Volatiles Composition and Antimicrobial Activities of Areca Nut Extracts Obtained by Simultaneous Distillation–Extraction and Headspace Solid-Phase Microextraction

The volatile components of areca nuts were isolated by headspace solid-phase microextraction (HS-SPME, DVB/CAR/PDMS fiber extraction) and simultaneous hydrodistillation–extraction (SHDE) and analyzed by gas chromatography/mass spectrometry. Furthermore, all SHDE fractions were tested for antimicrobial activity using the disk diffusion method on nine Gram-negative and Gram-positive bacteria (Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus canis, Streptococcus pyogenes, and Candida albicans). In total, 98 compounds (mainly alcohols, carbonyl compounds, fatty acids, esters, terpenes, terpenoids, and aliphatic hydrocarbons) were identified in SHDE fractions and by using SPME extraction Fatty acids were the main group of volatile constituents detected in all types of extracts. The microorganism most sensitive to the extract of the areca nut was Streptococcus canis. The results can provide essential information for the application of different treatments of areca nuts in the canning industry or as natural antibiotics.     

In vitro antimicrobial studies of naphthalen-1-ylmethyl substituted silver N-heterocyclic carbene complexes

Seven novel naphthalen-1-ylmethyl substituted silver N-heterocyclic carbene (Ag–NHC) complexes (1–7) were synthesized by the interaction of benzimidazolium salts with silver carbonate in dry dichloromethane at room temperature and characterized by means of spectroscopic methods and elemental analysis techniques. The Ag–NHC compounds were tested for their in vitro antibacterial and antifungal activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Candida albicans and Candida tropicalis and showed high antimicrobial activities. The synthesized complexes, in particular, demonstrated better results against both fungi and gram-positive bacteria.     

Antioxidant and antimicrobial properties of Casteanea sativa Miller chestnut honey produced on Mount Etna (Sicily)

The aim of this study was the evaluation of antibacterial and antioxidant properties of Monofloral Etna Castanea sativa Miller honeys. Escherichia coli ATCC 25,922, Pseudomonas aeruginosa ATCC 27,853, Enterococcus faecalis ATCC 29,211 and Staphylococcus aureus ATCC 29,213 were investigated for their susceptibilities to two different honeys. Antioxidant activity was evaluated by ORAC, NO scavenger assays, FRAP and DPPH. Antioxidant activity and antibacterial properties were compared with chestnut honeys from different geographical areas and with Manuka honey. UPLC-MS/MS was used for major components characteri sation.     

Antibacterial and Chemical Characterization of Silica-Quercetin-PEG Hybrid Materials Synthesized by Sol–Gel Route

This paper aims to synthesize, via the sol–gel method, a biomaterial usable in the medical field. Here, the silica-PEG-quercetin system was evaluated in relation to the different concentrations of PEG (0, 6, 12, 24, 50 wt%) and quercetin (0, 5, 10, 15 wt%), respectively. In addition, Fourier Transform-Infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Kirby–Bauer analyses were performed. FT-IR was used to evaluate the hybrid formation and the influence of both PEG and Quercetin in the hybrid synthesized materials, SEM was used to evaluate the morphological properties, while the Kirby–Bauer test was used to understand the ability of the materials to inhibit the growth of the assayed bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Staphylococcus aureus).     

Green synthesis of AgNPs from aqueous extract of Oxalis corniculata and its antibiofilm and antimicrobial activity

