the responses of the secondary metabolic system of B. natalensis and its influence on the antioxidant and antibacterial activities. The phytochemical analyses, antioxidant and antibacterial assays were conducted from using harvested leaves, underground stems and roots from whole plants exposed to simultaneous elevated CO2 and temperatures over eight days in a heatwave simulation. Most of the phytochemical groups were present in the leaves, however majority of the tested compounds had consistent presence throughout the plants in all treatments. The underground stems possessed a greater total phenolic, tannin and proanthocyanidin contents than the leaves and roots under elevated CO2 and temperatures. The leaves had a comparatively better antioxidant activity from the treatment than control. Overall, there was consistency in the antibacterial activity in both control and experimental conditions. The tannins and phenolics had greater concentrations throughout the plants under elevated conditions overall, which could indicate their leading role in plant defence and the improvement and maintenance of the medicinal activity of B. natalensis. The responses of the plant parts of B. natalensis under elevated CO2 and temperatures provides newfound insights on the physiological roles plant organs play on the overall productivity and medicinal activity of the species.

UJI EFEK ANTIBAKTERI KOMBINASI DAUN GEDI DAN DAUN KUMIS KUCING TERHADAP Staphyloccocus aureus

Gedi (Abelmoschus manihot (L.) Medik) and Java tea leaves (Orthosiphon aristatus (Blume) Miq.) are known to have antibacterial activity. The combination of these two plants in inhibiting Staphylococcus aureus bacteria needs to be known to determine whether there is a synergistic effect from the combination. The synergistic effects can be demonstrated by the presence of greater antibacterial activity in the combination of both plants compared to single plant extracts. The extraction of both leaves was carried out with 96% ethanol and the maceration method. Antibacterial assay utilized the disc diffusion method with an extract concentration of 10,000 ppm and an extract ratio between two extracts was 100:0, 75:25, 50:50, 25:75, and 0:100. The positive control used was gentamicin, while the negative control used was dimethyl sulfoxide (DMSO). The resulting inhibition zones of extract combinations were 8.21 mm, 9.49 mm, 7.86 mm, 8.03 mm, and 8.74 mm, respectively. The results of data analysis using One Way ANOVA showed a sig p&gt; 0.05, which indicated that there was no significant difference between extract comparisons, both single and combined. Based on the inhibitory zones was obtained and the statistical analysis, the combination of 10.000 ppm 96% ethanol extract of Gedi and Java tea leaves had an antibacterial activity in the weak category and did not have a synergistic effect in inhibiting the growth of Staphylococcus aureus.

Hydroxyapatite synthesis and characterization from marine sources: A comparative study

BackgroundHydroxyapatite (HAP) is a biocompatible material widely used in biomedical applications. Recent studies have explored various marine sources for HAP synthesis, demonstrating its potential for diverse applications. ObjectiveThis study aims to compare the characteristics of hydroxyapatite synthesized from sea shells and fish bones, specifically from the shells of Scylla olivacea (orange mud crab) and bones of Eleutheronema tetradactylum (fourfinger threadfin). Materials & methodsHAP was synthesized from Scylla olivacea shells and Eleutheronema tetradactylum bones. The synthesized HAP underwent comprehensive characterization, including scanning electron microscopy (SEM) for structural analysis, hemocompatibility testing, antibacterial assays, and energy-dispersive X-ray spectroscopy (EDS) analysis. ResultsSEM revealed a complex structure of HAP with a clustered arrangement and biofilm-like features. HAP derived from crab shells exhibited superior structural properties compared to that from fish bones. Both sources demonstrated good hemocompatibility, essential for biomedical applications. The antibacterial assays indicated effective antibacterial properties for both HAP sources, with crab shell-derived HAP showing slightly better performance. EDS analysis confirmed the presence of key elements necessary for HAP, with a consistent composition in both sources. ConclusionOur study concludes that hydroxyapatite derived from Scylla olivacea shells exhibits superior properties compared to that from Eleutheronema tetradactylum bones. This research establishes a precedent for future investigations into other marine species, thereby broadening the scope and potential of hydroxyapatite synthesis from natural sources.

