Lowest Minimum Inhibitory Concentration Value Research Articles

Unleashing the Potential of Benincasa hispida Peel Extract: Synthesizing Selenium Nanoparticles with Remarkable Antibacterial and Anticancer Properties.

In this study, we successfully synthesized selenium nanoparticles (P-SeNPs) using an environment-friendly approach. This method involves utilizing the aqueous peel extract of Benincasa hispida (ash gourd) in combination with selenium salt. Through our innovative procedure, we harnessed the impressive bio-reduction capabilities, therapeutic potential, and stabilizing attributes inherent in B. hispida. This results in the formation of P-SeNPs with distinct and noteworthy qualities. Our findings were thoroughly substantiated through comprehensive characterizations employing various techniques, including ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential analysis, and Fourier transform infrared spectroscopy (FTIR). The nanoparticles exhibited a spherical shape, considerable size (22.32 ± 2nm), uniform distribution, and remarkable stability (-24mV), all of which signify the effective integration of the phytoconstituents of B. hispida. Furthermore, P-SeNPs displayed robust antibacterial efficacy against pathogenic bacterial strains, as indicated by their low minimum inhibitory concentration values. Our research also revealed the remarkable ability of P-SeNPs to fight cancer, as demonstrated by their impressive IC50 value of 0.19µg/mL against HeLa cells, while showing no harm to primary human osteoblasts, while simultaneously demonstrating no toxicity toward primary human osteoblasts. These pivotal findings underscore the transformative nature of P-SeNPs, which holds promise for targeted antibacterial treatment and advancements in cancer therapeutics. The implications of these nanoparticles extend to their potential applications in therapies, diagnostics, and various biomedical contexts. Notably, the environmentally sustainable synthesis process and exceptional properties established this study as a significant milestone in the field of nanomedicine, paving the way for a more promising and health-enhancing future.

Expanding the Role of Boron in New Drug Chemotypes: Properties, Chemistry, Pharmaceutical Potential of Hemiboronic Naphthoids.

New chemotypes and bioisosteres can open a new chemical space in drug discovery and help meet an urgent demand for novel agents to fight infections and other diseases. With the aim of identifying new boron-containing drug chemotypes, this article details a comprehensive evaluation of the pseudoaromatic hemiboronic naphthoids, benzoxaza- and benzodiazaborines. Relevant physical properties in aqueous media (acidity, solubility, log P, and stability) of prototypic members of four subclasses were determined. Both scaffolds are amenable to common reactions used in drug discovery, such as chemoselective Suzuki-Miyaura, Chan-Lam, and amidation reactions. Small model libraries were prepared to assess the scope of these transformations, and the entire collection was screened for antifungal (Candida albicans) and antibacterial activity (MRSA, Escherichia coli), unveiling promising benzoxazaborines with low micromolar minimum inhibitory concentration values. Select DMPK assays of representative compounds suggest promising drug-like behavior for all four subclasses. Moreover, several drug isosteres were evaluated for anti-inflammatory and anticancer activity as appropriate.

Antibacterial and Anti-Biofilm Activities of Cinnamon Oil against Multidrug-Resistant Klebsiella pneumoniae Isolated from Pneumonic Sheep and Goats.

