Disc Diffusion Assay Research Articles

Evaluation of the Antibacterial and Antibiofilm Activity of Erythrina senegalensis Leaf Extract Against Multidrug-Resistant Bacteria

Biofilms are bacterial communities on surfaces within an extracellular matrix. Targeting biofilm-specific bacteria is crucial, and natural compounds with reported antibiofilm activity have garnered significant interest. The study evaluated the antibacterial and antibiofilm activity of Erythrina senegalensis leaf extract against multidrug-resistant (MDR) Gram-negative bacteria, including Salmonella typhimurium, Salmonella typhi, Salmonella enteritidis, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The leaf extract was prepared using aqueous and ethanol solvents, and qualitative phytochemical screening revealed the presence of various bioactive compounds such as tannins, saponins, cardiac glycosides, flavonoids, terpenoids, alkaloids, anthraquinone, reducing sugar, and ketones. A Kirby–Bauer disc diffusion assay was performed to test the susceptibility of antibiotics, and the antibacterial efficacy of the aqueous and ethanol extracts of E. senegalensis was determined using the cup-plate method, while the antibiofilm activities were determined using the crystal violet titer-plate method. The aqueous and ethanol extracts of Erythrina senegalensis revealed the presence of tannins, saponins, cardiac glycosides, flavonoids, terpenoids, alkaloids, anthraquinone, reducing sugar, and ketones. The study found that the Gram-negative bacteria isolates that were MDR were S. typhimurium, S. enteritidis, and P. aeruginosa, while K. pneumoniae was resistant to beta-lactam and fluoroquinolones, and S. typhi was sensitive to all antibiotics tested. Statistically, susceptibility to antibiotics had an inverse, weak, and significant relationship with biofilm production (r = −0.453, −0.106, −0.124, −0.106, −0.018, n = 10, p < 0.05). The aqueous extract showed good biofilm inhibition against K. pneumoniae and P. aeruginosa, and poor biofilm inhibition against S. enteritidis, while S. typhimurium and Salmonella typhi exhibited no biofilm inhibition. The ethanol extract did not demonstrate any antibiofilm activity against the tested Gram-negative pathogens. The study suggests that the Gram-negative bacteria’s capacity to form biofilms is negatively associated with their antibiotic resistance phenotypes, and the aqueous extract of E. senegalensis exhibited moderate antibiofilm activity against K. pneumoniae, P. aeruginosa, and S. enteritidis.

Microbial Profile and Antimicrobial Resistance in Enteric Pathogens of Farmed Catfish (Pangasianodon hypophthalmus) in Tropical Freshwater Farms

Background: Recently, Pangasianodon hypophthalmus has emerged as an important fish species farmed in India, contributing to food security in the region. Understanding the bacterial flora associated with this fish is essential to ensure food safety, particularly in the Indian context where such studies have been limited. Objective: This study aims to determine the aerobic bacterial flora and antimicrobial resistance in enteric pathogens associated with farmed Pangasianodon hypophthalmus cultured in freshwater ponds in Kerala, India. Methods: The study included enumeration of aerobic plate counts, Pseudomonads, Aeromonas, Enterobacteriaceae and Staphylococcus aureus using standard methods. Bacterial identification was performed using analytical profile index 20E (APE20E) and 16s rDNA sequencing. Antimicrobial resistance was assessed in E. coli, S. aureus and Aeromonas species using disc diffusion assays. Results: The aerobic bacterial flora in catfish muscle tissue included H2S-producing bacteria, Enterobacteriaceae, Pseudomonas, Aeromonas, and B. thermosphacta. Dominant genera identified were Pseudomonas, Burkholderia, Stenotrophomonas, Aeromonas, Klebsiella, and Psychrobacter. Multidrug-resistant strains of enterotoxigenic E. coli and A. hydrophila were recovered, raising concerns about the prevalence of multidrug resistance in A. hydrophila, an etiological agent of red disease in farmed catfish. Conclusion: This study highlights the microbiological risks posed by Aeromonas spp. and enterotoxigenic E. coli in farmed catfish, emphasising their potential as vectors for pathogenic and antibiotic-resistant determinants in the food chain. Recommendations for future research should focus on the development of effective biopreservatives to control these pathogens in processed Pangasius products.

