Pathogenic Gram-positive Bacteria Research Articles

Pharmacological Evaluation of Novel Organoiron Dendrimers as Antimicrobial and Anti-Inflammatory Agents.

The synthesis of a novel and attractive class of nonsteroidal anti-inflammatory and antimicrobial organoiron dendrimers attached to the well-known drug ibuprofen is achieved. The structures of these dendrimers are established by spectroscopic and analytical techniques. The antimicrobial activity of these dendrimers is investigated and tested against five human pathogenic Gram-positive and Gram-negative bacteria, and minimum inhibitory concentrations are reported. Some of these synthesized dendrimers exhibit higher inhibitory activity against methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, andStaphylococcus warnericompare to the reference drugs. As well, the in vitro and in vivo anti-inflammatory activities of these dendrimers are evaluated. The results of in vivo anti-inflammatory activity and histopathology of inflamed paws show that all dendrimers display considerable anti-inflammatory activity; however, second-generation dendrimer(G2-D6)shows the best anti-inflammatory activity, which is more potent than the commercial drug ibuprofen at the same tested dose. Results of the toxicity study reveal that G2-D6is the safest drug on biological tissues.

Antimicrobial activity of Lavandula stoechas phenolic extracts against pathogenic bacteria isolated from a hospital in Morocco

The objective of this study was to determine the chemical families and the total phenolic content in a hydro-ethanolic extract of Lavandula stoechas, as well as to evaluate the antibacterial effect of the different phenolic fractions of this plant against pathogenic bacterial strains isolated from a hospital in the city of Fez, Morocco. The hydro-ethanolic extract was obtained and phytochemical screening of the different chemical families of the plant was conducted using colorimetric methods. The quantification of the total concentration of polyphenols in the L. stoechas extract was conducted according to the Folin–Ciocalteu method. The antimicrobial effects of the hydro-ethanolic, flavonoid and tannin extracts against Gram-positive and Gram-negative pathogenic bacteria isolated from a hospital in Fez were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for all pathogenic and reference strains. The total phenolic content of L. stoechas was 130.15 ± 3.72 mg gallic acid equivalent/g plant extract. The total phenolic content of L. stoechas was 130.15 ± 3.72 mg gallic acid equivalent/g plant extract. The flavonoid extract had the highest effect against bacteria, with MIC and MBC values varying from 10 to 40 mg/ml and 20–80 mg/ml, respectively. The results also revealed that the hydro-ethanolic extract showed a MIC value of 80 mg/ml against all bacteria except Acinetobacter baumanii and Pseudomonas aeruginosa (ATCC27853). The results obtained in our study showed an important antibacterial effect of flavonoid extracts from L. stoechas compared to other extracts. These results can aid in the discovery of new antimicrobial molecules of natural origin. Further research on phenolic compounds in L. stoechas is required.

Synthesis and evaluation of protein-based biopolymer in production of silver nanoparticles as bioactive compound versus carbohydrates-based biopolymers.

This overall process deals with evaluating the performance of silver nanoparticles, synthesized from sodium caseinate (SC) as green biological active agent, in comparison with widely produced from carboxymethyl cellulose, other carbohydrates (oxidized nanocellulose fibres (OC) and starch (St)). The TGA, FTIR and TEM, as well as its antimicrobial activities toward pathogenic Gram-positive and Gram-negative bacteria in addition to the yeast strain Candida albicans NRRL Y-477 were examined. In addition, with regard to their anti-tumour activity, the evaluation was studied via many cancer cell lines against RPE1 (normal retina cell line). The results revealed that the SC–Ag(I) and CMC–Ag(I) complexes were formed in six- and five-membered chelate rings, respectively, as nanoparticles, while linear chelation structure was formed in case of OC–Ag(I) and St–Ag(I) complexes. The complexation of SC with Ag(I) ions was recommended as promising stable and antimicrobial agent, with lower free Ag(I) ions and particle size than other Ag-complexes. Moreover, it provided anti-tumour activity of most tested cell lines (in vitro), with the following sequence HCT116 > PC3 > HePG 2 > MCF-7 > A549 with IC50 and IC90 values of 25.8 and 54.73 µg ml−1, 45.1 and 66.7 µg ml−1, 64.3 and 110.7 µgml−1, 71.4 and 114.8 µgml−1 and 80.1 and 127.7 µgml−1, respectively. The promising effect of SC–Ag complex was also clear from its selective index versus RPE1 (normal retina cell line).

