Minimum Bactericidal Concentration Research Articles

Bio-functional properties and phytochemical composition of selected Apis mellifera honey from Africa

Globally, the demand for natural remedies such as honey to manage ailments has increased. Yet, the health benefits and chemical composition of African honeys are not well understood. Therefore, this study aimed to characterise the bio-functional properties and the phytochemical composition of 18 Apis mellifera honeys from Kenya, Uganda, and Cameroon in comparison to the popular and commercially available Manuka 5+ honey from New Zealand. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH-RSA) was used to determine the antioxidant property, whilst the agar well diffusion and broth dilution (Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)) assays were used to determine antimicrobial property. Further, colorimetric methods were used for phytochemical analysis. Our results showed that honeys collected from Rift Valley region of Kenya (e.g. Poi, Salabani and Mbechot) and Western region of Cameron (e.g. Bangoulap) had the highest antioxidant (DPPH RSA of 41.52–43.81%) and antimicrobial (MIC (3.125–6.25% w/v) and MBC (6.25–12.5% w/v)) activities. Additionally, the total flavonoid (770–970 mg QE/100 g), phenol (944.79–1047.53 mg GAE/100 g), terpenoid (239.78–320.89 mg LE/100 g) and alkaloid (119.40–266.57 mg CE/100 g) contents reached the highest levels in these bioactive African honeys, which significantly and positively correlated with their bio-functional properties. The functional and phytochemical composition of these bioactive African honeys were similar to or higher than those of the Manuka 5+ honey. Furthermore, gas chromatography-mass spectrometry analysis of African honeys revealed 10 most prominent volatile organic compounds that contribute to their geographical distinction: triacontane, heptacosane, (Z)-9-tricosene, tetracosane, 6-propyl-2,3-dihydropyran-2,4-dione, octacosane, 1,2,4-trimethylcyclohexane, 1,3-bis(1,1-dimethylethyl) benzene, 2-methylheptane and phytol. Overall, our findings suggest that some of the tested African honeys are natural sources of antimicrobial and antioxidant therapies that can be exploited upon further research and commercialized as high value honey.

Biomimetic Protein Structural Transitions Regulate Activation and Inhibition of the Broad-Spectrum Bactericidal Activity of Cationic Nanoparticles

The development of cationic polymers as alternative materials to antibiotics necessitates addressing the challenge of balancing their antimicrobial activity and toxicity. Here we propose a precise switching strategy inspired by biomimetic voltage-gated ion channels, enabling controlled activation and inhibition of cationic antimicrobial functions through protein conformational transitions in diverse physiological environments. Following thermodynamic studies on the specific recognition between mannose end groups on polycations and concanavalin A (ConA), we synthesized a type of ConA-polycation nanoparticle. The nanoparticle was inhibited under neutral conditions, with cationic moieties shielded by ConA's β-sheet. This shielding suppresses their antimicrobial activity, thereby ensuring satisfactory biocompatibility. In mildly acidic environments, however, the transition of a portion of ConA to an α-helix conformation exposed cations at the particle periphery, activating antibacterial functionality. Compared to inhibited nanoparticles, those in the activated state exhibited a 32–256 times reduction in the minimum bactericidal concentration against bacteria and fungi (2−16 μg/mL). In a murine acute pulmonary infection model, intravenous administration of inhibited nanoparticles effectively reduced bacterial counts by 4-log within 12 h. The biomimetic design, regulating cationic antimicrobial functionality through the alteration in protein secondary structure, significantly retards bacterial resistance development, holding great promise for intelligent antimicrobial materials. Statement of significanceCationic antimicrobial polymers exhibit advantages distinct from antibiotics due to their lower propensity for resistance development. However, the presence of cationic moieties also poses a threat to healthy cells and tissues, significantly constraining their potential for clinical applications. To address this challenge, we propose a biomimetic strategy that mimics voltage-gated ion channels to activate the antimicrobial functionality of cations selectively in bacterial environments through the conformational transitions of proteins between β–sheets and α–helices. In healthy tissues, the antimicrobial functionality is inhibited, ensuring satisfactory biocompatibility. Antimicrobial cationic materials capable of intelligent switching between an activated state and an inhibited state in response to environmental changes offer an effective strategy to prevent the development of resistance and mitigate potential side effects.

