Sensitive Bacteria Research Articles

High-Pressure Processing and Natural Antimicrobials Combined Treatments on Bacterial Inactivation in Cured Meat

The combination of high hydrostatic pressure (HHP) and natural antimicrobials can present an interesting efficiency in the decontamination process of cured meat. However, several factors, such as application method and antimicrobial type, must be better understood to improve the process and its total employment. Therefore, this study aimed to evaluate the combined effect (synergism or antagonism) of HHP and natural antimicrobials to inactivate pathogenic and spoilage bacteria in cured meat. After a systematic search of research articles in the databases (Web of Science, Scopus, PubMed, and Science Direct), 20 articles were eligible and resulted in 123 studies for meta-analysis. The effect on Listeria sp., Salmonella serovars, E. coli O157:H7, and total viable counts was investigated considering different application methods (spread onto the surface, incorporated into the product, and active packaging) and antimicrobial types (plant, bacterial and animal origins). Active packs showed the best synergy with HHP, exhibiting a mean effect of 0.78 (CI95: 0.25–1.32) log cfu/g. Antimicrobials of microbial origin (bacteriocins) were more effective in combination with HHP. In addition, Listeria sp. was the most sensitive bacterium considering all investigated combined methods. Hence, the use of natural antimicrobials has the potential to improve the decontamination process when HHP is applied.

Phenolic Content and in Vitro Antioxidant, Anti-Inflammatory and antimicrobial Evaluation of Algerian Ruta graveolens L.

Plants constitute a valuable source of natural antioxidants such as polyphenols and are responsible for exhibiting many biologically significant functions. Ruta species including Ruta chalepensis L. and Ruta graveolens L. are widespread species in Algeria and are used as medicinal plants to treat various diseases; however, so far, most of the conducted studies focused on analyzing alkaloids and essential oils mostly on R. chalepensis. The aim of the present research is to investigate the phenolic profile of the aerial parts of Ruta graveolens L. from Algeria and assess its in vitro antioxidant, anti-inflammatory and antimicrobial properties. The total polyphenols and flavonoids were assessed using colorimetric methods, and the individual polyphenols were identified and quantified using HPLC-DAD-ESI-MS. The antioxidant activity was evaluated with DPPH and β-carotene tests, and the anti-inflammatory activity with inhibition of bovine serum albumin denaturation and HRBC membrane stabilization methods. The results showed that Ruta graveolens extract is rich in phenolic compounds with a total phenol and flavonoid contents of 41.63±0.394 mg GAE/gE and 13.97±0.33 mg EQ/gE, respectively. Nine phenolic compounds were determined, including three phenolic acids and six flavonoids. Rutin was the major phenolic compound in Ruta graveolens (464.95 μg/g), followed by syringic acid (179.74 μg/g), and naringenin (109.78 μg/g). R. graveolens phenolic extract also showed good antioxidant activity with values of 0.77 mM TE/g DW and 0.37 mM β-CE/g DW with DPPH and β-carotene tests, respectively. For the anti-inflammatory activity, the highest tested concentration (200 μg/mL) gave 50.61 % of inhibition of the denaturation of albumin and 44.12 % of membrane stabilization. With regards to antimicrobial results, Staphylococcus aureus was the most sensitive bacteria with an inhibition zone of 14.37 mm and MIC value of 0.625 mg/mL, followed by Listeria monocytogenes (11.75 mm and MIC=1.25 mg/mL), and Escherichia coli (10.25 mm and MIC=1.25 mg/mL).

Phytochemical characterization and evaluation of antioxidant, antimicrobial, antibiofilm and anticancer activities of ethyl acetate seed extract of Hydnocarpus laurifolia (Dennst) Sleummer.

