Molecular design of luminescence ion probes for various cations based on weak gold(I)...gold(I) interactions in dinuclear gold(I) complexes

A series of luminescent dinuclear gold(I) complexes with different crown ether pendants, [Au(2)(PwedgeP)(S-B15C5)(2)] [S-B15C5 = 4'-mercaptobenzo-15-crown-5, P(wedge)P = bis(dicyclohexylphosphino)methane (dcpm) (1), bis(diphenylphosphino)methane (dppm) (2)] and [Au(2)(P(wedge)P)(S-B18C6)(2)] [S-B18C6 = 4'-mercaptobenzo-18-crown-6, P(wedge)P = dcpm (3), dppm (4)], and their related crown-free complexes, [Au(2)(P(wedge)P)(SC(6)H(3)(OMe)(2)-3,4)(2)] [P(wedge)P = dcpm (5), dppm (6)], were synthesized. The low-energy emission of the mercaptocrown ether-containing gold(I) complexes are tentatively assigned as originated from states derived from a S --> Au ligand-to-metal charge transfer (LMCT) transition. The crown ether-containing gold(I) complexes showed specific binding abilities toward various metal cations according to the ring size of the crown pendants. Spectroscopic evidence was provided for the metal-ion-induced switching on of the gold...gold interactions upon the binding of particular metal ions in a sandwich binding mode.     

Biomimetic Cerium Oxide Loaded Gelatin PCL Nanosystems for Wound Dressing on Cutaneous Care Management of Multidrug-Resistant Bacterial Wound Healing

Skin wound healing involves a coordinated cellular response to achieve complete reepithelialization. Elevated levels of reactive oxygen species (ROS) in the wound environment often pose a hindrance in wound healing resulting in impaired wound healing process. Herein, cerium oxide nanoparticles (CeNPs) matrices like nanofibers have also been explored for enhancing wound healing. In this work, we have established the fabrication of CeNPs functionalized gelatin polycaprolactone (PCL) nanofibers (PCLNF) and CeNPs laden with PCL nanofiber (PCLNPNF) matrices by the electrospun methods. The bioactive composition PCLNPNF maintained the fiber morphological behaviour for up to 15 days. Further, the PCLNPNF matrices enhanced the cell proliferation against the NIH-3T3 cell lines established by Alamar blue assay. Furthermore, the PCLNPNF matrices scavenged ROS property examined with DCFH-DA intensity of the fluorescence microscopy. The antibacterial property of the PCLNPNF shows the remarkable activity against the gram-positive (S. aureus), and gram-negative (P. aeruginosa). Additionally, the in vivo bacterial removals and invented wound injuries examined development were definite through the MRSA-infects mice model. Taking to the advantages of this work, the newly fabricated PCLNPNF is a promising antibiotic alternative to battle the various bacterial infections in future.

     

Improved Synthesis of (S)-1-Phenyl-2-Propanol in High Concentration with Coupled Whole Cells of Rhodococcus erythropolis and Bacillus subtilis on Preparative Scale

Bioreduction of 1-phenyl-2-propanone to prepare (S)-1-phenyl-2-propanol, a useful pharmaceutical intermediate, was performed with growing cells of Rhodococcus erythropolis JX-021, giving 14 mM (1.9 g/L) product in 99% e.e. at 5 h in the catalysis of 15 mM substrate. The reduction stopped afterwards due to strong inhibition of substrate and formed product, a problem that is often encountered in biotransformation. While the substrate inhibition was solved by stepwise feeding, product inhibition was tackled by different methods: repeated removal of the product by centrifugation, by absorption with Amberlite XAD-7 resin, and by the use of dodecanol as the second phase gave the final product in 58, 68, and 61 mM in the catalysis of 80 mM substrate, respectively. The inhibition was caused by the partial permeabilization of cell membrane of R. erythropolis JX-021, and addition of NADPH or glucose 6-phosphate to such cell culture retained the reduction activity. Therefore, higher productivity in the reduction of 1 with resting cells of R. erythropolis JX-021 was achieved through cofactor regeneration and recycling by the addition of glucose and permeabilized cells of Bacillus subtilis BGSC 1A1 containing a glucose dehydrogenase, giving the product in 62 mM without addition of cofactor and 78 mM with the addition of 0.01 mM NADP⁺ in the catalysis of 120 mM substrate. The product e.e. retained 99% during the process which showed industrial possibility.     

