Gram-positive Bacterial Strains Research Articles

Biomedical and therapeutic potential of marine-derived Pseudomonas sp. strain AHG22 exopolysaccharide: A novel bioactive microbial metabolite

Abstract Microbial exopolysaccharides (EPSs) are gaining interest as alternatives to chemical antioxidants and pharmaceuticals. This study mines the promising biomedical and antimicrobial potential of a marine bacterium, a prolific EPS producer, isolated from the Red Sea. Pseudomonas sp. strain AHG22 generated an EPS weighing 6.98 g·L−1, coded EPSF8, subjected to FT-IR and HPLC chemical analysis. EPSF8 was then investigated for antioxidant assessment by 2,2-diphenyl-1-picrylhydrazyl (DPPH), H2O2, ABTS˙ + , nitric oxide, total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP). EPSF8 had an IC50 of 46.99 μg·mL−1 in the DPPH antioxidant assay and antioxidant capacities of 219.45 μg·mg−1 ascorbic acid equivalent (AAE) in the TAC assay and 54.15 μg·mg−1 AAE in the FRAP assay. The in vitro anti-inflammatory effect of EPSF8 was tested against 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) enzymes and compared with the drugs ibuprofen and celecoxib used as controls. The IC50 values of 5-LOX, COX-2, ibuprofen, and celecoxib were found to be 14.82, 15.49, 1.5, and 0.28 μg·mL−1, respectively. Additionally, EPSF8 revealed antidiabetic activity toward α-amylase and α-glucosidase, and the IC50 values were 93.1 and 127.28 μg·mL−1, compared to those of acarbose (50.93 and 4.13 μg·mL−1, respectively). Anti-obesity activity of EPSF8 by lipase inhibition revealed IC50 = 56.12 μg·mL−1 compared to orlistat (IC50 = 20.08 μg·mL−1) as a control. EPSF8 displayed antibiofilm and bactericidal activity against Gram-positive (G +ve) and Gram-negative (G −ve) ATCC pathogenic bacterial strains. It had a minimum bactericidal concentration/minimum inhibitory concentration ratio ≤2, indicating a broad bactericidal spectrum. Furthermore, EPSF8 is evidenced to have a promising anti-butyrylcholinesterase activity for the control of Alzheimer’s disease. The findings of the present analysis suggest that the isolated Pseudomonas sp. strain AHG22 EPS can potentially be explored as a promising green therapeutic compound.

Superior antibacterial performance of surfactant-assisted ZnO nanoflakes produced via Co-precipitation method

Microbiological infections are one of the major problems that modern people encounter. Zinc oxide (ZnO) nanoflakes are excellent antimicrobial agents. The objective of this work was to synthesize ZnO nanoflakes with the assistance of surfactants and investigate the processes behind their antibacterial properties. The experiment involved the synthesis of ZnO using several surfactants, including cetyl trimethyl ammonium bromide (CTAB), polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG), and its analysis using XRD, FT-IR, SEM, EDAX, and BET methods. Both Gram-positive and Gram-negative bacterial strains were used in these investigations. ZnO nanoflakes aided by CTAB (R-2) had the most promising action against the tested bacterial strains like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Bacillus cereus. These ZnO nanoflakes with CTAB assistance consistently had greater inhibitory zones than other samples. The R-2 sample’s enhanced surface area and particle size, which result in improved antibacterial activity. The investigation’s outcomes show that the produced nanoflakes have the potential to be useful in antibacterial and other medicinal applications.

Design, synthesis, and evaluation of N1,N3-dialkyldioxonaphthoimidazoliums as antibacterial agents against methicillin-resistant Staphylococcus aureus