Various functional groups were observed in the FTIR analysis of Hydnocarpus laurifolia seeds ethyl acetate extract such as O-H, N-H, C-H, -CH2, O=C=O, C=O, C=O-NH, and CH3, etc. Eleven bioactive compounds were detected via GC-MS and the predominant compounds include (1S)-2-cyclopentene-1-tridecanoicacid (chaulmoogric acid) (80.59%); 2-cyclopentene-1-undecanoic acid (hydnocarpic acid) (6.76%); cyclobutylamine (5.28%); methyl thioacetate (ethanethioic acid) (4.84%); lignoceric acid (2.21%). The TPC and TFC values were 0.110 ± 0.04 GAE g-1 and 0.175 ± 0.05g CE g-1 respectively. Ethyl acetate extract showed strong DDPH free radical scavenging activity with IC50 value 10.64 ± 0.48µgml-1 and antioxidant activity index 3.759. The ethyl acetate extract also exhibited potential ABTS radical scavenging efficacy with a very low IC50 value, i.e., 07.81 ± 0.48µgml-1. P. aeruginosa was the most sensitive bacteria to the extract with 33.16 ± 0.88mm inhibition zone and MIC: 3.12mgml-1, MBC: 6.25mgml-1. P. aeruginosa biofilm was inhibited by ethyl acetate extract 99.22% at MIC concentration. The LM images displayed a decrease in the number of biofilm cells and FE-SEM micrographs showcased the extensive decrease as well as disintegration in biofilm. Additionally, ethyl acetate extract was found selectively cytotoxic to the K562 cancer cells having an IC50 of 25.41μgml-1 and barely cytotoxic to normal PBMCs having an IC50 of 482.54μgml-1, and the selectivity index value was 18.99. Data validate scientifically the traditional use of H. laurifolia seeds in folk medicines and confirmed that it can be used in modern phytomedicines as an antioxidant, antimicrobial, antibiofilm, and anticancer agent and is toxicologically safe.

Simplified Fabrication of Magnetic Nanoparticles With Directly Adsorbed Antibodies for Bacteria Detection

Antigen–antibody reactions with conjugated magnetic nanoparticles (MNPs) are widely used for detecting viruses, bacteria, and proteins. In this study, we proposed a novel method for adsorbing antibodies directly on the surface of MNPs without coating any proteins. MNPs (Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ; average size 4 nm) were synthesized by a thermal decomposition method using oleyl amine as a surfactant, the fabricated MNPs exhibit superparamagnetic characteristics, and the antibodies (anti- <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>Bifidobacterium longum</i></b> ) were adsorbed. We found that 15 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{g}$ </tex-math></inline-formula> /mg of antibody adsorbed to MNPs and were able to detect the bacteria bound to the produced antibody-MNPs based on the antigen–antibody reaction, offering potential for highly sensitive bacteria detection.

Antimicrobial Resistance in Bacteria Isolated from Exotic Pets: The Situation in the Iberian Peninsula.

Simple SummaryAntimicrobial resistance in exotic pets has not been widely studied. The close contact of this type of animal with the human population increases the risk of untreatable bacterial infections, which represent a veterinary and human public health challenge. We analyze the database of microbiological diagnoses and the bacterial susceptibility to antimicrobials in exotic pets from the Iberian Peninsula. We found that the most prevalent bacteria in birds and mammals were Staphylococcus spp., while in reptiles, they were the Pseudomonas spp. In addition, Pseudomonas showed the highest levels of resistance among the three animal groups, and on the other hand, the multidrug resistance level was significant in Enterobacterales. Most of the bacteria we found have zoonotic importance. The prevalent bacteria are resistant to antimicrobials that have been described as critical for human use, implying that the threat of antimicrobial resistance extends not only to domestic and companion animals but also to humans due to the potential transmission of resistant genes. Once seen from the lens of the One-Health paradigm, these findings are concerning, as they highlight the risk of spreading antibiotic-resistant genes between different individuals and their environments. In order to prevent antibiotic resistance, we encourage the development of joint work between animal and human health specialists.Literature related to antimicrobial resistant (AMR) bacteria in exotic pets is minimal, being essential to report objective data on this topic, which represents a therapeutic challenge for veterinary medicine and public health. Between 2016 and 2020, laboratory records of 3156 exotic pet specimens’ microbiological diagnoses and antibiotic susceptibility testing (AST) results were examined. The samples were classified into three animal classes: birds (n = 412), mammalia (n = 2399), and reptilian (n = 345). The most prevalent bacteria in birds and mammals were Staphylococcus spp. (15% and 16%), while in reptiles they were Pseudomonas spp. (23%). Pseudomonas was the genus with the highest levels of AMR in all animal groups, followed by Enterococcus spp. By contrast, Gram-positive cocci and Pasteurella spp. were the most sensitive bacteria. Moreover, in reptiles, Stenotrophomonas spp., Morganella spp., and Acinetobacter spp. presented high levels of AMR. Multidrug-resistant (MDR) bacteria were isolates from reptiles (21%), birds (17%), and mammals (15%). The Enterobacterales had the highest MDR levels: S. marcescens (94.4%), C. freundii (50%), M. morganii (47.4%), K. pneumoniae (46.6%), E. cloacae (44%), and E. coli (38.3%). The prevalence of MDR P. aeruginosa strains was 8%, detecting one isolate with an XDR profile. Regarding antimicrobial use, many antibiotics described as critically important for human use had significant AMR prevalence in bacteria isolated from exotic pets. Under the One-Health approach, these results are alarming and of public health concern since potential transmission of AMR bacteria and genes can occur from exotic pets to their owners in both senses. For this reason, the collaboration between veterinarians and public health professionals is crucial.