Enhancing the antioxidant and anti-inflammatory potentials of mulberry-derived postbiotics through submerged fermentation with B. subtilis H4 and B. amyloliquefaciens LFB112

Mulberry-derived postbiotics (MDP) have been scientifically proven to possess beneficial properties for human health, making them potential nutraceuticals. This study aims to enhance the antioxidant and anti-inflammatory effect of MDP via submerged fermentation with Bacillus subtilis H4 (H4) and Bacillus amyloliquefaciens LFB112 (LFB112) bacterial strains. Our results demonstrated compelling evidence that the combination of two strains with the optimized time (24 h), inoculum size (8%), and substrate size (10%) significantly increased the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities. When compared to the non-fermented mulberry (NFM), the MDP with the above-optimized conditions showed substantially higher antioxidant activities such as DPPH, 2,2′-Azino-bis (3-ethylebenzothiazoline-6-sulfonic acid) (ABTS), hydroxyl scavenging activities, and reducing power capabilities. Moreover, the MDP showed a significant decrease in the lipopolysaccharides (LPS)-induced reactive oxygen species (ROS) generated in RAW264.7 cells. The antibacterial assays such as minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) showed that MDP possesses antibacterial activity against various pathogenic bacterial strains with the lowest MIC recorded as 32.5 mg/ml against S. pullorum CVCC519, while the highest MIC observed was 40 mg/ml against P. aeruginosa. The lowest and highest MBCs observed were 40 and 55 mg/ml against S. aureus ATCC43300 and S. pullorum CVCC519 respectively. Furthermore, the MDP showed good ant-inflammatory activities by significantly reducing the nitric oxide (NO) concentration (p<0.0001) and mRNA expression of the proinflammatory cytokines in response to the LPS-induced inflammation in the RAW264.7 macrophage cell line. To sum up, our findings indicate that MDP as a novel postbiotics can be utilized both as a functional food and a safe feed additive, possibly benefiting gut and metabolic health.

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.

Mycofabrication of bimetal oxide nanoparticles (CuO/TiO2) using the endophytic fungus Trichoderma virens: Material properties and microbiocidal effects against bacterial pathogens

Bimetallic oxide nanoparticles (NPs) have gained the interest of researchers owing to the synergistic mechanism of action by the elements present. Mycosynthesis of nanostructures is a promising, facile, and an environmentally friendly approach. In the present study, CuO/TiO2 NPs were produced using the cell-free filtrate of the endophytic fungus Trichoderma virens. The reaction of the fungal filtrate with the two metal salts, CuSO4.5H2O and TiO2, resulted in the mycosynthesis of the CuO/TiO2 NPs. The prepared bimetal oxide NPs were characterized using XRD, FTIR spectroscopy, EDX, DLS, zeta potential analysis, XPS, Raman scattering, FESEM, and HRTEM. The mycosynthesized CuO/TiO2 NPs exhibited diffraction peaks characteristic of the monoclinic CuO and tetragonal rutile TiO2 crystal planes. Homogeneity and stability were observed as a result of the biological moieties present in the fungal filtrate, which capped the CuO/TiO2 NPs. The prepared CuO/TiO2 NPs were distributed as flake/plate-like and quasi-spherical/nanorod CuO and TiO2 NPs, respectively. A broad-spectrum antibacterial effect was recorded, with zones of inhibition as follows: foodborne pathogens Escherichia coli (14.34 mm), Salmonella enterica serovar Typhimurium (11.32 mm), and Staphylococcus aureus (9.63 mm); and phytopathogenic bacteria involving Clavibacter michiganensis subsp. michiganensis (Cmm, 12.16 mm), C. michiganensis subsp. capsici (Cmc, 11.26 mm), wild type and streptomycin-resistant Pectobacterium carotovorum subsp. carotovorum (Pcc, 11.06 and 12.37 mm, respectively), and wild type and streptomycin-resistant Xanthomonas citri pv citri (Xcc, 12.48 and 12.69 mm, respectively). The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the CuO/TiO2 NPs were determined using the broth microdilution assay. NP-treated bacterial cells at sub-MICs had rough surfaces with membrane defects and exhibited shrinkage, reduction of cell edges, cracks, and fractures on their surfaces. This study provides insights into the potential of the mycosynthesized CuO/TiO2 NPs as alternative nano-antimicrobial agents, which could be employed for future biomedical, agricultural, and pharmaceutical applications.