Synthesis and Pharmacological Evaluation of 2-(4-(3 (Substituted Phenyl) Acryloyl) Phenoxy)-N, N Diphenylacetamides

Recently a series of Schiff bases of diphenylamine derivatives have been synthesized and evaluated in vitro for their antibacterial activity against pathogenic both Gram-positive bacteria B. subtitles and Gram-negative bacteria E. coli using ciprofloxacin as standard drug at conc. of 50 μg/ml and 100 μg/ml. Literature review revels that chalcones possesses various biological activities like antimicrobial, antiviral, anti-inflammatory, anticancer and sedative etc. Therefore the present study was designed on synthesis and pharmacological evaluation of 2-(4-(3 (Substituted Phenyl) Acryloyl) Phenoxy)-N, N Diphenylacetamides. Target compound was synthesized by reaction of chloroacetylchloride with diphenylamine to afford 2-chloro-N, N-diphenylacetamide which further by reaction with substituted Chalcones and characterized following recrystallization and evaluated for anti-microbial potential through cup-diffusion method. In results, the target compounds were tested for activity against B. Subtilis, E.Coli and C. albicans. The chalcones having the lipophilic 4-chloro group (RKCT2) showed the greatest antimicrobial activity (zone of inhibition 20 & 22 mm against. B. subtilis, E. Coli, C. Albicans respectively. It suggests further researchers to go through anti-microbial evaluations against a more varieties of bacteria and fungi.
 Keywords: Schiff bases of diphenylamine derivatives, antibacterial activity, Gram-positive bacteria, 2-(4-(3 (Substituted Phenyl) Acryloyl) Phenoxy)-N, N Diphenylacetamides

A Novel Peptide Antibiotic Produced by Streptomyces roseoflavus Strain INA-Ac-5812 With Directed Activity Against Gram-Positive Bacteria.

In this work, we report the isolation and detailed functional characterization for the new non-ribosomally synthesized antibiotic 5812-A/C, which was derived from metabolites of Streptomyces roseoflavus INA-Ac-5812. According to its chemical structure, the studied 5812-A/C preliminary is composed of a cyclic peptide part covalently bounded with an arabinose residue. N-terminal amino acid sequencing of the native peptide has identified its partial structure of Leu-Asp-Gly-Ser-Gly and consisting of a Tyr residue that is supposed to have a two-component peptide nature for the molecule studied. However, the structural analysis of the antibiotic complex derived from S. roseoflavus INA-Ac-5812 is still ongoing. The mechanism of action of 5812-A/C was assessed in comparison with its most related analog, the lipopeptide antibiotic daptomycin, given the presence in both antimicrobials of an L-kynurenine amino acid residue. The inhibitory activity of 5812-A/C against Gram-positive bacteria including methicillin-resistant strain of Staphylococcus aureus was similar to daptomycin. The mechanism of action of 5812-A/C was associated with the disruption of membrane integrity, which differs in comparison with daptomycin and is most similar to the antimicrobial membrane-disturbing peptides. However, 5812-A/C demonstrated a calcium-dependent mode of action. In addition, unlike daptomycin, 5812-A/C was able to penetrate mature biofilms and inhibit the metabolic activity of embedded S. aureus cells. At the same time, 5812-A/C has no hemolytic activity toward erythrocyte, but possessed weak cytotoxic activity represented by heterochromatin condensation in human buccal epithelium cells. The biological properties of the peptide 5812-A/C suggest its classification as a calcium-dependent antibiotic effective against a wide spectrum of Gram-positive pathogenic bacteria.

