Minimum Inhibitory Concentration Values Research Articles

Antimicrobial effects and phytochemical analysis of guava leaf extracts on selected microorganisms

The misuse of antimicrobial agents can lead to emergence of resistance to microbes which in turn can lead to the search for alternative therapy. The use of phytopharmaceuticals and herbal medicines have a positive impact and represents a promising alternative. Guava extract has been reported to have antimicrobial properties. However, the aim of this study was to determine the antimicrobial activities of methanol and ethanol extract of guava leave against some certain bacteria (Staphylococus aureus and Escherichia coli) and a fungus (Candida albicans). Qualitative phytochemical screening showed that phenols, tannins, saponins, terpenoids, flavonoids and glycosides are all present in the leaf extract; phenols and tannins are moderately present while others are present in minute quantities. Out of the different concentrations use (50, 100, 200 and 250), The highest concentration which is 250mg/ml showed the highest zone of inhibition for both methanolic and ethanolic extracts against the isolates. Minimum inhibitory concentration and Minimum Bactericidal Concentrations value for both S. aureus and E. coli are 200mg/ml and 250mg/ml respectively; while 50mg/ml and 100mg/ml are for Candida albicans.

Synthesis, Antibacterial, Anti-Biofilm Properties, and Docking Study of Indeno[1,2-b]Pyridin-5-One Derivatives

In this context, we designed and synthesized a series of hydrazonal and their related indeno[1,2-b]pyridin-5-one derivatives to investigate their antibacterial and anti-biofilm properties. Several of the synthesized compounds exhibited significant efficacy against all microorganism species tested. Most of the compounds demonstrated favorable results when tested against Gram-positive bacteria. The derivatives 4a, 4f, 6c, and 6f exhibit the highest antimicrobial efficacy, as indicated by their minimum inhibitory concentration (MIC) values ranging from 4 to 512 μg/mL. We conducted additional investigations on 4a, 6c, and 6f for the purpose of examining their synergy using Checkerboard assay. Compound 6c demonstrated a synergistic impact against methicillin-sensitive Staphylococcus aureus (MSSA) and Pseudomonas aeruginosa, while exhibiting moderate synergistic activity against methicillin-resistant Staphylococcus aureus (MRSA). In addition, the simultaneous use of gentamycin with compounds 4a and 6f demonstrates a synergistic impact in fighting against methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. Three chosen compounds were evaluated for their antibiofilm efficacy. Application of 4a, 6c, and 6f effectively reduced the production of biofilms in MRSA, MSSA, and Pseudomonas aeruginosa, resulting in a significant decrease compared to the untreated samples. In addition, ADME and pharmacokinetic analyses were conducted for the three most potent derivatives, namely 4a, 6c, and 6f. Compounds 4a and 6c were subjected to docking in the LasR Quorum-Sensing Receptor, whereas compounds 6c and 6f were docked in the sortase enzyme.

Dodecanoyl-L-tryptophan: A Novel Natural Antibiotic Isolated from Mesophotic Sponge-associated Salinicola sp. LHM and its Biological Function

Background: Sponge-associated microbiota plays a crucial role in maintaining host health by providing chemical defense through the synthesis of diverse secondary metabolites. However, research on these secondary metabolites is still in its early stages. Objective: The present study aimed to investigate new natural antibiotics from mesophotic sponge symbiotic microbiota and explore its in vitro antibacterial activity and preliminary biological function. Methods: Bacteria strain Salinicola sp. LHM was isolated from sponge L. birotulata L26 and identified based on the 16S rRNA gene analysis. Subsequently, the strain was fermented using a liquid M9 medium and screened for antibiotics with an antibacterial guiding assay. Extensive chromatographic methods were introduced to isolate the target compound, and its chemical structure was elucidated by spectroscopic analysis (LC-MS, NMR). The minimum inhibitory concentration (MIC) and cytotoxicity experiments evaluated the isolated compound's biological activity. Furthermore, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and quartz crystal microbalance with dissipation (QCM-D) were used to study the bactericidal mechanism of DLT. Finally, the preliminary biological function was explored by performing the cell-feeding experiment. Results: We successfully identified one novel natural antibiotic, dodecanoyl-L-tryptophan (DLT), in Salinicola sp. LHM isolated from mesophotic sponge Lotrochota birotulata L26. DLT exhibited potent antibacterial activity against the Bacillus subtilis and Staphylococcus aureus, with MIC values of 32 μM and 16 μM, respectively. The bactericidal tests showed that DLT broke the cell membrane to cause cell death by leaking the cell's inner content. Furthermore, the cell-feeding experiment proved that DLT producer- Salinicola sp. LHM could feed on the inner content of death cells. In addition, DLT also exhibited cytotoxicity against bronchial epithelial cells BEAS-2B, with an EC50 value of 150 μM, indicating a favorable selectivity profile. result: We successfully identified one novel natural antibiotic, dodecanoyl-L-tryptophan (DLT), in Salinicola sp. LHM isolated from mesophotic sponge Lotrochota birotulata L26. DLT exhibited potent antibacterial activity against the Bacillus subtilis and Staphylococcus aureus, with MIC values of 32 μM and 16 μM, respectively. The bactericidal tests showed that DLT broke the cell membrane to cause cell death by leaking the cell's inner content. Furthermore, the cell-feeding experiment proved that DLT producer- Salinicola sp. LHM could feed on the inner content of death cells. In addition, DLT also exhibited cytotoxicity against bronchial epithelial cells BEAS-2B, with an EC50 value of 150 μM, indicating a favorable selectivity profile. Conclusion: This research identified one novel natural antibiotic DLT and provided initial insights into the chemical defense exerted by Salinicola sp. LHM with its secondary metabolite DLT.