Comparative antioxidant, antibacterial, and antidiabetic activities of in vitro-grown callus and wild-grown various parts of Piper longum L

BackgroundPiper longum L. is a tropical and subtropical medicinal plant that has been used as antidiabetic, diarrhea, stomachache, cough, asthma, and bronchitis since ancient times. The in vitro-grown callus from the leaf, however, has not been tested and utilized for any of these conditions. Thus, this research pursues to assess the comparative study of antioxidant, antibacterial, and antidiabetic activities of in vitro-grown callus and various parts of Piper longum-grown in the wild. MethodsThe antioxidant activity of crude extracts and the fractions were determined by DPPH (1,1-diphenyl-2-picrylhydrazyl) free-radical scavenging assay, the antibacterial activity by agar-well diffusion method, and antidiabetic activity by α-amylase and α-glucosidase inhibition assay. In addition, the total phenol content (TPC) and total flavonoid contents (TFC) were calculated using Folin-Ciocalteau reagent and aluminum chloride complex-forming assay respectively. ResultsThe highest antioxidant activity (IC50=134.81±1.16 µg/mL), TPC (41.22±0.50 mg of GAE/g dry weight), and TFC (73.41±0.53 mg of QE/g dry weight) were obtained in the dichloromethane (DCM) fraction of root than other crude extracts and fractions. The DCM fractions of root exhibited the minimum inhibitory concentration (MIC) at 5.0 mg/mL and minimum bactericidal concentration (MBC) of 8.35 mg/mL to the Staphylococcus aureus. Moreover, the DCM fraction of root showed the highest α-amylase and α-glucosidase inhibition (IC50=365.21±31.02 and 489.07±27.96 µg/mL) than other crude extracts and fractions. To the best of our information, comparative antioxidant (IC50=206.61±0.64 µg/mL), antibacterial (suppressed 80 % of tested bacteria), and antidiabetic (IC50=1165.15±15.63 and 1304.76±12.43 µg/mL) properties of the in vitro-grown callus were recorded for the first time in P. longum, and were found to be comparative to those of the wild-grown parts. ConclusionsThese results showed that wild-grown P. longum roots, particularly the DCM fraction, could be an important source of natural antioxidants, antimicrobials, and antidiabetics for better curative uses than other wild-grown parts and in vitro-grown callus. In vitro-grown callus, however, could be used as a natural drug source and used to conserve P. longum in its natural habitats in the future.

UPLC-qTOF-MS phytochemical profile of Commiphora gileadensis leaf extract via integrated ultrasonic-microwave-assisted technique and synthesis of silver nanoparticles for enhanced antibacterial properties

The utilization of metallic nanoparticles in bio-nanofabrication holds significant potential in the field of applied research. The current study applied and compared integrated ultrasonic-microwave-assisted extraction (US/MICE), ultrasonic extraction (USE), microwave-assisted extraction (MICE), and maceration (MAE) to extract total phenolic content (TPC). In addition, the study examined the antioxidant activity of Commiphora gileadensis (Cg) leaf. The results demonstrated that the TPC of US/MICE exhibited the maximum value at 59.34 ± 0.007 mg GAE/g DM. Furthermore, at a concentration of 10 μg/mL, TPC displayed a significant scavenging effect on DPPH (56.69 %), with an EC50 (6.48 μg/mL). Comprehensive metabolite profiling of the extract using UPLC-qTOF-MS/MS was performed to identify active agents. A total of 64 chromatographic peaks were found, out of which 60 were annotated. The most prevalent classes of metabolites found were polyphenols (including flavonoids and lignans), organic compounds and their derivatives, amides and amines, terpenes, and fatty acid derivatives. Transmission electron microscopy (TEM) revealed the aggregate size of the synthesized nanoparticles and the spherical shape of C. gileadensis-mediated silver nanoparticles (Cg-AgNPs). The nanoparticles had a particle size ranging from 7.7 to 42.9 nm. The Cg-AgNPs exhibited more inhibition zones against S. aureus and E. coli. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Cg-extract, AgNPs, and Cg-AgNPs were also tested. This study demonstrated the feasibility of using combined ultrasonic-microwave-assisted extraction to separate and extract chemicals from C. gileadensis on a large scale. These compounds have potential use in the pharmaceutical industry. Combining antibacterial and biocompatible properties in materials is vital for designing new materials for biomedical applications. Additionally, the results showed that the biocompatibility of the Ag-NPs using C. gileadensis extracts demonstrated outstanding antibacterial properties.