Characterisation of two novel cyclodextrinases using on-line microdialysis sampling with high-performance anion exchange chromatography

In this work, a real-time sampling/analytical method for on-line measurements of two newly discovered cyclomaltodextrinases (CDases) has been developed and evaluated. This novel methodology not only allows the final products to be investigated, but it also reveals enzyme-specific differences in the degradation pathways during the hydrolysis of different substrates, which is a great advantage in the important tasks of investigating the mechanisms of and classifying new hydrolases, and is an advantage that conventional techniques cannot offer. Two different enzymes, one CDase from Laceyella sacchari (LsCda13) and one from Anoxybacillus flavithermus (AfCda13), were investigated during the hydrolysis of α-, β- and γ-cyclodextrin, and the hydrolysis products were sampled via a microdialysis probe and injected on-line every 30 min into a high-performance anion exchange chromatography system equipped with a pulsed amperometric detector (HPAEC–PAD), where they were identified. The enzymes yielded the same end-products, maltose and glucose, in an approximate molar ratio of 2:1, but they exhibited distinctly different patterns of intermediate product formation before reaching the end-point. LsCda13 had a more random distribution of the intermediate products, whereas AfCda13 showed the distinct intermediate production of maltotriose, which in some cases accumulated.     

Combining Topology and Sequence Design for the Discovery of Potent Antimicrobial Peptide Dendrimers against Multidrug‐Resistant Pseudomonas aeruginosa

Multidrug‐resistant opportunistic bacteria, such as Pseudomonas aeruginosa, represent a major public health threat. Antimicrobial peptides (AMPs) and related peptidomimetic systems offer an attractive opportunity to control these pathogens. AMP dendrimers (AMPDs) with high activity against multidrug‐resistant clinical isolates of P. aeruginosa and Acinetobacter baumannii were now identified by a systematic survey of the peptide sequences within the branches of a distinct type of third‐generation peptide dendrimers. Combined topology and peptide sequence design as illustrated here represents a new and general strategy to discover new antimicrobial agents to fight multidrug‐resistant bacterial pathogens.     

In vitro antibiofilm activity of the freshwater bryozoan Hyalinella punctata: a case study of Pseudomonas aeruginosa PAO1

The antibiofilm and possible antiquorum sensing effects against the strain Pseudomonas aeruginosa PAO1 of five crude extracts of the freshwater bryozoan Hyalinella punctata (Hancock, 1850) were evaluated in vitro for the first time. H. punctata ethyl acetate extract (HpEtAc) exhibited the highest antibiofilm activity reducing the biofilm formation of P. aeruginosa PAO1 in the range of 80.63–88.13%. While all tested extracts reduced the twitching motility of the aforementioned bacterial strain, HpEtAc showed to be the most effective. Finally, at a concentration of 0.5 MIC, the same extract mostly inhibited the production of pyocyanin by P. aeruginosa PAO1 (71.53%). In comparison both with the positive controls used (streptomycin and ampicillin, 67.13 and 69.77%, respectively), HpEtAc was found to inhibit pyocyanin in a higher extent. An extensive chemical characterisation of this particular extract may result in isolation and identification of novel lead compounds targeting P. aeruginosa, an opportunistic human pathogen.     

Antimicrobial photodynamic therapy on drug-resistant Pseudomonas aeruginosa-induced infection. An in vivo study

Pseudomonas aeruginosa is considered one of the most important pathogens that represent life‐threatening risk in nosocomial environments, mainly in patients with severe burns. Antimicrobial photodynamic therapy (aPDT) has been effective to kill bacteria. The purpose of this study was to develop a burn wound and bloodstream infection model and verify aPDT effects on it. In vitro, we tested two wavelengths (blue and red LEDs) on a clinical isolate of P. aeruginosa strain with resistance to multiple antibiotics using HB:La⁺³ as photosensitizer. Verapamil^® associated to aPDT was also studied. In vivo, P. aeruginosa‐infected burned mice were submitted to aPDT. Bacterial counting was performed on local infection and bloodstream. Survival time of animals was also monitored. In this study, aPDT was effective to reduce P. aeruginosa in vitro. In addition, Verapamil^® assay showed that HB:La⁺³ is not recognized by ATP‐binding cassete (ABC) efflux pump mechanism. In the in vivo study, aPDT was able to reduce bacterial load in burn wounds, delay bacteremia and keep the bacterial levels in blood 2–3 logs lower compared with an untreated group. Mice survival was increased on 24 h. Thus, this result suggests that aPDT may also be a novel prophylactic treatment in the care of burned patients.     

