Minimum Inhibitory Concentration Values Research Articles

Acute toxicity assessment of bioactive constituents from Salvia algeriensis (Desf.) extracts: a promising natural agent against clinical bacterial isolates and pathogenic fungi

Salvia species are emerging as promising therapeutic agents due to their diverse bioactivity against various pathologies. This study was conducted to investigate the phytochemical profile, antimicrobial activity, and acute Toxicity of hydromethanolic extracts from Salvia algeriensis (Desf.) leaves, flowers, and roots. Chemical reaction tests and chromatographic analysis were employed to determine the chemical composition, while microdilution was used to determine the tested microorganisms' minimum inhibitory concentration (MIC). The acute Toxicity of the leaf extract was carried out following the rules and guidelines of OECD 425. Toxicity parameters in Swiss albino mice were evaluated after a single dose of 500 mg/kg and 2000 mg/kg. According to the preliminary phytochemical screening results, terpenoids and polyphenols (flavonoids and tannins) were found in all plant parts, but coumarins were only found in the root extract. The HPLC-DAD analysis revealed the presence of 16 phenolic compounds in varying amounts across the three extracts, of which rosmarinic acid, quercetin, caffeic acid, and 3-hydroxybenzoic acid were the most abundant. Selective antimicrobial activity was noticed, with the root extract demonstrating the most substantial effect against the two fungal strains tested. MIC values ranged from 0.3 to 10 mg/mL, and Gram-positive bacteria generally showedgreater susceptibility compared to Gram-negative bacteria. The LD50 was found to be greater than 2000 mg/kg. There were no overt clinical symptoms of Toxicity. Body weights, organ weights, and temperatures were not significantly altered, and hematological analysis showed no significant differences. Salvia algeriensis (Desf.) extracts emerge as potential candidates for natural, non-toxic antimicrobial agents. Keywords: Acute Toxicity; antimicrobial; HPLC-DAD; polyphenols; Salvia

The catalogue of Mycobacterium tuberculosis mutations associated with drug resistance to 12 drugs in China from a nationwide survey: a genomic analysis

WHO issued the first edition catalogue of Mycobacterium tuberculosis complex (MTBC) mutations associated with drug resistance in 2021. However, country-specific issues might lead to arising complex and additional drug-resistant mutations. We aimed to fully reflect the characteristics of drug resistance mutations in China. We analysed MTBC isolates from the nationwide drug-resistant tuberculosis surveillance with 70counties in 31provinces, municipalities, and autonomous regions in China. Three types of MYCOTB plates were used to perform drug susceptibility testing for 12antibiotics (rifampicin, isoniazid, ethambutol, levofloxacin, moxifloxacin, amikacin, kanamycin, ethionamide, clofazimine, linezolid, delamanid, and bedaquiline). Mutations were divided into five groups according to their odds ratios, positive predictive values, false discovery rate-corrected p values, and 95% CIs: (1) associated with resistance; (2) associated with resistance-interim; (3) uncertain significance; (4) not associated with resistance-interim; and (5) not associated with resistance. The Wilcoxon rank-sum and Kruskal-Wallis tests were used to quantify the association between mutations and minimum inhibitory concentrations (MICs). Our dataset was compared with the first edition of the WHO catalogue. We analysed 10 146MTBC isolates, of which 9071 (89·4%) isolates were included in the final analysis. 744(8·2%) isolates were resistant to rifampicin and 1339 (14·8%) to isoniazid. 208 (1·9%) of 11 065mutations were classified as associated with resistance or associated with resistance-interim. 33 (97·1%) of 34mutations in group 1and 92 (52·9%) of 174in group 2also appeared in groups 1or 2of the WHO catalogue. Of 81indel mutations in group 2, 15 (18·5%) were in the WHO catalogue. The newly discovered mutation gyrA_Ala288Asp was associated with levofloxacin resistance. MIC values for rifampicin, isoniazid, moxifloxacin, and levofloxacin corresponding to resistance mutations in group 1were significantly different (p<0·0001), and 12 high-level resistance mutations were detected. 61mutations in group 3occurred as solo in at least five phenotypically susceptible isolates, but with MIC values moderately higher than other susceptible isolates. Among 945phenotypically resistant but genotypically susceptible isolates, 433 (45·8%) were mutated for at least one efflux pump gene. Our analysis reflects the complexity of drug resistance mutations in China and suggests that indel mutations, efflux pump genes, protein structure, and MICs should be fully considered in the WHO catalogue, especially in countries with a high tuberculosis burden. National Key Research and Development Program of China and the Science and Technology Major Project of Tibetan Autonomous Region of China.

Two Novel Hydrate Salts of Norfloxacin with Phenolic Acids and Their Physicochemical Properties.

