Human Pathogenic Strains Research Articles

Insights into the acquisition of the pks island and production of colibactin in the Escherichia coli population.

The pks island codes for the enzymes necessary for synthesis of the genotoxin colibactin, which contributes to the virulence of Escherichia coli strains and is suspected of promoting colorectal cancer. From a collection of 785 human and bovine E. coli isolates, we identified 109 strains carrying a highly conserved pks island, mostly from phylogroup B2, but also from phylogroups A, B1 and D. Different scenarios of pks acquisition were deduced from whole genome sequence and phylogenetic analysis. In the main scenario, pks was introduced and stabilized into certain sequence types (STs) of the B2 phylogroup, such as ST73 and ST95, at the asnW tRNA locus located in the vicinity of the yersiniabactin-encoding High Pathogenicity Island (HPI). In a few B2 strains, pks inserted at the asnU or asnV tRNA loci close to the HPI and occasionally was located next to the remnant of an integrative and conjugative element. In a last scenario specific to B1/A strains, pks was acquired, independently of the HPI, at a non-tRNA locus. All the pks-positive strains except 18 produced colibactin. Sixteen strains contained mutations in clbB or clbD, or a fusion of clbJ and clbK and were no longer genotoxic but most of them still produced low amounts of potentially active metabolites associated with the pks island. One strain was fully metabolically inactive without pks alteration, but colibactin production was restored by overexpressing the ClbR regulator. In conclusion, the pks island is not restricted to human pathogenic B2 strains and is more widely distributed in the E. coli population, while preserving its functionality.

Synthesis, Characterization, Antimicrobial, MTT assay, DFT study of Co(II), Ni(II), Cu(II) and Zn(II) Complexes with some New Schiff Base Ligands

Novel Schiff base ligand HL was synthesized by the condensation of 3,5- dichlorosalicylaldehyde and 4-phenylsemicarbazide. Co(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized in 1:1 molar ratio of metal to ligand. The structure of the synthesized ligand was established using 1H NMR, IR, Mass spectrometry and the metal complexes were characterized using IR, Mass spectrometry, UV-Vis, powdered XRD and molar conductivity. The thermal stability of the complex was studied by TGA. In DFT studies, the geometries of Schiff bases and metal complexes were fully optimized with respect to the energy taking the 6-31+g (d,p) basis set using Gaussian 09w, several molecular properties were also calculated. The spectral data show that ligand HL behaves as uninegative tridentate. On the basis of spectral studies, an octahedral geometry has been assigned for Co(II), square planar for Cu(II) and tetrahedral for Ni(II) and Zn(II) complexes. The antimicrobial activities were examined against some human pathogenic strains. The MTT assay was screened against mouse fibroblast cell line. The result indicates that metal complexes show increase in cytotoxicity in proliferation to cell line as compared to the free ligand.

(NH4)2[Ni(H2O)6]2V10O28 ⋅ 4H2O; Structural Analysis and Bactericidal Activity against Pathogenic Gram Negative Bacteria

AbstractA bis(hexaaquanickel(II)) complex‐decavanadate cluster compound, (NH4)2[Ni(H2O)6]2V10O28 ⋅ 4H2O, was synthesized. This compound has been structurally characterized by infrared spectroscopy and single crystal XRD analysis that indicated its triclinic P −1 space group. Additionally, the thermal decomposition mechanism of the compound to a composite of V2O5 and Ni(VO3)2 was elucidated. The common antibacterial agents are organics that experience instability and cause pollution to the environment, therefore we wish to consider the synthesis of inorganic bactericides. (NH4)2[Ni(H2O)6]2V10O28 ⋅ 4H2O, in comparison to chloramphenicol, led to better inhibition of the growth of five Gram negative human pathogenic bacterial strains (Escherichia coli, Klebsiella pneumonia, Serratia marcescens, Serratia plymuthica and Pseudomonas aeruginosa). Remarkably, the highest inhibition was displayed against Escherichia coli that was inhibited completely at (NH4)2[Ni(H2O)6]2V10O28 ⋅ 4H2O (50 μg/ml), while the Escherichia coli growth was of 12.93×107±0.25 CFU/ml at (NH4)2[Ni(H2O)6]2V10O28 ⋅ 4H2O (5 μg/ml). This is in contrast to chloramphenicol (5 μg/ml) that allowed for Escherichia coli growth of 13.97×107±0.24 CFU/ml (control=17.33×107±0.48 CFU/ml).