The silver nanoparticles OC-AgNPs, synthesized from the aqueous extract of Oxalis corniculata (OC), showed antiviral activity against Herpes Simplex Virus-1 (HSV-1), and anti-biofilm, and antibacterial activities against human isolates of six multi-drug resistant (MDR) bacteria - Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, and Pseudomonas aeruginosa. The OC-AgNP was characterized by UV-Vis and FTIR spectroscopy; while its morphology and distribution were determined by transmission electron microscopy (TEM). The results revealed that the biogenic OC-AgNPs are spherical with an average diameter of 40 nm and has shown UV-Vis peak at 445 nm. The cytotoxicity and safety of OC-AgNP has been evaluated by MTT assay in Vero cells and triple-negative human breast cancer MDA-MB-468 cells. The plaque reduction assay has been used to test the antiviral activity against HSV-1F. The anti-biofilm activity was assessed by crystal violet staining, followed by light and confocal microscopy; while the antibacterial activity was determined by conventional disk-diffusion and broth-dilution methods. Moreover, the mechanism of anti-biofilm and antibacterial activity was examined by Field Emission Scanning Electron Microscopy (FESEM). The CC₅₀ (cytotoxicity) on Vero cells was 300 μg/ml; while the survival percentage of MDA-MB-468 cells was 27.12% at 20 μM and 80.97% at 100 μM of, respectively. The OC-AgNP showed moderate antiviral activity against HSV-1F at EC₅₀ of 25 μg/ml; but significantly inhibited the biofilm produced by Pseudomonus aeruginosa and Escherichia coli at 25-50 μg/ml; while at 30-50 μM we observed the dose-dependent lowering of fluorescence intensity under light and confocal microscope. Interestingly, the OC-AgNPs demonstrated significant antibacterial activity against Pseudomonas aeruginosa (20 mm), Klebsiella pneumoniae (15 mm), Escherichia coli (12 mm), Salmonella typhi (10 mm), Streptococcus pyogenes (11 mm) and Staphylococcus aureus (10 mm) with Minimum Inhibitory Concentration (MIC) of 0.65–0.90 μM (0.11- 0.153 μg), respectively. Further, the FESEM micrograph showed disruption of membrane structure with the damage of cell membrane integrity of Pseudomonus aeruginosa at its MIC.     

Antibacterial susceptibility of bacteria isolated from burns and wounds of cancer patients

In this study 540 burns and wound swabs were collected from cancer patients of some Egyptian hospitals. The single infection was detected from 210, and 70 cases among wounded and burned patients, while mixed infection was 30 and 45, respectively. We recovered where 60 isolates of Pseudomonas aeruginosa, 60 isolates of Staphylococcus aureus, 7 isolates of Staphylococcus epidermidis, 4 isolates of Streptococcus pyogenes, 25 isolates of Escherichia coli, 23 isolates of Klebsiella pneumoniae and 27 isolates of Proteus vulgaris from 355 burn and surgical wound infections . All bacterial isolates showed high resistance to the commonly used β-lactams (amoxycillin, cefaclor, ampicillin, vancomycin, amoxicillin/clavulonic), and low resistance to imepenim and ciprofloxacin. Plasmid analysis of six multidrug resistant and two susceptible bacterial isolates revealed the same plasmid pattern. This indicated that R-factor is not responsible for the resistance phenomenon among the isolated opportunistic bacteria. The effect of ultraviolet radiation on the isolated bacteria was studied.     

Synthesis,characterization and antimicrobial screening of quinoline based quinazolinone-4-thiazolidinone heterocycles

In an attempt to find new pharmacologically active molecules, we report here the synthesis and in vitro antimicrobial activity of various 2-(2-chloro-6-methyl(3-quinolyl))-3-[2-(4-chlorophenyl)-4-oxo(3-hydroquinazolin-3-yl)]-5-[(aryl)methylene]-1,3-thiazolidin-4-ones. In vitro antimicrobial activity of the title compounds are screened against two Gram positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), two Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and three strains of fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus) using broth micro dilution method. Some derivatives bearing chloro or hydroxy group exhibited very good antimicrobial activity.     

In Silico and Experimental Investigation of the Biological Potential of Some Recently Developed Carprofen Derivatives

The efficient regioselective bromination and iodination of the nonsteroidal anti-inflammatory drug (NSAID) carprofen were achieved by using bromine and iodine monochloride in glacial acetic acid. The novel halogenated carprofen derivatives were functionalized at the carboxylic group by esterification. The regioselectivity of the halogenation reaction was evidenced by NMR spectroscopy and confirmed by X-ray analysis. The compounds were screened for their in vitro antibacterial activity against planktonic cells and also for their anti-biofilm effect, using Gram-positive bacteria (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). The cytotoxic activity of the novel compounds was tested against HeLa cells. The pharmacokinetic and pharmacodynamic profiles of carprofen derivatives, as well as their toxicity, were established by in silico analyses.     

