Bacteriostatic Concentrations Research Articles

Preparation and characterization of nano silver antibacterial gel for gynecolog

In this experiment, nano silver was prepared by photo reduction method, the trisodium citrate, polyvinylpyrrolidone-K30 and silver nitrate were added under the condition of water as solvent. Polyvinylpyrrolidone-K30 was used as dispersant, silver nitrate as precursors, and sodium citrate as reducing agent. (UV-vis) and scanning electron microscopy (SEM) showed that the diameter of prepared nano silver were between 50 nm and 80 nm, and the results showed that the shape of the nanosized silver nanoparticles were spherical and irregular. Carbomer940 was selected as the gel matrix which is stable and no stimulation, and the viscosity changes with the PH changes. The nanometer silver gels were prepared by mixing nano silver and carbomer940. The antibacterial loop test was carried out with Escherichia coli and Staphylococcus aureus. The antibacterial test showed that the prepared silver nanoparticles had antibacterial effect, and the antibacterial effect was tested by several kinds of nano-silver gels with different concentrations of 0 μg/ml, 4 μg/ml, 8 μg/ml, 12 μg/ml, 16 μg/ml, 20 μg/ml and 24 μg/ml. The results of bacteriostatic circle test showed that the gel had significant bacteriostatic effect on E. coli and S. aureus, which could cause gynecological inflammation. The optimal bacteriostatic concentration was between 12 microns/ml and 24 microns/ml.

Silver nanoparticle-functionalized covalent organic frameworks for the inhibition of foodborne pathogenic bacteria and their application in green grape preservation

Foodborne pathogens continue to pose a significant threat to human health. This study aims to enhance the antimicrobial activity of low-dose silver nanoparticles (AgNPs) against foodborne pathogens and use the enhanced AgNPs to preserve green grapes. A chemical delivery carrier for covalent organic frameworks (COFs) impregnated with AgNPs was developed. We investigated the bacteriostatic properties (minimum bacteriostatic concentration, bacteriostatic growth curve), the mechanism of action of the bacteriostatic agent, and the performance of the bacteriostatic film. The bacteriostatic preservation rate of the AgNPs@COFs composite on green grapes was evaluated. The minimum bacteriostatic concentration of the AgNPs@COFs composite was 10μg/mL, and the bacteriostatic rate varied between 94.01% and 98.77%. The developed antibacterial AgNPs@COFs composite has potential applications in food packaging and preservation.

Phytochemicals and antimicrobial properties of Thai edible plant extracts and their prebiotic-like effects

Phytochemicals and antimicrobial properties of Thai edible plant extracts and their prebiotic-like effects

Design and Synthesis of Polyacrylamide Quaternary Ammonium Salt with Antibacterial Activity

Propenamine quaternary ammonium salt (NNDBAB) containing unsaturated bonds was synthesized from propenamine and bromobutane by alkylation reaction. Using NNDBAB as a monomer, PNNDBAB was further self-polymerized by free radical polymerization to produce propenamine quaternary ammonium salt (PNNDBAB). The structure of NNDBAB was characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The antibacterial properties of PNNDBAB were characterized by an antibacterial zone test, minimum inhibitory concentration, and smear plate counting. The results showed that PNNDBAB had good bacteriostatic activity, the diameter of the bacteriostatic zone was 27 mm, the minimum bacteriostatic concentration was 0.5 mg/L, and the bacteriostatic rate of 1wt% was 71.0%. The bacteriostatic effect was significant. The antibacterial effect of PNNDBAB is long-lasting. When added to the emulsion, the antibacterial effect of PNNDBAB can be sustained within 15 days.

New Chalcone Derivatives Containing 2,4-Dichlorobenzenesulfonamide Moiety with Anticancer and Antioxidant Properties.