In vitro photoprotective, antioxidant and antibacterial activity of Vernonia squarrosa (D. Don) Less

Vernonia squarrosa (D. Don) Less. (Asteraceae) is an ethnomedicinally important plant of unexplored medicinal potential. The Hydro-Methanolic Leaf Extract (HMLE) reveals presence of alkaloids, terpenoid, tannins, phenols, flavonoids, saponins and also cardiac glycosides with notable amount of phenol, flavonoid, ? carotene and lycopene. The high antioxidant activity of HMLE when assessed by 2, 2 diphenyl 1-picrylhydrazyl (DPPH) shows significant EC50 value of 11.63 ± 2.60 µg/ml. Photo-protection efficiency of HMLE was determined and expressed as Sun Protection Factor (SPF). Reasonably high SPF value of 38 (SPF=38 at 200 µg/ml) provides UV blockage up to 98%. HMLE extract was also screened for antibacterial activity against four human pathogenic bacterial strains, Staphylococcus aureus (MTCC 2940), Pseudomonas aeruginosa (MTCC 2453), Bacillus subtilis (MTCC 441), Escherichia coli (MTCC 739). Results showed prominent antibacterial impact on these tested bacteria. Lupeol, a pentacyclic triterpenoid was found to be present as a dominant member in Gas chromatography–mass spectrometry (GC-MS) analysis of HMLE. Lupeol is a pentacyclic triterpenoid compound with diverse pharmaceutical applications. This is the maiden report of bioactive compounds from V. squarrosa highlighting their antibacterial, photoprotective and antioxidant activities.

Volatile components and antimicrobial activity of the n-hexane extracts of Neomuretia pisidica (Kit Tan) Kljuykov, Degtjareva & Zakharova

The fruits, aerial parts and roots of Neomuretia pisidica (Kit Tan) Kljuykov, Degtjareva & Zakharova were extracted with n-hexane. Total of 18 compounds were characterised by GC analyses of the n-hexane extracts. Main volatile components of the n-hexane extract of aerial parts were characterized as 1,8-cineole (23.4 %), camphor (21.4 %), 2-ethyl hexanol (14.6 %), α-pinene (7.2 %), and verbenone (6.4 %). Methyl linoleate (19.3 %), 1,8-cineole (16.5 %), camphor (13.2 %), α-pinene (6.1 %) and 2-ethyl hexanol (4.9 %) were found in the n-hexane extract of roots. Whereas, 1,8-cineole (23.3 %), camphor (20.3 %), 2-ethyl hexanol (14.2 %), α-pinene (9.9 %), and limonene (4.1%) were the major components of the n-hexane extract of fruits. Antimicrobial activity were identified using a microdilution assay against selected human pathogenic strains. The most potent inhibitor activities with 156 µg/mL concentrations were detected against S. aureus and E. faecalis.