Increasing antibiotic resistance of bacterial pathogens poses a serious threat to human health worldwide. Methicillin-resistant Staphylococcus aureus (MRSA) is among the most deleterious bacterial pathogens owing to its multidrug resistance, necessitating the development of new antibacterial agents against it. We previously identified a novel dioxonaphthoimidazolium agent, c5, with moderate antibacterial activity against MRSA from an anticancer clinical candidate, YM155. In this study, we aimed to design and synthesize several novel cationic amphiphilic N1,N3-dialkyldioxonaphthoimidazolium bromides with enhanced lipophilicity of the two side chains in the imidazolium scaffold and improved antibacterial activities compared to those of c5 against gram-positive bacteria in vitro and in vivo. Our new antibacterial lead, N1,N3-n-octylbenzyldioxonaphthoimidazolium bromide (11), exhibited highly potent antibacterial activities against various gram-positive bacterial strains (MICs: 0.19–0.39 μg/mL), including MRSA, methicillin-sensitive S. aureus, and Bacillus subtilis. Moreover, antibacterial mechanism of 11 against MRSA based on the generation of reactive oxygen species (ROS) was evaluated. Although compound 11 exhibited cytotoxic effects in vitro and lacked a therapeutic index against the HEK293 and HDFa mammalian cell lines, it exhibited low toxicity in the Drosophila animal model. Remarkably, 11 exhibited better in vivo antibacterial efficacy than c5 and the clinically used antibiotic, vancomycin, in SA3-infected Drosophila model. Moreover, the development of bacterial resistance to 11 was not observed after 16 consecutive passages. Therefore, rational design of antibacterial cationic amphiphiles based on ROS-generating pharmacophores with optimized lipophilicity can facilitate the identification of potent antibacterial agents against drug-resistant infections.

Synthesis, characterization, antimicrobial and antioxidant activity of 2- (2′-hydroxyphenyl) -1,3,4-oxadiazolyl-5-amino acid derivatives

The synthesis and biological assessment of 2,5-disubstituted-1,3,4-oxadiazoles derivatives from amino acids as new potential antibacterial and antioxidant agents have been reported. The structures of the new synthesized compounds were characterized based on physicochemical and spectral data UV–Visible, IR, 1HNMR, 13CNMR. All the target compounds were screened for theirin vitroantibacterial activityagainst three Gram-positivebacterial strains,namely Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 14579, Listeria innocua ATCC 33090, and two Gram-negative bacterial strains,namely Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, andantifungal activityagainst Candida albicans ATCC 10231 in comparison with Amoxicillin, Tetracycline, Gentamicin and Oxacillin. The only compound 1-{(4S)-4-amino-4-[5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl]butyl}guanidine 5e with the amine radical thatshowed excellent results against all bacteria, particularly against L. innocua (IZ = 12 mm), has excellent antifungal activity (IZ = 32 mm). The compounds 2-[5-(1-amino-3-methylbutyl)-1,3,4-oxadiazol-2-yl]phenol 5b and 2-[5-(pyrrolidin-2-yl)-1,3,4-oxadiazol-2-yl]phenol 5j have excellent activities (IZ = 27 and IZ = 28 mm, respectively) against B. cereus and P. aeruginosa. Compounds 2-{5-[(1R)-1-amino-2-sulfanylethyl]-1,3,4-oxadiazol-2-yl}phenol 5c, 2-{5-[(1S)-1-amino-3-(methylsulfanyl)propyl]-1,3,4-oxadiazol-2-yl}phenol 5dwith the sulfur radical, 3--[5-(2-3-amino hydroxyphenyl)-1,3,4-oxadiazol-2-yl]propanamide 5g with the amide radical, 5j with the amino radical, and 4-amino-4-[5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl]butanoic acid 5k gave good results against B. cereus, where 19 mm < IZ < 23 mm. We also found that compound 5j has the greatest activity (IZ = 33 mm) against C. albicans, followed by compounds 5e (IZ = 32 mm) and 5b (IZ = 30 mm). The synthesized compounds were also screened for radical scavenging antioxidant activities by DPPH, FRAP, and TAC assays and found to be good antioxidant agents. According to the IC50 values, all compounds demonstrated good to excellent activity, especially 5b and 2-{5-[1-amino-2-(1H-imidazol-4-yl)ethyl]-1,3,4-oxadiazol-2-yl}phenol 5i for DPPH, 5e and 5i for FRAP and methyl 2-hydroxybenzoate 2,2-{5-[1-amino-2-(1H-indol-3-yl)ethyl]-1,3,4-oxadiazol-2-yl}phenol 5h with the imidazol group and 2-[5-(1,5-diaminopentyl)-1,3,4-oxadiazol-2-yl]phenol 5f with the imidazol group for TAC. All these compounds showed better activity than AA and BHT.

