26 research outputs found
Chromobacterium violaceum and Pseudomonas aeruginosa PAO1: Models for Evaluating Anti-Quorum Sensing Activity of Melaleuca alternifolia Essential Oil and Its Main Component Terpinen-4-ol
No full textCeylan, Ozgur/0000-0002-1865-1093; De Feo, Vincenzo/0000-0002-1070-3207; Snoussi, Mejdi/0000-0002-2309-2601; Alreshidi, Mousa/0000-0002-3763-9698; DE MARTINO, LAURA/0000-0002-9948-0862WOS: 000451201400267PubMed ID: 30336602The problem of antibiotic resistance among pathogens encourages searching for novel active molecules. The aim of the research was to assay the anti-quorum sensing (anti-QS) and antibiofilm potential of Melaleuca alternifolia essential oil and its main constituent, terpinen-4-ol, to prevent the infections due to methicillin-resistant Staphylococcus aureus strains as an alternate to antibiotics. The tea tree oil (TTO) was evaluated for its potential in inhibiting QS-dependent phenomena such as violacein production in Chromobacterium violaceum, swarming motility of Pseudomonas aeruginosa PAO1, and biofilm formation in MRSA strains on glass. The results showed that terpinen-4-ol was able to inhibit MRSA strain biofilm formation on the glass strips by 73.70%. TTO inhibited the violacein production at a mean inhibitory concentration (MIC) value of 0.048 mg/mL by 69.3%. At 100 mu g/mL TTO and terpinen-4-ol exhibited inhibition in swarming motility of PAO1 by 33.33% and 25%, respectively. TTO revealed anti-QS and anti-biofilm activities at very low concentrations, but it could be further investigated for new molecules useful for the treatment of MRSA infections.University of SalernoThe study was supported by The University of Salerno
Chromobacterium violaceum and pseudomonas aeruginosa pao1: Models for evaluating anti-quorum sensing activity of melaleuca alternifolia essential oil and its main component terpinen-4-ol
No full textThe problem of antibiotic resistance among pathogens encourages searching for novel active molecules. The aim of the research was to assay the anti-quorum sensing (anti-QS) and antibiofilm potential of Melaleuca alternifolia essential oil and its main constituent, terpinen-4-ol, to prevent the infections due to methicillin-resistant Staphylococcus aureus strains as an alternate to antibiotics. The tea tree oil (TTO) was evaluated for its potential in inhibiting QS-dependent phenomena such as violacein production in Chromobacterium violaceum, swarming motility of Pseudomonas aeruginosa PAO1, and biofilm formation in MRSA strains on glass. The results showed that terpinen-4-ol was able to inhibit MRSA strain biofilm formation on the glass strips by 73.70%. TTO inhibited the violacein production at a mean inhibitory concentration (MIC) value of 0.048 mg/mL by 69.3%. At 100 μg/mL TTO and terpinen-4-ol exhibited inhibition in swarming motility of PAO1 by 33.33% and 25%, respectively. TTO revealed anti-QS and anti-biofilm activities at very low concentrations, but it could be further investigated for new molecules useful for the treatment of MRSA infections
Chemical and biological evaluation of essential oils from cardamom species
No full textTo highlight the importance of the spices in the Mediterranean diet, the aim of the paper was to study the essential oil compositions and to clarify the potential differences in the biological activities of the three cardamom species. In the study, we compared the phytochemical profiles and biological activities of essential oils from Elettaria cardamomum, Aframomum corrorima and Amomum subulatum. The oils were analyzed using the GC and GC/MS techniques and were mainly constituted of the oxygenated monoterpenes which represents 71.4%, 63.0%, and 51.0% of all compounds detected in E. cardamomum, A. corrorima and A. subulatum essential oils, respectively, 1,8-cineole was the main common compound between the tree tested volatile oil. The essential oils showed significant antimicrobial activity against Gram-positive and Gram-negative microorganisms tested especially the fungal strains. The Ethiopian cardamom was the most active essential oil with fungal growth inhibition zone ranging from 12.67 to 34.33 mm, MICs values ranging from 0.048 to 0.19 mg/mL, and MBCs values from 0.19 to 1.75 mg/mL. The three tested essential oils and their main component (1,8-cineole) significantly increased the production of elastase and protease production, and motility in P. aeruginosa PAO1 in a dose dependent manner. In fact, at 10 mg/mL concentration, the three essential oils showed more than 50% of inhibition of elastolytic and proteolytic activities in P. aeruginosa PAO1. The same oils inhibited also the violacein production in C. violaceum strain. It was also noticed that at high concentrations, the A. corrorima essential oil significantly inhibited the germination of radish. A thorough knowledge of the biological and safety profiles of essential oils can produce applications of economic importance
Metabolic Profiles of Clinical Strain of Staphylococcus aureus to Subtle Changes in the Environmental Parameters at Different Phases of Growth
No full textStaphylococcus aureusis an important pathogen that can lead to high number of infections worldwide.