Norfloxacin (NORF) is a broad-spectrum quinolone that is widely utilized for the treatment of various bacterial infections and is considered one of the most commonly used fluoroquinolone antibiotics. However, NORF's clinical utility is limited by its poor water solubility and relatively low oral bioavailability. This study presents an optimization and synergistic enhancement approach through salt/co-crystal, aiming to maximize the biopharmaceutical properties of NORF with the use of phenolic acid. Following this strategy, two new hydrate salts of NORF with phenolic acid, namely, NORF-3,5-DBA hydrate (salt 1) and NORF-VA hydrate (salt 2), were prepared and systematically confirmed. Two hydrate salts were produced by means of the slow evaporation crystallization method, and the structures were determined through single-crystal X-ray diffraction (SCXRD). Additionally, powder X-ray diffraction (PXRD), Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and high-performance liquid chromatography (HPLC) were applied to analyze the features of the two salts. The experimental results indicated that the formation of the two salts could enhance the solubility and improve the release behavior of NORF. Interestingly, the physicochemical properties of NORF were significantly improved as a result, leading to an enhancement in its antibacterial activity. This was demonstrated by the enhanced inhibition of bacterial strains and the lower minimum inhibitory concentration values.

Development and Evaluation of Bis-benzothiazoles as a New Class of Benzothiazoles Targeting DprE1 as Antitubercular Agents.

Benzothiazole-bearing compounds have emerged as potential noncovalent DprE1 (decaprenylphosphoryl-β-d-ribose-2'-epimerase) inhibitors active against Mycobacterium tuberculosis. Based on structure-based virtual screening (PDB ID: 4KW5), a focused library of thirty-one skeletally diverse benzothiazole amides was prepared, and the compounds were assessed for their antitubercular activity against M.tb H37Ra. Most potent compounds 3b and 3n were further evaluated against the M.tb H37Rv strain by the microdilution assay method. Among the compounds evaluated, bis-benzothiazole amide 3n emerged as a hit molecule and demonstrated promising antitubercular activity with minimum inhibitory concentration (MIC) values of 0.45 μg/mL and 8.0 μg/mL against H37Ra and H37Rv, respectively. Based on the preliminary hit molecule (3n), a focused library of 12 more bis-benzothiazole amide derivatives was further prepared by varying the substituents on either side to obtain new leads and generate a structure-activity relationship (SAR). Among these compounds, 6a, 6c, and 6d demonstrated remarkable antitubercular activity with MIC values of 0.5 μg/mL against H37Ra and 1.0, 2.0, and 8.0 μg/mL against H37Rv, respectively. The most active compound, 6a, also displayed significant efficacy against four drug-resistant tuberculosis strains. Compound 6a was assessed for in vitro cytotoxicity against the HepG2 cell line, and it displayed insignificant cytotoxicity. Furthermore, time-kill kinetic studies demonstrated time- and dose-dependent bactericidal activity of this compound. The GFP release assay revealed that compound 6a targets the inhibition of a cell wall component. SNPs in dprE-1 gene assessment revealed that compound 6a binds to tyrosine at position 314 of DprE1 and replaces it with histidine, causing resistance similar to that of standard TCA1. In silico docking studies further suggest that the strong noncovalent interactions of these compounds may lead to the development of potent noncovalent DprE1 inhibitors.

Exploring antibacterial effectiveness: A comparative analysis of green and chemical synthesis of silver nanoparticles against Staphylococcus aureus

BackgroundSilver nanoparticles (AgNPs) are renowned for their broad-spectrum antibacterial properties. Various synthesis methods, particularly green synthesis using biogenic agents, have garnered significant attention. However, the detailed impact of green-synthesized AgNPs on the antibacterial mechanism against Staphylococcus aureus remain unclear, limiting the full potential of green synthesis compared to chemical methods. MethodsAgNPs were synthesized via chemical (sodium citrate, NaBH4) and green synthesis (green tea leaves, cassia seed extract) methods. The synthesized AgNPs were evaluated for toxicity and antibacterial activity against Staphylococcus aureus. Significant findingsThis study revealed a strong correlation (R2>0.9) between minimal inhibitory concentration (MIC) and AgNP size for both synthesis methods, with a similar exponential trend. MIC values were 45, 40, 25, and 5 µg mL-1 for citrate-, NaBH4-, green tea extract-, and cassia seed extract-assisted synthesis, respectively. Green-synthesized AgNPs showed higher antibacterial activity than chemical AgNPs at comparable sizes. Chemical AgNPs exhibited low and fluctuating scavenging activity, while green methods were more consistent. Cytotoxicity was noted in chemical AgNPs and at high concentrations of green tea extract-assisted AgNPs. Bacterial membrane disruption and ROS accumulation were also observed, contributing to the enhanced antibacterial activity of green-synthesized AgNPs.