The primary objectives were to isolate and identify Klebsiella pneumoniae (K. pneumoniae), and determine the antimicrobial resistance patterns and biofilm formation abilities of the isolates. Additionally, the study aimed to investigate the antimicrobial and anti-biofilm effects of cinnamon oil against K. pneumoniae isolates. A cross-sectional study was conducted from March 2022 to April 2023 to collect 200 samples (including 156 nasal swabs and 44 lung specimens) from pneumonic sheep and goats admitted to the Veterinary Teaching Hospital of Zagazig University, Egypt. K. pneumoniae was isolated from a total of 72 (36%) samples, with 53 (73.6%) isolates recovered from nasal swabs and 19 (26.4%) from lung samples. Among the samples, 52 (36.9%) were from sheep and 20 (33.9%) were from goats. Antimicrobial susceptibility testing of the 72 K. pneumoniae isolates to 18 antimicrobials revealed that all isolates were resistant to ampicillin, amoxicillin/clavulanic acid, cefotaxime, ceftriaxone, tetracycline, colistin, fosfomycin, and trimethoprim/sulphamethoxazole. None of the isolates were resistant to amikacin, imipenem, and norfloxacin. Multidrug resistance (MDR) was observed in all K. pneumoniae isolates recovered from sheep and goats. The average MAR index was 0.71, ranging from 0.50 to 0.83. Regarding biofilm formation, among the K. pneumoniae isolates with a high MAR index (n = 30), 10% exhibited strong formation, 40% showed moderate formation, 43.3% displayed weak formation, and 6.7% did not form biofilms. Additionally, the biofilm-forming genes treC and fimA were present in all 28 biofilm-forming K. pneumoniae isolates, while the mrkA gene was detected in 15 (53.6%) of the 28 isolates. MDR K. pneumoniae isolates with strong biofilm formation abilities were treated with cinnamon oil at varying concentrations (100%, 75%, 50%, and 25%). This treatment resulted in inhibition zone diameters ranging from 35 to 45 mm. Cinnamon oil exhibited lower minimum inhibitory concentration and minimum bactericidal concentration values compared to norfloxacin for all isolates. Additionally, cinnamon oil significantly reduced the expression of biofilm-associated genes (treC, fimA, and mrkA) when compared to isolates treated with norfloxacin or untreated. In conclusion, this study identified a high level of MDR K. pneumoniae with strong and moderate biofilm formation abilities in pneumonic sheep and goats in Sharika Governorate, Egypt. Although cinnamon oil demonstrated potential antibacterial and anti-biofilm properties against K. pneumoniae, further research is required to investigate its effectiveness in treating K. pneumoniae infections in pneumonic sheep and goats.

Combining antimicrobial substances for Campylobacter post harvest mitigation on chicken breast fillet and chicken skin - any synergistic effects?

To reduce Campylobacter along the food chain, we investigated the mitigation potential of four antimicrobial compounds against Campylobacter using a new evaluation scheme. Using the checkerboard method, the minimum inhibitory concentration (MIC) values of two organic acids (peroxyacetic acid and lactic acid) and two plant extracts (carvacrol and resveratrol) against a C. jejuni and a C. coli field isolate were determined as well as the fractional inhibitory concentration (FIC) indices of combined treatment. The lowest MIC values were found for peroxyacetic acid (0.03mg mL-1) and carvacrol (0.06mg mL-1). Based on subsequent sensory studies, peroxyacetic acid and carvacrol were selected for challenge tests to quantitatively determine the reducing potential against Campylobacter on chicken meat and chicken skin. Applying peroxyacetic acid significantly reduced Campylobacter counts on chicken skin with maximum reductions of 3.3 log-units (P<.0001), while the combination of peroxyacetic acid and carvacrol resulted in significant reductions of only 0.4 log-units on chicken breast fillet 24 hours after treatment but not thereafter (P=.0192). Peroxyacetic acid is suitable as a postharvest intervention measure to reduce Campylobacter concentration on chicken skin without reducing consumer acceptance.

Synthesis of Cu (II) and Zn (II) Complexes of a Quinoline Based Flexible Amide Receptor as Fluorescent Probe for Dihydrogen Phosphate and Hydrogen Sulphate and Their Antibacterial Activity.