A Bottom‐Up Proteomic Approach to Identify Substrate Specificity of Outer‐Membrane Protease OmpT

Identifying peptide substrates that are efficiently cleaved by proteases gives insights into substrate recognition and specificity, guides development of inhibitors, and improves assay sensitivity. Peptide arrays and SAMDI mass spectrometry were used to identify a tetrapeptide substrate exhibiting high activity for the bacterial outer‐membrane protease (OmpT). Analysis of protease activity for the preferred residues at the cleavage site (P1, P1′) and nearest‐neighbor positions (P2, P2′) and their positional interdependence revealed FRRV as the optimal peptide with the highest OmpT activity. Substituting FRRV into a fragment of LL37, a natural substrate of OmpT, led to a greater than 400‐fold improvement in OmpT catalytic efficiency, with a k _cat/K _m value of 6.1×10⁶ L mol⁻¹ s⁻¹. Wild‐type and mutant OmpT displayed significant differences in their substrate specificities, demonstrating that even modest mutants may not be suitable substitutes for the native enzyme.     

Epitope Mapping of Monoclonal Antibodies using Synthetic Oligosaccharides Uncovers Novel Aspects of Immune Recognition of the Psl Exopolysaccharide of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic Gram‐negative bacterium that can cause life‐threatening infections in critically ill and cystic fibrosis patients. The Psl exopolysaccharide of P. aeruginosa offers an attractive serotype‐independent antigen for the development of immunotherapies. Here, the first chemical synthesis of a panel of oligosaccharides derived from the exopolysaccharide of P. aeruginosa by a synthetic strategy that efficiently deals with the stereoselective installation of several β‐mannosides and the formation of a mannoside that is extended by saccharide moieties at C‐1, C‐2, and C‐3 in a crowded 1,2,3‐cis configuration is described. The approach was employed to prepare tetra‐, penta‐, and hexa‐ and decasaccharide part structures. The compounds were employed to define the epitope requirements of several functionally active monoclonal antibodies (mAbs) that can bind three distinct epitopes of Psl (class I, II, and III). The class II mAb reacted potently with each oligosaccharide indicating its epitope resides within the tetrasaccharide and does not require the branched mannoside of Psl. The class III antibody did not bind the tetra‐ or pentasaccharide; however, it did react potently with the hexasaccharide and weakly with the decasaccharide, suggesting a terminal glucoside is required for optimal binding. Unexpectedly, the class I mAb did not bind any of the oligosaccharides indicating that Psl contains a yet to be elucidated sub‐stoichiometric isoform. This study demonstrates that functional activity of a mAb does not only depend on the avidity of binding but also on the location of an epitope within a bacterial polysaccharide. The results also provide a strong impetus to analyze further the structure of Psl to identify the class I epitope, that is expected to provide an attractive target for the development of a synthetic vaccine for P. aeruginosa.     

Anti-Pathogenic Properties of the Combination of a T3SS Inhibitory Halogenated Pyrrolidone with C-30 Furanone

Antimicrobial resistance is one of the current public health challenges to be solved. The World Health Organization (WHO) has urgently called for the development of strategies to expand the increasingly limited antimicrobial arsenal. The development of anti-virulence therapies is a viable option to counteract bacterial infections with the possibility of reducing the generation of resistance. Here we report on the chemical structures of pyrrolidones DEXT 1–4 (previously identified as furan derivatives) and their anti-virulence activity on Pseudomonas aeruginosa strains. DEXT 1–4 were shown to inhibit biofilm formation, swarming motility, and secretion of ExoU and ExoT effector proteins. Also, the anti-pathogenic property of DEXT-3 alone or in combination with furanone C-30 (quorum sensing inhibitor) or MBX-1641 (type III secretion system inhibitor) was analyzed in a model of necrosis induced by P. aeruginosa PA14. All treatments reduced necrosis; however, only the combination of C-30 50 µM with DEXT-3 100 µM showed significant inhibition of bacterial growth in the inoculation area and systemic dispersion. In conclusion, pyrrolidones DEXT 1–4 are chemical structures capable of reducing the pathogenicity of P. aeruginosa and with the potential for the development of anti-virulence combination therapies.     