Chemical Profiling of Citrus fruit-peel and stem extracts by modified UHPLC-TOF-MS and their Antiplasmodial, Antioxidant and Antimicrobial Activities

Citrus jambhiri (Lush) and paradisi (Macf.) have wide usage as food spices. Therefore, the presence of profiled phytochemicals, the antioxidant, antimicrobial and anti-plasmodial activities of the stem and fruit-peel extracts were studied. The citrus stem and fruit-peel extracts were analyzed using ultra-high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC-qTOF/MS) and anti-plasmodial activities against chloroquine-sensitive (CQS) strain of Plasmodium falciparum, antimicrobial against Gram-positive and Gram-negative bacterial strains as well as antioxidant potentials were determined in triplicate. Metabolite fingerprinting of C. jambhiri stem and C. paradisi fruit-peel extracts revealed rutamarin and spicatin respectively. The stem and fruit-peel of C. jambhiri showed moderate antimalarial activity. C. paradisi stem revealed a weak activity; however, C. paradisi fruit-peel showed no antimalarial activity (IC50 >100μg/mL). C. paradisi and C. jambhiri extracts exhibited lower inhibition concentration (IC50: 3.0-7.0 µgmL-1), than ascorbic acid (IC50: 9.0 µgmL-1). C. paradisi stem DCM/methanol extract showed a reducing value of EC50: 8.00 µgmL-1 whereas reference compound used, (ascorbic acid) had EC50: 11.00 µgmL-1. Furthermore, C. jambhiri stem extract showed the best antimicrobial activity against the clinical isolates with high inhibition zones ≥ 15mm. There is a paucity of information on the identification and importance of rutamarin and spicatin from Citrus extracts as a functional food ingredient with a promising compound implicated in the development of antimalarial drugs. Overall result however showed that the two citrus plants contain antioxidant constituents whereas C. jambhiri could be important source of antimicrobial agents. The study profiled two new compounds from the citrus extract and showed the potentials of the plant as source of antimalaria drug.

Quinoxaline clubbed thiazole: Molecular docking, synthesis and antimicrobial evaluation

Novel hybrid molecules of thiazole with quinoxaline have been designed, synthesized and characterised by FT-IR, Mass, 1H and 13C NMR spectroscopic techniques. The pharmacological potential of synthesized compounds was checked for bacterial and fungal strains by the Broth microdilution method. All molecules exhibited significant antibacterial and antifungal activities. The compound (E)-4-(4-chlorophenyl)-2-(2-(1-(3-methylquinoxalin-2-yl)ethylidene)hydrazinyl)thiazole (3b) displayed (MIC = 12.5 μg/mL) excellent biological potential against Staphylococcus aureus [MTCC96] gram-positive bacterial strain. The molecular docking of thiazole derivatives was performed with S. aureus DNA gyrase (2XCT). The docked molecules displayed significant interactions with the active cavity of S. aureus DNA gyrase. The (E)-4-(4-chlorophenyl)-2-(2-(1-(3-methylquinoxalin-2-yl)ethylidene)hydrazinyl)thiazole (3b) molecule displayed the most stable conformation at the highest binding affinity (−10.9 kcal/mol) among the docked molecules with protein.

Secondary metabolites and essential oil analysis of Clematis simensis with antioxidant and antibacterial activities