Chalcones and their derivatives, both natural and synthetic, exhibit diverse biological activities. In this study, we focused on designing and synthesizing (E)-2,4-dichloro-N-(4-cinnamoylphenyl)-5-methylbenzenesulfonamides 4-8 with the following two pharmacophore groups: 2,4-dichlorobenzenesulfonamide and chalcone. The obtained compounds displayed notable anticancer effects on various human cancer cells, such as cervical HeLa, acute promyelocytic leukemia HL-60, and gastric adenocarcinoma AGS, when assessed with the MTT test. The activity of all compounds against cancer cells was significant, and the obtained IC50 values were in the range of 0.89-9.63 µg/mL. Among all the tested compounds, derivative 5 showed the highest activity on the AGS cell line. Therefore, it was tested for cell cycle inhibition, induction of mitochondrial membrane depolarization, and activation of caspase-8 and -9. These results showed that this compound strongly arrested the cell cycle in the subG0 phase, depolarized the mitochondrial membrane, and activated caspase-8 and -9. Similar to the anticancer effects, all the obtained compounds 4-8 were also assessed for their antioxidant activity. The highest antiradical effect was demonstrated for derivative 5, which was able to inhibit DPPH and ABTS radicals. All examined compounds showed dose-dependent activity against neutrophil elastase. Notably, derivatives 7 and 8 demonstrated inhibitory properties similar to oleanolic acid, with IC50 values of 25.61 ± 0.58 and 25.73 ± 0.39 µg/mL, respectively. To determine the antibacterial activity of derivatives 4-8, the minimum bacteriostatic concentration (MIC) values were estimated (>500 µg/mL for all the tested bacterial strains). The findings demonstrate the substantial potential of sulfonamide-based chalcone 5 as a promising drug in anticancer therapy.

Baktericidna svojstva nekih organskih kiselina u odnosu na mikobakterije

Despite current successes in fighting animal tuberculosis, sporadic cases of infection with both the disease’s causative agents and atypical mycobacteria still occur in animals. Since animal mycobacteriosis cannot be treated with medication, priority must be given to their prevention and elimination as non-specific measures, including disinfection. The unique structure of the mycobacteria cell de- termines their high resistance to antimicrobial agents, therefore the constant search for effective disinfectants is an urgent task of veterinary science. This study aimed to determine the bactericidal properties of several inorganic acids against mycobacteria. Experiments were carried out following modern methodological aspects using the atypical mycobacteria M. fortuitum, pathogens of tuberculosis M. bovis and M. avium. Orthophosphoric (phosphoric) acid (H3PO4) and nitric acid (HNO3) were used in the experiments. Using the suspension method, orthophosphoric acid was found to have a bactericidal effect against atypical mycobacteria- ria M. fortuitum and the pathogen of tuberculoussis M. avium when tested at a concentration of 1.5% (24 hours) and 2.0% (1–24 hours), against the causative agent of tuberculosis M. bovis at a concentration of 1.5% (5–24 hours) and 2.0% (1–24 hours). Nitric acid showed a bactericidal effect when tested in solution against mycobacteriaria M. fortuitum and M. avium at a concentration of 2.0% (5–24 hours), and against M. bovis at a concentration of 2.0% after 1 hour exposure. A different level of mycobacterial growth intensity in test tubes was observed after the action of inorganic acids in sub-bactericidal and bacteriostatic concentrations, which was directly dependent on the concentration and exposure of the acid, and on the type of test culture of microorganisms. It has been shown that inorganic acids can disinfect surfaces contaminated with the tuberculosis-causing agent. This refers to various surfaces like wood, tile, fabric, glass, and metal. It has been found that orthophosphoric acid (1.5% for 24 hours) and nitric acid (2.0% for 5 hours) can be used to disinfect in cases of tuberculosis infection. These findings have been confirmed through bioassays on laboratory animals. Future research will focus on discovering and developing new medications with strong bactericidal properties against mycobacteria.

Enhancement of Spirulina platensis bioactivity by probiotic fermentation and encapsulation by spray‐drying