Assessment of the antimicrobial and antibiofilm activity of the combination of N-acetyl cysteine and carvacrol against Staphylococcus aureus, the most common orthopedic infectious agent

BackgroundThe increasing prevalence of antibiotic-resistant bacterial infections has led to the search for new approaches. ObjectiveThis study aimed to evaluate the effects of carvacrol and N-acetyl cysteine, both individually and in combination, on the planktonic cells and biofilm formations of Staphylococcus aureus, including methicillin-resistant and methicillin-sensitive strains. Additionally, the study sought to perform cytotoxicity tests and chemical characterization to further understand the properties and potential applications of these substances. MethodsA total of 19 S. aureus strains were included in the study. Minimum inhibitory concentration and minimum bactericidal concentration were determined by assays. Synergy analysis tests were carried out. Cytotoxicity tests were conducted on the fibroblast cell line. Characterization test was performed. ResultsWhile Minimum inhibitory concentration and minimum bactericidal concentration values for carvacrol varied between 250 and 500 μg/ml, these values were in the range of 32–64 mg/ml for N-acetyl cysteine. Biofilm formation activities were identified. A total of eight strains, including six clinical and two standard strains with the highest biofilm-forming ability, were selected for combination studies. The combination of Carvacrol and N-acetyl cysteine exhibited synergistic and partially synergistic effects on the tested planktonic and biofilm strains, and these effects were dose-dependent. Carvacrol was found to be the most active drug at the end of 24, 48, and 72 h. Regarding the synergistic effect of N-acetyl cysteine + carvacrol, it was revealed to exhibit higher activity than N-acetyl cysteine and lower activity than carvacrol. ConclusionThe combination of carvacrol and N-acetyl cysteine demonstrated synergistic and partially synergistic effects against both planktonic and biofilm forms of Staphylococcus aureus. These results suggest potential for novel approaches in managing orthopedic infections, warranting further research to explore their therapeutic applications.

Evaluation of antifungal and apoptotic effects of linalool, citral, and carvacrol separately and in combination with nystatin against clinical isolates of Pichia kudriavzevii

Pichia kudriavzevii (formerly Candida krusei) poses a significant threat to immunocompromised patients due to its inherent resistance to various antifungal drugs. This study explored the anticandidal potential of citral, linalool, and carvacrol in combination with nystatin against P. kudriavzevii strains.Using the microdilution method following CLSI guidelines, Minimum Inhibitory Concentrations (MICs) and fungicidal concentrations (MFCs) were determined. Citral exhibited MIC values ranging from 50 to 100 µg/ml, averaging 70.24 ± 16.99 µg/ml, while carvacrol had MIC values of 50 to 100 µg/ml, averaging 86.90 ± 16.99 µg/ml. Linalool demonstrated weaker antifungal activity, with MIC values between 100 and 200 µg/ml, averaging 150 ± 38.73 µg/ml. The study assessed the synergistic effectsof these phenols with nystatin through fractional inhibitory concentration indices (FICIS). In addition, flow cytometry was employed to assess apoptosis induction in P. kudriavzevii cells.Carvacrol displayed a remarkable synergistic effect in combination with nystatin against all 21 isolates tested. Conversely, linalool showed synergy in 17 isolates, while citral exhibited synergy in only 2 isolates. These findings highlight distinct patterns of synergy between the different compounds and nystatin against P. kudriavzevii. Also, Carvacrol emerged as the most potent inducer of apoptosis across all P. kudriavzevii strains, followed by citral and linalool. This suggests that carvacrol not only possesses a stronger antifungal effect but also has a more pronounced ability to trigger programmed cell death in P. kudriavzevii. In conclusion, the study supports the potential of carvacrol, citral and linalool, as anticandidal agents, suggesting their supplementation with nystatin for treating P. kudriavzevii infections.

Exploring Cynara cardunculus L. by-products potential: Antioxidant and antimicrobial properties