Clematis simensis is one of the most commonly used folk medicines in Ethiopia. This study was aimed to investigate the chemical constituents, antioxidant and antibacterial activities of the aerial part of Clematis simensis, and analysis of the composition of its essential oil. The phytochemical study led to the isolation of five compounds: 1-tricosanol (1), 1-hexacosanol (2), 2-deoxy-D-ribono-1,4-lactone (3), 5-hydroxylevulinic acid (4), and β-sitosterol-3-O-β-D-glucoside (5). Their chemical structures were determined by a comprehensive analysis of HR-ESI-MS, FT-IR, UV-Vis, and 1D/2D NMR experiments. The chemical compositions of the essential oils obtained by hydrodistillation from the aerial part of Clematis semenses were determined by GC-MS, which led to the detection of ten major compounds: (E)-2-nonen-1-ol (38.33%), 4-cyclopentene-1,3-dione (28.69%), cyclofenchene (5.65%), benzene acetaldehyde (4.74%), methyl salicylate (2.77%), salicylaldehyde (2.68%), benzaldehyde (2.60%), α-terpineol (2.10%), eucalyptol (1.21%), and 2,6-dimethylcyclohexanol (1.15%). Compound 4 showed high antioxidant activity (IC50 14.89 μg/mL) but has no antibacterial activity against both Gram-positive and Gram-negative bacterial strains. According to the antimicrobial parameters, crude extract showed very weak activity at 500 mg/mL, 250 mg/mL, and 125 mg/mL. To our knowledge, this is the first report on the isolation of secondary metabolites from Clematis simensis. KEY WORDS: Clematis simensis, Essential oil, Phytochemical investigation, Biological activities Bull. Chem. Soc. Ethiop. 2024, 38(4), 1037-1049.                                                       DOI: https://dx.doi.org/10.4314/bcse.v38i4.18       

Biofabrication of Silver Nanoparticles Using Green Seaweed: Characterisation and Antibacterial Evaluation

This study investigates the Chaetomorpha antennina (CA) seaweed-mediated biosynthesis of silver nanoparticles (AgNPs). The synthesis process of silver nanoparticles was monitored over time with the help of an Ultraviolet-visible spectrophotometer and further characterisation studies were also performed. Differential Light Scattering (DLS) measurements revealed a mean particle size of approximately 103.5nm and a mean zeta potential value of -57.5mV for AgNPs. The spherical shape and size of the AgNPs were confirmed through High-Resolution Transmission Electron Microscopy (HR-TEM) imaging, while Energy Dispersive X-ray Spectroscopy (EDAX) analysis provided insights into the elemental composition. The concentration of AgNPs was estimated using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The antibacterial potential of AgNPs was evaluated against both gram-positive (Bacillus cereus, Staphylococcus aureus and Bacillus subtilis) and gram-negative bacterial strains (Klebsiella pneumoniae, Escherichia coli, Shigella dysentriae, Salmonella typhi, Pseudomonas aeruginosa and Proteus mirabilis) using the agar well diffusion method. From the results, AgNPs exhibited significant antibacterial activity against B. subtilis and S. typhi among all the tested concentration levels (25, 50, 75 and 100μl).

Novel Adamantane Derivatives: Synthesis, Cytotoxicity and Antimicrobial Properties

Seventeen adamantane derivatives were synthesized according to facile condensation reaction protocols. Spectral analysis (1H NMR and 13C NMR) was applied to confirm the chemical structure of the obtained substances. The synthesized compounds were tested for in vitro antimicrobial activity against a panel of Gram-positive and Gram-negative bacterial strains and towards fungi from Candida spp. Among them, four derivatives numbered 9, 14, 15 and 19 showed the highest antibacterial potential with MIC = 62.5–1000 µg/mL with respect to all Gram-positive bacteria. S. epidermidis ATCC 12228 was the most susceptible among the tested bacterial strains and C. albicans ATCC 10231 among fungi. Additionally, the cytotoxicity for three derivatives was measured with the use of the MTT test on A549, T47D, L929 and HeLa cell lines. Our cytotoxicity studies confirmed that the tested substances did not cause statistically significant changes in cell proliferation within the range of the tested doses.