A novel 8-hydroxy quinoline-derived amide receptor, in conjunction with its Cu (II) and Zn (II) complexes, has been strategically developed to function as remarkably efficient fluorescent receptors with a distinct capability for anion sensing. The comprehensive characterization of the synthesized compounds were achieved through UV-Vis, IR, NMR, and HRMS spectroscopic techniques. Among the Cu (II) and Zn (II) complexes, the latter exhibits superior selectivity for anions, specifically dihydrogen phosphate and hydrogen sulfate, as their tetrabutylammonium salts in a 9:1 acetonitrile-water (v/v) mixture. The Cu (II) complex demonstrates enhanced anion binding compared to the amide ligand, albeit with reduced selectivity. Furthermore, the affinity was evaluated using the Benesi-Hildebrand plot. The binding constants and Limit of Detection (LOD) for both complexes were precisely quantified. The Job plot illustrates a clear 1:1 binding interaction between the metal complexes and the guest anions. Significantly, both metal-complex receptors display a broad spectrum of antibacterial activity, against both gram-positive and gram-negative bacteria. It is worth highlighting that the Zn (II) complexed receptor outperforms the Cu (II) complexed receptor, as evidenced by its considerably lower Minimum Inhibitory Concentration (MIC) value against both bacterial strains.

Detection of Cladosporium spinulosum on an engraving by Rembrandt and susceptibility profile to eco-friendly antifungal treatments.

Interdisciplinary studies on cultural heritage artworks provide efficient solutions to control fungal growth and the negative effects of biodeterioration. In this study, we aimed to identify the population of filamentous fungi colonizing an engraving by the Dutch painter Rembrandt, whose conservation status was compromised and showed visible stains of biodeterioration. Microbiological techniques, such as cultivation-dependent approaches and molecular biology, have been used to identify fungal populations. In addition, the anaerobic atmosphere technique and eco-friendly antifungal agents, such as essential oils (EOs) of Curcuma longa, Thymus vulgaris, and Melaleuca alternifolia, were tested against the metabolically active fungal population Cladoposporium spinulosum. Furthermore, in vitro assays revealed that the interaction between the fungal strains and EO was positive, inhibiting the growth of these fungi, and the EOs from T. vulgaris and M. alternifolia showed low minimum inhibitory concentration values. Exposure to anaerobic conditions for 35 days was effective in the total elimination of isolated fungal strains. In conclusion, this study demonstrated the effectiveness of a nondestructive technique for artwork on engraving colonized by fungal strains and using EO as an alternative to toxic antifungals used in conventional treatments in artworks. Thus, this interdisciplinary study involving applied microbiology and botanical and preventive conservation presents a tool to control microbial growth while maintaining artwork integrity.

Phenotypic and genotypic diversity of yeast isolated from cancer patients and their environment and their antifungal sensitivity pattern

Abstract. Al-Darraji ZDG, Mohammed-Ameen MKM. 2023. Phenotypic and genotypic diversity of yeast isolated from cancer patients and their environment and their antifungal sensitivity pattern. Biodiversitas 24: 4166-4174. This study aimed to investigate yeast diversity and their antifungal susceptibility patterns in 853 samples collected from cancer patients, their apparently healthy companions, their beds, their tables, and indoor hospital air. The samples were cultured and identified using classical phenotypic characteristics and a molecular method utilizing amplification of ITS conservative regions of rRNA. The sum of phenotyping and genotyping identification revealed that 102 yeast isolates included 6 genera and 14 species. Candida sp. was the most dominant genera (84.31%), followed by Naganishia sp. (10.78%). Candida albicans (24.50%) and C. krusei (16.66%) were the most prevalent yeast species. Fluconazole, caspofungin, and voriconazole exhibited potent antifungal activities against the most yeast species with low minimum inhibitory concentration (MIC) values compared with high MIC (64 µg/mL) values against Meyerozyma guilliermondi, Naganishia difflunes, and C. tropicalis. To conclude, the antifungal activity was isolate- and species-specific and the higher antifungal concentrations led to a more-rapid expression of activity. The high isolation rate of yeasts from beds and tables, advocated the use of various monitoring systems to ensure thorough cleaning and consistent disinfection of surfaces around patients and health care providers. The study findings showed that the molecular method was superior to the phenotyping technique in identifying yeast isolates. While similar research has been performed in different locations, the current project represents a unique milestone for this particular institution, and offers an opportunity to advance research in this area.