SummaryThe enhancing impact of fermentation with Lactiplantibacillus plantarum and drying/coating on bioactivity properties of Spirulina platensis was investigated. The fermentation with Lp. plantarum took place anaerobically for 72 h at 37 C. Encapsulation of fresh and fermented samples was made by spray‐drying with a 170 °C air inlet temperature, a 20 mL/min feed flow rate and different ratios of coating material (1:0, 1:1 and 1:2 maltodextrin). Fresh Spirulina capsules exhibited different shapes, mostly rod form whilst fermented Spirulina exhibited a generally spherical shape. 1,1‐diethoxy‐ethane (34.02%) and tert‐butyldimethylsilyl 2,2,3,3,3‐pentafluoropropanoate (26.70%) were identified as the major compounds in fermented Spirulina. The total phenol content of Spirulina was in range from 14.22 mg gallic acid equivalent (GAE)/g for fermented wet spirulina to 77.27 mg GAE/g for fermented spray‐dried Spirulina coated with maltodextrin at a ratio of 1:1. The drying and fermentation processes significantly increased the total phenol content, total antioxidant activity and diphenyl picrylhydrazyl (DPPH) radical scavenging capacity of Spirulina (P < 0.05). Bacteriostatic concentration of fermented spray‐dried Spirulina was 25 mg/mL against Salmonella Paratyphi A, Staphylococcus aureus and Enterococcus faecalis, whereas bactericidal effect was at a concentration of 25 mg/mL vs. Pseudomonas aeruginosa and E. faecalis. The combination of fermentation with Lp. plantarum and drying after coating with maltodextrin of Spirulina enhanced its antimicrobial and antioxidant properties by 0.7–20‐fold compared to fresh, wet Spirulina.

Development of a Polymicrobial Checkerboard Assay as a Tool for Determining Combinatorial Antibiotic Effectiveness in Polymicrobial Communities.

The checkerboard assay is a well-established tool used to determine the antimicrobial effects of two compounds in combination. Usually, data collected from the checkerboard assay use visible turbidity and optical density as a readout. While helpful in traditional checkerboard assays, these measurements become less useful in a polymicrobial context as they do not enable assessment of the drug effects on the individual members of the community. The methodology described herein allows for the determination of cell viability through selective and differential plating of each individual species in a community while retaining much of the high-throughput nature of a turbidity-based analysis and requiring no specialized equipment. This methodology further improves turbidity-based measurements by providing a distinction between bacteriostatic versus bactericidal concentrations of antibiotics. Herein, we use this method to demonstrate that the clinically used antibiotic combination of ceftazidime and gentamicin works synergistically against Pseudomonas aeruginosa in monoculture but antagonistically in a polymicrobial culture also containing Acinetobacter baumannii, Staphylococcus aureus, and Enterococcus faecalis, highlighting the fundamental importance of this methodology in improving clinical practices. We propose that this method could be implemented in clinical microbiology laboratories with minimal impact on the overall time for diagnosis.

Cefoperazone rapidly and sensitive quantitative assessment via a validated RP-HPLC method for different dosage forms, in-use stability, and antimicrobial activities

Cefoperazone (Cfz) is a member of the third generation of parenteral cephalosporin antibiotics. It is used on a wide scale in prescribed antibiotic drugs as anti-infection, especially for Gram-negative and also against Gram-positive microorganisms. The current study aimed to find a rapid RP-HPLC method of Cfz analysis with high linearity, repeatability, sensitivity, selectivity, and inexpensive. In our developed method, there is no need to use special chemical reagents, a high percentage of organic solvent, a high flow rate, further guard column. The chromatographic system comprises an ODS column (150 mm × 4.6 mm × 5 μm). The mobile phase was prepared by mixing KH2PO4 solution: acetonitrile (80:20) with a flow rate of 1.0 mL/min at detection wavelength 230 nm, at room temperature using injection volume 20 μL. The method manifested a satisfied linearity regression R2 (0.9993) with a good repeatability range (0.34–0.92%) with LOD and LOQ; 4.04 μg/mL and 12.24 μg/mL respectively. The method proved its efficiency via system suitability achievement in the robustness and ruggedness conduction according to the validation guidelines. The shorter analysis time makes the method very valuable in quality control to quantify the commercial Cfz in pharmaceutical preparations. This improved HPLC method has been successfully applied for Cfz analysis for Peracef and Peractam vials in our routine finished and stability studies testing laboratories. Additionally, the detection limit of Cfz has been tested in our quality control lab to detect the smallest amount of traces that may be present after the cleaning process of the production machines for cephalosporins preparations. In a precedent for the first time, we were able to use the current analysis method to determine the minimum inhibitory concentration (MIC) and minimum bacteriostatic concentration (MBC). The conventional broth micro-dilution tube method was used to determine MIC at 250 µg/mL and MBC at 125 µg/mL of Cfz against the standard strain of Burkholderia cepacia (B. cepacia) ATCC 25416 as Gram-negative bacteria in vitro.

Application Study of Novel Eggshell/Ag Combined with Pit and Fissure Sealants.