Noteworthy enhancement of wound-healing activity of triphala biomass metabolite-loaded hydroxyapatite nanocomposite

Hydroxyapatite nanoparticles have been demonstrated as eminent nanomaterials because of their upgraded bioactivity, non-toxicity and biocompatibility properties. In this current examination, an upgraded wound healing activity of bioactive metabolites of medicinal polyherbal formulation Triphala fabricated hydroxyapatite nanocomposite was explored utilising in vivo excision wound Wistar rat model. Antibacterial activity of nanocomposite was studied against human pathogenic bacterial strains Pseudomonas aeruginosa and Staphylococcus aureus. Nanofabrication of the nanocomposite on wound dressing material and its antibacterial activity was additionally examined. Metabolites were extricated from Triphala utilising ethanol, and the extracted metabolites were fabricated with nano-hydroxyapatite utilising green science standards as profoundly stable hydroxyapatite nanocomposite. An ointment prepared from the synthesised nanocomposite was assessed for in vivo wound healing on excision wound created in a Wistar rat model. Nanocomposite treatment has shown complete wound-healing activity on the 21st day by recording all signs of the healing mechanism. Synthesised nanocomposite reveals growth inhibition of both the tested bacterial strains by showing zone of inhibition, biofilm inhibition. Antibacterial activity was also studied with nanocomposite, fabricated on dressing material which reveals the fabricated material inhibited the growth of the tested bacterial pathogenic strains. The current investigation proposes the possible use of phytonanotechnology standards as a successful course of wound mending and restraint of twisted disease without the help of manufactured antimicrobials.

Interspecies bacterial communication produces a delicate balance between Vibrio cholerae and the chironomid egg mass microbiome.

The evolution of antimicrobial resistance in bacterial pathogens is considered by the World Health Organization to be one of the ten most concerning public health threats facing humanity (World Health Organization, 2020). Bacterial diseases previously controllable by antibiotics are resurging and treatment options are dwindling. Cholera is one such disease. Human pathogenic strains of Vibrio cholerae cause as many as 4 million cases of disease resulting in over 100,000 deaths each year (Ali et al. 2015) and multidrug-resistant V. cholerae is now established where pandemic cholera persists. Vibrio cholerae is fundamentally an aquatic species thriving in brackish and estuarial waters. Its environmental prevalence, together with both extracellular and intracellular infection of alternative arthropod and mollusc hosts, produces a highly complex ecological milieu that is not well understood. With the absence of reliable antibiotic-based treatment options, it is necessary to build a better understanding of V. cholerae biology and ecology in order to develop alternative methods for risk modelling and disease control. In this issue of Molecular Ecology, authors Sela, Hammer, and Halpern experimentally investigated a mechanism by which V. cholerae pathogenicity is affected by interspecies quorum sensing involving an array of bacterial species from the microbiome of an alternative arthropod host, the egg mass of a chironomid midge (Diptera:Chironomidae) (Sela et al. 2020). Quorum sensing is a mechanism whereby bacteria communicate with each other using autoinducers and is known to be important, for example, in shaping virulence in a variety of pathogenic bacteria. The innovative methodologies they used, both in molecular and protein biology and reductive investigative microbiomics, are helping to develop the tools needed for understanding this understudied ecological system and fighting cholera in a post-antibiotic world.

Synthesis and Antimicrobial Activity of New 4-Methyl-2-(3-pyridyl)thiazolyl Chalcones and Pyrazolines

In an attempt to develop active antimicrobial agents, a set of new thiazolyl chalcones has been synthesized by the Claisen–Schmidt reaction of 5-acetyl-4-methyl-2-(3-pyridyl)thiazole with various heterocyclic aldehydes in alkali media. Reaction of chalcones with hydrazine hydrate has resulted in pyrazolines that have been assessed for in vitro antimicrobial activity against ten bacterial and five fungal human pathogenic strains using the disk diffusion assay. The synthesized pyrazolines demonstrate antimicrobial activity higher than that of synthesized chalcones. 2-Thienylchalcone has been determined as the most active against P. aeruginosa. Three pyrazolines are characterized by distinctive activity towards Gram-negative bacteria S. flexneri and P. aeruginosa. Two pyrazolines demonstrate equipotent antifungal activity with amphotricin B against A. clavatus.

Chemical Exchanges between Multilateral Symbionts.