Synthesis and antibacterial activities of copper(II) with [(2-hydroxy-3,5-diiodo-benzylidene)-amino]-acetic acid

A new tridentate ligand, [(2-hydroxy-3,5-diiodo-benzylidene)-amino]-acetic acid (HDBA), has been synthesized from 3,5-diiodosalicylaldehyde and glycine in ethanol. A 1-D coordination polymer has been synthesized by reaction of HDBA with Cu(Ac)₂ · H₂O in ethanol–water. The complex was characterized by UV, IR, ESI–MS, elemental analyses, and X-ray crystallography. The central copper(II) is five-coordinate by one nitrogen and two oxygens from HDBA, one oxygen from water, and one oxygen from another HDBA. The complex was assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae) activities by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide method. Complex 1 showed favorable antimicrobial activity with minimum inhibitory concentrations of 6.25, 6.25, 3.125, 6.25, 6.25, and 3.125 µg mL^?1 against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae, respectively.     

Synthesis,characterization and in vitro antimicrobial screening of quinoline nucleus containing 1,3,4-oxadiazole and 2-azetidinone derivatives

A series of 3-chloro-1-(aryl)-4-(2-(2-chloro-6-methylquinolin-3-yl)-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl)-4-ethyl-azetidin-2-ones (V)_1–12 have been synthesized and characterized by IR, ¹H NMR, ¹³C NMR and mass spectra. Synthesized compounds were screened for their antibacterial activity against four different strains like Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes, while antifungal activity was determined against three different strains like Candida albicans, Aspergillus niger and Aspergillus clavatus. On the basis of statistical analysis, it has been observed that compounds gave significant co-relation.     

Sintered and 3D-Printed Bulks of MgB2-Based Materials with Antimicrobial Properties

Pristine high-density bulk disks of MgB₂ with added hexagonal BN (10 wt.%) were prepared using spark plasma sintering. The BN-added samples are machinable by chipping them into desired geometries. Complex shapes of different sizes can also be obtained by the 3D printing of polylactic acid filaments embedded with MgB₂ powder particles (10 wt.%). Our present work aims to assess antimicrobial activity quantified as viable cells (CFU/mL) vs. time of sintered and 3D-printed materials. In vitro antimicrobial tests were performed against the bacterial strains Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Enterococcus faecium DSM 13590, and Enterococcus faecalis ATCC 29212; and the yeast strain Candida parapsilosis ATCC 22019. The antimicrobial effects were found to depend on the tested samples and microbes, with E. faecium being the most resistant and E. coli the most susceptible.     

Synthesis,characterization and crystal structures of new Zinc(II) and Nickel(II) complexes containing morpholine moiety and their antibacterial studies

The ligand 1,2-dimorpholinoethane (DME) was used to prepare Zn(II) and Ni(II) complexes of the general formulation MLX₂ (L = DME, X = Cl or NO₃). Zinc(II) complex exhibits spectral properties indicative of a distorted tetrahedral geometry, with DME coordinating through two nitrogen atoms and two chlorides completing the tetrahedron. This is in contrast to the six-coordinated, distorted octahedral geometry exhibited by nickel(II) complex of DME when NO₃ was used as counter ions. The X-ray diffraction confirms the structures of two complexes and shows that the ligand coordinates through two nitrogen atoms while the two ether linkages are not involved in complexation, which would have been the case if the morpholine rings were in the boat form. The ligand and related complexes have antibacterial activity against the five Gram-positive bacteria: Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Streptococcus pyogenes and also against the three Gram-negative bacteria: Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442 and Klebsiella pneumonia ATCC 70063. The results showed that in some cases the antibacterial activity of the complexes exceeded the one of sulfisoxazole used as a standard.     

Antimicrobial activity of spices essential oils and its effectiveness on mature biofilms of human pathogens

Abstract

The antibacterial activity of Pimpinella anisum L., Cinnamomum zeylanicum, Syzygium aromaticum, and Cuminum cyminum L. essential oils (EOs) against some common pathogenic microorganisms (Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 14990, Enterococcus faecalis ATCC 29212, Streptococcus pyogenes ATCC 1915, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 27853, Aeromonas hydrophila ATCC 7966, Proteus mirabilis ATCC 10005, Klebsiella pneumoniae ATCC 13883, and Candida albicans ATCC 10231) and their biofilms was studied. The EOs inhibitory effects were evaluated by both Agar Well Diffusion assay and Minimum Inhibitory Concentration (MIC) determination. The most active EOs, cinnamon and cloves, were also tested on 18, 24, 48, 72?hours mature biofilms. Cinnamon and cloves exhibited the best results showing a significant activity against all the tested bacteria. Concerning biofilm, results suggest that Cinnamomum zeylanicum oil may be a useful approach to impair the biofilm produced by the tested Gram-negative bacteria.      