Rhamnolipid Production by <Emphasis Type="Italic">Pseudomonas Aeruginosa</Emphasis> GIM 32 Using Different Substrates Including Molasses Distillery Wastewater

A rhamnolipid production strain newly isolated from oil-contaminated soil was identified as Pseudomonas aeruginosa GIM32 by its morphology and 16S rDNA sequence analysis. The effect of carbon source and carbon to nitrogen (C/N) ratio on rhamnolipids production was investigated. Palm oil was favorable as a carbon source for rhamnolipid production. The maximum biomass and rhamnolipid concentration were 8.24 g/L and 30.4 g/L, respectively, with an optimization medium containing 50 g/L palm oil and 5 g/L sodium nitrate. Molasses distillery wastewater as an unconventional substrate for rhamnolipid production was investigated. It was found that 2.6 g/L of rhamnolipids was produced; this amount was higher than that of past reports using wastewater as a substrate. In addition, 44% of the chemical oxygen demand of wastewater was removed at the same time under the optimization condition. Eleven kinds of different molecular weight rhamnolipid homologues were identified in the rhamnolipids obtained from molasses distillery wastewater by P. aeruginosa GIM32 by LC–MS analysis.     

Sequential one‐pot multicomponent synthesis of bis‐aminothiazols and evaluation of their antibacterial and antioxidant activities

A series of novel bis‐thiazoles were synthesized through a one‐pot semi‐five‐component reaction of the prepared α‐bisbromo ketones, aldehydes, and thiosemicarbazide in the presence of p‐TsOH under reflux condition. Products were obtained in reasonable yields via an efficient, convenient, and simple setup. The inhibitory activity on bacterial growth of the products was studied against Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) and Gram‐positive bacterial strains (Micrococcus luteus, Staphylococcus aureus) at different concentrations (25, 50, 100, and 200 μg/mL at 600 nm). Most of the products showed inhibitory activity at the concentration of 200 μg/mL. In addition, bis‐thiazoles showeed high to moderate antioxidant activity using the diphenylpicrylhydrazyl (DPPH) method. Bis‐thiazoles 6i and 6j showed higher antioxidant activity than vitamin C and vitamin E.     

Covalently Immobilized Battacin Lipopeptide Gels with Activity against Bacterial Biofilms

Novel antibiotic treatments are in increasing demand to tackle life-threatening infections from bacterial pathogens. In this study, we report the use of a potent battacin lipopeptide as an antimicrobial gel to inhibit planktonic and mature biofilms of S. aureus and P. aeruginosa. The antimicrobial gels were made by covalently linking the N-terminal cysteine containing lipopeptide (GZ3.163) onto the polyethylene glycol polymer matrix and initiating gelation using thiol-ene click chemistry. The gels were prepared both in methanol and in water and were characterised using rheology, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Antibacterial and antibiofilm analyses revealed that the gels prepared in methanol have better antibacterial and antibiofilm activity. Additionally, a minimum peptide content of 0.5 wt% (relative to polymer content) is required to successfully inhibit the planktonic bacterial growth and disperse mature biofilms of P. aeruginosa and S. aureus. The antibacterial activity of these lipopeptide gels is mediated by a contact kill mechanism of action. The gels are non-haemolytic against mouse red blood cells and are non-cytotoxic against human dermal fibroblasts. Findings from this study show that battacin lipopeptide gels have the potential to be developed as novel topical antibacterial agents to combat skin infections, particularly caused by S. aureus.     

A Solvent-Stable Metalloprotease Produced by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> A2 Grown on Shrimp Shell Waste and Its Application in Chitin Extraction

A solvent-stable protease-producing bacterium was isolated and identified as Pseudomonas aeruginosa A2. The strain was found to produce high level of protease activity when grown in media containing only fresh shrimp waste (FSW) or shrimp waste powder (SWP), indicating that it can obtain its carbon, nitrogen, and salts requirements directly from shrimp waste. Maximum protease activities 17,000 and 12,000 U/mL were obtained with 80 g/L SWP and 135 g/L FSW, respectively. The optimum temperature and pH for protease activity were 60 °C and 8.0, respectively. The crude protease, at different enzyme/substrate (E/S) ratio, was tested for the deproteinization of shrimp waste to produce chitin. The crude enzyme of P. aeruginosa A2 was found to be effective in the deproteinization of shrimp waste. The protein removals after 3 h hydrolysis at 40 °C with an E/S ratio of 0.5 and 5 U/mg protein were about 56% and 85%, respectively. ¹³C CP/MAS-NMR spectral analysis of the chitin prepared by treatment with the crude protease was carried out and was found to be similar to that of the commercial α-chitin. These results suggest that enzymatic deproteinization of shrimp waste by A2 protease could be applicable to the chitin production process.     