The present study was aimed to investigate cytoplasmic metabolites of S. aureus at mid-exponential
and stationary phases following growth in a combination of conditions including variations in pH and
temperature. The result of metabolic analysis demonstrated that most of the metabolites measured at
stationary phase under optimal conditions were significantly altered in comparison to equivalent cells
harvested at mid- exponential phase. The major alteration was mainly observed in nitrogenous bases
and organic acids, which were relatively decreased in cells grown to stationary phase, while mannitol,
galactonic acid and adenosine were relatively increased in the cultures harvested at stationary phase.
At both phases, the metabolic profiles were substantially different between cultures grown under
ideal control conditions compared with those grown under more acidic and alkali conditions with
lower temperature of 35°C. The analyses of cells harvested from control and treatment samples at
mid-exponential phase showed that nitrogenous bases including uracil and adenine were significantly
decrease in treatment groups compared with reference controls. However, these metabolites were
relatively increased in the treatment cells grown to stationary phase. It was evident that variants in
environmental parameters led to differential profiles of cytoplasmic metabolites during adaptation
processes to applied conditions. These results provided robust evidence supporting the hypothesis
that specific alterations in cytoplasmic metabolites were essential for S. aureus to adapt and hence
survive under changes in the environmental parameters
Amino acid consumption and secretion patterns of Staphylococcus aureus following growth in sub-optimal environmental conditions
No full textBackground: Staphylococcus aureus is highly associated with nosocomial infections due to its ability to adapt to wide range of environmental parameters. The aim of this study was to evaluate amino acids consumption and secretion by S. aureus at mid-exponential and stationary phases under growth in sub-optimal conditions, including changes in pH, temperature and osmolality.Methods: The consumption and secretion of amino acids were determined by subtracting the original concentrations of the free amino acids in the media from those estimated at both mid-exponential and stationary phases of growth.Results: The analysis revealed that the consumption and secretion profiles were substantially different between cells grown under optimal control conditions, when compared with those exposed to sub-optimal conditions. The analyses of the supernatants harvested at mid-exponential phase revealed that the total consumption of amino acids was increased by 1.2 and 1.7 times by cells grown at either pH 6 or 8 and 35°C with additional of 5 % NaCl, respectively. However, the final levels of amino acids consumed at stationary phase were significantly reduced in the cells grown in sub-optimal conditions compared with bacteria cells grown under optimal conditions.Conclusion: It was evident that various environmental conditions led to differential profiles of amino acid consumption and secretion.Keywords: Staphylococcus aureus; Amino acid metabolism; Stress response
Phytochemical Analysis, Antioxidant, and Antimicrobial Activities of Ducrosia flabellifolia: A Combined Experimental and Computational Approaches
No full textDucrosia flabellifolia Boiss. is a rare desert plant known to be a promising source of bioactive compounds. In this paper, we report for the first time the phytochemical composition and biological activities of D. flabellifolia hydroalcoholic extract by using liquid chromatography–electrospray tandem mass spectrometry (ESI-MS/MS) technique. The results obtained showed the richness of the tested extract in phenols, tannins, and flavonoids. Twenty-three phytoconstituents were identified, represented mainly by chlorogenic acid, followed by ferulic acid, caffeic acid, and sinapic acid. The tested hydroalcoholic extract was able to inhibit the growth of all tested bacteria and yeast on agar Petri dishes at 3 mg/disc with mean growth inhibition zone ranging from 8.00 ± 0.00 mm for Enterococcus cloacae (E. cloacae) to 36.33 ± 0.58 mm for Staphylococcus epidermidis. Minimal inhibitory concentration ranged from 12.5 mg/mL to 200 mg/mL and the hydroalcoholic extract from D. flabellifolia exhibited a bacteriostatic and fungistatic character. In addition, D. flabellifolia hydroalcoholic extract possessed a good ability to scavenge different free radicals as compared to standard molecules. Molecular docking studies on the identified phyto-compounds in bacterial, fungal, and human peroxiredoxin 5 receptors were performed to corroborate the in vitro results, which revealed good binding profiles on the examined protein targets. A standard atomistic 100 ns dynamic simulation investigation was used to further evaluate the interaction stability of the promising phytocompounds, and the results showed conformational stability in the binding cavity. The obtained results highlighted the medicinal use of D. flabellifolia as source of bioactive compounds, as antioxidant, antibacterial, and antifungal agent
Exploring the action of new FimH inhibitors against CTX– 15 enzyme by enzoinformatics approach: A plausible arsenal against drug-resistant uropathogenic bacterial strains