Physicochemical Properties, Chemical Composition, Antioxidant Properties, and Antibacterial Effects of Four Palestinian Honey Varieties

The present study evaluates the physicochemical attributes, antibacterial efficacy, and antioxidant capacities of four distinct varieties of honey from the West Bank region of Palestine: Assal Barsem (Medicago sativa) AB, Assal Morar (Centaurea dumulosa Boiss) AM, Assal Horfesh (Silybum) AH, and Assal Sader (Ziziphus spina-christi) AS. The analysis encompassed parameters such as pH, electrical conductivity, Total Flavonoid Content (TFC), and Total Phenolic Content (TPC). Furthermore, the antioxidant potential was gauged through Total Antioxidant Capacity (TAC) determination and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. In addition, the antibacterial effectiveness of the honeys was measured against a spectrum of bacterial strains including Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, and Bacillus subtilis, utilizing minimum inhibitory concentration (MIC) and Minimum Bactericidal Concentrations (MBC). The outcomes of the physicochemical analysis adhered to the quality benchmarks outlined by the European Union Commission and the Codex Alimentarius Commission. The MIC and MBC values exhibited notable variance across the tested honey varieties, with MIC values ranging from 0.024% w/w to 1.56% w/w, and MBC values ranging from 0.048% w/w to 3.15% w/w. Particularly, AH demonstrated superior efficacy against all seven bacterial strains, with MIC values spanning from 0.1 to 0.6% w/w, and MBC values ranging from 0.3% w/w to 0.8% w/w. Staphylococcus aureus and Escherichia coli were notably susceptible to all honey samples. Collectively, our findings underscore the therapeutic potential of Palestinian honey varieties, highlighting their multifaceted health-promoting attributes. Further exploration is warranted to elucidate the mechanistic underpinnings of bioactive constituents and explore their potential applications in healthcare.

Imidazolium, pyridinium and pyrazinium based ionic liquids with octyl side chains as potential antibacterial agents against multidrug resistant uropathogenic E. coli

Urinary tract infections (UTIs) are the second most prevalent infectious disease with E. coli being the most common etiological agent behind these infections, affecting more than 150 million people globally each year. In recent decades, the emergence of multi-drug resistant (MDR) pathogens has rapidly escalated. To combat antimicrobial resistance (AMR), it is important to synthesize new biologically effective alternatives like ionic liquids (ILs) to control the bacterial infection and their spread. Ionic liquids are poorly coordinated organic salts characterized by melting points typically below 100 °C. The ability of ILs to form anionic and cationic interactions contributes to their versatile chemical, physical and biological attributes. In the present study, a total of 9 previously chemically synthesized and characterized ILs were used. For exploration of their antibacterial potential against the urinary tract infections (UTIs) caused by MDR Uropathogenic E. coli (UPEC) strains, in vitro and in vivo evaluation of ILs were performed. ILs showed pronounced zone of inhibition (ZOI), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 29.5 mm, 3.81 μM and 5.08 μM by agar disk diffusion and broth micro-dilution methods, respectively. Scanning electron microscopy results depicted substantial morphological changes in UPEC biofilm formation ascertaining antibiofilm potential of tested ILs. Moreover, ILs showed exceptional antioxidant potential depicted by DPPH assay along with low cytotoxic effect toward mammalian cell lines (NB4), red blood cells and whole blood. Furthermore, the gene expression analysis results justified the antibacterial potential of ILs showing down-regulation of fimH, uvrY and up-regulation of csrA gene in UPEC after ILs treatment. In vivo dermal sensitivity assessment also established their non-cytotoxic behavior. In silico analysis validated these results, with the majority of the compounds exhibiting moderate to good absorption.Due to remarkable antibacterial and antioxidant potential and negligible cytoxicity, it could be inferred that ILs could serve as novel antimicrobial alternative agents in the treatment of UTIs.