The study aims to enhance the anti-caries performance of pit and fissure sealants through the synthesis of novel silver nanocomposites, and to evaluate their mechanical properties and biological safety in vitro and in vivo. The antibacterial properties of synthetic eggshell/Ag were detected by bacterial inhibition zone, minimum bacteriostatic concentration, fluorescence staining and scanning electron microscopy. The synthetic products were then combined with pit and fissure sealants to prepare specimens, and their effects on mechanical properties, antibacterial properties and cytotoxicity were evaluated. Furthermore, an oral mucosal contact model of golden hamsters was established according to the ISO10933 standard to evaluate local stimulation and systemic effects. The novel nanocomposite eggshell/Ag was confirmed to exhibit strong broad-spectrum antibacterial activity, and that the eggshell/Ag-modified pit and fissure sealant had strong antibacterial properties against common dental caries bacterial biofilms, without any significant change in mechanical properties. The gradient dilution extract showed acceptable cytotoxicity, and in the golden hamster oral contact model, there were no visible abnormalities in local mucosal tissues, blood indices, or liver and kidney histopathology. These findings suggest that eggshell/Ag combined with pit and fissure sealants has strong antibacterial activity and excellent biosafety in vitro and in vivo, making it a promising candidate for clinical applications.

PH-Responsive Intelligent Antibacterial Coatings Based on 2D-COF for Controlled Release of Capsaicin

Herein, we designed and synthesized a two-dimensional covalent organic framework (2D-COF) of a Schiff base using a mechanical chemical grinding method. Moreover, capsaicin@chitosan (CAP@CS) microcapsules were loaded on a TpPa-1 COF by a physical adsorption method to prepare composites (CAP@CS/TpPa-1), which realized the pH-sensitive controlled release of the fungicide CAP, dispersed in fluorocarbon resin to prepare an intelligent coating with environmentally friendly long-term antifouling performance. TpPa-1 improves the antibacterial efficiency by increasing the dispersity of CAP@CS in the resin. Therefore, a CAP release amount of 2 wt % composite coating can meet the minimum bacteriostatic concentration of 37.5 μg/mL required for antifouling. Importantly, pH-responsive controlled release caused by the protonation of CS and the electrostatic interaction between CAP@CS and TpPa-1 COF and increased bacterial contact area by CAP@CS reunion inhibited by TpPa-1 COF improve the bactericidal efficiency of the composite. The composite coating has excellent corrosion resistance, mainly because COF extends the propagation path of the corrosive medium.

Antimicrobial and cytotoxic synergism of biocides and quorum-sensing inhibitors against uropathogenic Escherichiacoli

Uropathogenic Escherichia coli (UPEC) are a primary cause of catheter-associated urinary tract infections (CAUTIs), often forming mature recalcitrant biofilms on the catheter surface. Anti-infective catheter coatings containing single biocides have been developed but display limited antimicrobial activity due to the selection of biocide-resistant bacterial populations. Furthermore, biocides often display cytotoxicity at concentrations required to eradicate biofilms, limiting their antiseptic potential. Quorum-sensing inhibitors (QSIs) provide a novel anti-infective approach to disrupt biofilm formation on the catheter surface and help prevent CAUTIs. To evaluate the combinatorial impact of biocides and QSIs at bacteriostatic, bactericidal and biofilm eradication concentrations in parallel to assessing cytotoxicity in a bladder smooth muscle (BSM) cell line. Checkerboard assays were performed to determine fractional inhibitory, bactericidal, and biofilm eradication concentrations of test combinations in UPEC and combined cytotoxic effects in BSM cells. Synergistic antimicrobial activity was observed between polyhexamethylene biguanide, benzalkonium chloride or silver nitrate in combination with either cinnamaldehyde or furanone-C30 against UPEC biofilms. However, furanone-C30 was cytotoxic at concentrations below those required even for bacteriostatic activity. A dose-dependent cytotoxicity profile was observed for cinnamaldehyde when in combination with BAC, PHMB or silver nitrate. Both PHMB and silver nitrate displayed combined bacteriostatic and bactericidal activity below the half-maximum inhibitory concentration (IC50). Triclosan in combination with both QSIs displayed antagonistic activity in both UPEC and BSM cells. PHMB and silver in combination with cinnamaldehyde display synergistic antimicrobial activity in UPEC at non-cytotoxic concentrations, suggesting potential as anti-infective catheter-coating agents.

