Lowest Minimum Bactericidal Concentration Research Articles

Synthesis, characterization, antibacterial efficacy, and Cytotoxicity of monoclinic KMg3(Al0.5B0.5)Si3O10F2: A novel material for anticariogenic applications

Fluorophlogopite is a well-known fluorosilicate glass-ceramic derivative known for its bioactivity, machinability and optimal mechanical properties. There is limited information regarding its antibacterial and biocompatible properties. This research paper presents the synthesis and characterization of a novel Boron-doped Fluorphlogopite [KMg3(Al0.5B0.5)Si3O10F2] aiming to improve its antibacterial properties intended for anticariogenic applications. The combustion synthesis method was employed, with oxalyl dihydrazide (ODH) (C2H6N4O2) serving as the fuel. X-ray Diffraction (XRD) analyses unveiled a monoclinic crystal system, showcasing a P21 space group, and an average crystallite size of approximately 28 nm. Morphological scrutiny divulged clustered, irregularly shaped, cluster-like structures. The energy gap was determined to be around 4.97 ± 0.0062 eV. Fourier-Transform Infrared (FTIR) spectroscopy depicted the presence of characteristic bonds. BET analysis indicated the presence of a large surface area and porous structure (mesopores), which may contribute to lower MIC and MBC values, enhancing antibacterial effectiveness. The antibacterial activity, evaluated via agar well diffusion, yielded an 8 mm zone of inhibition. Furthermore, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) against S mutans were determined to be 2 mg/ml and 16 mg/ml, respectively. The biocompatibility of the synthesized KMg3(Al0.5B0.5)Si3O10F2 was assessed through the MTT assay, indicating non-toxic behavior at a concentration of 12 μg/ml with 98 % cell viability, while showing moderate toxicity with 61 % viable cells at its highest concentration of 200 μg/ml.

In vitro Antibacterial Activity of Ethanolic Tanao Si Kan Dang RD1 (Cannabis sativa L.) Extracts Against Human Antibiotic-Resistant Bacteria.

<b>Background and Objective:</b> A new strain of cannabis, <i>Cannabis sativa</i> L. Tanao Si Kan Dang RD1, has been approved and registered by the Rajamangala University of Technology Isan, Thailand. The <i>C. sativa</i> is acknowledged for its medicinal properties which demonstrated various therapeutic properties, such as anti-cancer and antibacterial activities. This study aimed to investigate the antibacterial activity of ethanolic extracts from the stems and leaves of the Tanao Si Kan Dang RD1 strain against seven antibiotic-resistant bacteria. <b>Materials and Methods:</b> The primary antibacterial activity of ethanolic Tanao Si Kan Dang RD1 extracts were determined using the disc diffusion method, while the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined using the broth microdilution method. <b>Results:</b> The largest inhibition zone, measuring 12 mm, was observed in leaf extracts against <i>Pseudomonas aeruginosa</i> 101. The lowest MIC, at 0.78 mg/mL, was obtained from stem extracts against <i>Stenotrophomonas maltophilia</i>. The lowest MBCs, at 12.5 mg/mL, were observed in leaf extracts against <i>Enterococcus faecalis</i>, <i>Acinetobacter baumannii</i>, multidrug-resistant <i>Klebsiella</i> <i>pneumoniae</i>, <i>Stenotrophomonas maltophilia</i> and <i>Pseudomonas aeruginosa</i> 101 and stem extracts against <i>Acinetobacter baumannii</i>, multidrug-resistant <i>Klebsiella pneumoniae</i>, <i>Stenotrophomonas maltophilia</i> and <i>Pseudomonas aeruginosa</i> 101. <b>Conclusion:</b> This study presents a novel finding regarding the antibacterial activity of ethanolic extracts from the leaves and stems of Tanao Si Kan Dang RD1 against antibiotic-resistant bacteria. The potential application of these cannabis plant extracts in the development of antibiotics capable of combating antibiotic-resistant pathogenic bacteria represents a promising strategy to address a significant global health concern.

One-Pot Microfluidics to Engineer Chitosan Nanoparticles Conjugated with Antimicrobial Peptides Using "Photoclick" Chemistry: Validation Using the Gastric Bacterium Helicobacter pylori.