Antibacterial activity of angelica essential oil, its mechanism against Pseudomonas fluorescens, and its application in the preservation of chilled fresh beef

The mechanism by which Angelica essential oil (AEO) can act as an antimicrobial agent at cellular and metabolic levels to inhibit Pseudomonas fluorescens (P. fluorescens), and its effectiveness in beef preservation, were investigated and evaluated in this study. Our results showed that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AEO to P. fluorescens were 12.5 μL/mL and 25 μL/mL, respectively, at which AEO could effectively inhibit P. fluorescens reproduction and retard its growth (p < 0.05). Severe morphological damage to the AEO-treated cells of the microorganism, including cell walls and membranes, were observed via scanning electron microscopy (SEM). AEO treatment was also seen to lead to an increase in alkaline phosphatase (AKPase) activity and conductivity, and a significant leakage of intracellular macromolecular components (such as nucleic acids and proteins), providing further evidence of damage to the integrity of cell wall and cell membrane. Metabolomics analysis revealed that the differential metabolites in the AEO hindered nucleic acid synthesis and expression in the P. fluorescens, leading to tricarboxylic acid (TCA) cycle blockage and amino acid restriction, energy metabolism disorders and membrane damage, mainly through nucleotide metabolism, amino acid metabolism, carbohydrate metabolism and membrane transport. Moreover, application testing demonstrated the efficacy of AEO in slowing the increase of beef pH and total volatile basic nitrogen (TVB-N), extending the shelf life of chilled beef by 5.39 d, and effectively maintaining the organoleptic quality of beef. These results lay a foundation for the development of AEO as a natural bacteriostatic agent.

Antimicrobial and antibiofilm activities of Aleppo pine essential oil and enzymes against Salmonella enterica biofilms formed on stainless steel and plastic surfaces

Several foodborne illness outbreaks caused by Salmonella enterica have been associated with the presence of biofilms, particularly on food contact surfaces. The objectives of the current study were: i) to assess the minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) of Aleppo pine essential oil (APEO) against 5 S. enterica serotypes and their mixture in Tryptone Soy broth at 37 °C and, ii) investigate the antibiofilm activity of two mixtures of 3 hydrolytic enzymes (5% protease, 2.5% α-amylase, and 0.5% lipase or 10% protease, 5% α-amylase, and 1% lipase at 50 °C for 30 min, and APEO at 1, 2 and 4 MIC at 25 °C for 10, 20 or 30 min) as well as sequential use of enzyme mixtures and APEO against S. enterica on stainless steel and plastic surfaces. The results showed that the MIC and MBC values of APEO against S. enterica strains and their mixture were 250–500 μg/ml and 1000-4000 μg/ml, respectively. In general, the antibiofilm activity of enzymes and APEO increased as the concentration increased and exposure time was extended. The results showed that a 1.8 log CFU/coupon reduction (p < 0.05) was obtained using 4 MIC APEO for 30 min at 25 °C. The enzyme-based mixture containing 10% protease, 5% amylase and 1% lipase at 50 °C for 30 min reduced the microbial load of S. enterica in biofilms on stainless steel and plastic surfaces by 2.1 log CFU/coupon (p < 0.05). However, a sequential two-step treatment based on a mixture of 10% protease, 5% α-amylase, and 1% lipase for 30 min at 45 °C followed by 4 MIC APEO for 30 min at room temperature reduced the S. enterica cells in biofilms on stainless steel by 4.6 log CFU/coupon (p < 0.05). These results indicated that enzyme-APEO treatments may be applied as a natural alternative to overcome biofilm formation by S. enterica in the food industry.

Antimicrobial activity and mechanism of chitosan-coated epsilon-poly-lysine nanoliposomes against Alicyclobacillus spp. in apple juice