Characterization of two glutathione S-transferase genes involved in clothianidin resistance in Bradysia odoriphaga.

Glutathione S-transferase (GST) is a key phase II detoxification enzyme involved in xenobiotics metabolism, and plays a pivotal role in the evolution of resistance to various types of insecticides. However, the specific functions of GST genes in clothianidin resistance remain obscure in Bradysia odoriphaga. Here, a specific GST inhibitor, diethyl maleate (DEM), significantly increased the mortality of Bradysia odoriphaga larvae following exposure to clothianidin, and the activity of GST enzyme in clothianidin-resistant (CL-R) strain of Bradysia odoriphaga was markedly greater than that in the SS strain. Two sigma BoGSTs (BoGSTs1 and BoGSTs2) were markedly overexpressed in the CL-R strain and exhibited a higher abundance in the Malpighian tubules or midgut. Exposure to clothianidin resulted in a significant increased expression of BoGSTs1 and BoGSTs2. The knockdown of BoGSTs1 and BoGSTs2 increased sensitivity of larvae to clothianidin in the resistant strain. Furthermore, overexpression of BoGSTs1 and BoGSTs2 led to a significant increase in Escherichia coli cells tolerance to clothianidin. In vitro metabolic assays indicate that these two GSTs cannot directly metabolize clothianidin and its secondary metabolite desmethyl-clothianidin. Disk diffusion assays and fluorescence competitive binding assays indicated that BoGSTs1 and BoGSTs2 play a critical role in clothianidin resistance by antioxidant activity and non-catalytic binding activity. The docking results showed that BoGSTs1 and BoGSTs2 have strong binding affinity toward clothianidin. Collectively, these findings pinpoint the potential role of BoGSTs1 and BoGSTs2 in conferring insecticide resistance in Bradysia odoriphaga and contribute to our understanding of the underlying mechanisms of insecticide resistance. © 2024 Society of Chemical Industry.

In vitro, in vivo and in silico anticancer activity and toxicity of Usnic acid extracted from the mycobiont culture of Usneabaileyi.

Lichen has widespread uses in indigenous medicinal traditions, and it has been used to treat various conditions. Among the various active compounds in the lichen, Usnic acid has unique biological activities. However, the toxicology and the mechanism of action of Usnic acid need to be examined in detail to the extent of clinical trials. Hence, the present research is aimed to isolate usnic acid from the mycobiont culture of Usnea baileyi lichen and explore its toxicological properties and those of pharmacological importance. The methanolic extract of these mycobiont cultures has shown the presence of Usnic acid via column chromatography. The Usnic acid was computationally evaluated using molecular docking studies (GLIDE docking) and MMGBSA energy calculations. The results obtained from TLC, LC-MS, UV-VIS spectrophotometer, NMR spectroscopy (1H and 13c), and FT-IR indicated the presence of Usnic acid. An acute toxicity analysis by an in vivo study using a zebrafish animal model showed acute toxicity. The standard disc diffusion and DPPH assay suggested an antimicrobial and antioxidant activity with this lichen compound. The in vitro analysis of Usnic acid in G361 skin cancer cell lines demonstrated its anticancer potential against malignant melanoma. Furthermore, a molecular in silico study returned a good docking score of -7.977, and the MMGBSA free energy was measured as -18 and -30. Therefore, further extensive research on Usnic acid might lead to the development of novel anticancer drugs from the natural sources.

Evaluation of anti-acne activity of human whole saliva against acne vulgaris: An invitro study.

