Antimicrobial effect of different herbal plant extracts against different microbial population

This study evaluates the antimicrobial effects of ethanolic extract of five herbal plants; Guava (Psidium guajava), Sage (Salvia officinalis), Rhamnus (Ziziphusspina Christi), Mulberry (Morusalba L.), and Olive (Oleaeuropaea L) leaves against several microbial population representing Gram positive, Gram negative and Mollicutes; S. aureus, E. coli, Pasteurella multocida, B. cereus, Salmonella Enteritidis and M. gallisepticum using standard agar disc diffusion technique and minimal inhibitory concentration (MIC). Different extracts reveal variable results against the microorganism under study. All extracts have no antibacterial potency for Mycoplasma gallisepticum except Psidium guajava. The results of minimal inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of the extracts against the six bacteria ranged from 625 to 5000 μg/ml. The used herbal extract could inhibit the selected microorganism under study with variable minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC).     

Synergistic activity of melittin with mupirocin: A study against methicillin-resistant S. Aureus (MRSA) and methicillin-susceptible S. Aureus (MSSA) isolates

Methicillin-Resistant Staphylococcus aureus (MRSA) biofilms are involved in various nosocomial infections, being in the limelight of academic research. The current study aimed to determine the antimicrobial effects of melittin on planktonic and biofilm forms of S. aureus. Following the identification of MRSA and SCCmec types (using PCR method), Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and fractional inhibitory concentration index (FICi), for melittin and mupirocin were determined by broth microdilution assay. Melittin anti-biofilm activity was determined, using a microtiter-plate test (MtP) and scanning electron microscope (SEM) methods. The quorum sensing inhibitory activity of ½ MIC melittin was examined using a quantitative real-time RT-PCR method, and melittin cytotoxicity on Vero cells was examined by tetrazolium-based colorimetric (MTT) test. The Results of our study showed that Geometric means of MIC values of the melittin and mupirocin were 4.4 and 14.22 μg/ml respectively. The geometric mean of the FICi for both melittin-mupirocin was 0.75. No S. aureus biofilm was formed and hld gene (as a biofilm regulator) expression down-regulated. It seems that melittin can be useful in the treatment of S. aureus infections (especially MRSA) by reducing the hld expression. Furthermore, synergistic growth-inhibitory effects of mupirocin with melittin could be considered as a promising approach in the treatment of MRSA isolates.     

Screening of Indonesian peat soil bacteria producing antimicrobial compounds

The development and world-wide spread of multidrug-resistant (MDR) bacteria have a high concern in the medicine, especially the extended-spectrum of beta-lactamase (ESBL) producing Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). There are currently very limited effective antibiotics to treat infections caused by MDR bacteria. Peat-soil is a unique environment in which bacteria have to compete each other to survive, for instance, by producing antimicrobial substances. This study aimed to isolate bacteria from peat soils from South Kalimantan Indonesia, which capable of inhibiting the growth of Gram-positive and Gram-negative bacteria. Isolates from peat soil were grown and identified phenotypically. The cell-free supernatant was obtained from broth culture by centrifugation and was tested by agar well-diffusion technique against non ESBL-producing E. coli ATCC 25922, ESBL-producing E. coli ATCC 35218, methicillin susceptible Staphylococcus aureus (MSSA) ATCC 29,213 and MRSA ATCC 43300. Putative antimicrobial compounds were separated using SDS-PAGE electrophoresis and purified using electroelution method. Antimicrobial properties of the purified compounds were confirmed by measuring the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). In total 28 isolated colonies were recovered; three (25PS, 26PS, and 27PS) isolates produced proteins with strong antimicrobial activities against both reference strains. The substance of proteins from three isolates exerted strong antimicrobial activity against ESBL-producing E. coli ATCC 35,218 (MIC = 2,80 µg/mL (25PS), 3,76 µg/mL (26PS), and 2,41 µg/mL (27PS), and MRSA ATCC 43,300 (MIC = 4,20 µg/mL (25PS), 5,65 µg/mL (26PS), and 3,62 µg/mL (27PS), and also had the ability bactericidal properties against the reference strains. There were isolates from Indonesian peat which were potentials sources of new antimicrobials.     