Surface bioconjugation of antimicrobial peptides (AMP) onto nanoparticles (AMP-NP) is a complex, multistep, and time-consuming task. Herein, a microfluidic system for the one-pot production of AMP-NP was developed. Norbornene-modified chitosan was used for NP production (NorChit-NP), and thiolated-AMP was grafted on their surface via thiol-norbornene "photoclick" chemistry over exposure of two parallel UV LEDs. The MSI-78A was the AMP selected due to its high activity against a high priority (level 2) antibiotic-resistant gastric pathogen: Helicobacter pylori (H. pylori). AMP-NP (113 ± 43 nm; zeta potential 14.3 ± 7 mV) were stable in gastric settings without a cross-linker (up to 5 days in pH 1.2) and bactericidal against two highly pathogenic H. pylori strains (1011 NP/mL with 96 μg/mL MSI-78A). Eradication was faster for H. pylori 26695 (30 min) than for H. pylori J99 (24 h), which was explained by the lower minimum bactericidal concentration of soluble MSI-78A for H. pylori 26695 (32 μg/mL) than for H. pylori J99 (128 μg/mL). AMP-NP was bactericidal by inducing H. pylori cell membrane alterations, intracellular reorganization, generation of extracellular vesicles, and leakage of cytoplasmic contents (transmission electron microscopy). Moreover, NP were not cytotoxic against two gastric cell lines (AGS and MKN74, ATCC) at bactericidal concentrations. Overall, the designed microfluidic setup is a greener, simpler, and faster approach than the conventional methods to obtain AMP-NP. This technology can be further explored for the bioconjugation of other thiolated-compounds.

Anti-bacterial Effects of Allium atroviolaceum Hydroalcoholic Extract on Oral Bacteria of Streptococcus viridans Groups

: In light of the escalating global concern over antibiotic resistance, this study aimed to evaluate the antimicrobial activity of the hydroalcoholic extract of Allium atroviolaceum and compare it with 0.2% chlorhexidine using the well diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods against Streptococcus mitis (ATCC 6249), Streptococcus mutans (PTCC 16836), Streptococcus sanguinis (PTCC 1449), and Streptococcus salivarius (PTCC 1448). The well diffusion method revealed the inhibitory effect of the extract, with the highest activity observed against Streptococcus salivarius. Subsequently, MIC and MBC values were determined, indicating that the hydroalcoholic extract had MIC and MBC values of 3.12 mg/mL against Streptococcus sanguinis and 6.25 mg/mL against other strains (Streptococcus mitis, Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius). Chlorhexidine exhibited significantly lower MIC and MBC values of 0.0003%. Based on literature reviews, Allium species exhibit antimicrobial properties. The findings highlight the potential of Allium atroviolaceum extract as an alternative or complementary antimicrobial agent and warrant further investigation to identify its bioactive components and explore their mechanisms of action. This study contributes to understanding natural antimicrobial agents and their potential applications against bacterial infections.

Photocatalytic activity and synergistic antibacterial effects of PCN-222@AgNPs under visible light irradiation

Ag NPs were generated by reducing silver ions with sodium borohydride and then loaded into a zirconium-based MOF, PCN-222, resulting in a deep purple powder, PCN-222@AgNPs, which exhibited photocatalytic activity. The material was characterized and found to have Ag NPs uniformly dispersed in the pores of PCN-222, with a content of 6.0306%. PCN-222@AgNPs had rod-shaped structures of micrometer sizes with irregular spherical Ag NPs on their surfaces, as revealed by scanning electron microscopy and transmission electron microscopy. In experiments on Ag NPs release and reactive oxygen species (ROS) detection, PCN-222@AgNPs effectively released Ag NPs into an aqueous solution and promote ROS generation. Finally, the antibacterial activities of PCN-222@AgNPs against Escherichia coli and Staphylococcus aureus were assessed by in vitro experiments. Results indicated that PCN-222@AgNPs had lower minimum bactericidal concentration (MBC) compared to PCN-222 in both light and dark environments. The MBC further decreased under light conditions due to the enhanced photocatalytic performance of the composite material and the promotion of Ag NPs release by ROS. These findings demonstrate that PCN-222@AgNPs have synergistic antibacterial effects under visible light irradiation.