Epsilon-poly-lysine (EPL), a natural cationic antimicrobial peptide, is widely used in food processing and preservation. However, when applied to fruit and vegetable juice, EPL can cause turbidity and precipitation, which reduces the antimicrobial properties and juice quality. As a colloidal delivery system, nanoliposome provides a novel insight into improve the activity of EPL. In this study, the antibacterial activity and mechanism of chitosan-coated EPL nanoliposomes (CS-EPLLP) against Alicyclobacillus spp. in apple juice were evaluated. It was found that the minimum inhibitory concentration of CS-EPLLP against the strains of A. acidocaldarius, A. fructus and A. acidoterrestris were in the ranges of 0.625∼1.25 mg/L, while the minimum bactericidal concentration of CS-EPLLP against these strains in apple juice were 0.625-2.5 mg/L. Compared to A. fructus and A. acidoterrestris, A. acidocaldarius displayed a better resistance to CS-EPLLP. Meanwhile, the modification of chitosan can improve the bactericidal effect of EPL and EPL nanoliposomes. In addition, CS-EPLLP treatment can lead to the inactivation of bacteria cells by causing surface damage, destroying their membrane integrity, preventing the intracellular ATP synthesis, increasing intracellular protein leakage and cells membrane permeability. Furthermore, the addition of CS-EPLLP in the amounts of MBC had no significant effect on the color change, transmittance, centrifuge sedimentation rate and main volatile compounds of apple juice. The prepared CS-EPLLP and established method provides a new insight into the inactivation of bacteria in fruit juice.

ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES OF SOME HYDRAZONES SYNTHESIZED FROM NICOTINIC ACID HYDRAZIDE

N’-(2-pyridinylmethylene)nicotinohydrazide A, N’-(4-pyridinylmethylene)nicotinohydrazide B, N’-(2- ethoxybenzylidene)nicotinohydrazide C, N’-(4- ethoxybenzyldene)nicotinohydrazide D and N’-(2-hydroxyl-5-methoxybenzylidene)nicotinohydrazide E, was prepared by refluxing the ethanolic solution of nictonic acid hydrazide and ethanolic solutions of 2-pyridinrcarboxaldehyde, 4-pyridinecarboxaldehyde, 2-ethoxybenzaldehyde, 4-ethoxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde in 1:1 mole ratio for 4 hours in a separate reactions. The compounds obtained had a melting point between (120-236 oC) and a percentage yield between (52.38-77.70 %). They were crystalline solids. The compounds' solubility were assessed in water, ethanol, methanol, acetone, hexane, diethyl ether, dimethyl sulfoxide (DMSO), ethyl acetate, and chloroform. The substances were discovered to be fully soluble in DMSO and methanol. FT-IR, 1H-NMR and 13C-NMR were used for the characterization of the compounds. The antibacterial and antifungal properties were tested against Methicillin-resistant Staphylococcus Aureus, Vancomycin-resistant Enterococci, S. aureus, S. typhi, P. aeruginosa, A. nigre, A. flavus, and C. albicans. The zones of inhibitions ranged from 22 to 28 mm and the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were found to be 0.063 mg/mL, 0.125 mg/mL and 0.125 mg/mL respectively. These indicated that the compounds might be good potential drug candidates.

THE EFFICACY OF COCOA BEAN EXTRACT MOUTHWASH CONCENTRATION IN REDUCING PLAQUE INDEX IN THE ORAL CAVITY AMONG PRIMARY SCHOOL STUDENTS AT SDN KAYEE LEU, INGIN JAYA SUBDISTRICT, ACEH BESAR

Oral and dental diseases have a high prevalence in Indonesia, with 88.8% of the population experiencing dental caries and periodontitis. Dental plaque is a soft deposit that tightly adheres to tooth surfaces and is composed of microorganisms that contribute to the development of dental caries. Preventing caries and controlling plaque can be achieved through the use of mouthwash, which is more effective when herbal mouthwash containing antioxidants and antibacterial agents is used. Cocoa bean extract (Theobroma Cacao L.) contains secondary metabolites such as alkaloids, flavonoids, tannins, steroids, and exhibits antibacterial and anti-inflammatory properties, as well as strong inhibitory effects against S. mutans bacteria. The objective of this study is to determine the effectiveness of cocoa bean extract mouthwash concentration in reducing the plaque index in the oral cavity. The research methods included laboratory experiments and quasi-experiments with a post-test only control group design. The research was conducted at the Faculty of Veterinary Medicine laboratory, University of Syiah Kuala, and SDN Kayee Leu, Aceh Besar, involving 30 students. Data analysis was performed using ANOVA in the SPSS program. The results of the study indicate that the phytochemical analysis of cocoa bean extract contains alkaloids, steroids, terpenoids, saponins, flavonoids, phenols, and tannins. The Minimum Inhibitory Concentration (MIC) of cocoa bean extract mouthwash on the growth of Streptococcus mutans was observed at a concentration of 1%, and no Minimum Bactericidal Concentration (MBC) was found in this study. The 1% and 2% concentrations of the mouthwash effectively removed plaque compared to the 0% concentration. In conclusion, the use of cocoa bean extract mouthwash is effective in reducing the plaque index. Further research should consider clinical trials to explore its potential as an herbal remedy.