Acne vulgaris (AV) is a multifactorial inflammatory skin disorder, affecting 9.45% of the world's population. AV can be painful, discomforting, and disfiguring due to scarring, leading to physiological distress, and economic burden. AV pathogenies can be due to various factors, key ones include follicular plugging, colonization by the microorganism, endocrinological factors, and inflammation. Gram-positive bacteria Cutibacterium acnes and Staphylococcus epidermidis are the most common pathogens isolated from patients with AV. The present study aimed to investigate the anti-acne activity of whole human saliva against bacteria that cause AV. The saliva sample from four different individuals was collected at three different intervals. These samples were used to perform antimicrobial susceptibility test (AST) against the pathogens. Kirby-Bauer disk diffusion susceptibility test, and Broth dilution method using Resazurin were performed. The human saliva was effective in inhibiting Cutibacterium acnes and Staphylococcus epidermidis those causing AV. The Minimum inhibitory activity and disc diffusion assay depicted potency of saliva. The pH of the saliva samples was found to be more acidic in the morning samples when compared with the evening samples. The afternoon sample was found to be more effective when compared with the other two intervals. Saliva shows effective anti-acne activity by inhibiting the growth and proliferation of acne-causing bacteria.

Encapsulation of Rifampicin in Solid Lipid Nanoparticles by Microwave‐Assisted Microemulsion Method

AbstractRifampicin (RF) is a potent antibiotic, but its clinical effectiveness is limited by poor water solubility and stability. To overcome these limitations, RF is encapsulated in solid‐lipid nanoparticles (SLNs) using a one‐pot microwave microemulsion method. This study aimed to synthesize and characterize RF‐loaded SLNs, evaluating their physicochemical characteristics and antimicrobial efficacy. The synthesized SLNs exhibit particle sizes ranging from 150 to 200 nm, with a high encapsulation efficiency of ≈55% and high loading capacity. The particles are imaged by cryogenic‐transmission electron microscopy and found to be circular and elongated, with RF homogenously distributed throughout the particles. The RF‐loaded SLNs demonstrate potent antimicrobial activity, as evidenced by disc diffusion assays. The SLNs exhibits a sustained drug release profile, highlighting their potential as an effective drug delivery system for antimicrobial treatment. These findings suggest that SLNs can enhance the stability, bioavailability, and therapeutic efficacy of hydrophobic drugs like RF.

Frequency of Ceftazidime-Avibactam resistance in Pseudomonas aeruginosa: Experience at a Tertiary Care Hospital.

Objective: To isolate Pseudomonas aeruginosa from different clinical samples and determine the antimicrobial activity of Ceftazidime/avibactam against these isolates. Study Design: Prospective Cross-sectional study. Setting: Pathology Laboratory of Lahore General Hospital, Lahore. Period: July 2023 to June 2024. Methods: One hundred thirteen Pseudomonas aeruginosa were identified from different samples Bacterial identification was done by gram staining, bench tests, and API20NE. The antimicrobial sensitivity testing of the causative bacteria was conducted, using commercially available discs, by Kirby Bauer disc diffusion assay and reported in accordance with Clinical & Laboratory Standards Institute (CLSI) 2022. Results: Out of 113 resistant strains of Pseudomonas aeruginosa obtained from different clinical samples Ceftazidime/avibactam was only sensitive to 43.4% of strains and resistant to 56.6% of them. Conclusion: According to the findings of this study, Pseudomonas aeruginosa, a nosocomial organism is isolated from many different clinical samples. The findings of this study also indicate that even a new combination antibiotic fails to show sensitivity in more than half of the isolates. This is a frightening situation that places stress on avoiding the misuse of antibiotics and following anti-microbial stewardship.

Group B Strep during Pregnancy and Allium sativum L.