Quorum sensing inhibitors from marine bacteria Oceanobacillus sp. XC22919

In this study, three active compounds isolated from Oceanobacillus sp. XC22919 were identified as 2-methyl-N-(2′-phenylethyl) butyramide (1), 3-methyl-N-(2′-phenylethyl)-butyramide (2) and benzyl benzoate (3), and were first reported to exhibit the apparent quorum sensing inhibitory activities against C. violaceum 026 and P. aeruginosa. Compounds 1–3 inhibited violacein production of C. violaceum 026 by 10.5–55.7, 11.2–55.7, and 27.2%–95.7%, respectively, and inhibited pyocyanin production of P. aeruginosa by 1.7–50.8, 39.1–90.7, and 57.2%–98.7%, respectively. The azocasein-degrading proteolytic rates of P. aeruginosa were observed by 13.4–31.5, 13.4–28.8, and 11.3%–21.1%, respectively. With respect to elastase, the range of inhibition of activity of compounds 1–3 was 2.1–30.3, 4.2–18.2, and 8.9%–15.7%, respectively. Compounds 1 and 3 also showed a concentration-dependent attenuation in biofilm formation, with the maximum of 50.6% inhibition, and 37.7% inhibition at 100 μg/mL, respectively.     

Assessment of Acrylamide Degradation Potential of Pseudomonas aeruginosa BAC-6 Isolated from Industrial Effluent

Acrylamide finds diverse industrial applications but is considered an environmental threat because of its neurotoxic, carcinogenic, and teratogenic effects. Certain bacteria enzymatically degrade acrylamide to acrylic acid and ammonia. The present investigation was carried out to isolate and identify an acrylamide-degrading bacterium from industrial effluent. Bacterial growth and extent of acrylamide degradation in the presence of different acrylamide concentrations, nutrients, varied range of pH, and temperature were analyzed. Among the eight acrylamide-degrading isolates, isolate BAC-6 demonstrated the highest degradation, and based upon the partial 16S rDNA sequencing, it was identified as Pseudomonas aeruginosa. P. aeruginosa BAC-6 grew over a wide range of acrylamide concentrations, but the highest degradation was recorded at 500 mg/L concentration with concomitant cell growth. Among the carbon supplements, mannitol supported the highest growth and degradation. Maximum degradation was reported at neutral pH. A mesophilic temperature range (25–40 °C) facilitated conducive bacterial growth followed by degradation. The highest degradation and bacterial growth were observed at 30 and 35 °C, respectively. Thus, it could be inferred from the present investigation that cultural conditions strongly affected the degradation potential of P. aeruginosa BAC-6 and advocated the utilization of the isolate in bioremediation of sites polluted with acrylamide.     

Photosensitive and Biomimetic Core–Shell Nanofibrous Scaffolds as Wound Dressing

Tissue engineered skin grafts that mimic the native extracellular matrix of skin has gained huge popularity among clinicians since they increase the survival rate of the patients. Phototherapy shows promising results with respect to acute and chronic pain relief, treatment of inflammatory conditions and promotion of wound healing. Here, we encapsulated a photosensitive polymer poly (3‐hexylthiophene) (P3HT) and epidermal growth factor in the core–shell‐structured Gelatin/poly(L‐lactic acid)‐co‐poly‐(ε‐caprolactone) nanofibers [Gel/PLLCL/P3GF(cs)] by coaxial spinning and studied the potential application of the Gel/PLLCL/P3GF(cs) nanofibrous scaffold as a novel skin graft. The proliferation of fibroblasts was significantly improved on Gel/PLLCL/P3GF(cs) under light stimulation compared to fibroblasts on the same scaffold under dark condition. Studies on the in vitro wound healing ability of Gel/PLLCL/P3GF(cs) showed complete closure of wound after 9 days under “light stimulation” too. Furthermore, the potential of adipose‐derived stem cells (ASCs) to differentiate to epidermal cells on Gel/PLLCL/P3GF(cs) was evaluated. The differentiated ASCs with keratinocytes morphology were only found on the light stimulated Gel/PLLCL/P3GF(cs). Our results suggest that the photosensitive core–shell Gel/PLLCL/P3GF(cs) nanofibers could be a novel substrate to aid in the reestablishment of skin architecture.     