Antimicrobial Activity, Cytotoxicity, and Qualitative Phytochemistry of Leaf, stem bark, and root bark extracts from Prunus africana (Hook. F.) Kalkman

The rise of resistant strains poses a significant public health risk, particularly, in sub-Saharan Africa, where over 50% of global infectious disease-associated deaths occur, highlighting the urgent need for novel, safe, affordable, and accessible antimicrobials. Accordingly, we investigated the antimicrobial activity, cytotoxicity, and qualitative phytochemistry of the aqueous, hydroethanolic, and acetonic leaf, stem bark, and root bark extracts of Prunus africana (Hook. F.) Kalkman, based on its ethnomedicinal information. The results showed the aqueous root bark and aqueous/acetonic stem bark extracts demonstrated significant (p&lt;0.05) antimicrobial efficacy against S. aureus at 800 µg/ml, outperforming other extracts and the reference antibiotic. Growth inhibition zones for most extracts on S. aureus showed a concentration-dependent increase, though not significantly (p&gt;0.05) different. The acetonic root bark extract, particularly at 800 µg/ml, exhibited superior inhibitory effects against B. cereus compared to other extracts (p&lt;0.05), although the positive control antibiotic significantly (p&lt;0.05) outperformed all plant extracts. Notably, none of the studied extracts affected P. aeruginosa and E. coli, while varying effects were observed against C. albicans. Further we observed that the hydroethanolic and aqueous stem bark extracts' exceptionally low Minimum Inhibitory and Bactericidal Concentrations (MICs and MBCs) against S. aureus (3.125 µg/ml). Conversely, the acetonic leaf extract showed higher MIC and MBC values against S. aureus (100 µg/ml). Cytotoxicity assessments using brine shrimp nauplii revealed the percentage mortalities caused by Vincristine and aqueous root/stem bark extracts at 1000 µg/ml, were significantly (p&lt;0.05) higher than those caused by other extracts (Median lethal concentrations (LC50) of 513 µg/ml to 24327.82 µg/ml). Qualitative phytochemistry identified alkaloids in root bark and stem bark extracts, flavonoids, phenols, quinones, steroids, and terpenoids across all samples, with saponins in acetonic root bark and all three leaf extracts, and glycosides in acetonic stem bark, hydroethanolic root bark, and acetonic leaf extracts. These findings highlight the diverse antimicrobial and cytotoxic properties of P. africana extracts, suggesting potential therapeutic applications and emphasise the need for further exploration.

Iron-Based Nanoparticles Synthesis, Characterization, and Antimicrobial Effectiveness

Background: Antimicrobial resistance (AMR) has emerged as a significant and pressing public health concern, posing serious challenges to effectively preventing and treating persistent diseases. Developing new antibiotics with different mechanisms of action is crucial to effectively address challenges in treating infections. A lot of work has already been done on mono-metallic nanoparticles to address the issue.Methods: This study aimed to synthesize multi-metallic iron, silver, and chitosan-embedded nanoparticles using a green approach. Iron, silver, chitosan nanoparticles, and a composite of iron–silver–chitosan was also synthesized. The synthesized nanoparticles and composites were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier Transform Infrared Spectroscopy (FTIR) to evaluate their structural parameters. Their antimicrobial efficacy was investigated through MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration), and well-disk diffusion assays against Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans.Results: The size of the Cu-NPs, Cu-Ag NPs, and Cu-Ag-CS NPs were found to be in the range of 32-40 nm size with a spherical shape. The nanocomposites' MIC and MBC were calculated to be 125 μg/mL and 500 μg/mL, respectively. The nanocomposites exhibited a range of clear inhibition zones, with a minimum diameter of 12 ± 0.5 mm and a maximum diameter of 22 ± 0.5 mm. Conclusion: The iron–silver–chitosan nanocomposite has been shown to have significant antimicrobial effects in the laboratory environment compared to other nanoparticles hence can be applied as potential biomedical/biological candidates in future.Keywords: Antibacterial; Antifungal Agents; Iron; Silver; Chitosan; Nanoparticles

Bacteriophage Endolysins Antibacterial Effect against S. mutans Isolated from Dental Caries: An In-Vitro Study