Isolation and Characterization of Glycolipid Biosurfactant Produced by Marine Bacterium Cobetia marina Strain F1 and Investigation of Antimicrobial and Anti-Biofilm Activity

The marine environment is a rich source of microorganisms producing bioactive compounds, like biosurfactant-producing bacteria that exhibit unique characteristics and functionalities. In this study, we examined glycolipid biosurfactants produced by bacteria that live commensally with marine organisms. We isolated a biosurfactant-producing strain identified as Cobetia marina strain F1, which displayed high hemolytic activity (27 mm), oil spreading ability (4 mm), emulsification index (40%), and decreasing surface tension to 31.3 (mN·m−1). Fourier transform infrared (FT-IR) spectroscopy revealed the glycolipid composition of the biosurfactant. Furthermore, elemental analysis utilizing CHNS and energy-dispersive X-ray spectroscopy (EDS) confirmed the biosurfactant contained carbon, hydrogen, nitrogen, sulfur, chlorine, potassium, oxygen, and additional elements. The critical micelle concentration (CMC) of the crude biosurfactant was determined to be 350 mg·L−1, at which concentration, a decrease in surface tension was observed when the biosurfactant was dissolved in distilled water. Given the presence of impurities in the biosurfactant composition, this observed CMC is considered acceptable. Furthermore, the biosurfactant exhibited significant antimicrobial activity against both Gram-positive and Gram-negative bacterial strains, with the largest zone of inhibition (ZOI) of 27 mm against Pseudomonas aeruginosa. This demonstrates the potential of the biosurfactant to serve as an alternative to novel antibiotic agents. The biosurfactant exhibited considerable inhibition of biofilm formation, disruption of preformed biofilms, and reduced enzymatic activity in bacterial cells following treatment. Moreover, the combination of the biosurfactant and F1 bacterial strain enhanced the degradation of crude oil by 86%, indicating its potential application in environmental remediation. These findings highlight the importance of investigating commensal strains capable to produce biosurfactants for applications in hydrocarbon remediation, overcoming antibiotic resistance, and biofilm disruption.

PHB Production by Bacillus megaterium LSRB 0103 Using Cornstarch and Urea.

Polyhydroxybutyrates (PHBs) are biopolymers that are good green alternative for synthetic carbon-based polymers, and are also one of the most researched members of the Polyhydroxyalkanoates (PHA) family. In this study, a gram-positive bacterial strain Bacillus megaterium LSRB 0103 was isolated from Pallikaranai Marshland, Chennai, India. Primary screening using Sudan Black dye revealed the presence of intracellular PHB granules. Minimal Davis Media (MDM) which was used or PHB production gave a yield of 0.7107g/L. Subsequently, using response surface methodology (RSM), a central composite design (CCD) model was designed for media optimization having cornstarch, urea, and pH as independent variables. The findings of the CCD model were fitted into a second-order polynomial equation. The RSM model predicted the maximum PHB yield of 0.93g/L, at these independent variable levels, cornstarch, 5g/L; urea, 2.1g/L; and pH 7.0; while the experimental PHB yield was 0.94g/L, with a percentage error of 1.1%. This study is the first-time report of production of PHB by Bacillus megaterium using cornstarch and urea as substrate.

Biosynthesis and antibacterial activity of ZnO nanoparticles using Buchanania obovata fruit extract and the eutectic-based ionic liquid

The fruit extract of Buchanania obovata and the eutectic-based ionic liquid were utilized, in an eco-friendly, inexpensive, simple method, for synthesizing zinc oxide nanoparticles (ZnO NPs). The influence of the reducing, capping and stabilizing agents, in both mediums, on the structure, optical, and morphological properties of ZnO NPs was extensively investigated. The surface plasmon resonance peaks were observed at 340 nm and 320 nm for the fruit-based and the eutectic-based ionic liquid mediums, respectively, indicating the formation of ZnO NPs. XRD results confirmed the wurtzite structure of the ZnO NPs, exhibiting hexagonal phases in the diffraction patterns. The SEM and TEM images display that the biosynthesized ZnO NPs exhibit crystalline and hexagonal shape, with an average size of 40 nm for the fruit-based and 25 nm for the eutectic-based ionic liquid. The Brunauer–Emmett–Teller (BET) surface area analysis, revealed a value ∼13 m2 g−1 for ZnO NPs synthesized using the fruit extract and ∼29 m2 g−1 for those synthesized using the eutectic-based ionic liquid. The antibacterial activity of the biosynthesized ZnO NPs was assessed against clinically isolated Gram-negative (E. coli) and Gram-positive (S. aureus) bacterial strains using the inhibition zone method. The ZnO NPs produced from the eutectic-based ionic liquids confirmed superior antibacterial activity against both S. aureus and E. coli compared to those mediated by the utilized fruit extract. At a concentration of 1000, the eutectic-based ionic liquid mediated ZnO NPs displayed a maximum inhibition zone of 16 mm against S. aureus, while against E. coli, a maximum inhibition zone of 15 mm was observed using the fruit extract mediated ZnO NPs. The results of this study showed that the biosynthesized ZnO NPs can be utilized as an efficient substitute to the frequently used chemical drugs and covering drug resistance matters resulted from continual usage of chemical drugs by users.