Adaptation to the intracellular environment of primary human macrophages influences drug susceptibility of Mycobacterium tuberculosis

As a facultative intracellular pathogen, M. tuberculosis (Mtb) is highly adapted to evading antibacterial mechanisms in phagocytic cells. Both the macrophage and pathogen experience transcriptional and metabolic changes from the onset of phagocytosis. To account for this interaction in the assessment of intracellular drug susceptibility, we allowed a 3-day preadaptation phase post-macrophage infection prior to drug treatment. We found that intracellular Mtb in human monocyte-derived macrophages (MDM) presents dramatic alterations in susceptibility to isoniazid, sutezolid, rifampicin and rifapentine when compared to axenic culture. Infected MDM gradually accumulate lipid bodies, adopting a characteristic appearance reminiscent of foamy macrophages in granulomas. Furthermore, TB granulomas in vivo develop hypoxic cores with decreasing oxygen tension gradients across their radii. Accordingly, we evaluated the effects of hypoxia on preadapted intracellular Mtb in our MDM model. We observed that hypoxia induced greater lipid body formation and no additional shifts in drug tolerance, suggesting that the adaptation of intracellular Mtb to baseline host cell conditions under normoxia dominates changes to intracellular drug susceptibility. Using unbound plasma concentrations in patients as surrogates for free drug concentrations in lung interstitial fluid, we estimate that intramacrophage Mtb in granulomas are exposed to bacteriostatic concentrations of most study drugs.

Equilibria of complexes in the aqueous cobalt(II)–N-(2-hydroxybenzyl)phenylalanine system and their biological activity compared to analogous Schiff base structures

Data will be made available on request.

Butelase 1-Mediated Enzymatic Cyclization of Antimicrobial Peptides: Improvements on Stability and Bioactivity.

Antimicrobial peptides (AMPs) have broad-spectrum antibacterial properties and safety as food preservatives, whereas the stability and antibacterial activity require improvement. Here, the "head-to-tail" cyclization of linear AMP GKE was catalyzed by butelase 1, which resulted in an improved pronouncedly antibacterial effect. Cell morphology and propidium iodide uptake revealed that the increased membrane permeability was one of the bacteriostatic mechanisms of GKE and could be enhanced after cyclization. As cyclic GKE (cGKE) exhibited more stability than the linear counterpart under the microorganism culture environment, the increase in effective bacteriostatic concentration should be a reason for the superior antibacterial effect. Moreover, cGKE exhibited the ordered secondary structure, while GKE possessed a similar structure only in sodium dodecyl sulfate micelles. The structure was also beneficial to improve the antibacterial activity caused by the increased affinity of cGKE to the membranes. Overall, butelase 1-mediated cyclization is a promising strategy for enhancing the antibacterial activity of linear AMPs.

Analysis of the synergistic antifungal mechanism of small molecular combinations of essential oils at the molecular level

The bacteriostatic concentration of essential oil (EO) in practical application is usually higher than the flavor threshold, resulting in a lack of balance between bacteriostatic concentration and flavor, which has become the bottleneck of its application in the field of agriculture products. One of the effective ways to solve this problem is the synergistic antibacterial effect of the active components of EO. In this paper, molecular docking , independent gradient model (IGM) and symmetric matching perturbation theory (SAPT) are combined for the first time to investigated the molecular mechanism of eugenol and citral small molecules (E AC ) against Aspergillus niger . The results show that E AC can combine with β-(1,3)-glucan synthase and chitin synthase proteins, and then destroy the integrity of cell wall, in which the trans -citral has the best affinity with these two enzyme proteins. In addition, E AC can bind to tryptophan , tyrosine and phenylalanine in cell membrane. The binding of citral small molecules to these three amino acids is mainly hydrogen bond, while the binding force of eugenol to them is mainly van der Waals force or π-π interaction. Finally, the synergistic antifungal effect of E AC was confirmed by the damage of membrane proteins and the leakage of cell contents. In this combination, citral binds to the cell wall, which promotes the interaction between eugenol and cell membrane, and finally leads to the serious destruction of cell membrane. The above results show that E AC has the potential to be developed into a new type of agriculture products preservative with synergistic antifungal effect. • Eugenol and citral (E AC ) can combine with chitin synthase and β-(1,3)-glucan synthase to destroy the integrity of cell wall. • Trans-Citral has the best affinity with chitin synthase and β-(1,3)-glucan synthase. • Static electricity is the main contribution to the stability of essential oils molecules and amino acids. • The E AC could cause damages to Aspergillus niger cell membrane that led to a loss of cell viability.

