Bactericidal, Bacteriolytic, and Antibacterial Virulence Activities of Boesenbergia pandurata (Roxb) Schltr Extract against Streptococcus pyogenes

Purpose: To determine the anti-Streptococcus pyogenes activity of the chloroform extract of Boesenbergia pandurata (Roxb.) Schltr. (Zingiberaceae) and investigate its possible antibacterial mechanisms of action.Methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were investigated against 47 clinical isolates of S. pyogenes. Time-kill study was performed to determine how quickly the extract acts on S. pyogenes. The ability of the extract to damage bacterial cell wall and effects on S. pyogenes virulence factors including protease enzyme and haemolysin were investigated.Results: The extract exhibited good antibacterial activity against all of the clinical isolates of S. pyogenes with similar MIC and MBC ranging from 3.91-62.50 μg/ml. Complete killing of the bacterial cells by the extract at concentrations of 4MIC, 2MIC, and MIC occurred within 4, 8, and 12 h, respectively. Treatment of the bacterial cells with the extract at 2MIC and 4MIC caused cell lysis. All the test concentrations (1/32 - 1/2MIC) produced no effects on protease and haemolysin enzymes.Conclusion: Boesenbergia pandurata extract has powerful in vitro activity against S. pyogenes. The ability of the extract to lyse the bacterial cells suggests that the mechanism of action may be associated with cell wall and cell membrane damage.Keywords: Antibacterial, Bacteriocidal, Bacteriolytic, Virulence, Boesenbergia pandurata, Streptococcus pyogenes

Raman Spectroscopy of DLC/a-Si Bilayer Film Prepared by Pulsed Filtered Cathodic Arc

DLC/a-Si bilayer film was deposited on germanium substrate. The a-Si layer, a seed layer, was firstly deposited on the substrate using DC magnetron sputtering and DLC layer was then deposited on the a-Si layer using pulsed filtered cathodic arc method. The bilayer films were deposited with different DLC/a-Si thickness ratios, including 2/2, 2/6, 4/4, 6/2, and 9/6. The effect of DLC/a-Si thickness ratios on the sp3 content of DLC was analyzed by Raman spectroscopy. The results show that a-Si layer has no effect on the structure of DLC film. Furthermore, the upper shift in G wavenumber and the decrease in ID/IG inform that sp3 content of the film is directly proportional to DLC thickness. The plot modified from the three-stage model informed that the structural characteristics of DLC/a-Si bilayer films are located close to the tetrahedral amorphous carbon. This information may be important for analyzing and developing bilayer protective films for future hard disk drive

Effect of Thai medicinal plant extracts on cell aggregation of Escherichia coli O157: H7.

Medicinal plants have been used for treating diarrhoea but the interference mechanisms are not clearly understood. One possible hypothesis is that of an effect on cell surface hydrophobicity of microbial cells. In this study, we examined cell aggregation affected by crude extracts of Thai medicinal plants on cell surface hydrophobicity of Escherichia coli strains by salt aggregation test. Correlation between minimal inhibitory concentration and cell aggregation was performed. Aqueous and ethanolic extracts of 8 medicinal plants including Acacia catechu, Holarrhena antidysenterica, Peltophorum pterocarpum, Piper sarmentosum, Psidium guajava, Punica granatum, Quercus infectoria, and Tamarindus indica were tested with E. coli O157: H7 and other E. coli strains isolated from human, porcine, and foods. Aqueous extracts of Peltophorum pterocarpum, Psidium guajava, and Punica granatum were highly effective against E. coli O157: H7 with the MIC values of 0.09 to 0.39, 0.19 to 0.78, and 0.09 to 1.56 mg/ml, respectively. Ethanolic extract of Quercus infectoria and Punica granatum demonstrated good MIC values of 0.09 to 0.78, and 0.19 to 0.78 mg/ml, respectively. It was established that aqueous extracts of Punica granatum and Piper sarmentosum at high concentration (25 mg/ml) enhanced cell aggregation of almost all E. coli strains while aqueous and ethanolic extracts ofQuercus infectoria enhanced cell aggregation of some E. coli strains. Correlation between minimal inhibitory concentration and cell aggregation was not found in this study