The effect of coating chitosan from cuttlefish bone (Sepia Sp.) on the surface of orthodontic mini-screw

IntroductionPeri-implantitis is a significant complication resulting from the failure of orthodontic mini-screws. Recent strategies to address this issue include the application of natural antibacterial coatings to prevent bacterial colonization. Notably, cuttlefish (Sepia sp.) bones are rich in chitosan, which is recognized for its antibacterial effectiveness and biocompatibility. ObjectivesTo evaluate the effects of a chitosan coating derived from cuttlefish bone (Sepia sp.) on mini-screws against Aggregatibacter actinomycetemcomitans bacteria frequently linked to peri‑implantitis. Materials and MethodsThe surface functional groups, phase composition, and crystal morphology of chitosan were analyzed using conventional analytic techniques alongside energy-dispersive X-ray analysis. These prepared were tested for antibacterial activity against A. actinomycetemcomitans by disk diffusion assay; minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) were determined. Stainless steel mini-screws were coated with chitosan, and their surfaces were characterized using scanning electron microscopy (SEM). ResultsThe investigation revealed that chitosan exhibited a MIC value of 8 ppm against A. actinomycetemcomitans with MBCs recorded at 16 ppm. Zones of inhibition varied based on concentration; notably, concentrations at 0.4 %, 0.6 %, and 0.8 % produced zones averaging 16.17 ± 1.64 mm collectively while increasing to a mean zone size of 20.99 ± 3.63 mm at the highest tested concentration (0.8 %). SEM analyses further confirmed the successful adhesion of the chitosan compound onto immersed mini-screw surfaces. ConclusionThe prepared chitosan from cuttlefish bone (Sepia sp.) has antibacterial activity against the bacteria A. actinomycetemcomitans in vitro and can successfully coat SS mini-screws to enhance their efficiency.

Diversity and Anti-Infectious Components of Cultivable Rhizosphere Fungi Derived from Three Species of Astragalus Plants in Northwestern Yunnan, China.

Astragalus, a group of legume plants, has a pronounced rhizosphere effect. Many species of Astragalus with limited resource reserves are distributed in the high-altitude area of northern Yunnan, China. Although some of these plants have high medicinal value, the recognition of them is still at a low level. The aim of this research is to explore the species diversity of cultivable rhizofungi derived from Astragalus acaulis, A. forrestii and A. ernestii growing in a special high-cold environment of northwest Yunnan and discover anti-infective components from these fungi. A total of 93 fungal strains belonging to 38 species in 18 genera were isolated and identified. Antibacterial and antimalarial screening yielded 10 target strains. Among them, the ethyl acetate crude extract of the fermented substrate of the rhizofungus Aspergillus calidoustus AA12 derived from the plant A. acaulis showed broad-spectrum antibacterial activity and the best antimalarial activity. Further chemical investigation led to the first discovery of seven compounds from the species A. calidoustus, including sesterterpine 6-epi-ophiobolin G; three sesquiterpenes, penicisochroman A, pergillin and 7-methyl-2-(1-methylethylethlidene)-furo [3,2-H]isoquinoline-3-one; and three polyketides, trypacidin, 1,2-seco-trypacidin and questin. Among them, the compound 6-epi-ophiobolin G exhibited moderate to strong antibacterial activity against six Gram-positive pathogens with the minimum inhibitory concentration (MIC) ranging from 25 to 6.25 μg/mL and a prominent inhibitory effect on the biofilm of Streptococcus agalactiae at an MIC value of 3.125 μg/mL. This compound also displayed potent antimalarial activity against Plasmodium falciparum strains 3D7 and chloroquine-resistant Dd2 at the half-maximal inhibitory concentration (IC50) values of 3.319 and 4.340 µmol/L at 72 h, respectively. This study contributed to our understanding of the cultivable rhizofungi from characteristic Astragalus plants in special high-cold environments and further increased the library of fungi available for natural anti-infectious product screening.

New nano-chemotherapeutic chitosans-garlic oil-antibiotics against diabetic foot virulent Proteus spp.