SELECTION OF DECAMETHOXINE RESISTANT VARIANTS OF MICROORGANISMS WHILE USING QUATERNARY AMMONIUM COMPOUNDS UNDER CLINICAL CONDITIONS FOR 50 YEARS (1972-2022)

Antiseptic decamethoxine (decasan), which belongs to quaternary ammonium compounds,has been used in the form of aqueous, aqueous- alcoholic, alcoholic, aqueous- glycerin, and glycerin solutions in clinical practice since 1969. Experimental studies of theformation rate of Staphylococci (S. aureus 209-Р, S. epidermidis) resistance showed thatover 30 passages, the resistance of Staphylococci increases 16-64 times, which indicatesthe possibility of formation of resistant forms of microbiota in relation to decamethoxineantiseptic in clinical conditions.Purpose of the work – to analyze the formation of opportunistic resistance of microbiota,the causative pathogens of infectious and inflammatory processes, over a period of 50years of local application in clinical conditions of the antiseptic decamethoxine – dekasanin the departments of a surgical profile (surgical, gynecological, otorhinolaryngological,etc.).Materials and methods. Analysis of sensitivity to the antiseptic decamethoxine[1, 10-Decamethylene-bis (N1, N1-dimethylmentoxycarbonylmethyl) – ammoniumdichloride], which belongs to quaternary ammonium compounds was carried out inrelation to isolated and identified clinical and reference global strains of opportunisticmicroorganisms belonging to different taxonomic groups of bacteria and yeast-likefungi of the genus Candida. The level of antimicrobial activity was determined by themethod of successive two-fold serial dilutions in a liquid environment optimal for the testmicrobe. The establishment of bacteriostatic (fungistatic) and bactericidal (fungicidal)concentrations of the antiseptic was repeated three times.Results. The sensitivity of the reference test strains remained practically unchangedin the minimum bacteriostatic concentration for 50 years. The minimum bacteriostaticconcentration of decamethoxine in relation to clinical strains of S. aureus, over 50 yearsof use – increased by 13.46 times, and in relation to S. epidermidis – by 8.14 times. Thesensitivity of clinical strains of S. pyogenes was reduced by 5.42-3.63 times; as for S.anginosus, resistance to decamethoxine increased by 3.07-1.62 times. Clinical strainsof S. mitis, which is mainly responsible for the formation of dental caries, also acquiredresistance by 2.21-2.62 times, respectively, and the resistance of E. faecalis increased by3.10-1.90 times. The resistance of C. albicans increased by more than 2 times during thestudied period, and C. tropicalis – by 1.94 times.Conclusions. The antibacterial activity of decamethoxine (decasan) against standardtest strains of bacteria of the genera Staphylococcus, Streptococcus, Escherichia,Pseudomonas, and yeast-like fungi of the genus Candida is stable when these test strainsare stored in laboratory conditions without contact with an antiseptic for 50 years. The useof the antiseptic decamethoxine (decasan) in clinical conditions for 50 years (1972-2022)leads to the formation of different levels of resistance of gram-positive (2.21-13.46 timesincrease in the minimum bacteriostatic (MBsC) concentration) and gram-negative(increase of MBsC 1,25-3.38 times, MBcC 1.49-2.21 times) of bacteria. Decamethoxineresistant variants of yeast-like fungi of the genus Candida are slowly formed. Fungistaticresistance increases 1.94-2.23 times, fungicidal resistance 1.73-2.09 times. The resistanceof bacteria and yeast-like fungi of the genus Candida to decamethoxine (decasan) developsby mutation after short-term, single and multiple contacts in clinical conditions withoutnoticeable changes in the biological characteristics of bacteria (Staphylococcus), whichmakes it possible to state that mutations are not directional and are not associated withan antiseptic, and play the role of only a selective agent.