Cynara cardunculus L. (cardoon), a perennial crop indigenous to the Mediterranean region, has gained recognition for its remarkable resilience to diverse weather conditions and its multifaceted applications across various industries, which includes the use of the flower as a vegetable rennet to produce some cheeses, as a source of biomass for energy, or its seed oil for human consumption, biodiesel, and animal feed. In some applications (e.g. biomass or seed production), when crop is harvested at the end of the growth cycle, the leaves remain as the main by-products, along with the flowers. In the context of a circular economy, the aim of this work was to undergone studies to determinate their biological properties (antioxidant and antimicrobial). Methanolic and ethanolic extracts of C. cardunculus L. (globe artichoke var. scolymus (L.) Fiori) and cultivated cardoon (var. altilis DC.)) leaves and flowers were characterised in terms of their polyphenol profile (total phenolic content (TPC), total flavonoid compounds (TFC), and ultra-high performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-ToF-MS)), antioxidant capacity (free radical DPPH inhibition system, β-carotene bleaching assay), and antimicrobial capacity (minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antifungal). In addition, the cultivated cardoon leaves extracts were assessed before and after they were dried in an oven with forced air circulation to evaluate if this treatment affected their bioactive profile. Chlorogenic acid, apigenin, and luteolin were the most quantified of a total of sixteen compounds identified by UHPLC-ToF-MS. Cultivated cardoon dry leaf extract presented the best antioxidant capacity for both methanolic (EC50 = 0.8 mg/mL, antioxidant activity coefficient (AAC) = 279.67) and ethanolic (EC50 = 2.1 mg/mL, AAC = 448.06) extracts, compared to the cardoon flower extracts and the globe artichoke leaf extracts. Dried cultivated cardoon leaf extracts presented higher antioxidant capacity than fresh cultivated cardoon leaf extracts, but a greater number of polyphenolic compounds were identified in fresh cultivated cardoon leaf extract. The Gram-positive bacteria were more sensitive to the activity of both ethanolic and methanolic extracts than the Gram-negative and cultivated cardoon dry leaf ethanolic extract presented lower MIC and MBC values (125–2000 µg/mL) for most of the tested microorganisms, thus showing higher antimicrobial activity. As for the cultivated cardoon leaf extracts, the dried leaf extracts exhibited better antimicrobial activity, with lower MIC values, than the fresh leaf extracts. The extracts only demonstrated a slight inhibition against the fungi Aspergillus fumigatus. In conclusion, studies performed indicate that dried leaves maintain their biological activities compared to fresh leaves, and that flowers present significant biological activity which suggests the great potential of the by-products of this crop as a source of active compounds in different industrial applications (e.g. food industry).

Stimuli-responsive gelatin-coated alginate nanocarriers: Targeted delivery of efflux pump inhibitor and antibacterial agents to control multidrug resistant P. aeruginosa

Multidrug resistance is an inescapable obstacle in healthcare settings. As the over-expression of efflux pumps is an important mediator of bacterial drug resistance, stimuli-responsive co-delivery nanosystems were developed for the sequential release of efflux pump inhibitors (EPI) and antibacterial agents. Gelatin-coated alginate nanocarriers (AlNCs@Gel) were developed containing ciprofloxacin (Cip) and quercetin (Que) as antibacterial/antibiofilm agents and EPI, respectively. Heat plot maps revealed a synergistic interaction of Cip with Que as the minimum inhibitory concentration value of Cip was reduced in the presence of EPI (quercetin) against P. aeruginosa. The encapsulation efficiency of 82 ± 1 % was observed for Cip while it was 70 ± 1 % for Que in Cip/AlNCs@Que/Gel nanocarriers. FTIR analyses confirmed an interaction between alginate and gelatin by the occurrence of a blue shift that is associated with electrostatic interactions between alginate and gelatin. These nanocarriers loaded with quercetin as EPI would release it preferentially in the presence of gelatinase enzyme and subsequently prevent the efflux of ciprofloxacin from bacterial cells. Membrane-permeability assay confirmed no permeabilization while viability studies exhibited superior bacterial inhibition, as Cip/EPI combination encapsulated in AlNCs@Gel effectively controlled the growth of P. aeruginosa as compared to antibiotic alone in AlNCs@Gel and free drug combinations. In vitro, cytotoxicity-analysis confirmed the biocompatibility of the developed core-shell nanocarriers. Furthermore, gelatin coating improved the physico-chemical properties of nanocarriers and the on-demand-release of EPI and antibiotic molecules. Thus, smartly designed AlNCs@Gel nanocarriers for the co-delivery of EPI and antibiotics present an innovative solution for preventing drug efflux from P. aeruginosa to control resistant infections.

Unveiling the antimicrobial and antibiofilm potential of biosurfactant produced by newly isolated Lactiplantibacillus plantarum strain 1625.