Anti-Streptococcus pyogenes Activity of Selected Medicinal Plant Extracts Used in Thai Traditional Medicine

Purpose: To evaluate the anti-Streptococcus pyogenes activity of selected medicinal plants used in Thai traditional medicine.Methods: Sixty-nine extracts of 51 selected Thai medicinal plant species were tested for anti-S. pyogenes activity by paper disc agar diffusion and broth microdilution methods.Results: Ten plants including Boesenbergia pandurata (Roxb.) Schltr., Cinnamomum bejolghota (Buch.-Ham.) Sweet, Cinnamomum porrectum (Roxb) Kosterm, Eleutherine americana Merr., Gymnopetalum cochinchinensis (Lour.) Kurz, Piper betle L., Quercus infectoria G. Olivier, Quisqualis indica L, Rhodomyrtus tomentosa (Aiton) Hassk., and Walsura robusta Roxb. demonstrated good antibacterial activity against S. pyogenes NPRC 101. These plants were selected and further evaluated for their anti-S. pyogenes activity against 11 isolates of S. pyogenes from patients with upper respiratory tract infections. Three plants including Boesenbergia pandurata, Eleutherine americana, and Rhodomyrtus tomentosa exhibited good antibacterial activity against all S. pyogenes isolates and produced similar activities against different tested isolates. Boesenbergia pandurata and Rhodomyrtus tomentosa demonstrated antibacterial activity with the same minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) range of 3.91 - 31.25 μg/ml whereas Eleutherine americana displayed MIC and MBC values of 250 and 250-500 μg/ml against all S. pyogenes isolates.Conclusion: Boesenbergia pandurata, Eleutherine americana, and Rhodomyrtus tomentosa have great antibacterial potentials against S. pyogenes.Keywords: Antibacterial activity, Boesenbergia pandurata, Eleutherine americana, Rhodomyrtus tomentosa, Streptococcus pyogenes, Thai medicinal plant, Upper respiratory tract infection

The Effect of Heat Treatment on Crystal Structure in Zircon Monitored by ESR and XRD

AbstractX-band ESR spectra of zircon before and after heat treatment under oxygen rich atmosphere were measured with directions of the magnetic field applied in parallel and perpendicular to c-axis [001]. Seven peaks of Zeeman interaction were generated from the microwave energy absorptions due to the transitions between the spin states of natural impurity, gadolinium ions (Gd3+, S = 7/2). Angular variation of peak positions reflects that the symmetry surrounding of Gd3+ is D2d, signifying the replacement of Zr4+ by Gd3+ in the lattice. From XRD patterns, the unheated and after heated zircon are the same phase i.e. tetragonal phase of the space group I41/amd. The Rietveld refinement method was employed for derivation of the bond distance and bond angles of zirconium, silicon and oxygen atoms

Influence of off-cut angle of (0001) 4H-SiC on the crystal quality of InN grown by RF-MBE

AbstractThe effect of the off-cut angle of a 4H-SiC (0001) substrate on the growth of InN thick layer by RF-plasma assisted molecular beam epitaxy (RF-MBE) has been investigated. The off-cut angle used in this study was inclined from 0° (just surface) toward the [11–20] direction of 4° and 8°. Crystalline quality and surface morphology were remarkably sensitive to the value of off-angle. Higher off-cut angles result in a reduction of the full-widths at half-maximum of HRXRD (0002) ω-scans, compared to that of the layer on the (0001)-just surface. In addition, the full-widths at halfmaximum of μ-Raman scattering spectra at 490cm-1, which is attributed to E2 (high) phonon mode, was decreased with increase in off-cut angle. Furthermore, In-droplets, which are commonly observed on the (0001) InN grown surface under In rich-growth condition, were found to be suppressed owing to an improvement of a nucleation on the off-cut angle surface. In our case, the use of 8°-off substrate increased film density and growth rate, while a surface roughness was reduced. These results clearly demonstrate that the larger off-cut angles improve the crystalline quality of InN film with reducing the In-droplets due to a higher step surface density on the off-cut angle surface