Synergistic antimicrobial activity of essential oils and oleoresins of cinnamon (Cinnamomum zeylanicum), clove bud (Syzygium aromaticum) and ginger (Zingiber officinale)

The essential oils (EOs) and oleoresins (ORs) of Cinnamomum zeylanicum (cinnamon) and Syzygium aromaticum (clove bud), and Zingiber officinale (ginger) are highly important for therapeutical benefits. This study targeted on the evaluation of the antimicrobial activity of extracted EOs and ORs of three spices and their mixtures against five bacteria and two fungi compared to some commercial antimicrobial agents. The agar-disk diffusion assay and minimum inhibitory concentration (MIC) were done for evaluation of antimicrobial activity and the checkboard assay was done using fractional inhibition concentration to determine the synergism and efficacy of the essential oil and oleoresin combinations. The extracted EOs and ORs comprised a mixture of different chemical compounds and exhibited different in-vitro antimicrobial activity. The cinnamon bark oil exhibited the highest inhibition zones compared to other EOs, ORs and positive controls. The EOs and ORs of cinnamon and clove bud are highly effective against Aspergillus niger and Candida albicans as they exhibited significantly lower MIC values than antifungal agents. Nevertheless, MIC values of five kinds of bacteria implied no significant difference between cinnamon bark oil, clove bud oil and antibiotics. It was proven that EOs are more active in inhibiting microorganisms than ORs.

Metal complexes derived from tetradentate Schiff base ligands: Synthesis, spectroscopic analysis, thermogravimetric degradation and antimicrobial activities

In the present study a series of compounds which consist of two novel Schiff base ligands (L1 and L2) and their cupper, nickel and cobalt complexes (L1-Cu, L1-Ni, L1-Co, L2-Cu, L2-Ni, L2-Co) were synthesized under argon atmosphere. 4-aminomethylpyridine and 4-aminoquinoline were used as primary amines for the syntheses of L1 and L2, respectively, 2,2′-[propane-1,3-diylbis(oxymethylene)]dibenzaldehyde was used as carbonyl compound for both L1 and L2. The structures of synthesized compounds determined by FT-IR, ESI-MS and 1HNMR spectroscopic techniques. TGA-DSC technique was used to determine the thermal decomposition of all synthesized compounds. L1, L1-Ni, L1-Co, L2, L2-Co began to decompose at 250 °C, L1-Cu and L2-Cu at 200 °C, L2-Ni at 300 °C. In vitro Antimicrobial activities of ligands and complexes have been evaluated against three Gram-positive, three Gram-negative bacteria and a fungus using the broth microdilution method. The synthesized compounds possessed the activity against all examined microorganisms having the minimum inhibitory concentration (MIC) values between 9.7 and 5000 μg/mL. L2 and L2-Co showed the best antibacterial activity against S. epidermidis and S. aureus with the low MIC value of 9.7 μg/mL.

Steroid‐Hymecromone Conjugates with Improved Antiproliferative and Antimicrobial Potential: Synthesis, Biological Evaluation, and in silico ADME Prediction

AbstractIn this study, hymecromone with known therapeutic aspects was conjugated with steroids a class of natural products that widely exhibited broad biological functions. Cholic acid, diosgenin, cholesterol, DHEA, and testosterone were selected as steroid moiety, each of which has a different biological mechanism of action. This study focused on developing novel conjugates that can be used as multi‐targeted drugs for treating various diseases. All conjugates were evaluated in vitro for their antiproliferative and antimicrobial activities and discussed for the structure‐activity relationship. The conjugates 5 and 6 exhibited comparable cytotoxic effects to reference drugs against cancer cell lines (K562, MCF‐7, and HeLa) while showing no toxicity against healthy cells (L929). Conjugates 7 and 5 demonstrated antibacterial activity against Gram‐positive and Gram‐negative bacteria, with lower minimum inhibitory concentration (MIC) values than the standard ciprofloxacin drug. Conjugate 6, On the other hand, had the lowest MIC value against the fungus, comparable to that of the standard drug ketoconazole. The physicochemical and pharmacokinetic properties of conjugates were in silico computed and evaluated. Overall, the outputs of this study suggest that these conjugates have promising potential as therapeutic agents, offering a multi‐targeted approach for the treatment of various diseases.