Antibacterial Activities and Chemical Compounds of Plantago lanceolata (Ribwort Plantain) and Plantago major (Broadleaf Plantain) Leaf Extracts

Background: Plantago lanceolata L. (ribwort plantain) and Plantago major L. (broadleaf plantain) are widely used in ethnobotanical studies and for treating various diseases. This study aims to investigate the antimicrobial activity and chemical compounds of these plants. Methods: The leaf extracts of P. lanceolata and P. major were fractioned using different solvents. The phytochemical screening was carried out by the gas chromatography-mass spectrometry (GC-MS) method. The antibacterial activity of extracts was assessed using the disc diffusion method, and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) were measured by microtiter-broth dilution method. Results: The dichloromethane leaf extract of P. lanceolata and P. major showed the highest antibacterial activity against Salmonella paratyphi (diameter of the inhibition zone: 18.83 and 20.00 mm, respectively) at 100 mg/mL concentration. The lowest MIC was related to dichloromethane extracts of both plants against S. paratyphi (500 µg/mL). The lowest MBC (1000 µg/mL) was related to the dichloromethane extract of P. major against S. paratyphi. The main compounds of P. lanceolata leaf extracts were bis(2-ethylhexyl) phthalate (41.96%), 1-methoxy-3-(2-hydroxyethyl)nonane (32.69%), bicyclo[3.1.1]heptane, 2,6,6-trimethyl- (1.alpha.,2.beta.,5.alpha.)- (10.45%), and cycloheptasiloxane tetradecamethyl- (27.96% and 31.33%). The main compounds of P. major leaf extracts were eicosane (23.62%), cyclohexasiloxane dodecamethyl- (18.21%), 1-methyl-3-n-propyl-2-pyrazolin-5-one (18.08%), cycloheptasiloxane tetradecamethyl- (33.85%), and 1,2-benzisothiazole-3-acetic acid, methyl ester (34.26%). Conclusion: Fractionation of the methanolic leaf extract of P. lanceolata and P. major can help better isolate active components from these plants. The antibacterial properties of the extracts of two plants may be due to the presence of antibacterial compounds detected in GC-MS.

Total Phenolic and Flavonoid Contents, and Preliminary Antioxidant, Xanthine Oxidase Inhibitory and Antibacterial Activities of Fruits of Lapsi (Choerospondias axillaris Roxb.), an Underutilized Wild Fruit of Nepal

Choerospondias axillaris Roxb. (Anacardiaceae) is a deciduous tree, native to Nepal and the Himalayan region, that can reach a maximum height of 20 m. The study aimed to assess the total phenol, flavonoid, and carbohydrate content, and preliminary antioxidant potency, xanthine oxidase inhibition, and antibacterial properties of C. axillaris fruits extracts. Ethyl acetate, acetone, methanol, and water were used as extraction solvents. The quantitative analysis showed that the extracts had total polyphenols (68.28 μg to 154.91 μg gallic acid equivalent/mg extract), flavonoids (41.72 to 283.84 μg quercetin equivalent/mg extract), and carbohydrates contents (67.26 µg to 269.96 µg glucose equivalent/mg extract). The acetone extract exhibited the highest antioxidant activity (IC50: 15.72 µg/mL) and potent inhibition of xanthine oxidase (IC50: 20.80 µg/mL) among the extracts. The acetone extract exhibited the strongest antibacterial efficacy against Staphylococcus aureus and Bacillus cereus with inhibition zones of 13.76 mm and 12.56 mm, respectively. It also had the lowest minimum bactericidal concentration (MBC: 0.78 mg/mL) and minimum inhibitory concentration (MIC: 0.52 mg/mL) against S. aureus. In conclusion, the C. axillaris fruit extracts showed potent antioxidant, xanthine oxidase inhibitory, and antibacterial activities, suggesting their potential for pharmaceutical and nutraceutical applications. Further research should focus on the identification of active compounds and in vivo analysis of pharmacological activities.