IntroductionMaternal colonization with Streptococcus agalactiae, or Group B Streptococcus (GBS), during pregnancy increases the risk of neonatal infection through vertical transmission from the mother to the foetus, either before or during labour. This study aimed to evaluate the antimicrobial activity of the SP80 fraction derived from Allium sativum L. and its synergistic potential with antibiotics against GBS strains. MethodsAntimicrobial activity and potential synergism were assessed via broth microdilution and disk diffusion assays. Fifty-five clinical isolates and one ATCC strain of GBS were tested with the disk diffusion method to assess the combination of the SP80 fraction with ampicillin and penicillin G. A broth microdilution assay was performed on one ATCC strain. ResultsThe minimum inhibitory concentrations (MICs) of SP80, ampicillin, and penicillin G against Streptococcus agalactiae (ATCC 12386) were 5 mg/mL, 0.01 µg/mL, and 0.06 µg/mL, respectively. The combination of SP80 with antibiotics, assessed through broth microdilution, demonstrated an additive effect. Statistical analysis revealed that the mean inhibition zone for ampicillin, when combined with the SP80 fraction using the disk diffusion method, was greater than that for ampicillin alone, although the difference was not statistically significant. For penicillin G, the mean remained unchanged when it was combined with SP80. The inhibition zones of the isolated antibiotics revealed that the tested strains were more resistent to penicillin G than to ampicillin. ConclusionsThe SP80 fraction exhibits antimicrobial activity against GBS. When combined with antibiotics, it has an additive effect, suggesting that this approach could be promising for combating GBS infections.

2-Benzimidazolamine-Acetamide Derivatives as Antibacterial Agents: Synthesis, ADMET, Molecular Docking, and Molecular Simulation Studies

AbstractA series of 2-benzimidazolamine-acetamide derivatives were synthesized by substitution reaction of different anilines with chloroacetyl chloride followed by the reaction of 2-aminobenzimidazole with the formed substituted chloroacetamides. The structures of all the synthesized compounds were elucidated with various spectral techniques and all compounds were evaluated against five bacterial strains. Out of ten, the N-(2-fluorophenyl)-substituted acetamide displayed better minimum inhibitory concentration (MIC). Disk diffusion assay and combination studies were also performed on the same acetamide compound. Molecular docking of this acetamide compound with E. coli methionine aminopeptidase (METAP) displayed effective binding, and molecular dynamics simulation further suggested a stable complex formation. Thus, all these results indicate that these scaffolds can serve as a model for developing antibacterial agents.

Development of phage-containing hydrogel for treating Enterococcus faecalis-infected wounds.

Chronic wound infections caused by Enterococcus faecalis pose formidable challenges in clinical management, exacerbated by the emergence of vancomycin-resistant strains. Phage therapy offers a targeted approach but encounters delivery hurdles. Due to their biocompatibility and controlled release properties, hydrogels hold promise as carriers. This study aimed to fabricate phage-containing hydrogels using sodium alginate (SA), carboxymethyl cellulose (CMC), and hyaluronic acid (HA) to treat E. faecalis-infected wounds. We assessed the efficacy of these hydrogels both in vitro and in vivo. The hydrogel was prepared using SA-CMC-HA polymers. Phage SAM-E.f 12 was incorporated into the SA-CMC-HA hydrogel. The hydrogel's swelling index was measured after 24 h, and degradation was assessed over seven days. Surface morphology and composition were analyzed using Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Antibacterial activity was tested via optical density (OD) and disk diffusion assays. Phage release and stability were evaluated over a month. In vivo efficacy was tested in mice through wound healing and bacterial count assays, with histopathological analysis. Hydrogels exhibited a swelling index of 0.43, a water absorption rate of %30, and 23% degradation over seven days. FTIR confirmed successful polymer incorporation. In vitro studies demonstrated that phage-containing hydrogels significantly inhibited bacterial growth, with an OD of 0.3 compared to 1.1 for the controls. Hydrogels remained stable for four weeks. In vivo, phage-containing hydrogels reduced bacterial load and enhanced wound healing, as shown by improved epithelialization and tissue restoration. Phage-containing hydrogels effectively treat wounds infected with E. faecalis-infected wounds, promoting wound healing through controlled phage release. These hydrogels can improve clinical outcomes in the treatment of infected wounds.

Essential oils of thyme (Thymus vulgaris) and oregano (Origanum vulgare) as an alternative for the control of pesticide-resistant Fusarium spp. in quinoa seeds.