Chlorogenic acid loaded niosomes and proniosomes: in vitro antioxidant and antibacterial activities with efficacy in wound healing

ObjectiveTo develop and optimize niosomal and proniosomal vesicular delivery systems for a naturally occurring polyphenol chlorogenic acid (CGA), so as to improve its physicochemical properties and permeability, which may enhance its pharmacological activity. MethodsThe formulated CGA niosomes (CGANs) and CGA proniosomes (CGAPNs) were primed by thin film hydration and phase separation coacervation methods, and were characterized with different attributes including particle size, morphology, entrapment efficiency, zeta potential, deformability, in vitro diffusion, ex vivo permeability, and long-term stability. Their efficiency was further evaluated with in vitro antioxidant assay, antibacterial assays, and excision wound healing model in rats. ResultsOptimized CGANs and CGAPNs showed spherical vesicles with particle size of 490.1 ± 43.0 and 280.0 ± 22.0 nm, polydispersity index (PDI) values of 0.526 and 0.173, and stable zeta potential values of - 29.3 ± 6.4 and - 33.2 ± 6.5 mV, respectively. The CGANs and CGAPNs vesicles showed higher entrapment (98.27% ± 0.46% & 97.27% ± 0.25%) with good deformability (8.77 ± 0.22 & 6.87 ± 0.17), higher in vitro diffusion (97.96% ± 1.67% & 91.00% ± 1.32%), and permeability coefficient values (67 × 10-3 ± 1.72 & 52 × 10-3 ± 1.09) with long-term stability in comparison with plain CGA. Enhanced 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and Fe2 + chelation ability was obtained with CGAPNs > CGANs. They also demonstrated lethal bactericidal activity on different gram positive and gram negative strains with lower minimum inhibitory concentration (MIC) values (8 × and 16 × times less) as compared with plain CGA. Significant reduction (P < 0.05) in wound area with higher wound contraction percentages on day 9 was observed with CGANPs (99.56%) > CGANs (98.44%) in comparison with marketed (92.89%) and CGA (88.89%) hydrogel. ConclusionThese results show great potential of CGANs and CGAPNs for topical wound healing application. This is the first study of CGA in niosomal and proniosomal topical delivery systems.

The Anti-Acne Potential and Chemical Composition of Knautia drymeia Heuff. and Knautia macedonica Griseb Extracts.

The treatment of acne and other seborrheic diseases has arisen as a significant clinical challenge due to the increasing appearance of multi-drug resistant pathogens and a high frequency of recurrent lesions. Taking into consideration the fact that some Knautia species are valuable curatives in skin diseases in traditional medicine, we assumed that the thus far unstudied species K. drymeia and K. macedonica may be a source of active substances used in skin diseases. The purpose of this study was to evaluate the antioxidant, anti-inflammatory, antibacterial, and cytotoxic activities of their extracts and fractions. An LC-MS analysis revealed the presence of 47 compounds belonging to flavonoids and phenolic acids in both species while the GC-MS procedure allowed for the identification mainly sugar derivatives, phytosterols, and fatty acids and their esters. The ethanol as well as methanol-acetone-water (3:1:1) extracts of K. drymeia (KDE and KDM) exhibited great ability to scavenge free radicals and good capacity to inhibit cyclooxygenase-1, cyclooxygenase-2, and lipoxygenase. Moreover, they had the most favorable low minimal inhibitory concentration values against acne strains, and importantly, they were non-toxic toward normal skin fibroblasts. In conclusion, K. drymeia extracts seem to be promising and safe agents for further biomedical applications.