Antiseptic Activity of Alchornea cordifolia (Schumach &amp; Thonn.) Mull.-Arg. (Euphorbiaceae) Aqueous Leaves Extract on Oral and Dental Bacteria

Some infectious oral diseases are treated by medicinal plants in tropical areas, because they are abundant and cheap. The present work aimed to evaluate the antiseptic activity of the aqueous extract of Alchornea cordifolia leaves against three oral bacteria recognised as opportunistic pathogens, namely Streptococcus mitis, Staphylococcus epidermidis, and Micrococcus luteus. Fresh leaves of A. cordifolia were harvested, dried and pulverised. The extraction was performed by decocting in distilled water. The phytochemical screening was performed on the extract based on principles of colour change, and precipitation. Biological studies consisted in the in vitro antiseptic evaluation of the aqueous extract using the agar disc diffusion method, in comparison with a reference antiseptic mouthwash containing chlorhexidine. The extract had a 11.96% yield. The phytochemical screening revealed the presence of alkaloids, phenols, flavonoids, terpenes, tannins, glycosides, coumarins and saponins. The evaluation of the antiseptic activity revealed that the extract is active against S. mitis and S. epidermidis, and inactive against M. luteus. The diameters of inhibition zones were 16.9±1.1mm and 11.2±0.7mm at the concentration of 40mg/ml, and 7.7±0.3mm and 8.5±0.5mm at the concentration of 20mg/ml against S. mitis and S. epidermidis, respectively. Chlorhexidine did not inhibit S. mitis and showed diameters of inhibition of 13.0±1.0mm and 15.1±1.0mm against S. epidermidis and M. luteus, respectively. The minimal inhibitory concentration of the extract against the 2 sensitive bacteria was 20mg/ml.

How can nutritional additives modify ruminant nutrition?

This review illustrates the relationships between additives in the diets of ruminants and the consequence for ruminant nutrition. Feed additives are used to improve animal performance and/or the quality of the products. There are several categories of additives available for ruminant nutrition, with emphasis on antibiotics, prebiotics, probiotics, plant extracts, and exogenous enzymes. Antibiotics, essential oils, and chitosan act by selecting sensitive bacteria, consequently modulating the ruminal fermentation pattern. Prebiotics favor microbial growth, providing greater digestion and the production of volatile fatty acids. Probiotics are living microorganisms that improve the ruminal environment, promoting microbial growth and resulting in increased digestion and the production of volatile fatty acids. Exogenous enzymes act synergistically with the enzymes secreted by the ruminal microorganisms, besides favoring microbial adhesion and colonization and facilitating feed degradation. Tannins, whether altering the fermentation standard and/or modifying the ruminal microbiota population, are effective in improving animal performance. However, the effects of additives on the quality of the products are linked to diet quality. Highlights Exogenous enzymes act synergistically with the enzymes secreted by the ruminal microorganisms. Exogenous enzymes favoring the microbial adhesion and colonization of the particles, aid in the degradation of the feed. Tannins can altering the fermentation standard and/or modifying the ruminal microbiota population. Essential oils and chitosan act by selecting sensitive bacteria and consequently modulate the ruminal fermentation.

Isolation and Identificationof Bacteriocin by Dairy Products

Bacteriocins is an antimicrobial substances produced by bacteria, identified by lactic acid bacteria (LAB) which has been used as food bio-preservatives. The study was conducted at “Department of Life sciences, University of Management and Technology,” Lahore, Pakistan and was aimed to isolates and identify bacteriocin producing bacterial from milk and yogurt.A total of 30 samples were collected (milk n=15; yogurt n= 14)from different local areas of Lahore. All the samples were serially diluted (10-1 to 10-7) and processed on nutrient agar by spread plate method for 24 h at 37℃. All the isolates wereidentified through colony morphology on agar plates, Gram stain reaction and different biochemical tests such as catalase, oxidase, coagulase and indole respectively. Bacillus subtilis and Escherichia coli were used as sensitive indicator bacteria towards bacteriocin producing species. Out 87 isolates, 30 were found as bacteriocin producers. Out of 30 producer species, 45% were from milk and 24% were from yogurt samples. The prominent producer isolates were Lactobacillus (40%),Lactococcusspp. (17%) and Enterococcus spp. (7%) respectively. Good inhibitory activity was observed against indicator species such as B. subtilis whereas; it was moderate against E. coli. The result indicated that the raw milk as a potential source of bacteriocin producing bacteria. Further research should be done on molecular level of bacterial isolates from dairy products. Keywords: Bacteriocin, Bio-preservatives, Lactic acid bacteria, Antimicrobial activity