Synergistically-acting Enterocin LD3 and Plantaricin LD4 Against Gram-Positive and Gram-Negative Pathogenic Bacteria.

The efficacy of antimicrobials is an important aspect during their applications in food and therapeutics. In this study, combination of two bacteriocins, enterocin LD3 and plantaricin LD4, was studied against two pathogenic bacteria, Staphylococcus aureus subsp. aureus ATCC25923 and Salmonella enterica subsp. enterica serovar Typhimurium ATCC13311 for increasing their potency and bactericidal activity. The minimal inhibitory concentrations (MICs) of enterocin LD3 and plantaricin LD4 against Staph. aureus subsp. aureus ATCC25923 were 180 and 220 μg/mL, whereas in combination, reduced to 115 μg/mL, respectively. The MICs of enterocin LD3 and plantaricin LD4 against Salm. enterica subsp. enterica serovar Typhimurium ATCC13311 were 240 and 320 μg/mL, respectively, whereas in combination, these were found to be 130 μg/mL, respectively. The fractional inhibitory concentration (FIC) indices calculated as 0.50 against Staph. aureus subsp. aureus ATCC25923 and 0.43 against Salm. enterica subsp. enterica serovar Typhimurium ATCC13311 were found to be ≤ 0.5 indicating the synergy. The isobologram showed MIC of combined bacteriocins falls below the plotted straight line further signifies synergy. The growth response of Staph. aureus subsp. aureus ATCC25923 and Salm. enterica subsp. enterica serovar Typhimurium ATCC13311 was significantly reduced in the presence of combined bacteriocins in comparison with their individual effects. The number of dead cells was higher as a result of combined effect as compared with their independent effect evidenced by fluorescent microscopy. Transmission electron microscopy (TEM) revealed the higher disruption of cell membrane in the combined bacteriocin-treated cells as compared with alone effects. The FTIR spectra of enterocin LD3-treated cells showed alteration at ~ 1,451.82 and ~ 1,094.30/cm corresponding to nucleic acids and phospholipids suggesting its interaction with cell membrane and nucleic acids. In contrast, plantaricin LD4-treated cells did not show such alterations suggesting plantaricin LD4 may kill target cells using other mechanism. Our data suggest that different mode of action of both bacteriocins results in division of labour and may be responsible for their synergistic activity against target cells. Similarly, the synergistic effect of bacteriocins was also observed against other pathogenic bacteria such as Proteus mirabilis ATCC43071, Pseudomonas aeruginosa ATCC27853 and Escherichia coli ATCC25922. These bacteriocins, therefore, act synergistically against target pathogens and may be applied in appropriate combinations for food safety and medical applications.

Environmental and biomedical applications of AgNPs synthesized using the aqueous extract of Solanum surattense leaf

A novel eco-friendly and biocompatible method has been used with the help of Solanum surattense aqueous leaves extract to synthesis silver nanoparticles (AgNPs). The cost-effective green synthesis route has been given much care to ensure an environmentally friendly and straightforward approach, as it is most demanded in the biomedical industry. The proposed novel synthesis method offers additional compensations over other synthesizing approaches. Different analytical systems such as UV–vis, IR, XRD, DLS, SEM, EDAX, XPS, and TEM characterization techniques were used to understand the quality of the green synthesized nanoparticles for biomedical applications. The surface plasmon resonance peak of green synthesized silver nanoparticles at 446 nm was observed by UV absorbance spectral analysis. The XRD, SEM, and TEM analysis using to study the crystal structure, particle size, and surface morphology of the AgNPs. The results confirmed the synthesized spherical shape silver nanoparticles were crystallized in a face-centered cubic structure. The zeta potential measurement was used to authorize the excellent stability of AgNPs employing the dynamic light scattering method. FTIR spectral study confirmed that phytocompound participate in the bioreduction as well as stabilization of biosynthesized AgNPs by Solanum surattense. Also, the phytochemical content acts as the capping agent on surface AgNPs. The synthesized silver nanoparticles are subjected to antibacterial activity against both gram-positive and negative pathogenic bacteria for finding suitability in biocompatible applications. Also, the cytotoxicity of AgNPs was studied against the human breast cancer cell line and compared with one of the commercially available cancer drugs. Also, we have shown that the prepared AgNPs could serve as an excellent photocatalyst for degrading the Rhodamine B (RhB) dye and Acid Violet 7 (AV 7) dye under direct sunlight radiation.