Herein is a report on the molecular exchange occurring between multilateral symbiosis partners-a tit-for-tat exchange that led to the characterization of two new metabolites, conocandin B (fungal-derived) and dentigerumycin F (bacterial-derived). The structures were determined by NMR, mass spectrometry, genomic analysis, and chemical derivatizations. Conocandin B exhibits antimicrobial activity against both the bacterial symbionts of fungus-growing ant and human pathogenic strains by selectively inhibiting FabH, thus disrupting fatty acid biosynthesis.

Antibacterial Activity and Time-kill Assay of Terminalia catappa L. and Nigella sativa L. against Selected Human Pathogenic Bacteria

The current investigation aims to test the susceptibility of human pathogenic clinical isolates and MTCC strains to leaf and seed extracts of Terminalia catappa and Nigella sativa. Disc diffusion assay, micro dilution assay and minimum Bactericidal Concentration investigated the susceptibility of bacteria to the test extracts. The active extract was subjected to phytochemical screening, separation of the phytochemicals by Thin Layer Chromatography, bioactivity guided assay and Time- kill assay. Acetone and methanol extracts of T.catappa revealed, significant inhibition of clinical origin Staphylococcus aureus followed by Proteus vulgaris and the MTCC strains Staphylococcus aureus, Salmonella typhi, Pseudomonas aeroginosa and Bacillus subtilis. Nigella sativa inhibited the growth of clinical origin Staph.aureus and MTCC strain of Staph.aureus, Salmonella typhi and B.subtilis. Minimum inhibitory concentration for all the test bacteria was reported in the range of 5000μg/ml to 9 μg/ml in T. catappa extract. Most sensitive being the clinical isolate Staph. aureus and Proteus vulgaris. The bactericidal concentration for the test bacteria was found to be between 5000μg/ml and 625μg/ml. Phyto-chemical analysis of leaf extracts of T. catappa found to have dominated by polyphenols (Terpenoids, steroids, flavonoids, flavones, saponins and tannins) and N.sativa extracts recorded the presence of alkaloids, proteins and oils and fats. TLC profiling of the acetone extract revealed many antibacterial active bands. Bands having Retention factor 0.47 and 0.52 were active against the test bacteria. Time kill assay of the acetone extract of T. catappa were carried out for the first time. The extract exhibited dose dependent bactericidal and bacteriostatic activity against the clinical isolates.

Molecular Docking and Antibacterial Studies of Pyranopyrazole Derivatives Synthesized Using [Pap-Glu@Chi] Biocatalyst Through a Greener Approach

In the present work, papain enzyme was immobilized on a polymer support chitosan through a linkage of glutaraldehyde to form the [Pap-Glu@Chi] biocatalyst through the covalent bonding method. The immobilization of papain on Chitosan was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) which revealed the change in morphology of chitosan due to immobilization of papain through glutaraldehyde. Thus prepared heterogeneous biocatalyst was used for the four-component synthesis of pyranopyrazole derivatives by the reaction of substituted aromatic aldehydes, malononitrile, ethylacetoacetate and hydrazine hydrate affording excellent yields within short reaction times at moderate temperature. The catalyst exhibited significant activity up to six cycles. Synthesized compounds were checked for their molecular docking activity using AutoDock Vina against the bacterial protein receptors (PDB code 2VF5 and 1BAG) obtained from the RCSB Protein Data Bank. Significant binding energy values obtained from docking studies revealed good interaction between synthesized compounds and bacterial protein receptor. Synthesized compounds were tested against human pathogenic bacterial strains Escherichia coli, Salmonella typhi, Bacillus subtilis, Pseudomonas aeruginosa along with Gentamicine as a reference antibiotic using disk diffusion method. The compounds were found to exhibit moderate-to-high antibacterial activity.