Antimicrobial susceptibility and molecular characteristics of Mycoplasma bovis isolated from cases of bovine respiratory disease in Australian feedlot cattle

To date, antimicrobial susceptibility has not been reported for Australian Mycoplasma bovis isolates. This study determined minimal inhibitory concentrations (MICs) for 12 different antimicrobials against Australian M. bovis isolates and used whole genome sequencing to screen those showing high macrolide MICs for point mutations in target genes. Most lung tissue/swab samples from bovine respiratory disease cases (61/76, 80.3%) tested positive for M. bovis. A set of 50 representative isolates (50/61, 82.0%) that showed adequate growth, was used for MIC testing. Uniformly, low MIC values were confirmed for enrofloxacin (≤ 4 μg/mL), florfenicol (≤ 8 μg/mL), gamithromycin (≤ 2 μg/mL), spectinomycin (≤ 4 μg/mL), tetracycline (≤ 8 μg/mL), tiamulin (≤ 4 μg/mL), and tulathromycin (≤ 0.5 μg/mL). A small proportion (10%) of isolates exhibited high MICs (≥ 32 μg/mL) for tildipirosin, tilmicosin, tylosin, and lincomycin, which were above the epidemiological cut-off values for each antimicrobial (≥ 4 μg/mL). These isolates, originating from three Australian states, underwent whole genome sequencing/multilocus sequencing typing and were compared with the reference strain PG45 to investigate mutations that might be linked with the high macrolide/lincosamide MICs. All five belonged to ST52 and two macrolide associated mutations were identified within the 23 S rRNA gene (A2058G in two sequenced isolates and G748A in all sequenced isolates). Four additional 23 S rRNA gene mutations did not appear to be linked to macrolide resistance. Whilst the majority of Australian M. bovis isolates appear susceptible to the tested antimicrobials, emerging macrolide resistance was detected in three Australian states and requires continued monitoring.

Antimicrobial efficacy of cyclic α- and β-peptides incorporated in polyurethane coatings.

Microbial growth on surfaces poses health concerns and can accelerate the biodegradation of engineered materials and coatings. Cyclic peptides are promising agents to combat biofouling because they are more resistant to enzymatic degradation than their linear counterparts. They can also be designed to interact with extracellular targets and intracellular targets and/or self-assemble into transmembrane pores. Here, we determine the antimicrobial efficacy of two pore-forming cyclic peptides, α-K3W3 and β-K3W3, against bacterial and fungal liquid cultures and their capacity to inhibit biofilm formation on coated surfaces. These peptides display identical sequences, but the additional methylene group in the peptide backbone of β-amino acids results in a larger diameter and an enhancement in the dipole moment. In liquid cultures, β-K3W3 exhibited lower minimum inhibitory concentration values and greater microbicidal power in reducing the number of colony forming units (CFUs) when exposed to a gram-positive bacterium, Staphylococcus aureus, and two fungal strains, Naganishia albida and Papiliotrema laurentii. To evaluate the efficacy against the formation of fungal biofilms on painted surfaces, cyclic peptides were incorporated into polyester-based thermoplastic polyurethane. The formation of N. albida and P. laurentii microcolonies (105 per inoculation) for cells extracted from coatings containing either peptide could not be detected after a 7-day exposure. Moreover, very few CFUs (∼5) formed after 35 days of repeated depositions of freshly cultured P. laurentii every 7 days. In contrast, the number of CFUs for cells extracted from the coating without cyclic peptides was >8 log CFU.

In silico-chemogenomic repurposing of new chemical scaffolds for histoplasmosis treatment.

Histoplasmosis is a systemic form of endemic mycosis to the American continent and may be lethal to people living with HIV/AIDS. The drugs available for treating histoplasmosis are limited, costly, and highly toxic. New drug development is time-consuming and costly; hence, drug repositioning is an advantageous strategy for discovering new therapeutic options. This study was conducted to identify drugs that can be repositioned for treating histoplasmosis in immunocompromised patients. Homologous proteins among Histoplasma capsulatum strains were selected and used to search for homologous targets in the DrugBank and Therapeutic Target Database. Essential genes were selected using Saccharomyces cerevisiae as a model, and functional regions of the therapeutic targets were analyzed. The antifungal activity of the selected drugs was verified, and homology modeling and molecular docking were performed to verify the interactions between the drugs with low inhibitory concentration values and their corresponding targets. We selected 149 approved drugs with potential activity against histoplasmosis, among which eight were selected for evaluating their in vitro activity. For drugs with low minimum inhibitory concentration values, such as mebendazole, everolimus, butenafine, and bifonazole, molecular docking studies were performed. A chemogenomic framework revealed lanosterol 14-α-demethylase, squalene monooxygenase, serine/threonine-protein kinase mTOR, and the β-4B tubulin chain of H. capsulatum, respectively, as the protein targets of the drugs. Our strategy can be used to identify promising antifungal targets, and drugs with repositioning potential for treating H. capsulatum.