Design,synthesis, molecular docking,and spectral studies of new class of carbazolyl polyhydroquinoline derivatives as promising antibacterial agents with noncytotoxicity towards human mononuclear cells from peripheral blood

In the present study, we report the design and eco-benign synthesis of new class of carbazolyl-1,4-dihydropyridine (1,4-CDHP) and carbazolyl-1,8-dioxodecahydroacridine (CAD) derivatives via a three-component coupling reaction of substituted carbazole aldehydes, ethyl acetoacetate/dimedone, and ammonium acetate under solvent-free conditions at 112°C to 115°C. We also report an efficient one-pot synthesis of new class of carbazolyl polyhydroquinoline (CPQ) derivatives via a four-component coupling reaction of substituted ethyl acetoacetate, dimedone, ammonium acetate, and carbazole aldehydes in acetonitrile/water medium (3:1) at 73°C to 75°C in moderate yields. All the products were thoroughly characterized by ¹H NMR, ¹³C NMR, Fourier transform infrared (FTIR), mass spectral, and CHN analysis. The synthesized heterocyclic compounds were evaluated for their in vitro antibacterial activity against pathogenic strains of both Gram-negative and Gram-positive bacteria. Minimum inhibitory concentration (MIC) of the active compounds was evaluated by macrodilution method. The CPQ derivative ( 8a ) displayed superior antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi with the MIC values of 16.0 to 32.0 μg/mL in comparison with the reference drug. The mechanism of antibacterial action of the CPQ derivatives was investigated via scanning electron microscope (SEM) studies. The molecular docking studies indicate that the CPQ derivative ( 8a ) binds to the cell wall protein of E coli and P aeruginosa by formation of hydrogen bonds with amino acid residues (TYR328 and GLU249) of the bacterial cell wall protein. The 1,4-CDHP, CAD, and CPQ derivatives were either noncytotoxic or exhibited minimal cytotoxicity towards human mononuclear cells from peripheral blood. All the products were evaluated for Lipinski rule of five (RO5) and were found to have good oral bioavailability.     

Radical scavenging and antimicrobial activities of Croton zehntneri,Pterodon emarginatus and Schinopsis brasiliensis essential oils and their major constituents: estragole,trans-anethole, β-caryophyllene and myrcene

The essential oils (EOs) from the Brazilian species Croton zehntneri, Pterodon emarginatus and Schinopsis brasiliensis were examined for their chemical constituents, and antioxidant and antimicrobial activities. The composition of EOs was determined by using gas chromatography coupled with mass spectrometry analysis, while the antioxidant activity was evaluated through the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. Furthermore, the antimicrobial activity was investigated against Escherichia coli and Pseudomonas aeruginosa (both Gram-negative), Staphylococcus aureus (Gram-positive) and Candida parapsilosis (fungus). The main components of C. zehntneri, P. emarginatus and S. brasiliensis were identified as estragole, trans-anethole, β-caryophyllene and myrcene. Among the EOs, P. emarginatus showed the highest antioxidant activity, with an IC₅₀ of 7.36 mg/mL and a Trolox equivalent antioxidant capacity of 3748 μmol/g determined by DPPH and ORAC assays, respectively. All EOs showed low activities against the bacterial strains tested, whereas the C. zehntneri oil and its main constituent estragole exhibited an appreciable antifungal activity against C. parapsilosis.     

In vitro anti-quorum sensing activity of phytol

Anti-quorum sensing activity of the diterpene phytol was evaluated in vitro for the first time. This compound (at three sub-MIC concentrations – 0.5, 0.25 and 0.125 MIC, respectively) reduced the formation of Pseudomonas aeruginosa PAO1 biofilm in the range of 74.00–84.33% exhibiting higher activity than the both positive controls used, streptomycin and ampicillin. Phytol (0.5 MIC) also effectively reduced P. aeruginosa twitching and flagella motility. Indeed, the bacteria treated were incapable of producing a twitching zone and had almost round, smooth and regular colony edges. Finally, the tested compound (0.5 MIC) exhibited good P. aeruginosa pyocyanin inhibitory activity (51.94%) practically to the same extent as streptomycin (52.09%). According to the experimental data obtained, this phytol property may inspire design of medical foods targeting P. aeruginosa quorum sensing activity.