No full textPurpose: To explore the potency of FimH inhibitors against CTX-M β-lactamase enzyme type 15, in view of the increasing prevalence of CTX-M 15 in uropathogenic strains which has reduced the treatment options to minimal.Method: FimH inhibitors were targeted against CTXM-15 by a molecular docking approach. Thereafter, the best ligand-target confirmation was selected and analyzed using LIGPLOT+ Version v.2.1. The hydrophobic and hydrogen bonding among the catalytic site amino acids of CTXM-15 and the FimH inhibitors were analyzed and 3-D structures were converted into 2-D images by LIGPLOT algorithm.Results: Out of all the FimH inhibitors tested, 3′-chloro-4′- (α-D-mannopyranosyloxy) biphenyl-4- carbonitrile, para-biphenyl-2-methyl-3′-methylamidemannoside, para-biphenyl-2-methyl-3′,5′dimethylamide-α-D-mannoside, and thiazolylamino mannoside exhibited better interaction with the CTX-M15 active site than the positive control avibactam. Moreover, in CTX-M 15, the amino acid residues, Ser70, Tyr105, Ser130, Asn132, Thr216, Thr235, Gly236, and Ser237 were commonly interacting with these FimH inhibitors as well as avibactam.Conclusion: The predicted findings suggest that these FimH inhibitors could be explored as potential CTX-M 15 inhibitors to cope-up with resistance issues of uropathogenic bacteria in the form of an alternate strategy
Chloroquine and Hydroxychloroquine Interact Differently with ACE2 Domains Reported to Bind with the Coronavirus Spike Protein: Mediation by ACE2 Polymorphism
No full textThe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection inducing coronavirus disease 2019 (COVID-19) is still an ongoing challenge. To date, more than 95.4 million have been infected and more than two million deaths have been officially reported by the WHO. Angiotensin-converting enzyme (ACE) plays a key role in the disease pathogenesis. In this computational study, seventeen coding variants were found to be important for ACE2 binding with the coronavirus spike protein. The frequencies of these allele variants range from 3.88 × 10−3 to 5.47 × 10−6 for rs4646116 (K26R) and rs1238146879 (P426A), respectively. Chloroquine (CQ) and its metabolite hydroxychloroquine (HCQ) are mainly used to prevent and treat malaria and rheumatic diseases. They are also used in several countries to treat SARS-CoV-2 infection inducing COVID-19. Both CQ and HCQ were found to interact differently with the various ACE2 domains reported to bind with coronavirus spike protein. A molecular docking approach revealed that intermolecular interactions of both CQ and HCQ exhibited mediation by ACE2 polymorphism. Further explorations of the relationship and the interactions between ACE2 polymorphism and CQ/HCQ would certainly help to better understand the COVID-19 management strategies, particularly their use in the absence of specific vaccines or drugs
Analysis of Cytoplasmic and Secreted Proteins of Staphylococcus aureus Revealed Adaptive Metabolic Homeostasis in Response to Changes in the Environmental Conditions Representative of the Human Wound Site
No full textThe pathogenesis of Staphylococcus aureus is mainly attributed to its capability to adjust to changes in environmental conditions, including those present on human skin or within a wound site. This study investigated the changes in the cytoplasmic and secreted proteins in S. aureus that occurred in response to alterations in the environmental parameters that could be found in the human wound site. In total, sixty differentially regulated cytoplasmic proteins were detected using a label-free quantification approach, and these proteins were classified into ten molecular functions: protein biosynthesis, glycolysis, signal transduction, metabolism, cell cycle, transport, energy generation, cell anchorage, nucleotide biosynthesis and unknown. These changes represented characteristic protein profiles when evaluated by principal component analysis. The bacterium responded to elevated NaCl at pH 6 by decreasing the abundance of the majority of cytoplasmic proteins, while at pH 8 there was an increase in the levels of cytoplasmic proteins in comparison to the untreated cells. The analysis of the secreted proteins showed that there was a high degree of difference in both the intensity and the distribution of many individual protein bands in response to environmental challenges. From these results, it was deduced that specific metabolic homeostasis occurred under each combination of defined environmental conditions
Novel Polymeric Nanomaterial Based on Poly(Hydroxyethyl Methacrylate-Methacryloylamidophenylalanine) for Hypertension Treatment: Properties and Drug Release Characteristics
No full textIn this study, a novel polymeric nanomaterial was synthesized and characterized, and it its potential usability in hypertension treatment was demonstrated. For these purposes, a poly(hydroxyethyl methacrylate-methacryloylamidophenylalanine)-based polymeric nanomaterial (p(HEMPA)) was synthesized using a mini-emulsion polymerization technique. The nanomaterials were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and zeta size analysis. The synthesized p(HEMPA) nanomaterial had a diameter of about 113 nm. Amlodipine-binding studies were optimized by changing the reaction conditions. Under optimum conditions, amlodipine’s maximum adsorption value (Qmax) of the p(HEMPA) nanopolymer was found to be 145.8 mg/g. In vitro controlled drug release rates of amlodipine, bound to the nanopolymer at the optimum conditions, were studied with the dialysis method in a simulated gastrointestinal system with pH values of 1.2, 6.8 and 7.4. It was found that 99.5% of amlodipine loaded on the nanomaterial was released at pH 7.4 and 72 h. Even after 72 h, no difference was observed in the release of AML. It can be said that the synthesized nanomaterial is suitable for oral amlodipine release. In conclusion, the synthesized nanomaterial was studied for the first time in the literature as a drug delivery system for use in the treatment of hypertension. In addition, AML–p(HEMPA) nanomaterials may enable less frequent drug uptake, have higher bioavailability, and allow for prolonged release with minimal side effects