Antibacterial Activity of Steroids Isolated from the Madagascar Marine Sponge Biemna laboutei: Δ7 Steroids as New Potential Agents Against Pathogenic Bacteria

Background: Nowadays, the efficiency of antibiotics is endangered by the development of resistant bacterial strains. Consequently, novel bioactive agents are intensively searched. Marine sponges are well-known for being major sources of bioactive compounds, including unusual sterols. Until now, among sterols, noteworthy antibacterial activity has been reported exclusively for Δ5 sterols. Objectives: This study aims to describe the steroid composition of the marine sponge Biemna laboutei collected in the North coast of Madagascar, and the antibacterial activity of steroid mixture against human pathogenic strains. Methods: Sponge was extracted in CHCl3/MeOH. Free steroids were separated from other lipids by column chromatography with dichloromethane as specific eluent. Free sterols/steroids and sterol acetates were analysed by gas chromatography coupled with mass spectrometry. Antibacterial activity of steroid fractions was assessed for eight strains using agar diffusion with cellulose disks. Results: Neutral lipids were the major lipid class (79.1% of total lipids). The dichloromethane eluted fraction contained only free steroids giving rise to the identification of eleven compounds. These components presented exclusively Δ7 unsaturation, including lathosterol as the major one (38.4%) and four 3-oxo-steroids (11.8%). The steroid fraction of B. laboutei has exhibited inhibitory activity against pathogenic strains but more particularly against gram(+) Bacillus cereus (MIC of 12.5 μg/mL) and Staphylococcus aureus (MIC of 25 μg/mL) strains. This latter bacterium causes several illnesses, some of those strains being antibiotic-resistant and this becomes a worldwide health problem. Conclusion: This is the first report for an antibacterial activity of a mixture of Δ7 steroids against a resistant strain of S. aureus to many antibiotics.

Genome Sequence and Adaptation Analysis of the Human and Rice Pathogenic Strain Burkholderia glumae AU6208.

Burkholderia glumae causes rice (Oryza sativa) bacterial panicle blight, which is an increasingly economically important disease worldwide. As the first B. glumae strain isolated from patients with chronic infections, AU6208 has been reported as an opportunistic clinic pathogen. However, our understanding of the molecular mechanism underlying human pathogenesis by B. glumae remains rudimentary. In this study, we report the complete genome sequence of the human-isolated B. glumae strain AU6208 and compare this to the genome of the rice-pathogenic B. glumae type strain LMG 2196T. Analysis of the average nucleotide identity demonstrated 99.4% similarity between the human- and plant-pathogenic strains. However, the phenotypic results from this study suggest a history of niche adaptation and divergence. In particular, we found 44 genes were predicted to be horizontally transferred into AU6208, and most of these genes were upregulated in conditions that mimic clinical conditions. In these, the gene pair sbnAB encodes key enzymes in antibiotic biosynthesis. These results suggest that horizontal gene transfer in AU6208 may be responsible for selective advantages in its pathogenicity in humans. Our analysis of the AU6208 genome and comparison with that of LMG 2196T reveal the evolutionary signatures of B. glumae in the process of switching niches from plants to humans.

Screening of antibacterial and cytotoxicity of the copper (II) complexes of N-donor chelating ligand

Copper (II) complexes, namely dichloromono(1-amidino-O-ethylurea)copper (II), (1) and bis(1-amidino-O-ethylurea)copper (II) bromide, (2) were synthesized and characterized. The antibacterial screening of complexes 1 and 2 was performed along with their corresponding metal salts (CuCl2.2H2O) and (CuBr2), and ligand (dicyandiamide), against two human urinary pathogenic bacterial strains, Escherichia coli and Proteus mirabilis, by the disc diffusion method. All test compounds, except ligand have shown significant antibacterial activities on both bacterial strains. Their antibacterial effectiveness increased in a dose dependent manner, whereas their ability to inhibit the growth of both bacterial species decreased as their incubation time increased. The activity of complex 1 was found to be greater than its metal salt, while that of complex 2 was lower than the corresponding metal salt on both bacterial species. The in-vitro cytotoxic screening of complexes 1 and 2 was also assessed against human cervical adenocarcinoma cancer (HeLa) cell line using the MTT assay. Both complexes 1 and 2 have displayed cytotoxic effect in a dose-dependent manner with IC50 values of 59.64±6.68 µg/mL and 62.85±0.39 µg/mL, respectively. Overall, the highest antibacterial and cytotoxic activity of the present work is provided by complex 1.