Diabetes foot ulcer is recognized to have a major side effect that raises the risk of amputation. Diabetic ulcer bacterial infections caused by virulent and resistant bacteria like Proteus mirabilis lead to serious wounds that are incurable with conventional medications. In this study, we evaluated the antibacterial activity of a natural product nanochitosan - garlic oil against ten diabetic foot isolates of Proteus mirabilis. Various chitosans (Crab (CScr) - shrimp (CSsh) - squilla (CSsq)) in nano form were prepared and coated with garlic oil (GO). GC-MS analysis was carried out to determine the main components of the essential garlic oil. The physicochemical properties of GO-NCSsq were analyzed using dynamic light scattering (DLS), zeta potentials (ZP) and subsequently scan electron microscope (SEM). Additionally, the minimum inhibitory concentration (MIC) and fraction inhibitory concentration index (FICI) were determined. GC-MS analysis revealed the presence of major palmitic fatty acid. (GO) loaded on nanochitosan squilla (NCSsq) showed high activity. Although SEM showed lower nano-size, average size of the GO-NCSsq was 330.8 nm by DLS and its zeta potential formulation was +39.6 mV. The final formulation represented by GO-NCSsq + Pipercillin (Pi) inhibited the virulence factor of P. mirabilis and reduced the MIC value (p-value > 0.001). Moreover, the killing time at 9 h was found to be significantly higher for GO-NCSsq + pipercillin (Pi) against P. mirabilis. In order to manage diabetic foot infections, GO-NCSsq is a legitimate antibacterial agent that can be coupled with other antibiotics.

Analysis of genetic characteristics associated with reduced bedaquiline susceptibility in multidrug-resistant Mycobacterium tuberculosis

Bedaquiline (BDQ) has shown efficacy in shortening treatment duration and enhancing treatment success rates for multidrug-resistant tuberculosis (MDR-TB), thereby prompting widespread adoption. However, resistance to BDQ has emerged. This study aimed to identify genetic characteristics associated with decreased susceptibility to BDQ, using a public database to aid in the detection of resistant strains. Seventy-one BDQ-resistant and 929 BDQ-susceptible isolates from the open-source CRyPTIC database were selected for analysis. Variant calling was conducted via the clockwork pipeline. Univariate logistic regression was performed for each gene mutation, followed by LASSO regression for further variant selection. Ultimately, a multiple linear regression model was developed using log2-transformed Minimum Inhibitory Concentration values as the dependent variable, with variant selection refined through stepwise regression based on the Akaike Information Criterion. Ten gene mutations were significantly associated with reduced BDQ susceptibility, including two key gene mutations: Rv0678_141_ins_1 and Rv1979c_D249E, with effect estimates of 1.76 (95 % CI: 0.67–2.84) and 1.69 (95 % CI: 0.22–3.17), respectively. Other implicated genes included Rv2699c_-84_del_1, hsaB_I179T, mmpL9_T241A, pncA_C14R, Rv0373c_G621S, Rv0893c_L27F, Rv1770_A4D, and Rv3428c_S327C. This study identified ten gene mutations linked to decreased susceptibility to BDQ, providing a reference for developing a comprehensive catalog of BDQ-resistant genes.

Green extraction and partial purification of roselle (Hibiscus sabdariffa L.) extracts with high amounts of phytochemicals and in vitro antioxidant and antibacterial effects.

The aim of this study is to develop roselle (Hibiscus sabdariffa L.) extracts with high amounts of phytochemicals and in vitro antioxidant and antibacterial effects using green extraction technique. Roselle extract prepared by ultrasonic extraction with 80% ethanol and 1% hydrochloric acid (RSUEH) promoted the highest yield and high total phenolic (5.21±0.05g% gallic acid equivalent of dried extract), total flavonoid (1.29±0.06g% quercetin equivalent of dried extract), and total anthocyanin contents (0.21±0.00 and 0.44±0.00g% cyanidin 3-glucoside equivalent of dried extract determined by pH-differential method with standard calculation and pH-differential method with standard curve of cyanidin 3-glucoside, respectively). From the validated high-performance liquid chromatography analysis, delphinidin-3-sambubioside, delphinidin-3-glucoside, and cyanidin-3-glucoside were found to be the major anthocyanins in roselle extract. This extract exhibited moderate 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging effect (EC50 289.61±0.16µg/mL) and strong inhibitory effects against Escherichia coli, Staphylococcus aureus, Staphylococcus intermedius, Proteus mirabilis, and Pseudomonas aeruginosa with the inhibitory concentration (IC50) values in the range of 0.15±0.05 to 4.64±0.07mg/mL and the minimum inhibitory concentration (MIC) values ranged from 1.66±0.06 to 7.11±1.05mg/mL. From partial purification, fraction 28 (F28) contained higher amounts of all analyzed phytochemicals than roselle extracts and promoted stronger DPPH scavenging effects (EC50 54.88±2.23µg/mL). F28 showed antibacterial activity with IC50 values against all tested bacteria in the range of 0.19±0.07 to 4.69±0.09mg/mL, and the MIC values ranged from 2.46±0.08 to 6.24±0.09mg/mL.

Endophytic bacteria in Camellia reticulata pedicels: isolation, screening and analysis of antagonistic activity against nectar yeasts.