New strain Brevibacillus laterosporus TSA31-5 produces both brevicidine and brevibacillin, exhibiting distinct antibacterial modes of action against Gram-negative and Gram-positive bacteria.

The growing prevalence of antibiotic resistance has made it imperative to search for new antimicrobial compounds derived from natural products. In the present study, Brevibacillus laterosporus TSA31-5, isolated from red clay soil, was chosen as the subject for conducting additional antibacterial investigations. The fractions exhibiting the highest antibacterial activity (30% acetonitrile eluent from solid phase extraction) were purified through RP-HPLC. Notably, two compounds (A and B) displayed the most potent antibacterial activity against both Escherichia coli and Staphylococcus aureus. ESI-MS/MS spectroscopy and NMR analysis confirmed that compound A corresponds to brevicidine and compound B to brevibacillin. Particularly, brevicidine displayed notable antibacterial activity against Gram-negative bacteria, with a minimum inhibitory concentration (MIC) range of 1-8 μg/mL. On the other hand, brevibacillin exhibited robust antimicrobial effectiveness against both Gram-positive bacterial strains (MIC range of 2-4 μg/mL) and Gram-negative bacteria (MIC range of 4-64 μg/mL). Scanning electron microscopy analysis and fluorescence assays uncovered distinctive morphological alterations in bacterial cell membranes induced by brevicidine and brevibacillin. These observations imply distinct mechanisms of antibacterial activity exhibited by the peptides. Brevicidine exhibited no hemolysis or cytotoxicity up to 512 μg/mL, comparable to the negative control. This suggests its promising therapeutic potential in treating infectious diseases. Conversely, brevibacillin demonstrated elevated cytotoxicity in in vitro assays. Nonetheless, owing to its noteworthy antimicrobial activity against pathogenic bacteria, brevibacillin could still be explored as a promising antimicrobial agent.

Benzohydrazide as a good precursor for the synthesis of novel bioactive and anti-oxidant 2-phenyl-1,3,4-oxadiazol-aminoacid derivatives: Structural determination, biological and anti-oxidant activity

The synthesis and biological assessment of 2,5-disubstituted-1,3,4-oxadiazole derivatives from benzo hydrazide and amino acids as novel potential antioxidant and antibacterial agents have been reported. The structures of the new compounds were characterized by physicochemical properties and spectral methods. The synthesized compounds were screened for their in vitro antibacterial activity against three Gram-positive bacterial strains, namely Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 14579, Listeria innocua ATCC 33090, and two Gram-negative bacterial strains, namely Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, and antifungal activity against Candida albicans ATCC 10231 in comparison with Amoxicillin, Tetracycline, Gentamicin and Oxacillin as standards. Most of the compounds have excellent efficacy, and some of them, such as 5i, 5g, 5d, 5c, and 5j can inhibit their activity better or very close to that of Amoxicillin, Tetracycline, Gentamicin, Oxacillin used as standards. Compounds 5b and 5i provided good results against L. innocua with inhibition values of IZ = 14 mm and IZ = 22 mm, respectively, while the rest of the compounds and antibiotics were unable to inhibit it. Compounds 5c, 5d, 5g and 5j showed excellent activity against C. albicans with values between 31 mm and 34 mm. These results were better than all the standards used. The MIC value (25 µg/ml) for derivatives 5(c-e), 5g and 5(i-j) against B. cereus represent the best activity of the tested compounds. All the target compounds were also screened for radical scavenging antioxidant activities by DPPH, FRAP, and TAC assays and found to be excellent antioxidant agents. According to the results, it was observed that most derivatives synthesized showed excellent activity with a concentration of 250 µg/ml as an antioxidant agent (76 % < RSA < 95.5 %) which gave an inhibition percentage that was better or very close to that of ascorbic acid and better than BHT.