Bovine serum albumin and lysozyme nanofibers as versatile platforms for preserving loaded bioactive compounds

In this study, the electrospinning procedure was optimized to create polyethylene oxide (PEO) NFs highly enriched in proteins with non-structural functions while preserving their activity. For this purpose, several immune-related proteins of low, medium and high molecular weights were used as molecular models. Initially, the electrospinning parameters were adjusted using 3 % w/w PEO and bovine serum albumin (BSA, 5–20 % w/w). As determined by FESEM, their average diameters ranged from 301 to 752 nm, and those with higher protein content (15–20 %) yielded more uniform NFs in both size and morphology terms. Protein integrity remained stable as determined by SDS-PAGE and FTIR. Similar results were observed for the polypeptide lysozyme (LYZ) when incorporated in NFs under these settings. To further explore the potential of these materials, the antimicrobial peptide piscidin (PIS) and an antibody (Ab, HRP-IgG) were used to produce BSA/PIS, LYZ/PIS and BSA/Ab NFs and evaluate the preservation of their activity. The antibacterial assays showed that, in most bacterial species, the activity of PIS remained consistent after being incorporated into the NFs. Furthermore, the activity of HRP-IgG was maintained within the NFs, with enhanced preservation observed in BSA/Ab NFs. These findings expand the possibilities of protein utilization across various applications through nanomaterials.

Antibacterial, Antifungal, and Cytotoxic Effects of Endophytic Streptomyces Species Isolated from the Himalayan Regions of Nepal and Their Metabolite Study.

Background/Objectives: Recently, antimicrobial-resistant pathogens and cancers have emerged as serious global health problems, highlighting the immediate need for novel therapeutics. Consequently, we aimed to isolate and characterize endophytic Streptomyces strains from the rhizospheres of the Himalayan region of Nepal and identify specialized metabolites with antibacterial, antifungal, and cytotoxic potential. Methods: To isolate Streptomyces sp., we collected two soil samples and cultured them on an ISP4 medium after pretreatment. We isolated and identified the strains PY108 and PY109 using a combination of morphological observations and 16S rRNA gene sequencing. Results: The BLAST results showed that PY108 and PY109 resembled Streptomyces hundungensis PSB170 and Streptomyces sp. Ed-065 with 99.28% and 99.36% nucleotide similarity, respectively. Antibacterial assays of ethyl acetate (EA) extracts from both isolates PY108 and PY109 in a tryptic soy broth (TSB) medium were conducted against four pathogenic bacteria. They showed significant antibacterial potential against Staphylococcus aureus and Klebsiella pneumoniae. Similarly, these extracts exhibited moderate antifungal activities against Saccharomyces cerevisiae and Aspergillus niger. Cytotoxicity assays on cervical cancer cells (HeLa) and breast cancer cells (MCF-7) revealed significant potential for both extracts. LC-MS/MS profiling of the EA extracts identified 27 specialized metabolites, including diketopiperazine derivatives, aureolic acid derivatives such as chromomycin A, and lipopeptide derivatives. In comparison, GC-MS analysis detected 34 metabolites, including actinomycin D and γ-sitosterol. Furthermore, a global natural product social molecular networking (GNPS)-based molecular networking analysis dereplicated 24 metabolites in both extracts. Conclusions: These findings underscore the potential of endophytic Streptomyces sp. PY108 and PY109 to develop new therapeutics in the future.

PVA-Stabilized and Coassembled Nano/Microparticles with High Payload of Dual Phytochemicals for Enhanced Antibacterial and Targeting Effect.