Antibacterial Potency of Extracted Essential Oils of Some Plant Species against Common Gram-Positive and Gram-Negative Bacteria

Background: In the last decades, due to the rapid emergence of multidrug resistant pathogens, the antibiotic-resistance phenomenon has become a global health crisis. Therefore, there is a need to find new remedies against pathogenic microbes. Objectives: The main intention of this research was to appraise the antibacterial potency of extracted essential oils (EEOs) from various plant species versus human disease-causing bacterial strains. Materials and Methods: Antibacterial and bactericidal activity of EEOs was tested on human disease-causing strains which included Gram-positive as well as Gram-negative bacteria. Antibacterial analysis for various extracts of the different plants was performed by utilizing the method of disc diffusion and deduction of minimum inhibitory concentration (MIC) by microbroth dilution assays of the EEOs against the bacterial strains. Standard antibiotics (amoxicillin, metronidazole, rifampicin, clarithromycin, oxacillin, and clindamycin) were used to compare with EEO antibacterial activity. Results: Eclipta alba EEO was most effective against Streptococcus Pyogenes (2.06 ± 0.15), Neisseria gonorrhoeae (1.50 ± 0.20), Streptococcus aureus (0.05 ± 0.02), and Pseudomonas aeruginosa (4.56 ± 0.25). Leucas linifolia EEO was most effective against E. coli (3.13 ± 0.25) and Klebsiella Pneumoniae (4.33 ± 0.23). Bactericidal activity EEO from E. alba with minimum bactericidal concentration (MBC) ranged from 0.11 ± 0.03 to 10.60 ± 0.55; Atriplex hortensis (8.73 ± 2.62–12.07 ± 0.65); Hedyotis scandens (9.13 ± 0.50–15.30 ± 0.43); L. linifolia (0.94 ± 0.05–10.73 ± 0.20); Murraya koenigii (9.0 ± 0.55–12.90 ± 0.18); and Phlogacanthus thyrsiflorus (5.96 ± 1.15–13.0 ± 0.52). Bactericidal activity E. alba EEO was highest against S. Pyogenes (4.06 ± 0.15), N. gonorrhoeae (3.06 ± 0.40), and S. aureus (0.11 ± 0.03). L. linifolia EEO was most effective against P. aeruginosa (0.94 ± 0.05) and K. Pneumoniae (8.73 ± 0.41). Against E. coli (5.96 ± 1.15), the bactericidal activity of P. thyrsiflorus EEO was most effective. Conclusions: Comparison to the antibacterial activity of EEOs from six different plant species used in the study was more effective than the tested antibiotics. MIC and MBC values show that E. alba EEO plant species was the most effective against the tested human pathogenic bacterial strains.

Evaluation of the Antimicrobial Activity of Endophytic Fungus Isolated from <i>Cocos nucifera</i> (L.) Cotyledon against Medically-Important Pathogens