Bacteriocin PJ4 Active Against Enteric Pathogen Produced by Lactobacillus helveticus PJ4 Isolated from Gut Microflora of Wistar Rat (Rattus norvegicus): Partial Purification and Characterization of Bacteriocin

The increase of multidrug-resistant pathogens and the restriction on the use antibiotics due to its side effects have drawn attention to the search for possible alternatives. Bacteriocins are small antimicrobial peptides produced by numerous bacteria. Much interest has been focused on bacteriocins because they exhibit inhibitory activity against pathogens. Lactic acid bacteria possess the ability to synthesize antimicrobial compounds (like bacteriocin) during their growth. In this study, an antibacterial substance (bacteriocin PJ4) produced by Lactobacillus helveticus PJ4, isolated from rat gut microflora, was identified as bacteriocin. It was effective against wide assay of both Gram-positive and Gram-negative bacteria involved in various diseases, including Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Enterococcus faecalis, and Staphylococcus aureus. The antimicrobial peptide was relatively heat-resistant and also active over a wide pH range of 2–10. It has been partially purified to homogeneity using ammonium sulfate precipitation and size exclusion chromatography and checked on reverse-phase high-performance liquid chromatography. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis of bacteriocin PJ4 purified through size exclusion chromatography resolved ~6.5 kDa protein with bacteriocin activity. The peptide is inactivated by proteolytic enzymes, trypsin, and lipase but not when treated with catalase, α-amylase, and pepsin. It showed a bactericidal mode of action against the indicator strains E. coli MTCC443, Lactobacillus casei MTCC1423, and E. faecalis DT48. Such characteristics indicate that this bacteriocin may be a potential candidate for alternative agents to control important pathogens.     

Antimicrobial Activity of MgB2 Powders Produced via Reactive Liquid Infiltration Method

We report for the first time on the antimicrobial activity of MgB₂ powders produced via the Reactive Liquid Infiltration (RLI) process. Samples with MgB₂ wt.% ranging from 2% to 99% were obtained and characterized, observing different levels of grain aggregation and of impurity phases. Their antimicrobial activity was tested against Staphylococcus aureus ATCC BAA 1026, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. A general correlation is observed between the antibacterial activity and the MgB₂ wt.%, but the sample microstructure also appears to be very important. RLI-MgB₂ powders show better performances compared to commercial powders against microbial strains in the planktonic form, and their activity against biofilms is also very similar.     

Synthesis and Evaluation of Antimicrobial Activity of Some New Hetaryl‐Azoles Derivatives Obtained from 2‐Aryl‐4‐methylthiazol‐5‐carbohydrazides and Isonicotinic Acid Hydrazide

A series of new 1,3,4‐oxadiazole/thiadiazole and 1,2,4‐triazole derivatives have been synthesized starting from 2‐aryl‐4‐methylthiazol‐5‐carbohydrazides and isonicotinic acid hydrazide. All the newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectrometry. The synthesized compounds were screened for their antibacterial and antifungal activity, assessed as growth inhibition diameter. Some of them showed good antibacterial activity against gram positive Staphylococcus aureus, while the antibacterial activity against Listeria monocytogenes, Escherichia coli, and Salmonella typhymurium and antifungal activity against Candida albicans was modest. None of the tested compounds showed inhibitory activity against gram positive bacteria Enterococcus faecalis and Bacillus cereus and against gram negative bacteria Pseudomonas aeruginosa.     

Potential bioactive secondary metabolites of Actinomycetes sp. isolated from rocky soils of the heritage village Rijal Alma,Saudi Arabia