The codelivery of multiple bioactive phytochemicals via nano/microparticles (NPs/MPs) represents a promising strategy for enhancing therapeutic efficacy. This study presents the development of novel poly(vinyl alcohol) (PVA)-stabilized hybrid particles designed for codelivery of palmatine hydrochloride (PAL) and glycyrrhizic acid (GL). Employing a straightforward coassembly method, we synthesized dual-drug particles achieving a high payload capacity of over 70%. The particles were characterized as uniform in size, within the nano/micron range, and exhibited a ζ-potential of -5.0 mV. The incorporation of PVA not only stabilized the particles but also refined the aggregation process, resulting in more uniform and finer particles approximately 1 μm in size. Spectral analysis and molecular dynamics simulations verified the presence of π-π stacking and hydrogen bonding between PAL and GL within the particles. In vitro antibacterial assays indicated that the hybrid particles had a lower minimum inhibitory concentration against Escherichia coli and Multidrug-Resistant Staphylococcus aureus than those of the pure drugs. In vivo biodistribution study in rats revealed that the PVA-stabilized particles revealed enhanced targeting to the liver, lung, and heart, demonstrating improved tissue selectivity compared with the solution group. In summary, the PVA-stabilized hybrid NPs/MPs represent an innovative and efficient platform for codelivery of multidrugs. These findings highlight the promise of coassembled particles for high loading, enhanced bioactivity, and targeted delivery, making them a strong candidate for future clinical applications.

Discovery of Active Antibacterial Fractions of Different Plant Part Extracts of clove (Syzigium aromaticum) Against Streptococcus mutans

Nowadays, dental cavities caused by Streptococcus mutans are a major focus of research in Indonesia. While several antibiotics are available to combat this bacterium, concerns about antibiotic resistance have prompted researchers to explore natural remedies. Clove (Syzigium aromaticum) is a commonly studied natural remedy against dental cavities and S. mutans. Among the different parts of the clove plant, clove bud is the most widely used against dental cavities or S. mutans, and the potential of other clove parts has not been thoroughly explored. Identifying which parts of the clove plant have higher concentrations of active ingredients and exhibit the strongest antibacterial activity is important. Therefore, this study evaluated the antibacterial activity of three different parts, i.e., leaf, stems, and buds of the clove plant ethanolic extracts against S. mutans. The ethanolic extracts of clove leaf, stems, and buds were prepared using the maceration method with 70% ethanol, and their activity against S. mutans was tested using the disc diffusion method at three different concentrations (10%, 5%, 2.5% b/v). Fractionation was carried out using hexane and water to obtain two fractions: hexane and water fraction. These fractions were then subjected to antibacterial assays. The ethanolic leaf, stems, and bud extracts exhibited varying antibacterial activity levels. The best activity was observed with the 10% clove bud ethanolic extract, which produced an inhibition zone of 20.83 ± 0.77 mm. The leaf and stem extracts showed inhibition zones of 16.38 ± 3.84 mm and 17.95 ± 5.15 mm, respectively. Furthermore, the hexane-soluble fraction of the clove bud displayed the highest activity with an inhibition zone diameter of 23.7 ± 3.21 mm at 10%. This activity was twice as high as ampicillin, used as the positive control. In conclusion, clove bud remains the best source of antibacterial compounds against S. mutans. Fractionation of the bud extract using hexane can significantly enhance its activity. Further investigation should be conducted to optimize the effectiveness of this active fraction for use as an anti-dental caries treatment.

Leveraging colloid and interface science for long-term marine performance of hybrid coatings: Effects of different nanoparticles on anticorrosion and antifouling properties

This study leveraged the unique colloidal and interfacial properties of synthesized SiO2, ZnO, and carbon (CN) nanoparticles as effective nanofillers to enhance the anti-corrosion and antifouling properties of PMMA coatings. By optimizing nanoparticle dispersion, stability, and functional performance within the polymer matrix, we achieved improved surface roughness, hydrophobicity, mechanical stability, and antimicrobial properties. Hybrid coatings containing 1.5 wt% of these nanoparticles were applied to stainless steel (SS) substrates and evaluated through water contact angle measurements, pull-off adhesion strength tests, antibacterial assays, and electrochemical impedance spectroscopy (EIS). The results demonstrate that the synergistic effects of SiO2, ZnO, and CN nanoparticles significantly enhance the coatings' anticorrosion and antifouling characteristics by increasing hydrophobicity, total impedance, and antibacterial activity via reactive oxygen species generated by ZnO and CN. Additionally, over two years, the coating’s long-term protection was assessed by submerging coupons at a 6-meter depth in the Bocana Chica reef barrier, a site with rapid biofouling colonization, making this test a demanding evaluation.