Microbiological and Antibiotic Profile of Broncho-Alveolar Lavage Aspirate in Mechanically Ventilated Patients in a Tertiary Care Hospital

Introduction: VAP increases the patient stay in the ICU and indirectly increases the cost of patient management. Based on the time of onset of VAP, it can be divided into two types. Early-onset VAP occurs during the first four days of mechanical ventilation and is usually caused by antibiotic sensitive bacteria. Late-onset VAP develops five or more days after initiation of MV and is caused by multidrug-resistant (MDR) pathogens.5 Early diagnosis of VAP with appropriate antibiotic therapy can reduce the emergence of resistant organisms. Methods: This cross-sectional study was done in College of Medical Sciences Teaching Hospital, Bharatpur, Chitwan after taking clearance from the institutional review committee. Study included all the patients who required mechanical ventilation for more than 72 hoursAll the included patients had their endotracheal tube aspirated using an ambu bronchoscope and sent to microbiology department for culture and sensitivity. The reports were collected after 72. Results: The most common organism grown during culture and gram staining were Acinetobacter Baumannii (81), followed by Klebsiella Peumoniae (44) than Pseudomonas Aeroginosa (32).. We observed a higher rate of culture positivity from the samples of male patients than those obtained from the female patients. Similar findings were observed by Morehead et al13and debjita debnath et al12 . In our study, gram-negative bacilli were the most commonly isolated pathogen from BAL which is similar to studies done by, debjita debnath, Fagon et al14 and Şimşek et al15. In our study, Acinetobacter Baumannii (81) was the most common followed by Klebsiella Peumoniae (44) than Pseudomonas Aeroginosa (32),first line of antibiotics in patients who were mechanically ventilated were piperacillin plus tazobactam, meropenem,cotrimoxazole, amikacin and gentamicin. The second line drugs were polymyxin B, colistimethate and tigecycline. Conclusions: Acinetobactor Baumanni is the most common causative organism of ventilator associated pneumonia. In most of the cases first line antibiotics ( meropenem, amikacin and clotrimoxazole) are sensitive. Among the second line antibiotics, Polymyxin B was found to be most effective.

Green Biosynthesis of Selenium Nanoparticles Using Orange Peel Waste: Characterization, Antibacterial and Antibiofilm Activities against Multidrug-Resistant Bacteria.

There is an increase of pathogenic multidrug-resistant bacteria globally due to the misuse of antibiotics. Recently, more scientists used metal nanoparticles to counteract antibacterial resistance. In this study, orange peel waste (OPW) was used for selenium nanoparticles’ (Se-NPs) biosynthesis through the green and ecofriendly method, and their applications as antibacterial and antibiofilm agents. Green biosynthesized Se-NPs were characterized using FTIR, XRD, SEM, EDAX, and TEM. Characterization results revealed that biosynthesized Se-NPs were highly crystalline, spherical, and polydisperse, and had sizes in the range of 16–95 nm. The biosynthesized Se-NPs were evaluated as antibacterial and antibiofilm activities against multidrug-resistant bacteria. Results illustrated that Se-NPs exhibited potential antibacterial activity against Gram-positive bacteria (S. aureus ATCC 29213 and biofilm-producing clinical isolates of S. aureus) and Gram-negative bacteria (Pseudomonas aeruginosa PAO1, MDR, biofilm, and quorum-sensing and producing clinical isolates of MDR P. aeruginosa, MDR E. coli, and K. pneumonia). Moreover, results illustrated that S. aureus ATCC 29213 was the most sensitive bacteria to Se-NPs at 1000 µg/mL, where the inhibition zone was 35 mm and MIC was 25 µg/mL. Furthermore, Se-NPs at 0.25 and 0.5 MIC decreased the biofilm significantly. The largest inhibition of biofilm was noticed in MDR K. pneumonia, which was 62% and 92% at 0.25 and 0.5 MIC, respectively. In conclusion, Se-NPs were successfully biosynthesized using OPW through the green method and had promising antibacterial and antibiofilm activity against multidrug-resistant bacteria, which can be used later in fighting resistant bacteria.