An In Vitro Evaluation of the Ability of Ozone Nano-bubble Water to Kill Pathogenic Gram-Negative and Gram-Positive Bacteria

An In Vitro Evaluation of the Ability of Ozone Nano-bubble Water to Kill Pathogenic Gram-Negative and Gram-Positive Bacteria

Preparation of poly(butylene adipate-co-terephthalate)/ZnSnO3 composites with enhanced antimicrobial activity

Poly(butylene adipate-co-terephthalate) (PBAT) composites with ZnSnO3 nanosheets as inorganic dispersed constituent have been prepared by a convenient solution mixing method, where ZnSnO3 is obtained by hydrothermal synthesis. The structure and morphology of ZnSnO3 and PBAT/ZnSnO3 composite are characterized. The obtained composite films, made by drop casting, display significantly-improved antimicrobial activity against Gram-negative (E. coli) and Gram-positive (S. aureus) food-borne pathogenic bacteria. The results suggest that the PBAT/ZnSnO3 composites may serve as promising candidate for antimicrobial food packaging materials.

MMPphg from the thermophilic Meiothermus bacteriophage MMP17 as a potential antimicrobial agent against both Gram-negative and Gram-positive bacteria

BackgroundNew strategies are urgently needed to deal with the growing problem of multidrug-resistant bacterial pathogens. As the natural viruses against bacteria, recently, bacteriophages have received particular attention. Here, we identified and characterized a novel peptidoglycan hydrolase named MMPphg by decoding the complete genome sequence of Meiothermus bacteriophage MMP17, which was isolated in Tengchong hot spring in China and contains a circular genome of 33,172 bp in size and a GC content of 63.4%.FindingsWe cloned the MMPphg gene, overproduced and purified the phage lytic protein, which contains a highly conserved M23 metallopeptidase domain and can be activated by Mg2+ and Zn2+. MMPphg is capable of withstanding temperatures up to 70 °C, and preserved more than 80% of its activity after a 30 min treatment between 35 and 65 °C. More interestingly, by disrupting bacterial cells, MMPphg exhibits surprising antimicrobial activity against both Gram-negative and Gram-positive pathogenic bacteria, especially antibiotic-resistant strains such as Escherichia coli O157, Staphylococcus aureus and Klebsiella pneumonia.ConclusionsIn the current age of mounting antibiotic resistance, these results suggest the great potential of MMPphg, the gene product of bacteriophage MMP17, in combating bacterial infections and shed light on bacteriophage-based strategies to develop alternatives to conventional antibiotics for human or veterinary applications.

Antimicrobial Effect of Natural Berry Juices on Common Oral Pathogenic Bacteria.

(1) Background: Antimicrobial agents such as chlorhexidine (CHX) are commonly used in oral plaque control. However, sometimes those agents lack antimicrobial efficiency or cause undesired side effects. To identify alternative anti-infective agents, the present study investigated the antibacterial activity of all-fruit juices derived from blackcurrant, redcurrant, cranberry and raspberry on common oral pathogenic gram-positive and gram-negative bacteria (Streptococcus mutans, Streptococcus gordonii, Streptococcus sobrinus, Actinomyces naeslundii, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Enterococcus faecalis). (2) Methods: Antibacterial efficiency was evaluated by agar diffusion assay and in direct contact with bacteria in planktonic culture. Furthermore, cytotoxicity on human gingival fibroblasts was determined. (3) Results: Blackcurrant juice was most efficient at suppressing bacteria; followed by the activity of redcurrant and cranberry juice. Raspberry juice only suppressed P. gingivalis significantly. Only high-concentrated blackcurrant juice showed minimal cytotoxic effects which were significantly less compared to the action of CHX. (4) Conclusion: Extracts from natural berry juices might be used for safe and efficient suppression of oral pathogenic bacterial species.