A photocrosslinkable and hemostatic bilayer wound dressing based on gelatin methacrylate hydrogel and polyvinyl alcohol foam for skin regeneration

The enormous potential of multifunctional bilayer wound dressings in various medical interventions for wound healing has led to decades of exploration into this field of medicine. However, it is usually difficult to synthesize a single hydrogel with all the required capabilities simultaneously. This paper proposes a bilayer model with an outer layer intended for hydrogel wound treatment. By adding gelatin methacrylate (GelMA) and tannic acid (TA) to the hydrogel composition and using polyvinyl alcohol-carboxymethyl chitosan (PVA-CMCs) foam layer as supports, a photocrosslinkable hydrogel with an optimal formulation was created. The hydrogels were then examined using a range of analytical procedures, including mechanical testing, rheology, chemical characterization, and in vitro and in vivo tests. The resulting bilayer wound dressing has many desirable properties, namely uniform adhesion and quick crosslinking by UV light. When used against Gram-positive and Gram-negative bacterial strains, bilayer wound dressings demonstrated broad antibacterial efficacy. In bilayer wound dressings with GelMA and TA, better wound healing was observed. Those without these elements showed less effectiveness in healing wounds. Additionally, encouraging collagen production and reducing wound infection has a major therapeutic impact on wounds. The results of this study could have a significant impact on the development of better-performing wound dressings.

Morin Hydrate Mediated Biosynthesis of Silver Nanoparticles and Its Antimicrobial Activity

Morin hydrate is a flavonoid that is chosen as an active ingredient for synthesizing silver nanoparticles. In order to characterize the morin hydrate assisted silver nanoparticles (MHNP), field emission scanning electron microscopy (FE-SEM), ultraviolet-visible spectrophotometry, energy dispersive X-ray spectroscopy (EDAX), dynamic light scattering analyzer (DLS) was used, and inductively coupled plasma-optical emission spectroscopy (ICP-OES) studies were used to determine the total amount of silver contained in the liquid state of the MHNP. Then, the formed nanoparticles were evaluated for antimicrobial effect. In the UV-visible spectroscopy, maximum absorption was observed at 444.5 nm, which is characteristic of silver nanoparticles. According to FE-SEM data, the generated nanoparticles were spherical, and DLS analysis determined that the average particle size was 83.4 nm. EDAX images additionally proved that silver was present in the sample. The antibacterial studies revealed that the nanoparticles were effective only against certain gram-positive bacterial strains; therefore, they can be used in biomedical applications, especially for treating infections caused by gram-positive bacteria.

Rakicidin J and K, two cytotoxic and antibacterial cyclic depsipeptides from the marine bacterium Micromonospora chalcea

Rakicidin J (1) and rakicidin K (2), two new cyclic depsipeptides, were isolated from culture broth of Micromonospora chalcea FIM-R150103. Their structures were elucidated by extensive analysis of NMR, HR-ESI-MS, and electronic circular dichroism (ECD) data. The two compounds showed strong cytotoxic activity against human colon carcinoma HCT-8 and human pancreatic cancer PANC-1 cells under normoxic and hypoxic conditions in the range of IC50 values from 0.024 to 0.79 μg/mL. Moreover, compounds 1 and 2 also showed moderate antibacterial activity against ten Gram-positive bacterial strains with MIC values ranging from 4 to more than 32 μg/mL. Structure–activity relationship of these two compounds with a close analogue, rakicidin B1, is also discussed.

Current Perspectives on Biological Screening of Newly Synthetised Sulfanilamide Schiff Bases as Promising Antibacterial and Antibiofilm Agents.