Background: Many bacterial infections including dental caries that caused by Streptococcus mutans (S. mutans) were difficult to be treated due to the unavailability of effective antibiotics. Therefore, it requires to focus the attention on endolysin as an antibacterial agent. This study was designed to evaluate the In-vitro effectiveness of specific bacteriophage endolysins against S. mutans isolated from dental caries.Methods: Twenty-five isolates of S. mutans were collected from patients with dental caries attended to Al-Imamain Al-Kadhimain, Medical City Hospital, and AL-Ameen Health Center, during the period from December 2021 to May 2022. The S. mutans isolates were identified by culturing them on their specific mitis salivarius sucrose bacitracin tellurite media (MS-SBT agar), morphological characteristics, gram staining, biochemical tests and VITEK 2 compact system. Seven of these S. mutans isolates were used for the in-vitro study.Results: The bacteriophage endolysin enzyme extracted from the corresponding S. mutans isolate was effective as In-vitro antibacterial agent with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) ranging between (13.63 – 17.83) µg/ml and (17.04-22.28) µg/ml respectively.Conclusion: The endolysin was effective as antibacterial agent against multi-drug resistant (MDR) S. mutans upon growing and testing on culture media.

Antibacterial, Phytochemical and Toxicological Activities of Garcinia kola Extracts against Multidrug Resistant Clinical Bacteria

Objective: The rise in multiple antibiotic resistant microorganisms has led to a decline in the efficacy of many antibiotics, prompting the investigation of alternative solutions such as medicinal plants. To tackle this concerning issue, this study was undertaken to evaluate the phytochemical composition, antibacterial activity, and toxicological characteristics of Garcinia kola extracts against multidrug-resistant bacteria commonly found in clinical settings. Material-Method: The cold maceration technique was employed to extract the root and leaf of Garcinia kola using water and methanol. The extracts were then subjected to phytochemical screening. To evaluate the extracts' potential to inhibit bacterial growth, five multidrug-resistant isolates were utilized in this study. Agar well assay was used to determine the zones of inhibition. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined using the broth macro dilution technique. Additionally, Brine shrimp lethality assay was conducted to determine the lethal concentration (LC50) of the extracts. The extracts were also combined for synergism. Results: The investigation found that the root extract in methanol had the highest yield at 25.58%. All four extracts contained ten out of the fourteen tested phytochemicals. The methanol leaf and root extracts exhibited the highest and lowest inhibition zones of 20mm and 9mm against Staphylococcus aureus, respectively. The MIC values ranged from 250 to 600 mg/ml, indicating broad-spectrum antibacterial activity. The cytotoxicity test showed a range of 33.03 to 126.3µg/mL for the aqueous and methanol extracts. Conclusion: Although Garcinia kola shows potential as a source of antibacterial compounds, caution should be exercised due to its toxic effects.

Synthesis, characterization, and investigation of antibacterial activity of Novel CMC/CuO NPs/CQDs bionanocomposite coating

In recent decades, healthcare-associated infections (HAIs) have become a common problem in healthcare facilities such as hospitals. As a result, researchers are currently developing nanocomposite coatings that are strengthened with antibacterial nanoparticles. In this research, a novel antibacterial bionanocomposite coating based on carboxymethyl cellulose polymer/copper oxide nanoparticles/carbon quantum dots was coated on medical grade 316 stainless steel by sol-gel dip-coating method. The effect of the concentration of nanocomposite components was investigated at four different levels to determine the best ratio with the most antibacterial activity. Structural characteristics of nanocomposite and coating were investigated using different analysis methods. The coating analysis showed that reinforcements are uniformly distributed in the polymer matrix. Antibacterial test of disc diffusion was performed by the Kirby-Bauer method and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) antibacterial test. The results showed that bionanocomposite was effective in the MIC assays against Staphylococcus aureus and Escherichia coli with MIC values of 25 mg/ml and >50 mg/ml, respectively. The inhibition zones for E. coli and S. aureus were 17 and 32 mm, respectively, at 10 μg/disc of gentamicin. SEM images displayed significant and evident alterations in the structure of bacterial morphology, indicating cellular damage.

Green Synthesized Chitosan Nanoparticles for Controlling Multidrug-Resistant mecA- and blaZ-Positive Staphylococcus aureus and aadA1-Positive Escherichia coli.