The phytopathogenic genus Fusarium can cause damage such as root and stem rot in economically important crops, with significant implications. To seek a sustainable method for controlling this phytopathogen in seeds, the antifungal activity of essential oils (EOs) from thyme (Thymus vulgaris) and oregano (Origanum vulgare) was evaluated against isolates of F. graminearum, F. equiseti, F. culmorum and F. oxysporum originating from quinoa (Chenopodium quinoa) crops in the Boyacá (Colombia). Initially, the effectiveness of commercial fungicides against the mentioned phytopathogenic fungi was evaluated. Upon verifying that these isolates exhibited high resistance to these compounds, the EOs were assessed as a potential control alternative. A disk diffusion assay demonstrated complete in vitro inhibition of the growth of the evaluated phytopathogens when undiluted EOs were used. Subsequently, the minimum inhibitory concentration (MIC) of these oils was determined using the agar well diffusion technique, revealing a MIC of 10 and 1 μL mL-1 for thyme and oregano oil, respectively. Following this, the antifungal activity of the EOs applied to quinoa seeds was evaluated, and germination indices were measured as an indirect indicator of their toxicity. Despite both EOs successfully inhibiting microbial growth in the seeds, it was also found that thyme EO at 100 μL mL-1 and oregano EO at 10 μL mL-1 inhibited seed emergence and germination. However, lower concentrations exhibited a reduction in fungal population without affecting these germination indices. Therefore, it is suggested that the use of these compounds has potential in the treatment and disinfection of quinoa seeds. © 2024 Society of Chemical Industry.

Unravelling The Bioactivities of Acmella paniculata Extract-Mediated Green Deep Eutectic Solvent of Citric Acid Monohydrate and Glycerol

Plants are important sources of underlying medicinal value properties. The extraction of bioactive compounds from botanical sources using green solvents has gained interest due to its environmental sustainability. This study highlighted the bioactivities potential of Acmella paniculata extract mediated by green deep eutectic solvent (DES) composed of the citric acid monohydrate and glycerol. Acmella paniculata, a local flowering shrub was selected due to its rich medicinal value compounds. The synergistic effect between plant’s bioactive compounds and DES is capable of enhancing bioactivity, making DES a promising plant solvent extractor candidate. The plant extracts were prepared in leaf and flower parts using the centrifugation method. The phytochemical screening for both extracts showed the presence of terpenoids and steroid constituents which have valuable bioactivity functions. The antibacterial activity assessed by disc diffusion assay exhibited higher susceptible bacterial response of E. coli, Salmonella enterica ser. Typhimurium and S. aureus against the flower extract compared to the leaf extract. The DPPH assay was conducted to assess free radical scavenging activity. The flower extract demonstrated radical scavenging activity (RSA) of 75%-77% while the leaf extract demonstrated 65%-69%. The flower extract results showed higher RSA emphasizing its potential as a natural antioxidant. The anti-inflammatory activity was determined by egg albumin denaturation assay, which showed a greater inhibition rate in flower extract than the leaf extract which was up to 95% and 89% respectively. Thus, both extracts possess an in vitro anti-inflammatory effect. Conclusively, flower extract exhibited better bioactivities value than leaf extract in a green DES. Hence, offering a new insight into its application as an effective alternative in natural product-based therapeutics.