Green Synthesis of Zinc Oxide Nanoparticles Using an Aqueous Extract of Punica granatum for Antimicrobial and Catalytic Activity.

The peel aqueous extract of Punica granatum was utilized to fabricate zinc oxide nanoparticles (ZnO-NPs) as a green approach. The synthesized NPs were characterized by UV-Vis spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy, which was attached to an energy dispersive X-ray (SEM-EDX). Spherical, well arranged, and crystallographic structures of ZnO-NPs were formed with sizes of 10-45 nm. The biological activities of ZnO-NPs, including antimicrobial and catalytic activity for methylene blue dye, were assessed. Data analysis showed that the antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria, as well as unicellular fungi, was observed to occur in a dose-dependent manner, displaying varied inhibition zones and low minimum inhibitory concentration (MIC) values in the ranges of 6.25-12.5 µg mL-1. The degradation efficacy of methylene blue (MB) using ZnO-NPs is dependent on nano-catalyst concentration, contact time, and incubation condition (UV-light emission). The maximum MB degradation percentages of 93.4 ± 0.2% was attained at 20 µg mL-1 after 210 min in presence of UV-light. Data analysis showed that there is no significant difference between the degradation percentages after 210, 1440, and 1800 min. Moreover, the nano-catalyst showed high stability and efficacy to degrade MB for five cycles with decreasing values of 4%. Overall, P. granatum-based ZnO-NPs are promising tools to inhibit the growth of pathogenic microbes and degradation of MB in the presence of UV-light emission.

Comparative study between three carbonaceous nanoblades and nanodarts for antimicrobial applications

The design of nanostructured materials occupies a privileged position in the development and management of affordable and effective technology in the antibacterial sector. Here, we discuss the antimicrobial properties of three carbonaceous nanoblades and nanodarts materials of graphene oxide (GO), reduced graphene oxide (RGO), and single-wall carbon nanotubes (SWCNTs) that have a mechano-bactericidal effect, and the ability to piercing or slicing bacterial membranes. To demonstrate the significance of size, morphology and composition on the antibacterial activity mechanism, the designed nanomaterials have been characterized. The minimum inhibitory concentration (MIC), standard agar well diffusion, and transmission electron microscopy were utilized to evaluate the antibacterial activity of GO, RGO, and SWCNTs. Based on the evidence obtained, the three carbonaceous materials exhibit activity against all microbial strains tested by completely encapsulating bacterial cells and causing morphological disruption by degrading the microbial cell membrane in the order of RGO > GO > SWCNTs. Because of the external cell wall structure and outer membrane proteins, the synthesized carbonaceous nanomaterials exhibited higher antibacterial activity against Gram-positive bacterial strains than Gram-negative and fungal microorganisms. RGO had the lowest MIC values (0.062, 0.125, and 0.25 mg/mL against B. subtilis, S. aureus, and E. coli, respectively), as well as minimum fungal concentrations (0.5 mg/mL for both A. fumigatus and C. albicans). At 12 hr, the cell viability values against tested microbial strains were completely suppressed. Cell lysis and death occurred as a result of severe membrane damage caused by microorganisms perched on RGO nanoblades. Our work gives an insight into the design of effective graphene-based antimicrobial materials for water treatment and remediation.