Experimental and theoretical exploration of bactericidal and photo-catalytical activities of hierarchically porous AuNRs@CuO nanocomposite

In this study, a novel binary nanocomposite consisting of CuO nanosheets functionalized with gold nanorods (AuNRs@CuO), was successfully prepared using a two-step synthetic procedure and further investigated via Density Functional Theory. The physicochemical properties of prepared nanomaterials were analysed using Fourier transform infrared spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, High-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy confirming successful fabrication with improved surface properties. Experimental analyses, including antibacterial assays and morphological studies of bacterial cells demonstrates superior bactericidal properties of AuNRs@CuO nanocomposite compared to pristine CuO nanosheets. Furthermore, molecular docking score provide theoretical insights into the underlying mechanism governing the enhanced antibacterial activity, highlighting the favorable interaction with the bacterial cells. The synergistic effect of CuO nanosheets and AuNRs further improves the photocatalytic efficacy, culminating in a high-yield photocatalyst that achieves 98.7% degradation for Indigo carmine under Xenon lamp irradiation compared to 40.8% and 62.4% for AuNRs and CuO nanosheets alone. Improved charge separation and generation of H+ as major reactive oxygen species from the nanocomposite to Indigo carmine was revealed by radical scavenger activity and photoluminescence studies. After cycles of operation, the morphology and surface state of the photocatalyst remained unchanged, as investigated by FESEM and HRTEM analysis. The novelty of this study lies in the integration of AuNRs and CuO nanosheets as an efficient photocatalytic material for the remediation of toxic organic dyes in wastewater, presenting a promising advancement in sustainable water treatment technologies.

Inhibition of Oral Pathogenic Bacteria, Suppression of Bacterial Adhesion and Invasion on Human Squamous Carcinoma Cell Line (HSC-4 Cells), and Antioxidant Activity of Plant Extracts from Acanthaceae Family.

Medicinal plants have traditionally been used to treat various human diseases worldwide. In this study, we evaluated the leaf extracts of plants from the Acanthaceae family, specifically Clinacanthus nutans (Burm.f.) Lindau, Thunbergia laurifolia Lindl., and Acanthus ebracteatus Vahl., for their compounds and antioxidant activity. The ethanolic extracts of A. ebracteatus showed the highest total phenolic content at 22.55 mg GAE/g extract and the strongest antioxidant activities, with IC50 values of 0.24 mg/mL and 3.05 mg/mL, as determined by DPPH and ABTS assays. The antibacterial efficacy of these extracts was also tested against Streptococcus pyogenes, Streptococcus mutans, Staphylococcus aureus, and Klebsiella pneumoniae. The diameters of the inhibition zones ranged from 14.7 to 17.3 mm using the agar well diffusion method, with MIC and MBC values ranging from 7.81 to 250 mg/mL. Anti-biofilm formation, antibacterial adhesion, and antibacterial invasion assays further demonstrated that these medicinal plant extracts can inhibit bacterial biofilm formation and prevent the adhesion and invasion of oral pathogenic bacteria on the human tongue squamous cell carcinoma-derived cell line (HSC-4 cells). The ethanolic extracts of C. nutans and A. ebracteatus were able to inhibit the gtfD and gbp genes, which facilitate biofilm formation and bacterial adherence to surfaces. These findings provide new insights into the antibacterial and antioxidant properties of plant extracts from the Acanthaceae family. These activities could enhance the clinical and pharmaceutical applications of plant extracts as an alternative therapy for bacterial infections and a dietary supplement.

Insights into the fabrication and antibacterial effect of fibrinogen hydrolysate-carrageenan loading apigenin and quercetin composite hydrogels