The present study aimed to characterize the biosurfactants synthesized by lactic acid bacteria (LAB) obtained from fermented foods, optimize the conditions for increasing the yield of biosurfactants and explore their antimicrobial and antibiofilm potential. Out of the 26 LAB isolates, isolate BS2 showed the highest biosurfactant production as indicated in the oil displacement test, drop collapse and emulsification activity. BS2 was identified as Lactiplantibacillus plantarum 1625 using 16S-rRNA gene sequencing and phylogenetic analysis. The biosurfactant produced by BS2 was identified as an anionic glycol-lipo-proteins by employing Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The biosurfactants produced by L. plantarum 1625 demonstrated strong antibacterial and antibiofilm characteristics against pathogenic strains such as Staphylococcus aureus MTCC 1049, Escherichia coli MTCC 1587, and Pseudomonas putida MTCC 1655. The minimal inhibition concentration value of antibacterial activity was found to be 0.1 mg/mL with the inhibition percentage ranging from 90 to 95%. Further, the effect of temperature, pH, and substrate composition on biosurfactant production was also studied to enhance it production using the Box-Behnken Design approach of Response surface methodology (RSM). Application of biosurfactant led to a considerable decrease in biofilm-forming harmful bacteria, as proven by scanning electron microscopy analysis. The results highlight the potential uses of biosurfactants in distinct industries, and biotechnological contexts, especially in the creation of new antimicrobial and antibiofilm agents.

Characterization of cyclotides Mra30 and cycloviolacin O17 derived from Viola dalatensis Gadnep.

Bacteria threaten human and animal health, and standard antibiotics no longer effective. Antibiotic-resistant microorganisms can make infection treatment challenging and perhaps fail. Investigating the attributes of cyclotide, a peptide with promising antibacterial properties that holds great potential in the field of antibiotic research. The structure of these cyclic peptides involves six conserved cysteine residues that form three disulfide bonds, resulting in a cyclic cystine knot (CCK). This feature guarantees their durability when exposed to changes in temperature, chemicals, and enzymatic degradation. The two cyclotides, cycloviolacin O17 and mra30, were obtained from Viola dalatensis Gadnep through a series of techniques including the use of a 50% acetonitrile/49% miliQ water/1% formic acid solution for extraction, ammonium salt precipitation, RP-HPLC purification and sequence identification by LC-MS/MS. These cyclotides exhibit antibacterial effects on specific strains of bacteria like Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa at a concentration of 0.2mg/mL, leading to inhibition zones ranging from 10 to 14mm. In addition, the disulfide bonds play a crucial role in the antibacterial function of cyclotides. Disrupting the disulfide bonds through ankylation reaction results in the loss of antibacterial properties in the cyclotides (cyO17 and mra30). The minimum inhibitory concentration (MIC) values of mra30 and cyO17 are significantly low, ranging from 0.1 to 0.6 µM. These values are approximately three times lower than the MIC values observed in salt precipitation samples.

Unveiling the bioactive potential of organotin(IV) complexes of hydrazones: Synthesis, spectral characterization, in vitro and in silico exploration

In the quest of compounds with potent antimicrobial and antioxidant properties, we conducted a comprehensive investigation involving four hydrazone ligands [H2L1–4] (1–4) and their respective sixteen organotin(IV) complexes (5–20) with general formula R″2SnL1–4 [R″ = Me, Et, Bu, Ph]. Various spectroscopic and physicochemical studies were employed for the thorough characterization of the synthesized compounds, which demonstrated the tridentate chelation of ligands via ONO donor domains by Ophenolic, Nazomethine and Oenolic atoms displaying pentacoordinated geometry. Further, the compounds were subjected to bioactivity assays by targeting their in vitro antioxidant and antimicrobial studies. Complex 8 [Ph2SnL1], 12 [Ph2SnL2], 16 [Ph2SnL3], 19 [Bu2SnL4] and 20 [Ph2SnL4] emerged as particularly noteworthy antimicrobials, exhibiting a higher level of inhibition having minimum inhibition concentration (MIC) value in the range of 0.0042–0.0095 µmol/mL. Among them, complex 20 exhibited superior activity with MIC values of 0.0042 µmol/mL against C. albicans and S. aureus, surpassing the standard drugs ciprofloxacin (0.0047 µmol/mL) and fluconazole (0.0051 µmol/mL). Additionally, all the compounds showed notable radical scavenging activity, and the activity of complexes increases in the order Ph2SnL1−4 (1.93–3.68 µM) > Bu2SnL1−4 (2.26–4.15 µM) > Et2SnL1−4 (2.91–4.97 µM) > Me2SnL1−4 (3.49–5.10 µM) (DPPH assay). Furthermore, In silico studies including Molecular docking, Density Functional Theory (DFT), Molecular Electrostatic Potential (MESP), Absorption, Distribution, Metabolism, Excretion and Toxicity ADMET) analysis highlighted the significance of highly potent antimicrobial compounds (4, 17–20) as potential drug candidates. Each compound exhibited binding affinity with protein binding site, including carbon-hydrogen bonds, conventional hydrogen bonds, alkyl interactions and pi-alkyl interactions. Compound 20 exhibited a superior docking score of −137.644 kcal/mol at the active site of C. albicans (PDB ID: 4HOE). The binding energy of the compounds followed the order: 20 (−11.6577 eV) < 19 (−11.3193 eV) < 18 (−9.23989 eV) < 17 (−8.23386 eV) < 4 (−7.01131 eV) and coincided well with the findings of experimental research. In summary, this comprehensive research underscores the substantial biological activity of the synthesized compounds and their promising potential for future applications in drug development.