The study aimed to evaluate the endophytic fungi isolated from Cocos nucifera (L.) cotyledon for their possible antimicrobial activity. A total of twelve endophytic fungal species were successfully isolated, from which five were selected and presumptively identified, including Aspergillus niger, Raffaelea sp., Aspergillus flavus, Cladosporium sp. and Pseudallescheria spp. based on their macro and microscopic characters. The agar blocks of actively growing pure culture were assessed for antibacterial activity against five human pathogenic bacterial and fungal strains: Escherichia coli (BIOTECH 1634), Bacillus subtilis (BIOTECH 1697), Staphylococcus aureus (BIOTECH 1592), Serratia marcescens (BIOTECH 1748), and Candida tropicalis (BIOTECH 2085). Among the selected five endophytic used for antimicrobial activity screening, the Raffaelea sp. (CN-EF 2) has shown a high zone of inhibition of 11 mm against Bacillus subtilis, 18 mm against Escherichia coli, 15 mm against Staphylococcus aureus, and 11 mm against Candida tropicalis. Correspondingly, Aspergillus niger (CN-EF 1) has shown a zone of inhibition of 16 mm against C. tropicalis. The endophytic fungus Raffaelea sp. was effective against all test organisms except for Serratia marcescens, while Aspergillus niger was only effective for pathogenic fungi C. albicans. Hence, further in-depth studies of the isolated endophytic fungi are needed to determine the mechanisms behind the endophytes’ inhibitory effects.

Synthesis, characterization, synergistic antimicrobial properties and molecular docking of sugar modified uridine derivatives

Abstract Nucleosides and their analogues are an important, well-established class of clinically useful medicinal agents that exhibit antiviral and anticancer activity. Thus, our research group has focused on the synthesis of new nucleoside derivatives that could be tested for their broad-spectrum biological activity. In this study, two new series of nucleoside derivatives were synthesized from uridine (1) through facile two-step reactions using the direct acylation method, affording 5’-O-acyl uridine derivatives in good yields. The isolated uridine analogs were further transformed into two series of 2’,3’-di-O-acyl derivatives bearing a wide variety of functionalities in a single molecular framework to evaluate their antimicrobial activity. The new synthesized compounds were characterized through physicochemical, elemental and spectroscopic analysis, and all were screened for their in vitro antimicrobial activity against selected human and plant pathogenic strains. The test compounds revealed moderate to good antibacterial and antifungal activities and were more effective against fungal phytopathogens than against bacterial strains, while many of them exhibited better antimicrobial activity than standard antibiotics. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) tests against all microorganisms were also conducted for five compounds based on their activity (6, 11, 13, 16, and 17). In addition, all the derivatives were optimized using density functional theory (DFT) B3LYP/6-31g+(d,p) calculations to elucidate their thermal and molecular orbital properties. A molecular docking study was performed using the human protein 5WS1 to predict their binding affinity and modes, and ADMET and SwissADME calculations confirmed the improved pharmacokinetic properties of the compounds. Besides, structure–activity relationship (SAR), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) studies were also performed. Thus, the improvement of the bioactivity of these compounds is expected to significantly contribute to the design of more antimicrobial agents for therapeutic use in the future.

Antimicrobial activities of crude solvent extract and synthesized silver nanoparticles of Opuntia ficus-indica L. Cladodes

Opuntia ficus-indica cladodes was examined for their antimicrobial activities by using crude extract and synthesized silver nanoparticles against human pathogenic microbial strains, namely Staphylococcus aureus, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis and Candida albicans. All extracts demonstrated moderate activity against the tested microbes in a range between 0.53 and 2.33 cm. The maximum inhibition activity was found to be against K. pneumoniae while the lowest against S. aureus. Synthesized silver nanoparticles (Ag-NPs) showed inhibition activities between 1.82 and 2.03 cm. The maximum activity was recorded against K. oxytoca, while the lowest activities against P. mirabilis. In context of antimicrobial activity, there was no significant difference either solvent crude extract or synthesized silver nanoparticles against tested microbes. Therefore, crude extracts of O. ficus-indica cladodes or Ag-NPs could be used as an alternative natural drug.

Antimicrobial and Anti-Biofilm Activities of Citrus sinensis and Moringa oleifera Against the Pathogenic Pseudomonas aeruginosa and Staphylococcus aureus.