Inhibitory Effects of Stem Bark Extract of <i>Chrysophyllum albidum</i> (G. Don) against Selected Gastrointestinal Tract Pathogens

This study investigated the inhibitory effects of stem bark extract of Chrysophyllum albidum against selected gastrointestinal tract pathogens. Powdered stem bark was cold extracted using methanol and sterile distilled water in ratio 3:2 (v/v). The mixture obtained was concentrated in vacuo using a rotary evaporator and lyophilized. The stem bark extract was screened for antibacterial, phytochemicals and antioxidant properties using standard method. The antibacterial activities were determined using agar well diffusion method while the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using agar dilution method. Results obtained indicate that the zones of inhibition shown by the stem bark extract at 10 mg/mL against the bacterial isolates ranged between 10±0.82 mm and 25±0.00 mm. The MICs ranged between 0.31 mg/mL and 5mg/mL while the lowest MIC was 0.31 mg/mL. The MBCs ranged between 0.63 mg/mL and 10 mg/mL while we recorded 0.63 mg/mL as the lowest MBC. The phytochemical screening of the extract revealed the presence of tannins, alkaloids, flavonoids, saponins, steroids, terpenoids, reducing sugar and cardiac glycosides. The antioxidant analysis of stem bark extract showed appreciable antioxidant properties when compared with vitamin C used as control. The stem bark extract exhibited percentage inhibition of 62.80% at a concentration of 15.63 µg/mL while vitamin C exhibited percentage inhibition of 63.53% at the same concentration. This study showed that stem bark extract of Chrysophyllum albidum possessed bioactive compounds that exhibited appreciable antibacterial and antioxidant activities against the gastrointestinal tract pathogens.

Comparison of Blueberry and Dandelion Aqueous Extracts in the Synthesis of Gold and Silver Nanostructures, and Their Applications as Anti‐Pseudomonas aeruginosa Agent

AbstractWe performed a comparative study using aqueous extracts of dandelion flowers and blueberry fruits to synthesize gold‐ (Au) and silver‐ (Ag) nanostructures (NSs). The blueberry extracts gave nanowire and spherical AuNSs upon changing the ratio of the extracts to Au3+precursor while altering the ratio for the dandelion extracts resulted in formation of only anisotropic AuNSs. Similar results were obtained during the AgNSs, where the dandelion extracts resulted in formation of quasi‐spherical AgNSs at the tested ratio (extract/AgNO3 ratio) while altering the ratio for the blueberry extracts resulted in nanorod and nanoplates formation. We argued that this could be from dominancy of a lone compound or a group of compounds and tested this claim by introducing chrysin and amino acid mixtures to the blueberry extracts. Altering the added chrysin amount triggered nanoplate and spherical AuNSs formation while alteration in amino acid mixture content did not change the morphology, and spherical AuNSs were obtained. The antibacterial studies revealed the AgNSs are toxic to Pseudomonas aeruginosa with 8 μg/mL MBC (minimum bactericidal concentration) and 3 μg/mL values for the blueberry and dandelion extracts synthesized AgNSs while penicillin/streptomycin sulfate mixture carrying Dandelion‐AuNSs gave 12‐times lower MBC value in comparison to free penicillin/streptomycin sulfate mixture.

Chemical characterization and antimicrobial activity of essential oils from Croton grewioides Baill. accessions on the phytopathogen Xanthomonas campestris pv. campestris

Croton grewioides Baill. is an aromatic species with proven bioactive properties. Considering the potential of the species, the aim of this study was to chemically characterize and evaluate the in vitro antibacterial activity of the essential oils of C. grewioides on Xanthomonas campestris pv. campestris. The essential oils of the accessions of C. grewioides were extracted by the hydrodistillation method and analyzed by gas chromatography – mass spectrometry. For determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the essential oils and of the compound eugenol, the microdilution method was used at concentrations that ranged from 125 to 4000 μg.mL−1. Streptomycin sulfate was used as a positive control (12.5 to 100 μg.mL−1). Growth kinetics and the membrane permeability trial were evaluated for the concentrations 2×, 1×, 1/2×, 1/4×, and 1/8× MIC of the essential oil CGR-108. The major compounds identified in the essential oils were eugenol, methyl eugenol, and methyl chavicol. The essential oil of the accession CGR-108 had a lower MIC (> 500 and < 1000 μg.mL−1) and MBC equal to <2000 μg.mL−1. For eugenol, MIC was obtained with contractions >250 and < 500 μg.mL−1 and MBC with >500 μg.mL−1 and < 1000 μg.mL−1. A loss of cell viability of the bacteria was observed after 30 min of exposure to the essential oil of the accession CGR-108 at the concentrations of 2× and 1× MIC, which was proven by the fluorescence intensity with propidium iodide. The essential oils of Croton grewioides Baill. and the compound eugenol show antibacterial potential on Xanthomonas campestris pv. campestris.