Design and synthesis of amphiphilic 2-hydroxybenzylphosphonium salts with antimicrobial and antitumor dual action

Here we report the synthesis and biological evaluation of a series of new 2-hydroxybenzylphosphonium salts (QPS) with antimicrobial and antitumor dual action. The most active compounds exhibit antimicrobial activity at a micromolar level against Gram-positive bacteria Sa (ATCC 209p and clinical isolates), Bc (1–2 μM) and fungi Tm and Ca, and induced no notable hemolysis at MIC. The change in nature of substituents of the same length led to a drastic change of biological activity. Self-assembly behavior of the octadecyl and oleyl derivatives was studied. QPS demonstrated self-assembly within the micromolar range with the formation of nanosized aggregates capable of the solubilizing hydrophobic probe. The synthesized phosphonium salts were tested for cytotoxicity. The most potent salt was active against on M−Hela cell line with IC₅₀ on the level of doxorubicin and good selectivity. According to the cytofluorimetry analysis, the salts induced mitochondria-dependent apoptosis.     

Novel isoniazid embedded triazole derivatives: Synthesis,antitubercular and antimicrobial activity evaluation

In the present study, a series of new isoniazid embedded triazole derivatives have been synthesized. These compounds were evaluated for their in vitro antitubercular and antimicrobial activities. Among the screened compounds, six have exhibited potent antitubercular activity against Mycobacterium tuberculosis H37Rv strain with MIC value 0.78 μg/mL, whereas, three compounds have displayed activity with MIC value ranging from 1.56 to 3.125 μg/mL. The cytotoxicity of the active compounds was studied against RAW 264.7 cell line by MTT assay and no toxicity was observed even at 25 μg/mL concentration. The five compounds have displayed good antimicrobial activities. Molecular docking have been performed against mycobacterial InhA enzyme to gain an insight into the plausible mechanism of action which could pave the way for our endeavor to identify potent antitubercular candidates. We believe that further optimization of these molecules may lead to potent antitubercular agents.     

Improving NK1R-targeted gene delivery of stearyl-antimicrobial peptide CAMEL by conjugating it with substance P

Specificity is a crucial condition that hampers the application of non-viral vectors for cancer gene therapy. In a previous study, we developed an efficient gene vector, stearyl-CAMEL, using N-terminal stearylation of the antimicrobial peptide CAMEL. Substance P (SP), an 11-residue neuropeptide, rapidly enters cells after binding to the neurokinin-1 receptor (NK1R), which is expressed in many cancer cell lines. In this study, the NK1R-targeted gene vector stearyl-CMSP was constructed by conjugating SP to the C-terminus of stearyl-CAMEL. Our results indicated that stearyl-CMSP displayed significant transfection specificity for NK1R-expressing cells compared with that shown by stearyl-CAMEL. Accordingly, the stearyl-CMSP/p53 plasmid complexes had significantly higher antiproliferative activity against HEK293-NK1R cells than they did against HEK293 cells, while the stearyl-CAMEL/p53 plasmid complexes did not show this specificity in antiproliferative activity. Consequently, conjugation of the NK1R-targeted ligand SP is a simple and successful strategy to construct efficient cancer-targeted non-viral gene vectors.     

Toward insights on antimicrobial selectivity of host defense peptides via machine learning model interpretation

Host defense peptides are promising candidates for the development of novel antibiotics. To realize their therapeutic potential, high levels of target selectivity is essential. This study aims to identify factors governing selectivity via the use of the random forest algorithm for correlating peptide sequence information with their bioactivity data. Satisfactory predictive models were achieved from out-of-bag prediction that yielded accuracies and Matthew's correlation coefficients in excess of 0.80 and 0.57, respectively. Model interpretation through the use of variable importance metrics and partial dependence plots indicated that the selectivity was heavily influenced by the composition and distribution patterns of molecular charge and solubility related parameters. Furthermore, the three investigated bacterial target species (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) likely had a significant influence on how selectivity was realized as there appears to be a similar underlying selectivity mechanism on the basis of charge-solubility properties (i.e. but which is tailored according to the target in question).     

Influence of Wolbachia infection on antimicrobial peptide gene expressions in a cell line of the silkworm,Bombyx mori (Lepidoptera: Bombycidae)

Wolbachia, a symbiotic bacterium found in a broad range of insects, manipulates host reproduction. In addition to reproductive alterations, Wolbachia may also modify the immune system of host insects to protect them from additional pathogenic infection. We hypothesized that Wolbachia exerts protective effects by activating antimicrobial peptide (AMP) genes. To test this hypothesis, we established immunocompetent cell lines derived from the silkworm, Bombyx mori, which were transinfected with two Wolbachia strains, wKue and wCauB, originating from lepidopteran insects and quantified the expression of four AMP genes, cecropin B, defensin B, attacin, and lebocin 3. The expression was measured in wKue-infected, wCauB-infected, and uninfected cells, before and after treatment with peptidoglycan (PGN) that mimicked a bacterial infection. A two-way ANOVA for each gene showed that both Wolbachia infection and PGN treatment significantly increased the gene expression and their interaction. When treated with PGN, wKue- and wCauB-infected cells showed higher expression of the four AMP genes than those in uninfected cells, suggesting that Wolbachia infection increased the ability of host cells to produce AMPs in response to immune stimulation with PGN. These observations suggest that the two Wolbachia strains have immune priming effects and may protect the host insects from a secondary infection.     