ContextThe plant Moringa oleifera Lam (Moringaceae), generally termed as drumstick tree, and Citrus sinensis Linn (Rutaceae) fruit have the ability to treat multiple human infections. A biofilm is none other than a complicated microbial community whose nature is greatly resistant to antimicrobial elements. The development of biofilms in abiotic and biotic surfaces has a connection with higher levels of mortality and morbidity. Along with that, it is regarded as a vital element of bacterial pathogenicity.AimThe present study evaluated the inhibitory effect and anti-biofilm activity of Moringa oleifera (M. oleifera) and Citrus sinensis (C. sinensis) extracts against those of pathogenic Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus).Materials and methodsTwo plant materials were collected from the local market of Tabuk city and two human pathogenic microbial strains were used in the study: S. aureus and P. aeruginosa. Further, a series of morphological, physiological, and conventional biochemical tests were performed to identify the selected microorganisms. In addition to this, the study conducted the following tests: antibiotic sensitivity test, extended-spectrum β-lactamase (ESβL), and methicillin-resistant Staphylococcus aureus (MRSA) production, biofilm formation in 96-well microtiter plates, minimum inhibitory concentration (MIC) determination, the effect of sub-MICs of C. sinensis extract and M. oleifera extract on the viability of test bacteria, and finally, measurement of the inhibition of biofilm.ResultsA remarkable result of the research is that the peel extract of C. sinensisand the flesh extract of M. oleifera efficiently inhibited biofilm formation by the addition of sub-inhibitory concentrations of (1/16 x MIC - 1/2 x MIC) MRSA and ESBL, respectively. P. aeruginosa shows high resistance to piperacillin (85.0%). Similarly, the resistance of MRSA was also high (65%) against gentamycin and amikacin antibiotics. Regarding ESBL, 12 (60%) isolates showed confirmed positive and 45% of S. aureus showed MRSA activity. On observing the 12 ESβL-positive P. aeruginosa, it was found that five strains (PS1, PS4, PS6, PS8, and PS11) have formed strong biofilm, methicillin-resistant S. aureus while four strains showed strong biofilm activity (SA2, SA4, SA5, and SA8). The MIC of C. sinensis extract and M. oleifera extract against strong biofilm producers had a range of 50-2000 µg/ml concentration after overnight incubation. The study results revealed that the antibiofilm activity comparatively showed the extract of M. oleifera was better than C. sinensisagainst the mixed culture (PS1+SA8, PS6+SA2, and PS8+SA4). Hence, it is recommended to use M. oleifera as an option to monitor the development of microbial biofilms or as a model for looking for better medicines.ConclusionThe presence of antimicrobial activity found in M. oleifera and C. sinensis extracts offers convincing evidence of their likely action as antimicrobial metabolites against the studied microorganism. Anti-biofilm assay findings have shown that M. oleifera and C. sinensis extracts have effectively blocked MRSA and ESBL development in the biofilm matrix.

Antimicrobial activity of plant based Essential Oils and Synergistic effect against selected Human Pathogenic Bacteria

The occurrence of multidrug resistant by pathogens is a universal issue for providing tolerable treatment for various infectious diseases. The predictable anti-microbial proxies are relatively active against plentiful strains, still need of more drugs against multidrug resistant pathogens. Herbal drugs have potential against antimicrobial activity from ancient days and their treatment of pathogenic diseases is increasing for developing plant based natural products. Essential oils have combat against antibiotic resistant bacteria. Thus our study was focused on plant based essential oil against human pathogenic bacteria. The necessary oil extracted from Curcuma longa and C. martini revealed protuberant anti-microbial accomplishments against B. subtilis, Escherichia coli, P. aeruginosa and S. aureus. Low concentration of C. longa oil at 10 µl inhibited the growth of all strains Bacillus subtilis followed by E. coli and S. aureus. Maximum bustle was noted in P. aerogenosa at 40 µl in both C. longa and C. martini oils. Human pathogenic strain treated with C. martini oil showed maximum inhibition in P. aerogenosa followed by B. subtilis, E. coli and S. aureus. Synergistic activity of oils against the strains showed maximum inhibition at 40 µl in P. aerogenosa.