In Vitro Phytobiological Investigation of Bioactive Secondary Metabolites from the Malus domestica-Derived Endophytic Fungus Aspergillus tubingensis Strain AN103.

Endophytic fungi including black aspergilli have the potential to synthesize multiple bioactive secondary metabolites. Therefore, the search for active metabolites from endophytic fungi against pathogenic microbes has become a necessity for alternative and promising strategies. In this study, 25 endophytic fungal isolates associated with Malus domestica were isolated, grown, and fermented on a solid rice medium. Subsequently, their ethyl acetate crude extracts were pretested for biological activity. One endophytic fungal isolate demonstrated the highest activity and was chosen for further investigation. Based on its phenotypic, ITS ribosomal gene sequences, and phylogenetic characterization, this isolate was identified as Aspergillus tubingensis strain AN103 with the accession number (KR184138). Chemical investigations of its fermented cultures yielded four compounds: Pyranonigrin A (1), Fonsecin (2), TMC 256 A1 (3), and Asperazine (4). Furthermore, 1H-NMR, HPLC, and LC-MS were performed for the identification and structure elucidation of these metabolites. The isolated pure compounds showed moderate-to-potent antibacterial activities against Pseudomonas aeruginosa and Escherichia coli (MIC value ranged from 31 and 121 to 14.5 and 58.3 μg/mL), respectively; in addition, the time–kill kinetics for the highly sensitive bacteria against isolated compounds was also investigated. The antifungal activity results show that (3) and (4) had the maximum effect against Fusarium solani and A. niger with inhibition zones of 16.40 ± 0.55 and 16.20 ± 0.20 mm, respectively, and (2) had the best effect against Candida albicans, with an inhibition zone of 17.8 ± 1.35 mm. Moreover, in a cytotoxicity assay against mouse lymphoma cell line L5178Y, (4) exhibited moderate cytotoxicity (49% inhibition), whereas (1–3) reported weak cytotoxicity (15, 26, and 19% inhibition), respectively. Our results reveal that these compounds might be useful to develop potential cytotoxic and antimicrobial drugs and an alternative source for various medical and pharmaceutical fields.

Antibacterial Activity of Silver Nanoparticles Synthesized by Aqueous Extract of Carthamus oxycantha M.Bieb. Against Antibiotics Resistant Bacteria

Antibiotics resistant bacteria have become a global problem as a result of the unprogrammed use of antibiotics, resulting in bacterial strains resistant to many antibiotics, or to all available antibiotics. Plants are a good source of primary and secondary metabolites that have a major role in reducing silver nitrate to silver nanoparticles (AgNPs). The production of these nanoparticles were carried out by using aqueous extract of Carthamus oxycantha M.Bieb. This can be verified by color change of the reaction solution from yellow to dark brown because of the excitation of the surface plasmon resonance. AgNPs were characterized by UV-Vis spectroscopy, where they recorded the peak at 420 nm. Fourier Transformation-infrared (FTIR) was conducted to identify the effective plant group that contributes to the formation of AgNPs and it was found that proteins and phenols have the major role in the formation of those nanoparticles. Shapes and sizes of the synthesized AgNPs were characterized by Scanning Electron Microscope (SEM) with a range of 50-80nm in size and spherical in shapes. Antibacterial activity of AgNPs were tested against Multi-Drug Resistant bacteria (MDR), Extremely antibiotics Resistant (XDR), and Pan drug-resistant (PAN) bacteria, was done in concentrations ranging from 1000-63 µg/ml. The results showed that there were significant variations between the concentrations, the tested bacteria also showed significant differences in its sensitivity to AgNPs. The results recorded a proportional relation between the type of bacterial resistance to antibiotics and it's resistant to AgNPs, therefore the most resistant bacteria to AgNPs in this study Enterobacter cloacae EN2 was resistant to all antibiotics (PAN), while Escherichia coli E11 recorded was the most sensitive bacteria to AgNPs and its resistant only to 3 antibiotics. unprogrammed use of antibiotics, resulting in bacterial strains resistant to manyantibiotics, or to all available antibiotics. Plants are a good source of primary andsecondary metabolites that have a major role in reducing silver nitrate to silvernanoparticles (AgNPs). The production of these nanoparticles were carried out by usingaqueous extract of Carthamus oxycantha M.Bieb. This can be verified by color changedof the reaction solution from yellow to dark brown because of the excitation of thesurface plasmon resonance. AgNPs were characterized by UV-Vis spectroscopy, whererecorded peak at 425 nm. Fourier Transformation-infrared (FTIR) was conducted toidentify the effective plant group that contributes to the formation of AgNPS and it wasfound that proteins and phenols have the major role in the formation of thosenanoparticles. Shapes and sizes of synthesized AgNPs were characterized by ScanningElectron Microscope (SEM) with a range of 50-80nm in size and spherical in shapes.Antibacterial activity of AgNPs were tested against Multi-Drug Resistant bacteria(MDR), Extremely antibiotics Resistant (XDR), and Pandrug-resistant (PAN) bacteria,was done in concentrations ranging from 1000-63 µg/ml. The result showed that theconcentrations from 1000-125 µg/ml inhibited all tested bacterial strains except the S1strain