Biovolume and spatial distribution of foodborne Gram-negative and Gram-positive pathogenic bacteria in mono- and dual-species biofilms

The objective of this study was to characterize the biofilms formed by Salmonella enterica serotype Agona, Listeria monocytogenes, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) after 12, 48, 72, 120 and 240 h of incubation at 10 °C. Biofilms containing a single species, together with dual-species biofilms in which S. enterica and a Gram-positive bacterium existed in combination, were formed on polystyrene and evaluated by using confocal laser scanning microscopy (CLSM). All strains were able to form biofilm. The greatest biovolume in the observation field of 14,161 μm2 was observed for mono-species biofilms after 72 h, where biovolumes of 94,409.0 μm3 ± 2131.0 μm3 (S. enterica), 58,418.3 μm3 ± 5944.9 μm3 (L. monocytogenes), 68,020.8 μm3 ± 5812.3 μm3 (MRSA) and 59,280.0 μm3 ± 4032.9 μm3 (VRE) were obtained. In comparison with single-species biofilms, the biovolume of S. enterica was higher in the presence of MRSA or VRE after 48, 72 and 120 h. In dual-species biofilms, the bacteria showed a double-layer distribution pattern, with S. enterica in the top layer and Gram-positive bacteria in the bottom layer. This spatial disposition should be taken into account when effective strategies to eliminate biofilms are being developed.

Structural characterization, antioxidant and antibacterial activities of a novel water soluble polysaccharide from Cordia myxa fruits

In this study, water-soluble polysaccharide and fatty acids of Cordia myxa fruit harvested from the southwest of Iran were isolated and investigated. The extraction yield of water-soluble polysaccharide of C. myxa fruit (WSPCM) was 24.12%, and its experimental purity was 79.43%. The High Performance Liquid Chromatography results indicated that the WSPCM consisted of glucose, fructose, sucrose, maltose, ribose, maltitol, and maltoheptaose. The atomic absorption spectrometer analysis indicated that WSPCM was a rich source of Ca and Na. The dynamic light scattering results illustrated that the average particle size and zeta potential were 1510.7 nm and − 64.96, respectively. Fourier transform infrared spectroscopy revealed the presence of α and β-configurations in WSPCM. The total unsaturated and saturated fatty acids were 60.62% and 39.38%, respectively and oleic, palmitic, and linoleic were the main fatty acids. The WSPCM represented good antibacterial activities against both Gram-positive and Gram-negative pathogenic bacteria. Moreover, it showed a relatively good antioxidant activity. In conclusion, WSPCM could be introduced as a novel natural antioxidant and antibacterial substance in functional food.

Synthesis, Characterization and Antibacterial Studies of (3,3-Dimethyl-7-oxo-6-(2-phenylacetamido)-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid-Cr (III) Complex

Benzylpenicillin, also known as (3,3-Dimethyl-7-oxo-6-(2-phenylacetamido)-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic, is a common bactericidal antibiotic of the betalactamin family which is mostly used to treat infections caused by gram-positive bacterial strains and few gram-negative bacterial strains. Cr (III) complex of benzylpenicillin was synthesized by the reaction of benzylpenicillin with CrCl3.6H2O. The structure of the complex was confirmed through elemental analysis, electrical conductivity, FT-IR, electronic spectra, 1H-NMR, and 13C-NMR spectroscopic methods. The physical properties such as solubility, color and melting point were also determined for both the ligand and the complex. The complex has a deep green color. Both the ligand and the complex are ionic (236.0 and 126.0 Sm2.mol-1). From the spectroscopic result, the ligand behaved as a pentadentate ligand coordinating to the metal ion through OH, NH, C=O of amide, carboxylate& β-lactam. A trigonal bipyramidal geometry has been proposed for the metal complex. The prepared complex was evaluated in vitro for its antibacterial activity against some pathogenic gram-positive (Staphylococcus aureus, Bacillus substilis, Bacillus cereus, and Enterococcus faecalis) and gram-negative bacteria (Escherichia coli, Enterobacter cloacae, Pneumonia aeruginosa and Campylobacter fetus). The metal complex showed enhanced antibacterial activity as compared to the uncomplexed ligand.