In vitro antibacterial effect of Argentine propolis extracts on Streptococcus mutans and Actinomyces viscosus

Aim: In the present study, the antibacterial activity of the Ethanol Extract of Propolis (EEP), collected from various regions (Mendoza, Santiago del Estero, and Corrientes) in Argentina, against Streptococcus mutans ATCC® 35668™ and Actinomyces viscosus ATCC® 15987™ (MicroBioLogics Inc., USA) was investigated. Methods: Identification of geographic and botanical origin was based on a reconnaissance survey. Phytochemical screening of propolis was carried out on ethanolic extracts using standard methods to identify the constituents (aluminum chloride colorimetric method, Folin-Ciocalteu colorimetric method, thin layer chromatography). The agar diffusion method (discs and wells) and serial dilution method (plates and tubes) were used to evaluate the antibacterial activity of EEP. Results: EEP exerted various degrees of antibacterial activity against S. mutans and A. viscosus, depending on the geographic area of collection. Phytochemical screening showed that the bioactive compounds correspond to phenolic compounds and flavones. EEP from Tunuyán (Mendoza), where the most abundant vegetation belongs to Populus sp., showed the highest content of phenolic compounds (220.92±2.01 mg/g) and flavonoids (30.39±0.25 mg/g). This sample showed the most profound antibacterial activity among the EEP tested. By the agar-well diffusion method, we found a high susceptibility with an inhibitory halo of 11.25 ± 4.68 mm and 10.90 ± 4.21 mm against S. mutans and A. viscosus, respectively. It also presented low Minimum Inhibitory Concentration and Minimum Bactericidal Concentration values against S. mutans (MIC 0.05 mg/mL - MBC 0.46 mg/mL) followed by A. viscosus (MIC 0.11 mg/mL - MBC 0.93 mg/mL). Conclusions: The combined results from all methods indicated that S. mutans is more susceptible to the effect of the Tunuyán EEP than A. viscosus.Uniterms: Propolis. Streptococcus mutans. Actinomyces viscosus. Microbial sensitivity tests.

Antibacterial and Antibiofilm Effect of Unifloral Honeys against Bacteria Isolated from Chronic Wound Infections.

Honey is known as an alternative remedy for the treatment of wounds. To evaluate the potential of five Hungarian honey types against wound-associated bacteria, in vitro microbiological assays were conducted on Pseudomonas aeruginosa, Staphylococcus epidermidis and methicillin-resistant Staphylococcus aureus (MRSA). Minimum inhibitory concentration (MIC) was determined with the broth macrodilution method, and biofilm degradation capacity was tested with a crystal violet assay. To understand the underlying mechanisms, the effects of honey treatments were assessed on bacterial membrane integrity and quorum sensing (QS). The highest antibacterial activity, indicated by the lowest MIC values, as well as the highest biofilm inhibition rates and membrane disruption, was displayed by chestnut and linden honeys. The most sensitive bacterium was S. epidermidis. Bacterial membrane degradation took place 40 min after treatment with honey solutions of at least a 40% concentration. Each honey sample exhibited anti-QS activity, which was most pronounced in the case of chestnut honey. It was concluded that the antibacterial, biofilm-inhibiting and anti-QS activities of linden and chestnut honeys were superior to those of acacia, goldenrod and milkweed honeys. In addition to the floral source, the antibacterial effect of honey is influenced by the microbial species treated. The use of honey in wound treatment can be justified by its diverse antibacterial mechanisms.

Synthesis of nickel oxide nanoparticles as an agent for antibacterial and wastewater remediation applications by calcination

Abstract In this paper, a nickel complex with the general formula [Ni(HST)(OAc)] (HST: 1-salicylaldehydethiosemicarbazone, OAc: acetate) was subjected to thermal decomposition to produce nanoparticles at three different temperatures. The semiconductor nanoparticles have a particle size of 22.18 nm and a band gap of 2.68 eV. Furthermore, it was observed that the nanoparticles exhibiting a zeta-potential value of −26.1 are stable in colloidal media. The produced nanoparticles have the potential to be used as wastewater treatment agents under optimized conditions, as evidenced by the photocatalytic activity on methylene blue degradation with a 69.30% decomposition. Although all the synthesized compounds exhibit high antibacterial activity with low minimal inhibitory concentration values, the nanoparticles obtained by calcination at 400 °C had the highest activity, which is consistent with the literature.