Proteomic Study of the Adaptive Mechanism of Ciprofloxacin-Resistant Staphylococcus aureus to the Host Environment.

Antibiotic-resistant bacteria can escape host immune killing and settle in the host to form persistent infections. In this study we investigated the adaptive mechanism of resistant Staphylococcus aureus to the host environment by data-independent acquisition-based quantitative proteomics and functional validation. The growth curve and minimum inhibitory concentration (MIC) indicated that ciprofloxacin-resistant (Cip-R) S. aureus showed a survival advantage over sensitive strains. Cip-R also exhibited a stronger invasion and biofilm formation ability than sensitive bacteria. Cip-R stimulation resulted in the improved production of inflammatory factors of the host cells. Proteomics study combined with biochemical validations showed that Cip-R obtained adaptability to the host via upregulation of the tricarboxylic acid cycle (TCA cycle) and downregulation of ribosome metabolism and protein folding to maintain energy to support Cip-R's survival. Thus, this study will help us to further explain the growth strategy of resistant bacteria to adapt to the host environment, and provide important information for the development of new antibacterial drugs.

In vitro Antimicrobial Activity Profile of Modified Pyrimidine Nucleosides Derivatives

Background: The increase in prevalence of antimicrobial-resistant bacteria (ARB) is currently a serious threat, thus there is a need for new classes antimicrobial compounds to combat infections caused by these ARB. The growth inhibition ability of derivatives of the components of nucleic acids has been well-characterized but not for its antimicrobial characteristics.&#x0D; Aims: To evaluate in vitro antimicrobial activity profile of modified pyrimidine nucleosides derivatives.&#x0D; Methodology: Modified nucleosides arabinofuranosylcytosine (cytarabine, ara-C), [1-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)-4-(1,2,4-triazol-1-yl)]uracil (TTU), and nucleotides cytarabine-5′-monophosphate (ara-CMP), and O2,2′-cyclocytidine-5′-monophosphate (cyclocytidine monophosphate, cyclo-CMP) were synthetized and subsequentially checked for antibacterial activity. Bacterial cells characteristics were assessed by antiproliferative and the production of intracellular reactive oxygen species (ROS) assays.&#x0D; Results: It was found that modified nucleosides ara-C, and TTU, and nucleotides ara-CMP, and cyclo-CMP were able to inhibit Escherichia coli, Sarcina lutea, Bacillus cereus, and Proteus mirabilis strains in a time and dose dependent manner via killing kinetics assay. Gram-negative (E. coli and P. mirabilis) bacteria stains were more sensitive to the exposure of TTU and cyclo-CMP and less sensitive to the exposure of ara-C and ara-CMP compared to gram-positive ones. The most effective cells growth inhibitor for gram-positive strains (S. lutea, B. cereus) was ara-CMP with ED50 = 5.2•10-5 M and 3.1•10-4 M, respectively. Sarcina lutea appeared to be the most sensitive bacteria strain to the exposure of all studied compounds. It was demonstrated that studied modified pyrimidine nucleosides derivatives enhanced the production of intracellular ROS over time (validated via DCFA-DA probe assay).&#x0D; Conclusion: This study has revealed the mechanism of action of cytarabine, cyclocytidine monophosphate, and TTU as an antimicrobial agent for the first time, and has shown that these pyrimidine derivatives enhanced might be able to combat infections caused by Escherichia coli, Sarcina lutea, Bacillus cereus, and Proteus mirabilis in the future.