A Novel Bactericidal Drug Effective Against Gram-Positive and Gram-Negative Pathogenic Bacteria: Easy as AB569.

Global antibiotic resistance, driven by intensive antibiotic exposure/abuse, constitutes a serious challenge to all health care, particularly in an era when new antimicrobial development has slowed to a trickle. Recently, we published work demonstrating the discovery and partial mechanism of action of a novel bactericidal agent that is effective against both gram-positive and gram-negative multidrug-resistant bacteria. This drug, called AB569, consists of acidified nitrite (A-NO2-) and EDTA, of which there is no mechanism of resistance. Using both chemistry-, genetic-, and bioinformatics-based techniques, we first discovered that AB569 was able to generate bactericidal levels of nitric oxide (NO), while the EDTA component stabilized S-nitrosyl thiols, thereby furthering NO and downstream reactive nitrogen species production. This elegant chemistry triggered a paralytic downregulation of vital genes using RNA-seq involved in the synthesis of DNA, RNA, ATP, and protein in the representative ESKAPE pathogen, Pseudomonas aeruginosa.

Green biosynthesis of ZnO nanomaterials and their anti-bacterial activity by using Moringa Oleifera root aqueous extract

Fabrication of anti-bacterial nanomaterials made considerable progress in the catalytic method of green synthesis. In the current research work, a simple and environmentally convenient method was used for the synthesis of zinc oxide nanomaterials (ZnO-NMs) using the root extract of the Moringa oleifera. The fabricated MOR-ZnONMs were analysed by various analytical techniques such as UV–Vis absorption spectroscopy, Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), and photoluminescence spectroscopy. XRD analysis revealed that the synthesized MOR-ZnONMs have the hexagonal wurtzite structure. FT-IR confirmed the presence of various functional groups were responsible for the reduction of the metal ion into MOR-ZnONMs. The particles size, morphology and topography of the synthesized MOR-ZnONMs were determined by Dynamic Light Scattering and Transmission Electron Microscopy with significant measures. The intense and narrow widths of the zinc and oxygen present in the MOR-ZnONMs have been identified by utilizing EDX of high purity and crystalline nature. The prepared MOR-ZnONMs were tested for anti-bacterial activities and revealed that the maximum zones of inhibition were observed against Gram-positive and Gram-negative pathogenic bacteria.

Extraction and characterization of phytochemical compounds from araçazeiro (Psidium cattleianum) leaf: Putative antioxidant and antimicrobial properties

Underexplored species have phytochemical potential for pharmacological and nutraceutical applications. The fruits of such species, including aracá (Psidium cattleianum Sabine), are rich in specialized metabolites with putative antioxidant and antimicrobial activity; therefore, the leaves of these species are also a potential source of bioactive compounds. In this study, araçazeiro leaves were extracted using an aqueous infusion (Al) and a pressurized liquid extraction system with water (PLE-W), ethanol (PLE-E), and 1:1 water:ethanol ratio combination (PLE-W:E). PLE-W:E yielded a greater diversity of extracted compounds. Nonetheless, all extracts showed inhibitory activity against pathogenic Gram-positive and Gram-negative bacteria and antioxidant activity in the in vitro thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS) assays with rat brain and yeast model systems. Thus, araçazeiro leaves can be exploited as a promising source of bioactive compounds.