Unique iminotetrahydroberberine-corbelled metronidazoles as potential membrane active broad-spectrum antibacterial agents

In an effort for fighting with dreadful drug resistance, iminotetraberberine was hybridized with metronidazole to construct a unique type of potential broad-spectrum antibacterial iminotetrahydroberberine-corbelled metronidazoles. Some prepared hybrids exerted promising inhibitory effects against the tested microorganisms in comparison to the natural berberine, clinical metronidazole and norfloxacin. Noticeably, phenyl oxime derivative 8e displayed a broad antibacterial spectrum with a quite low MIC value of 0.024mM against P. aeruginosa, being 63-, 62- and 2-fold to berberine, metronidazole and norfloxacin, respectively. The active compound 8e with low cytotoxicity under effective bacteriostatic concentration could decrease biofilm viability and show much lower trend to induce the resistant development than norfloxacin in the tested period. Mechanism investigation showed that compound 8e could disturb the bacterial membrane to lead to the leakage of cellular contents, thus exerting potent antibacterial potency. It was also revealed that compound 8e could interact with penicillin binding protein via multi-site non-covalent binding in docking simulation. The above results manifested that iminotetrahydroberberine-corbelled metronidazoles might bring hope for the exploitation of new broad-spectrum antibacterial agents with a membrane-destruction mechanism.

Urinary Tract Pathogens: Analysis and Antimicrobial Effects of Ocimum Gratissimum Leaf

The search for alternative medicine for the treatment of pathogenic organisms associated with urinary tract infection (UTI) is on increase. The study was carried out to determine the antimicrobial activities of Ocimum gratissimum leaf extracts on three urinary tract pathogens; Escherichia coli, Staphylococcus aureus and Candida albicans, using their corresponding standard oganisms as controls. The phytochemical analysis of aqueous and alcoholic contents of Ocimum gratissimum leaf extracts revealed the presence of; alkaloids, carbohydrates, flavonoids, glycosides, phenolics, saponins, steroids, and tannins. The minimum inhibitory concentration (MIC), minimum bacteriostatic concentration (MBC) and minimum fungustatic concentration (MFC) of the extracts tested on the three uropathogens was 62.5 to 125 mg/ml. The ethanolic extracts at the concentration of 500mg/ml exhibited strong activity against the urinary pathogens with maximum zones of inhibitions of 23.5±1.5, 23.6±0.6 and 18.25±1.3mm while the aqueous extracts at the same concentration showed weak antimicrobial activity at 3.5±0.5mm as the highest zone of inhibition and 1.4±0.0mm as the lowest zone of inhibition. Notably, the inhibition zones increased with increase in extracts concentration and decreased with decrease in the concentration of extracts. Meanwhile, 12 fractions were eluted from O. gratissimum leave extract. The major phytochemical fractions were mainly alkaloids, flavonoid, and saponins. This study showed that the ethanolic extracts of Ocimum gratissimum is a good antimicrobial agent in-vitro and should not be neglected as an alternative medicine for treatment of pathogenic UTIs

Synthesis and antibacterial against Staphylococcus aureus of new ruthenium (II) polypyridine complexes containing pyrene groups

AbstractAs the treatment of Staphylococcus aureus infection becomes more and more difficult, it is particularly important to develop new antibacterial agents against S. aureus infection. Herein, three ruthenium (II) complexes containing pyrene groups, [Ru (bpy)2(PYIP)](PF6)2 (Ru‐1), [Ru (dtbpy)2(PYIP)](PF6)2 (Ru‐2), and [Ru (ttbpy)2(PYIP)](PF6)2 (Ru‐3) (PYIP = 2‐(pyren‐1‐yl‐1H‐imidazo[4,5‐f][1,10]phenanthroline, bpy = 2,2′‐bipyridine, dtbpy = 4,4′‐dimethyl‐2,2′‐bipyridine and ttbpy = 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine) were designed and synthesized. The antibacterial activities of them against S. aureus were evaluated by determining the minimum inhibitory concentration and minimum bactericidal concentration. The results showed that three ruthenium complexes had excellent antibacterial activities against S. aureus. Among them, Ru‐2 exhibited the best bacteriostatic concentration and bactericidal activities, which was selected for the further antibacterial mechanism exploring. Ru‐2 can obviously inhibit the growth of bacterial biofilm, and the drug resistance results showed that Ru‐2 can effectively prevent the development of bacterial resistance. Moreover, the in vivo antibacterial activity of Ru‐2 was evaluated by establishing mouse infection model with the results that Ru‐2 could effectively inhibit the growth of bacteria and make mouse wounds heal faster.