Antimicrobial resistance has recently been considered an emerging catastrophe globally. The public health and environmental threats were aggravated by the injudicious use of antibiotics in animal farming, aquaculture, and croup fields, etc. Consequently, failure of antibiotic therapies is common because of the emergence of multidrug-resistant (MDR) bacteria in the environment. Thus, the reduction in antibiotic spillage in the environment could be an important step for overcoming this situation. Bear in mind, this research was focused on the green synthesis of chitosan nanoparticles (ChiNPs) using Citrus lemon (Assam lemon) extract as a cross-linker and application in controlling MDR bacteria to reduce the antibiotic spillage in that sector. For evaluating antibacterial activity, Staphylococcus aureus and Escherichia coli were isolated from environmental specimens, and their multidrug-resistant pattern were identified both phenotypically by disk diffusion and genotypically by detecting methicillin- (mecA), penicillin- (blaZ), and streptomycin (aadA1)-resistance encoding genes. The inhibitory zone's diameter was employed as a parameter for determining the antibacterial effect against MDR bacteria revealing 30 ± 0.4 mm, 34 ± 0.2 mm, and 36 ± 0.8 mm zones of inhibition against methicillin- (mecA) and penicillin (blaZ)-resistant S. aureus, and streptomycin (aadA1)-resistant E. coli, respectively. The minimum inhibitory concentration at 0.31 mg/mL and minimum bactericidal concentration at 0.62 mg/mL of yielded ChiNPs were used as the broad-spectrum application against MDR bacteria. Finally, the biocompatibility of ChiNPs was confirmed by showing a negligible decrease in BHK-21 cell viability at doses less than 2 MIC, suggesting their potential for future application in antibiotic-free farming practices.

Relationships among Hydrogen Peroxide Concentration, Catalase, Glucose Oxidase, and Antimicrobial Activities of Honeys.

Honey is a natural sweetener made by bees that exhibits antimicrobial activity, mainly related to its H2O2 content. The aim of this work was to research the H2O2 concentration of 24 Spanish honeys from different botanical origins, studying their possible correlation with glucose oxidase (GOx), catalase (CAT), and anti-Staphylococcus aureus activities (minimal inhibition concentration (MIC), minimal bactericidal concentration (MBC), and percentage of inhibition at 5% (w/v) honey against Staphylococcus aureus), as well as possible correlations among all the analyzed parameters. The results showed that the H2O2 concentration did not depend on the botanical origin of the honeys. There were neither correlations between the H2O2 concentration and the activities of GOx and CAT, nor between GOx and antimicrobial activity. However, CAT and antimicrobial activities were positively correlated. Therefore, CAT could be successfully used as a possible marker of the antimicrobial activity of honeys against Staphylococcus aureus. Furthermore, a linear regression model has been fitted to explain the antimicrobial activity from CAT and GOx activity and H2O2 concentration. Although H2O2 is one of the compounds involved in honey's antibacterial activity, this capacity also strongly depends on other honey components (such as low water activity, acidity, osmolarity, and phenolic compounds). The very high anti-Staphylococcus aureus activity exhibited by all samples could be interesting for commercial honey-based formulations also helping to promote local beekeeping.

Antibacterial activity of the black soldier fly (Hermetia illucens) larva protein hydrolysates against some pathogenic bacterial strains on freshwater fish

The study was carried out to determine the antibacterial activity of protein hydrolysates from black soldier fly (Hermetia illucens) larva (PHBSF) on some pathogenic bacteria including E. ictaluri, A. hydrophila, A. verroni, and S. agalactiae on freshwater fish. The results showed that the tested bacteria were highly sensitive with significant difference (P &lt; 0.05) in diameter clear zone compared to the negative control at the tested concentrations of 20, 35, and 70 mg/100 µL. Particularlly, E. ictaluri was sensitive at all three test concentrations with the diameter of clear zones following 14.0 ± 1.0, 18.7 ± 0.7, and 20.7 ± 0.7 mm, respectively. A. veronii and S. agalactiae were sensitive at concentrations of 35 and 70 mg/100 µL, and A. hydrophila with a clear zone diameter of 14.3 ± 0.3 mm at the concentration of 70 mg/100 µL. The PHBSF was able to kill A. veronii and S. agalactiae with MIC (minimum inhibitory concentration) = MBC (minimum bactericidal concentration) = 44 mg/mL, while E. ictaluri and A. hydrophila were inhibited at MIC 44 mg/mL, and MBC was 88 mg/mL. These results indicated that PHBSF could be potentially used to prevent fish diseases caused by E. ictaluri, A. hydrophila, A. verroni, and S. agalactiae.