NHR-49 Transcription Factor Regulates Immunometabolic Response and Survival of Caenorhabditis elegans during Enterococcus faecalis Infection.

Immune response to pathogens is energetically expensive to the host; however, the cellular source of energy to fuel immune response remains unknown. In this study, we show that Caenorhabditis elegans exposed to pathogenic Gram-positive and Gram-negative bacteria or yeast rapidly utilizes lipid droplets, the major energy reserve. The nematode's response to the pathogenic bacterium Enterococcus faecalis entails metabolic rewiring for the upregulation of several genes involved in lipid utilization and downregulation of lipid synthesis genes. Genes encoding acyl-CoA synthetase ACS-2, involved in lipid metabolism, and flavin monooxygenase FMO-2, involved in detoxification, are two highly upregulated genes during E. faecalis infection. We find that both ACS-2 and FMO-2 are necessary for survival and rely on NHR-49, a peroxisome proliferator-activated receptor alpha (PPARα) ortholog, for upregulation during E. faecalis infection. Thus, NHR-49 regulates an immunometabolic axis of survival in C. elegans by modulating breakdown of lipids as well as immune effector production upon E. faecalis exposure.

Assessment of Antimicrobial Activity, Mode of Action and Volatile Compounds of Etlingera pavieana Essential Oil.

Etlingera pavieana (Pierre ex Gagnep.) R.M.S. is a rhizomatous plant in the Zingiberaceae family which could be freshly eaten, used as a condiment or as a traditional remedy. Our work investigated the chemical composition and antimicrobial activity of the E. pavieana essential oils extracted from the rhizome (EOEP). We extracted the EOEP from the rhizome by hydrodistillation and analyzed the chemical composition by headspace solid-phase microextraction coupled with gas chromatography/mass spectrometry (HS-SPME-GC/MS). A total of 22 volatile compounds were identified where trans-anethole (78.54%) and estragole (19.36%) were the major components in the EOEP. The antimicrobial activity of EOEP was evaluated based on the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values using the broth dilution method and enumerating cell death overtime. Our work shows that the EOEP exhibits potent antibacterial activity against foodborne pathogenic Gram-positive bacteria, namely Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes in the range of 0.1–0.3% (v/v). We further investigated the mechanism of EOEP inhibition using Synchrotron Fourier transformation infrared (FTIR) microspectroscopy. Here, we show significant differences in DNA/nucleic acid, proteins and cell membrane composition in the bacterial cell. To conclude, EOEP exhibited antimicrobial activity against foodborne pathogens, especially the Gram-positive bacteria associated with ready-to-eat (RTE) food and, thus, has the potential to serve as a natural preservative agent in RTE products.

Biosynthesis and characterization of iron nanoparticles produced by Thymus vulgaris L. and their antimicrobial activity

Research in the area of nanoparticles has grown considerably in recent years. Plant leaf extracts provide a platform for nanoparticle synthesis from metal and metal oxides, which is more economical and environmentally friendly than other methods, such as chemical reduction and physical methods. The present study conducted the biosynthesis of iron nanoparticles (FeNPs) using Thymus vulgaris L. (Thyme) leaf aqueous extract. The characterization of FeNPs was carried out by transmission electron microscopy (TEM), UV-visible spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-Ray diffraction (XRD) techniques. UV-vis spectroscopy analysis demonstrated a visible peak around 440 nm. FTIR demonstrated the presence of iron metallic ions. Structural analysis of the nanoparticles by TEM showed agglomerations of spherical shapes. The average size of the synthesized FeNPs was around 40 nm. Regarding application, the ability of the FeNPs to degrade methyl orange was recorded as 95%. They were also examined for potential antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria and fungi. FeNPs demonstrated high antifungal activity against Candida albicans, C. parapsilosis and Aspergillus flavus, while their antibacterial activity was much weaker compared to commercial antibacterial agent. Thus, FeNPs synthesized using T. vulgaris could play an important role in controlling C. albicans, C. parasilosis and A. flavus and bioremediation of dyes.