Antibiofilm Efficacies of Flavonoid-Rich Sweet Orange Waste Extract against Dual-Species Biofilms.

The current study evaluated the antibacterial properties of industrial sweet orange waste extracts (ISOWEs), which are a rich source of flavonoids. The ISOWEs exhibited antibacterial activity towards the dental cariogenic pathogens Streptococcus mutans and Lactobacillus casei with 13.0 ± 2.0 and 20.0 ± 2.0 mg/mL for MIC (minimum inhibitory concentration) and 37.7 ± 1.5 and 43.3 ± 2.1 mg/mL for MBC (minimum bactericidal concentration), respectively. When evaluated in a 7-day dual-species oral biofilm model, ISOWEs dose-dependently reduced the viable bacteria count, and demonstrated strong synergistic effects when combined with the anti-septic chlorhexidine (at 0.1 and 0.2%). Similarly, confocal microscopy confirmed the anti-cariogenic properties of ISOWEs, alone and in combination with chlorhexidine. The citrus flavonoids contributed differently to these effects, with the flavones (nobiletin, tangeretin and sinensetin) demonstrating significantly lower MICs and MBCs compared to the flavanones hesperidin and narirutin. In conclusion, our study demonstrated the potential of citrus waste as a currently underutilised source of flavonoids for antimicrobial applications, such as in dental health.

Rapid biosynthesis and antibacterial activity of zinc oxide nanoparticles using fruit peel of Punica granatum L as cellulose

A biosynthesis of zinc oxide nanoparticles (ZnONPs) is investigated by using Punica granatum (PG) fruit peels as cellulose nanocrystals (CNC). As a first step, the phytochemical properties of (PG) were evaluated as reducing agents and as control agents for nanocomposites. The second step involved biosynthesizing PG–CNC–ZnONPs using a simple and rapid method, which was then confirmed by spectroscopy and microscopy. In addition, the antibacterial activity of PG–CNC–ZnONPs was tested against S. aureus, E.coli, S. typhi, and S.flexneri in vitro. E. coli and S. flexneri had zones of inhibition (mean values) of 14.19 mm and 14.16 mm, respectively, for PG–CNC–ZnONPs. For PG–CNC–ZnONPs, the minimum inhibitory concentration (MICs) that completely inhibited the growth of S. aureus was 250 μg/mL, while for E. coli, S. flexneri, and S. typhi the minimum inhibitory concentration (MICs) was achieved at 125 μg/mL, 31.2 μg/mL, and 15.6 μg/mL respectively. Moreover, the results of minimum bactericidal concentration (MBC) also showed that S. typhi had the lowest MBC (31.2 μg/mL) of all tested strains. The current work has the advantages of simplicity, a low particle size, a high concentration of Zn, and maximum inhibition zones.

In vitro antimicrobial activity of Bixa orellana L . Leaves extract against anaerobic bacteria associated to bacterial vaginosis and Lactobacillus spp.

Motivation for the study: bacterial vaginosis is a bacterial infection that frequently affects women of reproductive age. The treatment is based on synthetic antimicrobials. Bixa orellana L. possesses antimicrobial properties and could represent a potential non-synthetic therapeutic alternative. Main findings: in vitro results suggest that, methanolic extract of Bixa orellana L. leaves possesses potential antimicrobial properties against bacteria associated to bacterial vaginosis. Implications: to identify new sources with therapeutic potential, and to promote research, discovery, and characterization of non-synthetic antimicrobials. To describe the in vitro antimicrobial activity of the methanolic extract of Bixa orellana L. leaves against anaerobic bacteria associated to bacterial vaginosis and Lactobacillus spp. Eight ATCC reference strains; Gardnerella vaginalis, Prevotella bivia, Peptococcus niger, Peptostreptococcus anaerobius, Mobiluncus curtisii, Atopobium vaginae, Veillonella parvula, and Lactobacillus crispatus, and twenty-two clinical isolates; eleven Gardnerella vaginalis and eleven Lactobacillus strains, were included in the study. The antimicrobial susceptibility was determined by the agar diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by using agar dilution and a modified dilution plating method, respectively. All ATCC reference strains showed high levels of susceptibility to the extract, except P. vibia, V. parvula and L. crispatus. Interestingly, all G. vaginalis clinical isolates and the G. vaginalis ATTC strain were the most susceptible to the extract, given their low MIC (1.0 - 2.0 mg/mL) and MBC (1.0 - 4.0 mg/mL) values, whereas, the Lactobacillus spp. clinical isolates and the L. crispatus ATCC strain were the least susceptible bacteria given their high MIC (32.0 mg/mL) and MBC (≥ 32.0 mg/mL) values. In vitro experiments suggest that the extract possesses selective antimicrobial properties given its high activity against bacterial vaginosis-associated anaerobic bacteria and low activity against Lactobacillus species.