New N-phenylpyrrolamide inhibitors of DNA gyrase with improved antibacterial activity.

This study presents the discovery of a new series of N-phenylpyrrolamide inhibitors of bacterial DNA gyrase with improved antibacterial activity. The most potent inhibitors had low nanomolar IC50 values against Escherichia coli DNA gyrase (IC50; 2-20 nM) and E. coli topoisomerase IV (22i, IC50 = 143 nM). Importantly, none of the compounds showed activity against human DNA topoisomerase IIα, indicating selectivity for bacterial targets. Among the tested compounds, 22e emerged as the most effective against Gram-positive bacteria with minimum inhibitory concentration (MIC) values of 0.25 μg mL-1 against Staphylococcus aureus ATCC 29213 and MRSA, and 0.125 μg mL-1 against Enterococcus faecalis ATCC 29212. For Gram-negative bacteria, compounds 23b and 23c showed the greatest efficacy with MIC values ranging from 4 to 32 μg mL-1 against E. coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Acinetobacter baumannii ATCC 17978 and A. baumannii ATCC 19606. Notably, compound 23b showed promising activity against the clinically relevant Gram-negative pathogen Klebsiella pneumoniae ATCC 10031, with an MIC of 0.0625 μg mL-1. Furthermore, compounds 23a and 23c exhibited significantly lower susceptibility to resistance development compared to novobiocin in S. aureus ATCC 29213 and K. pneumoniae ATCC 10031. Overall, the most promising compounds of this series showed excellent on-target potency, marking a significant improvement over previous N-phenylpyrrolamide inhibitors.

Antibacterial and Anti-Biofilm Effect of Silver Nanoparticles Synthesized from Origanum majorana and Echinacea purpurea (L.) Moench Plants via Green Synthesis

Objective: Nanotechnology has gained importance in the fight against epidemics and antibiotic resistance. Nanotechnology is a potential way to prevent the increase of multidrug-resistant bacterial species. The aim of this study was to determine the antimicrobial and anti-biofilm activities of Origanum majorana and Echinacea purpurea silver nanoparticles (AgNPs) against Staphylococcus aureus (S.aureus) ATCC 25923, Escherichia coli (E.coli) 25922, Pseudomonas aureginosa (P.aureginosa) 27853, Klebsiella pneumoniae (K. pneumoniae) 700603. Methods: Minimum Inhibitory Concentration (MIC) values of silver nanoparticles were determined by microdilution method in 96-well ELISA plates. The anti-biofilm effect of silver nanoparticles was performed by crystal violet method in 96-well microplates. Results: The MIC value of four isolates was determined as 128 µg/ml for two nanoparticles. Only 256 µg/ml and 512 µg/ml were found for S. aureus. In vitro, anti-biofilm effect of AgNPs against biofilm forming bacteria was evaluated in a dose-dependent manner. S. aureus, AgNP synthesized from Origanum majorana plant extract (512 µg/ml) reduced biofilm formation by 92% after 24 hours of incubation. As a result of 24 hours incubation of S. aureus with AgNP (512 µg/ml) synthesized from Echinacea purpurea (L.) It was determined that biofilm formation decreased by 85%. It was observed that both different nanoparticles significantly inhibited the biofilm mass. Conclusion: AgNPs showed antimicrobial and antibiofilm effects for standard strains. The use of AgNPs as antimicrobials is promising for the future.

Antimicrobial activity evaluation of combinations of essential oils, thymol and R-limonene against food-borne pathogens and spoilage agents

The application of essential oils has been shown to be an effective and sustainable alternative against the multiplication of spoilage and pathogenic microorganisms in food. The aim of this work was to study the antimicrobial activity effect of Cerrado Rosemary (Baccharis dracunculifolia DC.), Pepper Rosemary (Lippia sidoides Cham.), Mandarin (Citrus nobilis Lour.), Mexican Lime (Citrus aurantifolia Swingle) essential oils, and the thymol and R-limonene compounds against strains of Penicillium expansum, Pichia kudriavzevii, Salmonella Thypimurium and Staphylococcus aureus. The essential oils were characterized in terms of their chemical composition, the Minimum Inhibitory Concentration, and Minimum Bactericidal and Fungicidal Concentration; using the microdilution method in 96-well plates. In addition, effects from mixtures of the essential oils, and the isolated compounds in sub-inhibitory concentrations were performed. The Pepper Rosemary essential oil and thymol, separately, showed the lowest Minimum Inhibitory Concentration values against all the microorganisms evaluated, with the lowest ranging from 0.03 to 1.25 mg. mL−1 for P. expansum and 0.31–1.25 mg. mL−1 for S. Thypimurium. Mandarin and Mexican lime, have an enhanced antimicrobial effect when used in mixture. The R-limonene compound showed a synergistic additive effect when combined with the essential oils, against S. aureus strains only. The application of thymol and Lippia was able to reduce growth by 3 log10 for S. aureus and S. Typhimurium in 24 h. Therefore, the Pepper Rosemary essential oil, applied freely or in combination with the thymol compound, has greater potential for use as an antifungal and bactericidal agent, against the microorganisms evaluated.