Growing resistance to antimicrobials, combined with pathogens that form biofilms, presents significant challenges in healthcare. Modifying current antimicrobial agents is an economical approach to developing novel molecules that could exhibit biological activity. Thus, five sulfanilamide Schiff bases were synthesized under microwave irradiation and characterized spectroscopically and in silico. They were evaluated for their antimicrobial and antibiofilm activities against both Gram-positive and Gram-negative bacterial strains. Their cytotoxic potential against two cancer cell lines was also determined. Gram-positive bacteria were susceptible to the action of these compounds. Derivatives 1b and 1d inhibited S. aureus's growth (MIC from 0.014 mg/mL) and biofilm (IC from 0.029 mg/mL), while compound 1e was active against E. faecalis's planktonic and sessile forms. Two compounds significantly reduced cell viability at 5 μg/mL after 24 h of exposure (1d-HT-29 colorectal adenocarcinoma cells, 1c-LN229 glioblastoma cells). A docking study revealed the increased binding affinities of these derivatives compared to sulfanilamide. Hence, these Schiff bases exhibited higher activity compared to their parent drug, with halogen groups playing a crucial role in both their antimicrobial and cytotoxic effects.

Synthesis, characterization and Antibacterial Evaluation of Novel Thiazolidine Derivatives

Background: Heterocyclic compounds, which incorporate atoms such as nitrogen and sulfur alongside carbon, play a crucial role in nature and organic chemistry. Thiazolidine derivatives, characterized by sulfur and nitrogen atoms with a carbonyl group at the -4 position, are particularly noteworthy for their stability and diverse biological activities. We synthesized novel thiazolidine derivatives and determined their antibacterial properties. the synthesis of novel thiazolidine compounds was perforemd using thioglycolic acid with hydrazides, generated from the combination of hydrazides with benzaldehyde. Methods: The esters, hydrazides, hydrazones, and thiazolidines, were synthesized and characterized using infrared spectroscopy, nuclear magnetic resonance, and melting point analysis. Assessment of anti-bacterial activity was carried out against Gram-positive and Gram-negative bacterial strain of Staphylococcus aureus, Acinetobacter baumannii, Aeromonas sobria, and Escherichia coli. . Results: We synthesized ethyl 2-acetate (benzo[d]thiazol-2-yloxy), followed by the formation of 2-(benzo[d]thiazol-2-yloxy)acetohydrazide (hydrazide) through the reaction of this acetate with hydrazine. 16 compounds were synthesized with rigorous validation at each stage through spectral analysis. Thiazolidine derivatives exhibited promising inhibitory effects against bacterial growth, indicating their potential as antibacterial agents.Compound SH8 exhibited moderate to strong inhibitory effects against all tested species, notably Aeromonas sobria and Staphylococcus aureus, at a concentration of 0.1 mg/ml. Conclusion: In conclusion, the synthesized compounds exhibited both structural integrity and potent antibacterial activity, suggesting avenues for further exploration in pharmaceutical research.

Synthesis, characterization and Antibacterial Evaluation of Novel 1,3-Oxazepine Derivatives Using A Cycloaddition Approach

This study demonstrated the synthesis and characterization of novel heterocyclic compounds, particularly oxazepine derivatives, using a cycloaddition procedure. The synthesis involved the reaction of chloroacetohydrazide with various aromatic aldehydes under acidic conditions in ethanol solvent to produce hydrazone compounds. These hydrazones subsequently underwent pericyclic synthesis with phthalic anhydride to yield oxazepine derivatives. The physicochemical properties of the synthesized compounds (F1 to F13) were characterized using FT-IR and H-NMR spectroscopy. The antibacterial activity of the synthesized oxazepine derivatives (F8, F9, F10, F11, F12, and F13) was evaluated against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterial strains using the cup plate agar diffusion technique. Notably, compounds F8, F9, and F10 exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria, suggesting their potential as effective antibacterial agents. Molecular docking studies were also conducted to investigate the binding interactions of selected compounds with bacterial protein receptors, specifically Escherichia coli K-12 (PDB ID: 4QGS) and Staphylococcus aureus (PDB ID: 7PQ1). The results demonstrate the potential of these novel oxazepine derivatives as antibacterial agents, highlighting their promising biological activities and molecular interactions with bacterial proteins.