The anticancer and antibacterial properties of aqueous and methanol extracts of weeds

In recent years, the use of plant compounds has been considered due to their lower side effects and drug resistance. In this study, the antitumor and antibacterial properties of methanolic and aqueous extracts of Acroptilon repens, Amaranthus retroflexus L , Chenopodium album L and Convolvulus arvensis L were investigated. In addition, the antioxidant, as well as apoptosis activity of these extracts, were evaluated using DPPH and flow cytometry, respectively. The results showed that methanolic extracts of weeds had higher anti-tumor activity compared to their aqueous extract on AGS cells. The lowest IC50 value of aqueous weeds extract against AGS cells was 0.75 mg/mL, which was observed in C. album , while this amount for the methanolic weeds extract was 0.23 mg/mL, which was observed in A. retroflexus . The DPPH and flow cytometry results revealed that the extracts of A. retroflexus is more appropriated compared to other extracts of weeds for future antitumoral application due to high ratio of apoptosis and antioxidant activity. The concentration of aqueous and methanolic extracts of A. retroflexus . required to inhibit 50% of free radical were 51.66 and 23.04 mg/mL respectively. Antimicrobial assays showed that the weeds extracts have good effective on Staphylococcus arouse compared to Escherichia coli . Generally, C. album extracts had higher antimicrobial properties than the extracts of A. repens, A. retroflexus and Convolvulus arvensis L . The lowest minimum bactericidal concentration (MBC) value of weed extract against E. coli and Staphylococcus bacteria was 500 and 1000 μg/mL, respectively, which was observed after their treatment with methanol extract of C. album . Weeds have various beneficial compounds, which many of them are still unknown, therefore, more research is needed to identify these compounds. • Methanolic extract of Amaranthus retroflexus L have potent anticancer activities against AGS cells. • Methanolic extract of Amaranthus retroflexus L reduces cell viability by induction of apoptosis of AGS cells. • Methanolic extract of Acroptilon repens have high antimicrobial potential on Escherichia coli and staphylococcus arouse.

Anti-Salmonella activity on multidrug-resistant strains and cytotoxicity of extracts and constituents of Garcinia brevipedicellata and Garcinia epunctata

The morbidity of Salmonella infections remains high partly due to emergence of multidrug-resistant (MDR) strains. Garcinia species have demonstrated activity against a wide range of infectious organisms including bacteria. Two species, Garcinia brevipedicellata and G. epunctata were investigated for activity against MDR clinical isolates of Salmonella. Methanol extracts of the leaves of both plants were serially re-extracted using ethyl acetate (EtOAc), acetone (Ace) and methanol (MeOH); and the three extracts tested for antibacterial activity by disc diffusion and microdilution methods, and cytotoxicity effects against monkey kidney epithelial (LLCMK2) cells. Five of eighteen pure compounds isolated, identified and tested for activity include β-sitosterol (1), stigmasterol (2), epunctosides A (3), B (4) from G. epunctata and brevipedicelone D (5) from G. brevipedicellata; among which three are new compounds (3, 4 and 5). The EtOAc extract of G. epunctata and brevipedicelone D (5), recorded maximum diameters of zones of inhibition of 18 and 17 mm respectively corresponding to moderate activity. All the four crude extracts recorded the lowest minimum inhibitory concentration (MIC) of 0.125 µg/mL, corresponding to high activity against MDR Salmonella isolates and control strains. Brevipedicelone D (5) showed moderate activity with the lowest MIC of 16 µg/mL. All the crude extracts and compound 5 were not cytotoxic (CC50 = 250 - 809µg/mL). Low minimum bactericidal concentrations (≤ 2 mg/mL) were recorded against most bacteria strains which may indicate bactericidal activity. This is the first report of moderate to high activity against MDR Salmonella and no cytotoxicity of the leaves and pure compounds from G. brevipedicellata and G. epunctata; hence, the leaves should be further investigated as a potential alternative treatment for infections of these strains and source of an antibacterial natural product lead.