ANTIBACTERIAL ACTIVITY OF PAPUYU FISH SCALE CHITOSAN (Anabas testudineus) AGAINST Staphylococcus aureus

Backgrounds: Pulp disease due to caries can be treated through endodontic treatment, which aims to eliminate bacteria in the root canal so microorganisms cannot multiply. Staphylococcus aureus is a resistant microorganism causing root canal treatment failure. Chlorhexidine as a gold standard cannot remove biofilm and other organic debris. Utilization of nature, chitosan of papuyu fish scales (Anabas testudineus) has antibacterial properties that can be an alternative root canal irrigation material. Purpose: Analyze the antibacterial activity of chitosan of papuyu fish scales against Staphylococcus aureus based on the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Methods: This research is a true experimental design with posttest only with control group design. The research groups were chitosan of Papuyu fish scales with concentrations of 25%, 50%, 75%, 100%, chlorhexidine gluconate 2% (positive control), and aquadest (negative control) with 6 repetitions. Results: The MIC value in the One-Way ANOVA test showed a significant difference (p&lt;0.05). Data analysis followed by Post Hoc Games-Howell test showed all treatment groups had significant differences between each other (p&lt;0.05). The MBC value in the Kruskal Wallis test shows that there is a significant difference (p&lt;0.05). Data analysis followed by MannWhitney test showed significant differences between each other (p&lt;0.05) except for the group of papuyu fish scale chitosan 25% concentration against papuyu fish scale chitosan 50% concentration, papuyu fish scale chitosan 100% concentration against chlorhexidine gluconate 2% (p&gt;0.05). Conclusion: There is a difference in the antibacterial activity of chitosan of Papuyu fish scales concentrations of 25%, 50%, 75%, 100%, chlorhexidine gluconate 2% (positive control) and aquadest (negative control) against Staphylococcus aureus bacteria.

Clinical aPDT's effect on Candida albicans: Antifungal susceptibility, virulence gene expression, and correlation with leukocyte and neutrophil counts

BackgroundOur previous clinical trial demonstrated that antimicrobial photodynamic therapy (aPDT) with methylene blue (MB) and potassium iodide (KI) effectively killed Candida albicans (C. albicans) in adult AIDS patients with oral candidiasis, regardless of biofilm formation or 25S rDNA genotype. This study evaluated changes in antifungal susceptibility and virulence gene expression in C. albicans before and after aPDT, and explored factors related to clinical aPDT efficacy. MethodsTwenty-one adult AIDS patients with C. albicans oral candidiasis were divided into Group a (400 μM MB, N = 11) and Group b (600 μM MB, N = 10). Both groups received two aPDT treatments, where MB was applied for 5 min, followed by 300 mM KI, and illuminated for 30 min (37.29 J/cm²). C. albicans isolates were collected before and after treatment to assess antifungal susceptibility (fluconazole, itraconazole, flucytosine, amphotericin B) and gene expression (CAT1, HWP1). Peripheral blood tests were analyzed for correlations with aPDT efficacy. ResultsaPDT reduced minimum inhibitory concentration (MIC) values for amphotericin B, fluconazole, and flucytosine, with significant reductions primarily after the first treatment. MIC reductions differed between groups, with Group a showing greater decreases in flucytosine and fluconazole MICs, and Group b in amphotericin B MICs. No significant changes in CAT1 or HWP1 expression were observed. Clinical efficacy of aPDT negatively correlated with leukocyte and neutrophil levels. ConclusionsaPDT effectively reduces MICs of antifungal drugs against C. albicans isolated from treated patients, particularly after the first treatment. The concentration of MB required to reduce MICs varies among different antifungal drugs. aPDT does not alter CAT1 or HWP1 expression, and its clinical efficacy in eradicating C. albicans is negatively associated with leukocyte and neutrophil levels.