Escherichia coli and Staphylococcus aureus are the most prevalent pathogenic bacteria, often resulting in the foodborne disease outbreaks through food spoilage and foodborne infections. To prevent and control food spoilage and foodborne infections induced by Escherichia coli and Staphylococcus aureus, the antibacterial hydrogels were fabricated using fibrinogen hydrolysate-carrageenan (AHs-C) and flavonoids (apigenin and quercetin), and the antibacterial effect of the composite hydrogels against Escherichia coli and Staphylococcus aureus was further investigated. The results of mechanical property exhibited that the composite hydrogels with 0.2 % of apigenin and quercetin (AHs-C-Ap/Que) showed the highest hardness and swelling property compared with the separate addition of apigenin or quercetin. Scanning electron microscopy and atomic force microscopy showed that the dense networks were formed in the hydrogels of AHs-C-Ap/Que., and the average roughness of AHs-C-Ap/Que. significantly increased to 30.70 nm compared with AHs-C. 1H NMR and FTIR spectra demonstrated that apigenin and quercetin were bound to AHs-C by hydrogen bond, hydrophobic interaction and Schiff base, where the interactions between Ap/Que. and AHs-C was stronger compared with the separate addition of apigenin or quercetin. The hydrogels of AHs-C-Ap/Que. showed the highest antibacterial capacity and antibacterial adhesion against Escherichia coli and Staphylococcus aureus. The antibacterial adhesion assay showed that 99 % removal ratios for E. coli and S. aureus were observed in AHs-C-Ap/Que. hydrogels, which showed a great potential to prevent food spoilage and foodborne infections.

Chemoenzymatic Modification of Daptomycin: Aromatic Group Installation on Trp1.

Daptomycin is a cyclic lipodepsipeptide antibiotic used to treat infections caused by Gram-positive pathogens, including multi-drug resistant strains such as methicillin-resistant Staphylococcus au-reus (MRSA) and vancomycin-resistant enterococci (VRE). The emergence of daptomycin-resistant bacterial strains has renewed interest in generating daptomycin analogs. Previous studies have shown that replacing the tryptophan of daptomycin with aromatic groups can generate analogs with enhanced potency. Additionally, we have demonstrated that aromatic prenyltransferases can attach diverse groups to the tryptophan of daptomycin. Here, we report the use of the prenyltransferase CdpNPT to derivatize the tryptophan of daptomycin with a library of benzylic and heterocyclic pyrophosphates. An analytical-scale study revealed that CdpNPT can transfer various aromatic groups onto daptomycin. Subsequent scaled-up and purified reactions indicated that the enzyme can attach aromatic groups to N1, C2, C5 and C6 positions of Trp1 of daptomycin. In vitro antibacterial activity assays using six of these purified compounds identified aromatic substituted daptomycin analogs show potency against both daptomycin-susceptible and resistant strains of Gram-positive bacteria. These findings suggest that installing aromatic groups on the Trp1 of daptomycin can lead to the generation of potent daptomycin analogs.

Antibacterial and cytotoxic metabolites produced by Streptomyces tanashiensis BYF-112 isolated from Odontotermes formosanus

Chemical investigations of the termite-associated Streptomyces tanashiensis BYF-112 resulted in the discovery of four novel alkaloid derivatives: vegfrecines A and B (1 and 2), exfoliazone A (3), and venezueline H (7), in addition to nine known metabolites (4−6, 8−13). The structures of these compounds were elucidated through comprehensive spectroscopic analysis and comparison with existing literature data. Antibacterial assays revealed that viridomycin A (11) exhibited potent antibacterial activity against Staphylococcus aureus, with a zone of inhibition (ZOI) of 12.67 mm, in comparison to a ZOI of 17.67 mm for the positive control gentamicin sulfate. Viridomycin A (11) showed moderate activity against Micrococcus tetragenus and Pseudomonas syringae pv. actinidae, with ZOI values of 15.50 and 14.33 mm, respectively, which were inferior to those of gentamicin sulfate (34.67 and 24.00 mm). Viridomycin F (12) also exhibited moderate antibacterial effects against S. aureus, M. tetragenus, and P. syringae pv. actinidae, with ZOI values of 8.33, 16.50, and 10.83 mm, respectively. Cytotoxicity assays demonstrated that viridobruunine A (5), exfoliazone (6), viridomycin A (11), and X-14881E (13) exhibited significant cytotoxicity against human malignant melanoma (A375), ovarian cancer (SKOV-3), and gastric cancer (MGC-803) cell lines, with IC50 values ranging from 4.61 to 19.28 μmol·L−1. Furthermore, bioinformatic analysis of the complete genome of S. tanashiensis suggested a putative biosynthetic gene cluster (BGC) responsible for the production of compounds 1−12. These findings indicate that the secondary metabolites of insect-associated S. tanashiensis BYF-112 hold promise as potential sources of novel antibacterial and anticancer agents.