Camellia reticulata, an ancient plant species endemic to Yunnan Province, China, remains underexplored in terms of its endophytic bacterial communities. The plant tissue pedicel serves as the connection between the flower and the stem, not only delivers nutrients but also transmits metabolic substances from endophytic bacteria to the nectar during long-term microbial colonization and probably improves the antagonistic activity of nectar against yeast. Hence, 138 isolates of endophytic bacteria have been isolated in this study from the pedicels of 12- and 60-year-old C. reticulata. Comparative analysis revealed significantly higher density of endophytic bacteria in older trees. Among these isolates, 29 exhibited inhibitory effects against nectar yeasts. Most of the isolates displayed positive results for Gram staining, catalase reaction, gelatin liquefaction, and motility. Additionally, the isolates demonstrated the ability to utilize diverse substrates, such as glucose, nitrate, and starch. Based on 16S rRNA molecular biology analysis, these isolates were identified to be 11 different species of 6 genera, with the majority belonging to Bacillus genus. Notably, C1 isolate, identified as Bacillus spizizenii, exhibited strongest antagonistic effect against three yeasts, i.e., Metschnikowia reukaufii, Cryptococcus laurentii, and Rhodotorula glutinis, with minimum inhibitory concentration values below 250 μg/mL. Major metabolites of B. spizizenii were aminoglycosides, beta-lactams, and quinolones, which possess antimicrobial activities. Furthermore, KEGG enrichment pathways primarily included the synthesis of plant secondary metabolites, phenylpropanoids, amino acids, alkaloids, flavonoids, neomycin, kanamycin, and gentamicin. Therefore, antagonistic activity of B. spizizenii against yeasts could be attributed to these antibiotics. The findings highlight the diverse endophytic bacteria associated with C. reticulata, indicating their potential as a valuable resource of bioactive metabolites. Additionally, this study provides new insights into the role of endophytic bacteria of pedicels in enhancing nectar resistance against yeasts.

SYNERGISTIC EFFECT OF HERBAL TEA SAMPLES WITH CIPROFLOXACIN AGAINST MRSA AND THEIR ANTIOXIDANT ACTIVITIES

OBJECTIVE: Sambucus nigra L. (elderberry), Salvia sclarea L. (clary sage), Rosmarinus officinalis L. (rosemary), and Coriandrum sativum L. (coriander) are all consumed as flavoring agents for food and are well-known in traditional medicine for the treating various diseases worldwide. These herbs are also commonly used for microbial infections, especially to relieve cough, fever, and cold symptoms. This study aims to screen and compare the content of total phenols and antioxidant activity potential of three different extracts from each commercial sample of S. nigra, S. sclarea, R. officinalis and C. sativum from Türkiye. We also investigated the (Minimum Inhibitory Concentration (MIC) values against Staphylococcus aureus ATCC 29213 (methicillin-susceptible, MSSA) and Staphylococcus aureus ATCC 43300 (methicillin-resistant, MRSA) and the synergistic activity with an antibiotic, ciprofloxacin, by checkerboard assay. MATERIAL AND METHODS: The fruits of S. nigra and C. sativum, the aerial parts of S. sclarea, and the leaves of R. officinalis were purchased from a trading company that marketed them as herbal tea in Türkiye. This study investigated the total phenolic content and antioxidant potential of extracts from commercial samples. We also determined the synergistic effect of herbal tea samples with ciprofloxacin against methicillin-resistant Staphylococcus aureus (MRSA). RESULTS: R. officinalis (rosemary) and Salvia sclarea (clary sage) extracts showed high phenolic content and antioxidant activity, whereas it was determined that C.sativum (coriander) and S. nigra (elderberry) extracts exhibited lower antioxidant activity and low phenolic compounds. Moreover, ciprofloxacin in combination with the ethanolic extract of S. sclarea showed additive antibacterial activity against S. aureus ATCC 43300. CONCLUSIONS: We conclude that herbal tea prepared from commercial R. officinalis (rosemary) and S.sclarea (clary sage) samples can support the antioxidant activity with high phenolic content and that ciprofloxacin combined with the ethanolic extract of clary sage showed additive antibacterial activity against methicillin-resistant S. aureus ATCC 43300. Further studies are needed to understand the mechanism of additive action in detail.