Multicomponent synthesis of pyranonicotinonitrile and chromene-3-carbonitrile: Studies on bioactivities and molecular docking

Dehydroacetic acid (DHA) and derivatives are widely used in the synthesis of pharmacologically active heterocyclic compounds. In this study, two new series of pyranonicotinonitriles and chromene-3-carbonitriles have been synthesized under microwave irradiation using DHA synthons, as starting materials, through multicomponent reaction (MCR), involving domino Knoevenagel-Michael addition or one pot intramolecular cyclization. All the resulting heterocyclic compounds have been characterized by 1H NMR and 13C NMR, 2D NMR (HSQC, HMBC) and mass spectroscopy. Mass peaks of the synthetized compounds correspond perfectly to molecular ions [M + H] or [M+Na]. Notably, 1H NMR spectra of all the compounds display a characteristic doublet at δH 6.07 ppm, which is assigned to the pyran-2-one heterocycle. Biological activities, such as the antioxidant DPPH radical scavenging and antibacterial/antifungal assays against ATCC strains have been evaluated in-vitro. Results showed that all compounds are capable to reduce DPPH with different IC50 values. The germs sensitivity towards the synthesized compounds is variable with Staphylococcus aureus being the most sensitive bacteria. Further docking simulations have been carried out targeting S. aureus penicillin binding proteins group (PBP2, PBP3 and PBP4) and thymidylate kinase (TMK) and the cell division Z ring protein (FtsZ) using AutoDock Vina software. The validity of docking results have been confirmed based on the best affinity scores and types of interactions. The molecular mechanisms of the synthesized heterocycles towards target proteins involved in S. aureus growth have been predicted through molecular docking studies.

Zinc oxide-coated carboxyl-riched graphene oxide efficiently degrades microcystin-leucine arginine and antibiotics under visible light

Microcystin-leucine arginine (Mc-LR) and antibiotic residual in water bodies threaten human health and necessitate the development of efficient processing scheme. Photocatalytic composites are promising alternatives for eliminating these hazardous substances. Herein, we prepared a nanohybrid composed of zinc oxide (ZnO) and carboxyl-riched graphene oxide (cGO). The sustainable material termed ZnO@cGO rapidly degraded Mc-LR (k = 0.68 min−1, t1/2 = 1.02 min, pH 7) under visible light. Mc-LR degradation products were nontoxic to human L0–2 cells. Animal experiments revealed that oral administration of Mc-LR impaired the hepatic function and caused mice death, which could be inspiringly relieved once the toxin was processed by ZnO@cGO. Furthermore, ZnO@cGO efficiently degraded three quinolone antibiotics, ciprofloxacin (k = 2.30 min−1, t1/2 = 0.30 min), ofloxacin (k = 2.11 min−1, t1/2 = 0.33 min), and norfloxacin (k = 0.94 min−1, t1/2 = 0.74 min) at pH 7 under visible light. Owing to the antibiotic removal, ZnO@cGO dramatically suppressed the development of drug resistance of sensitive bacteria. This study characterizes an easy-to-produce photocatalysed nanohybrid to eliminate Mc-LR and antibiotics in water that enriches the existing measures for water detoxication and benefits environmental improvement.

An ultrasensitive fluorescence detection template of pathogenic bacteria based on dual catalytic hairpin DNA Walker@Gold nanoparticles enzyme-free amplification

Integrating the advantages of catalytic hairpin components and multi-foot DNA walker, we designed a 16S rRNA detection probe template for pathogen bacteria, which utilizes DNA ligation quencher and dual catalytic hairpin@DNA walker to induce signal recovery. The dual catalytic hairpin@DNA walker uses the walking position of the target on the AuNP as a foothold to promote the reaction, so that the biosensing of the low-abundance target sequence can induce signal recovery. During the entire experiment, no enzyme is required, which can avoid the limitation of enzyme degradation under unfavorable conditions and the inability to detect the target. Most importantly, the detection template has the advantages of high sensitivity, and its detection limit is significantly better than that of single hairpin DNA walker probe. As the detection system can sensitively and rapidly detect its targeted bacteria and not rely on any enzyme and sophisticated instrumentation, it has great potential for sensitive and specific pathogenic bacteria detection.