Antipathogenic Activity of Betainized Polyethyleneimine Sprays Without Toxicity

Background/Objectives: The design of alternative antipathogenic sprays has recently attracted much attention due to the limitations of existing formulations, such as toxicity and low and narrow efficacy. Polyethyleneimine (PEI) is a great antimicrobial polymer against a wide range of pathogens, but toxicity limits its use. Here, betainized PEI (B-PEI) was synthesized to decrease the toxicity of PEI and protonated with citric acid (CA), boric acid (BA), and HCl to improve antimicrobial activity. Methods: Cytotoxicity of the PEI-based solutions was determined on L929 fibroblast cells. Antibacterial/fungal activity of PEI-based antipathogenic sprays was investigated by microtiter and disc diffusion assays, in addition to bacterial viability and adhesion % of common bacteria and fungi on the PEI-treated masks. Furthermore, the antiviral effect of the PEI-based solutions was determined against SARS-CoV-2 virus. Results: The biosafe concentration of PEI was determined as 1 μg/mL with 75 ± 11% cell viability, but B-PEI and its protonated forms had great biocompatibility even at 1000 μg/mL with more than 85% viability. The antibacterial/fungal effect of non-toxic B-PEI was improved by protonation with BA and HCl with 2.5–10 mg/mL minimum bactericidal/fungicidal concentrations (MBCs/MFCs). Bacterial/fungal viability and adhesion on the mask was almost eliminated by using 50 μL with 5–10 mg/mL of B-PEI-BA. Both protonated bare and betainized PEI show potent antiviral activity against SARS-CoV-2 virus. Conclusions: The toxicity of PEI was overcome by using betainized forms of PEI (B-PEI). Furthermore, the antimicrobial and antiviral efficacy of PEI and B-PEI was improved by protonation with CA, BA, and HCl of amine groups on B-PEI. B-PEI-BA spray solution has great potential as an antipathogenic spray with broad-spectrum antimicrobial potency against harmful bacteria, fungi, and viruses without any toxicity.

Sodium Alginate Microneedles Loaded with Vancomycin for Skin Infections

Background: Skin and soft tissue infections (SSTIs) present significant treatment challenges. These infections often require systemic antibiotics such as vancomycin, which poses a risk for increased bacterial resistance. Topical treatments are hindered by the barrier function of the skin, and microneedles (MNs) offer a promising solution, increasing patient compliance and negating the need for traditional needles. Methods: This study focused on the use of sodium alginate MNs for vancomycin delivery directly to the site of infection via a cost-effective micromolding technique. Dissolving polymeric MNs made of sodium alginate and loaded with vancomycin were fabricated and evaluated in terms of their physical properties, delivery ability, and antimicrobial activity. Results: The MNs achieved a 378 μm depth of insertion into ex vivo skin and a 5.0 ± 0 mm zone of inhibition in agar disc diffusion assays. Furthermore, in ex vivo Franz cell experiments, the MNs delivered 34.46 ± 11.31 μg of vancomycin with around 35% efficiency, with 9.88 ± 0.57 μg deposited in the skin after 24 h. Conclusions: These findings suggest that sodium alginate MNs are a viable platform for antimicrobial agent delivery in SSTIs. Future in vivo studies are essential to confirm the safety and effectiveness of this innovative method for clinical use.

The effect of coating chitosan from cuttlefish bone (Sepia Sp.) on the surface of orthodontic mini-screw

IntroductionPeri-implantitis is a significant complication resulting from the failure of orthodontic mini-screws. Recent strategies to address this issue include the application of natural antibacterial coatings to prevent bacterial colonization. Notably, cuttlefish (Sepia sp.) bones are rich in chitosan, which is recognized for its antibacterial effectiveness and biocompatibility. ObjectivesTo evaluate the effects of a chitosan coating derived from cuttlefish bone (Sepia sp.) on mini-screws against Aggregatibacter actinomycetemcomitans bacteria frequently linked to peri‑implantitis. Materials and MethodsThe surface functional groups, phase composition, and crystal morphology of chitosan were analyzed using conventional analytic techniques alongside energy-dispersive X-ray analysis. These prepared were tested for antibacterial activity against A. actinomycetemcomitans by disk diffusion assay; minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) were determined. Stainless steel mini-screws were coated with chitosan, and their surfaces were characterized using scanning electron microscopy (SEM). ResultsThe investigation revealed that chitosan exhibited a MIC value of 8 ppm against A. actinomycetemcomitans with MBCs recorded at 16 ppm. Zones of inhibition varied based on concentration; notably, concentrations at 0.4 %, 0.6 %, and 0.8 % produced zones averaging 16.17 ± 1.64 mm collectively while increasing to a mean zone size of 20.99 ± 3.63 mm at the highest tested concentration (0.8 %). SEM analyses further confirmed the successful adhesion of the chitosan compound onto immersed mini-screw surfaces. ConclusionThe prepared chitosan from cuttlefish bone (Sepia sp.) has antibacterial activity against the bacteria A. actinomycetemcomitans in vitro and can successfully coat SS mini-screws to enhance their efficiency.