Improvement of Hygienic and Phytochemical Qualities of Mangosteen (Garcinia Mangostana) Peel by Irradiation

The aim of this study was to compare the effects of gamma ray and x-ray irradiation at different dose levels 95, 10, 15 and 20 kGy) on in mangosteen peel. The antioxidant activities were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP), while total phenolic contents and antibacterial activities against Staphylococcus aureus and Escherichia coli of 60 % ethanolic mangosteen powder extracts were analyzed. The results indicated that both types of ionizing radiations showed a non-significant decrease in measured parameters with increasing doses. The minimum inhibitory concentration (MIC) values of irradiated mangosteen peel extracted against S. aureus and E. coli ranged from 0.125 to 2.0 mg/mL. The quantity of bioactive compound mangostin determined via high-performance liquid chromatography (HPLC), did not show significant decrease with different irradiation sources and doses. In microbiological aspect, total yeast and mold from both irradiation sources were reduced by 1 log cycle after irradiation at 5 kGy. The irradiation induced color changes corresponding to Hunter color L a b value. X-ray irradiation caused slight color alteration compared to gamma rays. The advantage of x-ray irradiation was that it revealed non-significant changes in b values, whereas gamma irradiation showed the significant change in L, and b values with increasing dosage. The x-ray irradiation at the dose 5 kGy effectively decreased microbial contamination while causing minimal changes to phytochemical qualities and color. HIGHLIGHTS Irradiation at 5 kGy was sufficient to control microbial contamination There were no significant changes in antioxidant activities (DPPH, FRAP), a-mangostin contents, total phenolic contents (TPC) and antibacterial activities: after irradiation up to 20 kGy X-ray irradiation was an excellent alternative to gamma irradiation for decontamination with a non-significant alteration in b values. GRAPHICAL ABSTRACT

Ag induced plasmonic TiO2 for photocatalytic degradation of pharmaceutical under visible light: Insights into mechanism, antimicrobial and cytotoxicity studies

Global concerns include water scarcity and shortage, which are escalated by organic pollutants such as naproxen (NPX) that deteriorate drinking water and taint access to safe drinking water by humans. Moreover, NPX may cause gastrointestinal difficulties, cardiovascular risks, kidney damage, allergic reactions, liver toxicity, bleeding issues and pregnancy risks, hence it is essential to remove it in water. Ag-TiO2 was synthesized by hydrothermal method for NPX degradation. Ag on TiO2 reduced the band gap and surface area of TiO2 and resulted in a plasmonic Ag-TiO2 composite of 0.2 % Ag. The photocatalytic degradation of 0.2 % Ag-TiO2 was 80 % in 180 minutes using a solar simulator during NPX degradation with a first order reaction rate that was 3.6 times faster than that of pure TiO2 and the catalyst showed good stability for four cycles. The dual activity of Ag0 surface plasmon resonance improved light absorption capability and enhanced charge transfer for increased photodegradation rate and stability. The antibacterial studies demonstrated that 0.2 % Ag-TiO2 posted strong antibacterial properties under light irradiation and less in the dark, with a greater effect on gram-negative than gram-positive bacteria. The minimum inhibitory concentration (MIC) values of 620, 1250, 2500, 2500 µg/mL were attained against B. subtilis, S. aureus, E. coli and S. typhimurium bacteria, respectively. The low cell toxicity of 0.2 % Ag-TiO2 was determined using human embryonic kidney (HEK293) cells with an inhibitory concentration (IC50) of 61.09 ± 0.24 µg/mL under light irradiation. Radical trapping experiments demonstrated that hydroxyl radicals (OH•) played a vital role during the degradation and bactericidal activity of NPX under light irradiation. This work advances new insights on the synthesis of less toxic nanoparticles with high photocatalytic and bactericidal activity for possible applications at industrial scale.

Combinations of Terminalia bellirica (Gaertn.) Roxb. and Terminalia chebula Retz. Extracts with Selected Antibiotics Against Antibiotic-Resistant Bacteria: Bioactivity and Phytochemistry.

Antimicrobial resistance (AMR) has arisen due to antibiotic overuse and misuse. Antibiotic resistance renders standard treatments less effective, making it difficult to control some infections, thereby increasing morbidity and mortality. Medicinal plants are attracting increased interest as antibiotics lose efficacy. This study evaluates the antibacterial activity of solvent extracts prepared using Terminalia bellirica and Terminalia chebula fruit against six bacterial pathogens using disc diffusion and broth microdilution assays. The aqueous and methanol extracts of T. bellirica and T. chebula showed substantial zones of inhibition (ZOIs) against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). The activity against those bacteria was strong, with minimum inhibitory concentrations (MIC) ranging from 94 µg/mL to 392 µg/mL. Additionally, the T. bellirica methanolic extract showed noteworthy antibacterial activity against Escherichia coli and an extended spectrum β-lactamase (ESBL) E. coli strain (MIC values of 755 µg/mL for both). The aqueous T. bellirica and T. chebula extracts also inhibited Klebsiella pneumoniae growth (MIC values of 784 µg/mL and 556 µg/mL, respectively). The corresponding methanolic extracts also inhibited ESBL K. pneumoniae growth (MIC values of 755 µg/mL and 1509 µg/mL, respectively). Eighteen additive interactions were observed when extracts were combined with reference antibiotics. Strong antagonism occurred when any of the extracts were mixed with polymyxin B. Liquid chromatography-mass spectroscopy (LC-MS) analysis of the extracts revealed several interesting flavonoids and tannins, including 6-galloylglucose, 1,2,6-trigalloyl-β-D-glucopyranose, 6-O-[(2E)-3-phenyl-2-propenoyl]-1-O-(3,4,5-trihydroxybenzoyl)-β-D-glucopyranose, propyl gallate, methyl gallate, sanguiin H4, hamamelitannin, pyrogallol, gallic acid, ellagic acid, chebulic acid, and chebuloside II. All extracts were nontoxic in brine shrimp assays. This lack of toxicity, combined with their antibacterial activities, suggests that these plant species may be promising sources of antibacterial compound(s) that warrant further study.