Mn3O4 nanoparticles: Synthesis,characterization and their antimicrobial and anticancer activity against A549 and MCF-7 cell lines

Due to their inexpensive and eco-friendly nature, and existence of manganese in various oxidation states and their natural abundance have attained significant attention for the formation of Mn₃O₄ nanoparticles (Mn₃O₄ NPs). Herein, we report the preparation of Mn₃O₄ nanoparticles using manganese nitrate as a precursor material by utilization of a precipitation technique. The as-prepared Mn₃O₄ nanoparticles (Mn₃O₄ NPs) were characterized by using X-ray powder diffraction (XRD), UV–Visible spectroscopy (UV–Vis), High-Resolution Transmission electron microscopy (HRTEM), Field emission scanning electron microscopy (FESEM), Thermal gravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FT-IR). The antimicrobial properties of the as-synthesized Mn₃O₄ nanoparticles were investigated against numerous bacterial and fungal strains including S. aureus, E. coli, B. subtilis, P. aeruginosa, A. flavus and C. albicans. The Mn₃O₄ NPs inhibited the growth of S. aureus with a minimum inhibitory concentration (MIC) of 40 μg/ml and C. albicans with a MIC of 15 μg/ml. Furthermore, the Mn₃O₄ NPs anti-cancer activity was examined using MTT essay against A549 lung and MCF-7 breast cancer cell lines. The Mn₃O₄ NPs revealed significant activity against the examined cancer cell lines A549 and MCF-7. The IC₅₀ values of Mn₃O₄ NPs with A549 cell line was found at concentration of 98 µg/mL and MCF-7 cell line was found at concentration of 25 µg/mL.     

Antimicrobial resistance patterns among different Escherichia coli isolates in the Kingdom of Saudi Arabia

Antimicrobial resistance patterns among different Escherichia coli isolates in the Kingdom of Saudi Arabia. This study aimed to investigate the patterns of antimicrobial resistance in E. coli isolated from different samples, and to identify potential pathogenic isolates in Riyadh, Kingdom of Saudi Arabia (KSA). In total, 51 bacterial isolates were recovered from 113 samples of human urine, food (raw meat, raw chicken, raw egg surface, and fresh vegetables), water, and air. Twenty-four E. coli isolates were tested for susceptibility to 26 antibiotics. The air sample isolates were most resistant to amoxicillin, ampicillin, amoxicillin/clavulanic acid, amoxicillin/sulbactam, piperacillin/tazobactam, cefalotin, cefuroxime, cefoxitin, cefixime, nitrofurantoin, and trimethoprim/sulfamethoxazol. The isolates from vegetable samples were resistant to amoxicillin, ampicillin, amoxicillin/clavulanic acid, amoxicillin/sulbactam, cefalotin, cefuroxime, cefoxitin, and cefixime. By contrast, the isolates from the water samples were resistant only to amoxicillin and ampicillin. The isolates from the human urine samples were most frequently resistant to norfloxacin (80%) followed by amoxicillin and ampicillin (70%), trimethoprim/sulfamethoxazole (55%), ciprofloxacin and ofloxacin (50%), cefalotin (30%), cefuroxime, cefixime and cefotaxime (25%), ceftazidime, ceftriaxone, cefepime and aztreonam (20%), amoxicillin/clavulanic acid, piperacillin/tazobactam and gentamicin (10%), and amoxicillin/sulbactam and cefoxitin (5%). Almost all (23/25, 95.8%) (n = 23) of the isolates were multi-drug resistant (MDR) (i.e., resistant to 3 or more classes of antibiotics), and 16.7% (n = 4) of those were positive for extended spectrum β-lactamase (ESBL). Of the 4 ESBL-producers, 3 were positive for blaCTX_-M-15 and blaCTX_-M1_group, 2 were positive for blaCMY_-2, and 1 each was positive for blaCTX_{-M-2 group,} blaSHV, and blaOXA_-47. The quinolone resistance gene qnrS was detected in 25% (n = 6) of the E. coli strains isolated from urine (N = 5) and air (N = 1) samples. The considerable number of antimicrobial resistance genes detected among E. coli isolates tested here is alarming and should raise public health concern.