Effect of Oxidation of the Hydroalcoholic Extract of Myracrodruon urundeuva All. (Anarcadiaceae) on its Antimicrobial Activity

This study investigates the relaction between oxidation and antimicrobial activity of the hydroalcoholic extract of Myracrodruon urundeuva, a plant known for its traditional medicinal uses. The primary objective was to evaluate how the oxidation of bioactive compounds within the extract affects its antimicrobial efficacy against common pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The extract was prepared following a standardized methodology, and its antimicrobial properties were assessed using disk diffusion assays over a 60-day period, with samples tested every 15 days to monitor changes in activity. The results revealed that the extract exhibited significant antimicrobial activity, particularly at higher concentrations (100%~50%), with inhibition zones reaching up to 16.7 mm against Staphylococcus aureus by day 30. However, a notable decline in activity was observed between days 30 and 45, indicating a potential degradation of the extract's efficacy over time. Interestingly, lower concentrations (12.5% and 0.4%) showed a resurgence in inhibitory activity towards the end of the study, suggesting that certain oxidative processes may enhance the antimicrobial properties of specific compounds. The study highlights the complex relationship between oxidation and antimicrobial activity demonstrating that certain compounds lose effectiveness, while others become more potent after oxidative modification. This finding is particularly relevant in the context of increasing bacterial resistance to conventional antibiotics, as it suggests that the oxidation of plant-derived compounds could be a viable strategy to enhance their antimicrobial properties. Overall, this research underscores the potential of Myracrodruon urundeuva as a natural alternative in combating resistant pathogens and emphasizes the need for further investigation into the mechanisms by which oxidation influences the activity of bioactive compounds in medicinal plants.

Characterization and Antibacterial Activity of Silver Nanoparticles Synthesized from Oxya chinensis sinuosa (Grasshopper) Extract.

In this study, silver nanoparticles (AgNPs) were synthesized using a green method from an extract of the edible insect Oxya chinensis sinuosa (O_extract). The formation of AgNPs (O_AgNPs) was confirmed via UV-vis spectroscopy, and their stability was assessed using Turbiscan analysis. The size and morphology of the synthesized particles were characterized using transmission electron microscopy and field-emission scanning electron microscopy. Dynamic light scattering and zeta potential analyses further confirmed the size distribution and dispersion stability of the particles. The average particle size was 111.8 ± 1.5 nm, indicating relatively high stability. The synthesized O_AgNPs were further characterized using X-ray photoelectron spectroscopy (XPS), high-resolution X-ray diffraction (HR-XRD), and Fourier transform infrared (FTIR) spectroscopy. XPS analysis confirmed the chemical composition of the O_AgNP surface, whereas HR-XRD confirmed its crystallinity. FTIR analysis suggested that the O_extract plays a crucial role in the synthesis process. The antibacterial activity of the O_AgNPs was demonstrated using a disk diffusion assay, which revealed effective activity against common foodborne pathogens, including Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus, and Bacillus cereus. O_AgNPs exhibited clear antibacterial activity, with inhibition zones of 15.08 ± 0.45 mm for S. Typhimurium, 15.03 ± 0.15 mm for E. coli, 15.24 ± 0.66 mm for S. aureus, and 13.30 ± 0.16 mm for B. cereus. These findings suggest that the O_AgNPs synthesized from the O_extract have potential for use as antibacterial agents against foodborne bacteria.

Synthesis of metal nanoparticles on graphene oxide and antibacterial properties.