Chemical Composition, Antibacterial and Antibiotic-Modifying Activity of Croton grewioides Baill Essential Oil

Background: Croton grewioides Baill., a species native to the Caatinga, popularly known as canela de cunhã, is used in traditional medicine to treat gastrointestinal diseases such as diarrhea, gastritis and stomach ulcers. The combination of essential oils with antibiotics reveals several beneficial effects associated with the increased efficacy of these drugs against pathogenic agents. Through this perspective, this study aimed to identify the chemical composition of the essential oil of C. grewioides (OECG) and evaluate its antibacterial and antibiotic-modifying activities against standard and multiresistant bacteria. Methods: To analyze the compounds present in the oil, the techniques of gas chromatography coupled with mass spectrometry (GC/MS) and gas chromatography with a flame ionization detector (GC/FID) were used. In the bacteriological tests, the Minimum Inhibitory Concentration (MIC) was obtained by the broth microdilution technique. The modulating effect of the essential oil was determined by calculating the subinhibitory concentration, followed by a serial microdilution of the antibiotics. The MIC reduction factor (CRF) was calculated, and its data were expressed as a percentage. Results: The analysis of the chemical composition identified the presence of the major compound estragole with a relative abundance of 50.34%. The MIC values obtained demonstrated efficacy in K. pneumoniae isolated from urine with MIC values of 512 µg/mL. OECG potentiated the effects of all antibiotics tested on the strains S. aureus ATCC 29213, K. pneumoniae Carbapnemase, E. coli ATCC 25922 and S. aureus ATCC 29213 with their CRF of 97.65%, 99.80%, 99.85% and 99.88%, respectively. Conclusions: Thus, the essential oil of C. grewioides presents synergistic effects when combined with the antibiotics tested, in addition to acting in the fight against bacterial resistance to antibiotics.

Antimicrobial Activity of Commercial Essential Oils Available in the Market of Kathmandu

Given the increasing global apprehension surrounding antibiotic resistance, there has been growing interest in exploring natural compounds, specifically essential oils, as potential substitutes for combating microbial pathogens. This research work aimed to evaluate the antimicrobial activity exhibited by commercial essential oils and by diluting them with the carrier oils at equal concentration. The screening of antimicrobial activity was conducted using the agar well diffusion method with eight essential oils. Using the broth dilution method, the antibacterial activity of eight commonly used essential oils: lavender, tea tree, eucalyptus, peppermint, thyme, citrus, rosemary, and cinnamon were assessed. Both Gram-positive and Gram-negative species were selected for antimicrobial activity. The minimum inhibitory concentration (MIC) was determined by the broth dilution method. Following MIC determination, a sub-culture was performed on nutrient agar plates to ascertain the minimum bactericidal concentration (MBC). All the antibiotics used in the study demonstrated sensitivity when subjected to the antibiotic susceptibility test. Thyme, cinnamon and peppermint strongly inhibited the growth of S. epidermidis 46 mm, 30mm, and 34 mm respectively. Findings revealed distinct variations in the MIC values among the different essential oils and bacteria tested. Thyme and tea tree oils exhibited the broadest antibacterial spectrum, inhibiting both Gram-positive and Gram-negative bacteria at relatively low concentrations. Thyme (15.625 μl/ml) and tea tree (31.25 μl/ml) oil demonstrated promising activity against Gram-positive pathogen, while tea tree oil (15.625 μl/ml) displayed better efficacy against Gram-negative bacteria. A significant outcome was observed when the essential oils were diluted with carrier oils, indicating promising results in terms of antibacterial activity. These findings highlight the potential of essential oils, particularly thyme and tea tree oils, as effective natural antimicrobial agents.