Antibiofilm Efficacy of Silver Nanoparticles Alone or Mixed with Calcium Hydroxide as Intracanal Medicaments: An Ex-Vivo Analysis

IntroductionThis study aimed to determine the most effective antibiofilm concentration of silver nanoparticles (AgNPs) alone or in combination with calcium hydroxide (Ca[OH]2) against Fusobacterium nucleatum biofilm. MethodsThe minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AgNPs alone or with Ca(OH)2 were determined. Dentin slices were sterilized and inoculated with F. nucleatum for 3 weeks to establish a biofilm. Samples were randomly assigned to determine the MIC and MBC for AgNPs alone or mixed with Ca(OH)2. A higher concentration of AgNPs for both preparations was also used. Triple antibiotic paste, Ca(OH)2, and saline were used as controls. Specimens in each group were subdivided over 2 observation periods: 7 and 14 days. At the end of each period, specimens were analyzed with 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to determine the metabolic activity. Also, samples from each group were assessed by scanning electron microscopy. ResultsThe MIC and MBC of AgNPs alone against F. nucleatum coincided at 0.04%. The combination of AgNPs + Ca(OH)2 exhibited a lower MIC and MBC of 0.03%. MTT analysis showed a significant reduction in bacterial viability in all groups compared with negative controls (P < .05). A more substantial reduction in bacterial cells was observed with increasing concentrations of AgNPs at both periods. The combination (AgNPs [0.06%] + Ca[OH]2) was the most potent against F. nucleatum. ConclusionsThe findings demonstrated that combining AgNPs with Ca(OH)2 was more effective on the F. nucleatum biofilm than either material alone, suggesting a combined effect.

Antibacterial Photodynamic Therapy in the Near-Infrared Region with a Targeting Antimicrobial Peptide Connected to a π-Extended Porphyrin.

The increase of antimicrobial resistance to conventional antibiotics is worldwide a major health problem that requires the development of new bactericidal strategies. Antimicrobial photodynamic therapy (a-PDT) that generates reactive oxygen species acting on multiple cellular targets is unlikely to induce bacterial resistance. This localized treatment requires, for safe and efficient treatment of nonsuperficial infections, a targeting photosensitizer excited in the near IR. To this end, a new conjugate consisting of an antimicrobial peptide linked to a π-extended porphyrin photosensitizer was designed for a-PDT. Upon irradiation at 720 nm, the conjugate has shown at micromolar concentration strong bactericidal action on both Gram-positive and Gram-negative bacteria. Moreover, this conjugate allows one to reach a low minimum bactericidal concentration with near IR excitation without inducing toxicity to skin cells.

In Vitro Activity of the Arylaminoartemisinin GC012 against Helicobacter pylori and Its Effects on Biofilm.

This study evaluated the in vitro activity of the arylaminoartemisinin GC012, readily obtained from dihydroartemisinin (DHA), against clinical strains of Helicobacter pylori (H. pylori) with different antibiotic susceptibilities in the planktonic and sessile state. The activity was assessed in terms of bacteriostatic and bactericidal potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by the broth microdilution method. After treatment with GC012, all bacterial strains showed significantly lower MIC and MBC values compared to those of DHA. The effect of combination of GC012 with antibiotics was examined using the checkerboard method. GC012 displayed synergistic interactions with metronidazole, clarithromycin, and amoxicillin in all the strains. The antibiofilm activity was evaluated via crystal violet staining, AlamarBlue® assay, colony-forming unit count, and fluorescence microscopy. At ½ MIC and ¼ MIC concentration, both GC012 and DHA inhibited biofilm formation, but only GC012 showed a minimal biofilm eradication concentration (MBEC) on mature biofilm. Furthermore, both compounds induced structural changes in the bacterial membrane, as observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is thereby demonstrated that GC012 has the potential to be efficacious against H. pylori infection.