Photogenerated reactive oxygen species and hyperthermia by Cu3SnS4 nanoflakes for advanced photocatalytic and photothermal antibacterial therapy

BackgroundThe rapid spread of infectious bacteria has brought great challenges to public health. It is imperative to explore effective and environment-friendly antibacterial modality to defeat antibiotic-resistant bacteria with high biosafety and broad-spectrum antibacterial property.ResultsHerein, biocompatible Cu3SnS4 nanoflakes (NFs) were prepared by a facile and low-cost fabrication procedure. These Cu3SnS4 NFs could be activated by visible light, leading to visible light-mediated photocatalytic generation of a myriad of reactive oxygen species (ROS). Besides, the plasmonic Cu3SnS4 NFs exhibit strong near infrared (NIR) absorption and a high photothermal conversion efficiency of 55.7%. The ROS mediated cellular oxidative damage and the NIR mediated photothermal disruption of bacterial membranes collaboratively contributed to the advanced antibacterial therapy, which has been validated by the efficient eradication of both Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus strains in vitro and in vivo. Meanwhile, the exogenous copper ions metabolism from the Cu3SnS4 NFs facilitated the endothelial cell angiogenesis and collagen deposition, thus expediting the wound healing. Importantly, the inherent localized surface plasmon resonance effect of Cu3SnS4 NFs empowered them as an active substrate for surface-enhanced Raman scattering (SERS) imaging and SERS-labeled bacteria detection.ConclusionsThe low cost and biocompatibility together with the solar-driven broad-spectrum photocatalytic/photothermal antibacterial property of Cu3SnS4 NFs make them a candidate for sensitive bacteria detection and effective antibacterial treatment.Graphical

Chemical Composition and Biological Activities of Marrubium vulgare L

The present study was conducted to evaluate the antioxidant and antibacterial activity of the extract of leaves and flowering of Marrubium vulgare L. The quantification of total phenols was determined using the Folin-Ciocalteu reagent, it is 2.23 mg EAG/g DM. The identification of flavonoids by the Alcl3 method, revealed the presence of anthocyanins, C-glycosides and aglycones, whose contents are 1.266mg/g, 0.385mg/g and 0.0331 mg/g, respectively. The antioxidant activity of the compounds in the methanolic extract was evaluated in vitro through two tests. In the case of DPPH test, the IC50 are 0.55, 0.97, and 1.2, 0.033 mg/ml for anthocyanins, c-glycosides, polyphenols and aglycones respectively. For FRAP assay, at a concentration of 1 mg/ml, the reducing power of iron manifested ODs of 1.389 nm; 0.752 nm, 0.496 and 0.114 nm for anthocyanins, C-glycosides, total polyphenols and aglycones respectively. The results show an excellent correlation between the two tests used, and the contents of anthocyanins and c-glycosides. The antimicrobial activity was evaluated by the agar diffusion method against (ATCC 25923), (ATCC 25922). The antibiogram shows that anthocyanins have a very Staphylococcus aureus Escherichia coli important antibacterial activity on with an inhibition zone of 16.5 mm and a diameter of 13.5 for Anthocyanins show S. aureus Escherichia coli. the lowest MIC values against the two strains and (MIC=1/16 and 1/8 respectively). C-glycosides also Staphylococcus aureus Escherichia coli have an inhibitory effect on the growth of and particularly on (MIC= 1/32 and 1/8 respectively) which is Escherichia coli Staphylococcus aureus a sensitive bacterium (gram+). Anthocyanins have marked a strong sensitivity towards the two strains. In conclusion, this work presents the compounds of L as novel antimicrobial agents and as a potential source for combating bacteria, which are increasingly Marrubium vulgare resistant to antibiotics

Target recognition triggered CRISPR-Cas12a assisted allosteric scaffold for sensitively analyzing bacterial infection after dental implantation

Accurate identification and sensitive quantification of infected bacteria after dental implant both play crucial roles in early-diagnosis of bacterial infection and guiding medicine applications. Herein, we propose a sensitive and accurate bacteria detection method based on CRISPR-Cas12a system assisted allosteric scaffold. In the method, the allosteric scaffold takes the responsibility of specifically identifying target bacteria and inducing CRISPR-Cas12a based signal amplification. Eventually, the method exhibits a wide detection range from 6 × 106 cfu/mL to 6 × 102 cfu/mL with the limit of detection (LOD) of 47 cfu/mL. Furthermore, the established approach also possesses a high specificity due to high selectivity of aptamer and robust accuracy in recognizing double strand DNA by CRISPR-Cas12a system. We believe that this work can provide new strategies in the field of diagnosing bacterial infections after dental implantation.