Antifungal effects of three natural branched medium-chain fatty acids and their potential as fumigants against Aspergillus flavus in stored peanut seeds

The contamination of peanuts with aflatoxins predominantly produced by Aspergillus flavus poses a worldwide threat to both food safety and agricultural economies. Antifungal compounds from natural sources may offer a safe and effective alternative strategy to control A. flavus in peanuts. We evaluated the contact and fumigant antifungal effects of three natural branched medium-chain fatty acids (branched-MCFAs), (E)-2-methyl-2-pentenoic acid, 2-methylhexanoic acid, and 2-methylheptanoic acid against A. flavus relative to their straight-chain isomers and sorbic acid a commonly used preservative. In vitro experiments showed that the inhibitory effects of these three branched-MCFAs on A. flavus were stronger than their straight-chain isomers and sorbic acid. In addition, fumigant effects of the branched-MCFAs were more effective than their direct contact inhibitory effects against the growth of A. flavus. 2-Methylhexanoic acid, 2-methylheptanoic acid, and (E)-2-methyl-2-pentenoic acid showed significant fumigant activity, with the minimum inhibitory concentration (MIC) values of 0.10, 0.10, and 0.12 g/l air, respectively. Fumigation of these branched-MCFAs also significantly slowed the growth of A. flavus in peanut seeds, and completely inhibited A. flavus growth at 2.0 g/l air. After 24 h of fumigation exposure to the branched-MCFAs, the fumigated A. flavus on medium or peanut seeds was re-incubated to observe whether the A. flavus could continue to grow, and the results revealed that the in vitro and in vivo minimum fungicidal concentrations (MFC) were 0.15 and 2.5 g/l air, respectively. This study indicated that these three natural branched-MCFAs have strong antifungal fumigation activity with application potential in protecting peanut seeds from A. flavus contamination during storage.

The Nephroprotective Effect of Punica granatum Peel Extract on LPS-Induced Acute Kidney Injury

Sepsis is an exaggerated immune response resulting from systemic inflammation, which can damage tissues and organs. Acute kidney injury has been detected in at least one-third of patients with sepsis. Sepsis-associated acute kidney injury increases the risk of a secondary infection. Rapid diagnosis and appropriate initiation of antibiotics can significantly reduce mortality and morbidity. However, microorganisms are known to develop resistance to antibiotics. Estimations indicate that the annual casualties caused by microbial resistance will surpass cancer fatalities by 2050. The prevalence of bacterial infections and their growing antibiotic resistance has brought immediate attention to the search for novel treatments. Plant-derived supplements contain numerous bioactive components with therapeutic potential against a variety of conditions, including infections. Punica granatum peel is rich in phenolic compounds. The purpose of this study was to determine the anti-inflammatory and anti-bacterial properties of P. granatum peel extract (PGPE) on lipopolysaccharide (LPS)-induced acute kidney injury. Experimental groups were Control, LPS (10 mg/kg LPS, intraperitoneally), PGPE100, and PGPE300 (100 and 300 mg/mL PGPE via oral gavage, respectively, for 7 days). According to biochemical results, serum blood urea nitrogen (BUN), creatinine (Cr) and C-reactive protein (CRP), kidney tissue thiobarbituric acid reactive substances (TBARS), and reduced glutathione (GSH) levels significantly decreased in the PGPE groups compared to the LPS group. Histopathological and immunohistochemical findings revealed that toll-like receptor 4 (TLR4) level and nuclear factor kappa B (NF-κB) expression increased in the LPS group compared to the Control group. In addition, the anti-Gram-negative activity showed a dose-dependent effect on Acinetobacter baumannii, Escherichia coli, and Pseudomonas aeruginosa with the agar well diffusion method and the minimal inhibitory concentration (MIC). The MIC value was remarkable, especially on A. baumannii. We conclude that PGPE has the potential to generate desirable anti-bacterial and anti-inflammatory effects on LPS-induced acute kidney injury in rats.

Antimicrobial susceptibility of Clostridium botulinum group III field strains isolated in Europe from animal outbreaks

Neurotoxins produced by Clostridium (C.) botulinum group III are responsible for the majority of botulism outbreaks occurring in animals and in this study we report the drug susceptibility of 71 field strains. The minimum inhibitory concentration (MIC) of 13 antimicrobials was established through the agar dilution method. The MIC50 matched or differed for one or two dilutions from MIC90 of the same antimicrobial, showing a unimodal distribution of the MIC values, irrespective of the geographical origin, the animal source and the toxinotype of the strain. Beta-lactams and rifampin showed the lowest MIC values, while gentamicin, polymyxin B and sulfamethoxazole showed the highest MICs. As for similar studies conducted in human botulism, the results could be helpful to avoid the administration of antimicrobials that could worsen the health condition of the affected animals and to develop selective media for the isolation of these fastidious anaerobes. Indeed, the isolation of the strain from affected animals and from environmental samples is important to perform epidemiological studies based on the genetic characterization and to produce tailor-made vaccines.