In-vitro antibacterial activity of Annona senegalensis root and stem extracts against Salmonella typhimurium, Shigella flexneri and Escherichia coli

The aim of the preset study was to determine the efficacy of Annona Senegalensis stem and root extracts against Salmonella typhimurium Shigella flexneri and Escherichia coli through the evaluation of bacterial sensitivity and determination of the minimum inhibitory and bactericidal concentration of the extracts against the test isolates. Plant materials were collected and duly authenticated. The methanoic and aqueous extracts prepared from the powdered forms were tested on the bacterial after cultural and biochemical identification of the isolates. The antibiotic sensitivity test was carried out using the Kirby Bauer disk diffusion method while chloramphenicol was used as the standard control. The Minimum Inhibitory Concentration (MIC) of the plant extracts were determined by broth dilution method while the Minimum Bactericidal Concentration (MBC) was determined by a method described using standard protocols. The ratio of MBC:MIC was computed to determine the bactericidal or bacteriostatic effects of the extracts. Data were analyzed using the Minitab 16 statistical package. Descriptive statistics (mean and standard error) and analysis of variance tools were applied while mean separation was done Fischer’s method at 5% level of significance. Antibacterial sensitivity test showed that the control test (Chloramphenicol) had significantly higher antibacterial sensitivity ( P&lt;0.05) than any of the plant extract. Minimum Inhibitory Concentration (MIC) of the plant extract ranged from 6.25 mg/ml to 25.0 mg/ml. The lowest MIC of 6.25mg/ml was observed in Salmonella typhimurium among all extract types. Root and stem had similar effects on the test organisms (P&gt;0.05) but, methanoic root extract had the lowest MBC of 6.25mg/ml against S.typhimurium and S. flexneri. Based on the MBC/MIC ratio, all extract types had bactericidal effects on Salmonella typhimurium and Shigella flexneri except aqueous root extract that showed bacteriostatic effect. Only the methanoic root and stem extracts exhibited bactericidal effects on Escherichia coli. Annona Senegalensis root and stem could possibly be explored commercially as an antibacterial agent against species of Salmonella, Shigellia and Escherichia.

&lt;strong&gt;The MIC and MBC of calcium hydroxide medicament against bacteria that cause chronic periapical abscess in the vulnerable initial 7-days of endodontic treatment&lt;/strong&gt;

Introduction: The primary aetiology of chronic periapical abscesses, including E. faecalis, S. mutans, S. sanguinis, and P. gingivalis, can be eliminated using intracanal medicaments such as calcium hydroxide. The purpose of this study was to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) value of calcium hydroxide paste in the vulnerable initial 7-day of treatment against E. faecalis ATCC 29212, S. mutans ATCC 25175, S. sanguinis ATCC 10556, and P. gingivalis ATCC 33277. Methods: An in-vitro laboratory experiment using a spectrophotometer as a microdilution method was conducted to determine bacteria's MIC and MBC values on calcium hydroxide paste. The sample used in this study was four bacteria using intracanal medicament of calcium hydroxide (Ca(OH)2), incubated for seven days at 37°C, and then bacterial growth was observed. The cell inhibition percentage was calculated using optical density measurements to determine the MIC value. The low MIC and MBC were defined as sensitive bacteria to calcium hydroxide. Results: Calcium hydroxide paste against E. faecalis (ATCC 29212) with MIC values at a concentration of 750 μg/ml and MBC values at a concentration of 96,000 μg ml; S. mutans (ATCC 25175) with MIC value at a concentration of 3,000 ug/ml and MBC value at a concentration of 48,000 ug/ml; S. sanguinis (ATCC 10556) with MIC value at a concentration of 3,000 ug/ml and MBC value at a concentration of 6,000 ug/ml; P. gingivalis (ATCC 33277) with MIC value at a concentration of 6,000 ug/ml and MBC value at a concentration of 48,000 ug ml. Conclusions: Calcium hydroxide can inhibit bacterial growth activity. E. faecalis (ATCC 29212) and S. sanguinis (ATCC 10556) are more sensitive to calcium hydroxide paste than other bacteria, with the lowest MIC and MBC on seven days of incubation since the maximum calcium and hydroxyl ions are released.