The present study was designed to discover novel secondary antibiotic metabolites from Actinomycetes species from the soil of Rijal Almaa, Saudi Arabia. A laboratory-scale benchtop fermentation was utilized for the demonstration of antibiotics from the soil actinomycetes. Fourier transform-infrared spectroscopy (FT-IR) spectroscopy analysis of the fermented product (FP) was carried out, which showed unique fingerprint regions indicating the presence of phenolic hydroxyl groups, aliphatic compounds, carboxylic groups, esters, isothiocyanate, etc. GC-MS analysis of the FP depicted the unique structures of secondary metabolites, such as cyclononasiloxane octadecamethyl, cercosporin, ethyl iso-allocholate, octadecane, 3-ethyl-5-(2-ethylbutyl), dasycarpidan-1-methanol (acetate), heptadecane, 9-hexyl-, phthalic acid-butyl, and octadecane, 3-ethyl-5-(2-ethylbutyl). The TGA analysis showed the thermal stability of FP and the initial weight loss in FP was observed at 277.29 °C. The ¹H NMR and ¹³C NMR spectra of FP analysis demonstrated the various characteristic peaks presence of secondary metabolites. The XRD analysis at 2θ revealed distinct particles based on specific diffraction peaks. A set of six human bacterial pathogens, namely, the Gram-positive bacteria Staphylococcus aureus (S. aureus), Streptococcus pyogenes (S. pyogenes), and Bacillus subtilis (B. subtilis) and Gram-negative bacteria Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), and Klebsiella pneumoniae (K. pneumoniae), were utilized for screening. The FP exhibited promising antibacterial effects against both Gram-positive and Gram-negative bacterial organisms. The antibacterial spectrum of activity was greater for E. coli and B. subtilis than for K. pneumoniae.     

Synthesis,identification and antimicrobial activity of substituted thiazolines and 1,3,4-thiadiazines from dehydroacetic acid

The reaction of thiosemicarbazones with various α-chloroketones in the presence of anhydrous NaOAc led to 4-thiazolines 5, 7 or 1,3,4-thiadiazines 11 in good yields. Structure elucidation was carried out by ¹H, ¹³C, and FT-IR spectroscopy. The purity of these new products was confirmed by HRMS. A possible mechanism for the formation of 5, 7, and 11 was discussed. All the synthesized novel 4-thiazoline and 1,3,4-thiadiazine derivatives were evaluated in vitro for their antibacterial and antifungal activities against six pathogenic bacteria and a strain of yeast: Escherichia coli ATCC 25992, Pseudomonas aeruginosa ATCC 27852, Staphylococcus aureus ATCC 25923 methicillin-resistant, Staphylococcus aureus ATCC 43300 methicillin-sensitive, Micrococcus luteus ATCC 4698 Enterococcus faecalis ATCC 29212 and Candida albicans IPA (200). Some compounds exhibited relatively significant antibacterial and antifungal activities.     

Antimicrobial effects of vanillin-based pyridyl-benzylidene-5-fluoroindolins

In this study, the antimicrobial effect and DNA gyrase inhibitor potential of vanillin-based pyridyl–substituted fluoro-indolines were evaluated. These compounds are synthesized and established through green-chemistry approaches. The inhibition effect on both DNA gyrase A and B was evaluated in silico and in vitro. Agar well diffusion method–based antimicrobial activity against Gram-ve Pseudomonas aeruginosa (MTCC 424) and Escherichia coli (MTCC 443), Gram+ve Streptococcus pyogenes (MTCC 442) and Staphylococcus aureus (MTCC 96), and a clinical isolate of Candida albicans (Fungi) was evaluated. The cytotoxicity of the compounds was assessed over macrophages using the MTT assay. In the results, the target compounds exhibited a broad-spectrum antimicrobial activity against both bacterial types and fungal.     

Spectral characterization and biological evaluation of Schiff bases and their mixed ligand metal complexes derived from 4,6-diacetylresorcinol

In the present study two new series of Copper(II), Nickel(II) and Cobalt(II) complexes with two newly synthesized Schiff base ligands 4,6-bis(1-(4-bromophenylimino)ethyl)benzene-1,3-diol (H₂L¹), 4,6-bis(1-(4-methoxyphenylimino) ethyl)benzene-1,3-diol (H₂L²) and organic ligands 8-hydroxy quinoline, 1,10-phenanthroline have been prepared. The Schiff bases H₂L¹ and H₂L² ligands were synthesized by the condensation of 4,6-diacetyl resorcinol with 4-bromo aniline and 4-methoxy aniline. The ligands and their metal complexes have been characterized by FT-IR, Mass, ¹H NMR, UV–Vis., elemental analysis, ESR and Thermal gravimetric analysis. The Schiff base and their metal complexes were tested for antimicrobial activity against gram positive bacteria Staphylococcus aureus, Streptococcus pyogenes and gram negative bacteria Escherichia coli, Pseudomonas aeruginosa and fungus Candida albicans, Aspergillus niger and Aspergillus clavatus using Broth Dilution Method.