Pathogen-induced infections and the rise of antibiotic-resistant bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), pose significant global health challenges, emphasizing the need for new antimicrobial strategies. In this study, we synthesized graphene oxide (GO)-based composites functionalized with silver nanoparticles (AgNPs) and copper nanoparticles (CuNPs) as potential alternatives to traditional antibiotics. The objective is to assess the antibacterial properties of these composites and explore their efficacy against E. coli and S. aureus, two common bacterial pathogens. The composites are prepared using eco-friendly and conventional methods to ensure effective nanoparticle attachment to the GO surface. Structural and morphological characteristics are confirmed through SEM, AFM, EDS, XRD, UV-vis, FTIR, and Raman spectroscopy. The antibacterial efficacy of the composites is tested through disk diffusion assays, colony-forming unit (CFU) counts, and turbidimetry analysis, with an emphasis on understanding the effects of different nanoparticle concentrations. The results demonstrated a dose-dependent antibacterial effect, with GO/AgNP-1 showing superior antibacterial activity over GO/AgNP-2, particularly at lower concentrations (32.0μg/mL and 62.5μg/mL). The GO/CuNP composite also exhibited significant antibacterial properties, with optimal performance at 62.5μg/mL for both bacterial strains. Turbidimetry analysis confirmed the inhibition of bacterial growth, especially at moderate concentrations, although slight nanoparticle aggregation at higher doses reduced efficacy. Lastly, both GO/AgNP and GO/CuNP composites demonstrated significant antibacterial potential. The results emphasize the need to fine-tune nanoparticle concentration and refine synthesis techniques to improve their efficacy, positioning these composites as strong contenders for antimicrobial use.

Fabrication and evaluation of a biodegradable electrospun chip loaded with chlorhexidine for periodontal disease

Electrospinning technique is used for the manufacturing matrices of drug delivery systems. This study aimed at fabricating and evaluating an electrospun chip for prolonged retention and controlled drug release at the lesion site. A biodegradable electrospun chip loaded with chlorhexidine (BESC-CHX) was manufactured to treat periodontal diseases. Then, physicochemical properties and efficacy of BESC-CHXs were investigated. The CHX content of BESC was analyzed using high-performance liquid chromatography. The antimicrobial activity and anti-inflammation effects of BESC-CHX were assessed using a disc diffusion assay and a periodontal disease model. BESC-CHX, which is composed of 700 nm fibers, was observed by scanning electron microscopy. Many BESC-CHX batches maintained consistent CHX levels, with a drug entrapment efficiency of 83.3 %. The chip released CHX for seven days and was completely degraded in artificial saliva. BESC-CHX exhibited 99.99 % antimicrobial activity against 11 species of microorganisms. In a beagle periodontal disease model, BESC-CHX demonstrated improvements in periodontal probing depth and clinical attachment level, but these changes were not statistically significant. However, alveolar bone regeneration was observed in cementoenamel junction-alveolar bone crest measurements. The lowest inflammation scores were observed in this group. These findings suggest that BESC-CHXs may be beneficial for the treatment of periodontal disease.

Monomelittoside and Dichotomoside D from bark extract of Alstonia scholaris (L.) R. Br. inhibits dental caries pathogen Streptococcus mutans

Dental caries advances to be a significant global health concern, primarily attributed to the virulent actions of Streptococcus mutans. The antibacterial property of the bark extract of Alstonia scholaris was assessed using standard disc diffusion assays, which revealed significant inhibition of S. mutans. Subsequently, we determined the Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) revealed potent antibacterial activity of bark extract against S. mutans, at MIC and MBC values 62.5 and 125 µg/mL, respectively and antibiofilm activity at 125 µg/mL. Furthermore, cytotoxicity assays showed no adverse effects on mammalian cells. Moreover, we employed liquid chromatography–mass spectrometry to identify bioactive compounds in the bark extract and revealed the presence of major active compounds as Monomelittoside and Dichotomoside D effective in targeting the S. mutans. These findings showed that, the promising antibacterial efficacy of Monomelittoside and Dichotomoside D, highlighting their potential as natural therapeutics for combating dental caries.