Association between in vitro susceptibility and clinical outcomes in fungal keratitis

PurposeThe purpose of this study was to assess the association between antifungal susceptibility as measured by minimum inhibitory concentration (MIC) and clinical outcomes in fungal keratitis.MethodsThis pre-specified secondary analysis of the Mycotic Ulcer Treatment Trial II (MUTT II) involved patients with filamentous fungal keratitis presenting to Aravind Eye Hospitals in South India. Antifungal susceptibility testing for natamycin and voriconazole was performed on all samples with positive fungal culture results according to Clinical and Laboratory Standards Institute Guidelines. The relationship between MIC and clinical outcomes of best-corrected visual acuity, infiltrate or scar size, corneal perforation, need for therapeutic penetrating keratoplasty, and time to re-epithelialization were assessed.ResultsWe obtained MIC values from 141 patients with fungal keratitis. The most commonly cultured organisms were Aspergillus (46.81%, n = 66) and Fusarium (44.68%, n = 63) species. Overall, there was no association between antifungal MICs and clinical outcomes. Subgroup analysis revealed that among Fusarium-positive cases, higher voriconazole MIC was correlated with worse three-month best-corrected visual acuity (p = 0.03), increased need for therapeutic penetrating keratoplasty (p = 0.04), and time to re-epithelialization (p = 0.03). No significant correlations were found among Aspergillus-positive cases. There were no significant correlations found between natamycin MIC and clinical outcomes among organism subgroups.ConclusionsDecreased susceptibility to voriconazole was associated with increased odds of requiring a therapeutic penetrating keratoplasty in Fusarium-positive cases. Susceptibility to natamycin was not associated with any of the measured outcomes.

In vitro antibacterial effect of a nano-zinc oxide eugenol sealer alone and in combination with chitosan, propolis, and nanosilver on Enterococcus faecalis

ABSTRACT Background: This study aimed to assess the antibacterial effect of a nano-zinc oxide eugenol (nZOE) sealer alone and in combination with chitosan, propolis, and nanosilver on Enterococcus faecalis. Materials and Methods: In this in vitro, experimental study, nanosilver, chitosan, and propolis with 10wt%, 20wt%, and 60wt% concentrations, respectively, were added to nZOE sealer, and their antibacterial activity against E. faecalis was evaluated by agar diffusion and broth microdilution tests. The diameter of the growth inhibition zones was measured, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were calculated for all materials. Data were analyzed by t-test (alpha = 0.05). Results: The addition of nanosilver, chitosan, and propolis to nZOE did not change the diameter of growth inhibition zone in agar diffusion test. Propolis and eugenol alone showed the lowest MIC and MBC. Chitosan alone showed the highest MIC and MBC. Furthermore, nZOE showed lower MBC than micro-ZOE (P = 0.000). All groups containing nZOE showed the lowest MIC and MBC values. Conclusion: The addition of propolis to nZOE can enhance its antibacterial activity against E. faecalis in vitro.

Algerian Artemisia herba-alba (Asso): Extract and Essential Oils Investigation

Background/Objective: Numerous studies have demonstrated the ethno-and pharmacological properties of various Artemisia species. However, this plant genus which grows abundantly and wildly in the ‘Tébessa’ Algerian region has not been investigated. This study focuses on the phytochemical characterization, biological activities evaluation with the antibacterial fraction identification of the aerial part aqueous extract (AE) and essential oil (EO) from Algerian Artemisia herba alba ( Aha) growing wild in the ‘Tebessa' region. Methods: Polyphenols, flavonoids, and condensed tannins were analyzed by spectrophotometer and the antimicrobial activity was determined by the gel diffusion followed by micro-dilution methods. The antioxidant effect was assayed using 2,2-diphenyl-1-picrilhidrazil (DPPH), total antioxidant capacity (TAC), and ferric reducing power (FRAP) tests. The cytotoxic and anti-leishmaniasis activities were experienced on Raw 264.7 cell line and on L. infantum and L. major promastigotes respectively. Thin-layer chromatography (TLC)/autobiography and gas chromatography-mass spectrometry (GC-MS) techniques were used to isolate and identify the antibacterial compounds. EO profile was determined by GC-MS analysis. Results: The extracts (AE and EO) demonstrated antioxidant activity, with the AE exhibiting the most pronounced levels. Both extracts showed antimicrobial activity against all the strains tested however; the EO effect was more effective, especially against the E. feacalis strain with a minimum inhibitory concentration (MIC) value of 0.0625 mg/mL. The antibacterial fraction exerted by AE towards E. feacalis was identified. AE and EO extracts showed antileishmanial activity and no toxic effect however, volatile extract was the most effective. EO profile revealed 19 identified compounds, led by camphor (51.14%), followed by 1,8 Cineole (19.30%), camphene (6.90%) and chrysanthenone (5.68%). Conclusion: As a result, the both extracts promise a high potential applications in agri-food, pharmaceutical, cosmetic sectors. This study aligns with Sustainable Development Goals (SDGs) 3, 12, and 15, emphasizing potential health benefits, the responsible use of natural resources, and biodiversity conservation.