Growth of Silver Nanoparticles by DC Magnetron Sputtering

Silver (Ag) nanoparticles are of great interest for many applications. However, their fabrications have been limited by the synthesis methods in which size, shape, and aggregation are still difficult to control. Here, we reported on using direct current (DC) magnetron sputtering for growing Ag nanoparticles on unheated substrates. Effects of sputtering condition on grain size of Ag nanoparticle were discussed. At constant sputtering current and deposition time, the average sizes of Ag nanoparticles were 5.9 ± 1.8, 5.4 ± 1.3, and 3.8 ± 0.7 nm for the target-substrate distances of 10, 15, and 20 cm, respectively. The morphology evolution from nanoparticles to wormlike networks was also reported. High-resolution transmission electron microscopy image represented clear lattice fringes of Ag nanoparticles with a d-spacing of 0.203 nm, corresponding to the (200) plane. The technique could be applied for growth of nanoparticles that were previously difficult to control over size and size uniformity

Irradiation effect on natural quartz from Zambia

AbstractThe effects of high gamma-irradiation doses (50-300 kGy) on natural quartz crystals have been investigated by ESR technique. The ESR spectrum carried out at low temperature (120K) displayed lines group of Al center. The higher amount of gamma doses affected ESR spectra by increasing of intensity, especially the increasing intensity in the range of the Al center. The complex ESR spectra of Al center observed to contain 9 peaks that did not reach saturation even though the level of gamma-irradiation dose was as high as 300 kGy. The total area under ESR spectra of Al center was increased as a polynomial function of irradiated dose. The overlapping of ESR signal from defects in the range of Al center was also investigated

Proteome Analyses of Cellular Proteins in Methicillin-Resistant Staphylococcus aureus Treated with Rhodomyrtone, a Novel Antibiotic Candidate

The ethanolic extract from Rhodomyrtus tomentosa leaf exhibited good antibacterial activities against both methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus ATCC 29213. Its minimal inhibitory concentration (MIC) values ranged from 31.25–62.5 µg/ml, and the minimal bactericidal concentration (MBC) was 250 µg/ml. Rhodomyrtone, an acylphloroglucinol derivative, was 62.5–125 times more potent at inhibiting the bacteria than the ethanolic extract, the MIC and MBC values were 0.5 µg/ml and 2 µg/ml, respectively. To provide insights into antibacterial mechanisms involved, the effects of rhodomyrtone on cellular protein expression of MRSA have been investigated using proteomic approaches. Proteome analyses revealed that rhodomyrtone at subinhibitory concentration (0.174 µg/ml) affected the expression of several major functional classes of whole cell proteins in MRSA. The identified proteins involve in cell wall biosynthesis and cell division, protein degradation, stress response and oxidative stress, cell surface antigen and virulence factor, and various metabolic pathways such as amino acid, carbohydrate, energy, lipid, and nucleotide metabolism. Transmission electron micrographs confirmed the effects of rhodomyrtone on morphological and ultrastructural alterations in the treated bacterial cells. Biological processes in cell wall biosynthesis and cell division were interrupted. Prominent changes including alterations in cell wall, abnormal septum formation, cellular disintegration, and cell lysis were observed. Unusual size and shape of staphylococcal cells were obviously noted in the treated MRSA. These pioneer findings on proteomic profiling and phenotypic features of rhodomyrtone-treated MRSA may resolve its antimicrobial mechanisms which could lead to the development of a new effective regimen for the treatment of MRSA infections

Native New Zealand plants with inhibitory activity towards Mycobacterium tuberculosis

<p>Abstract</p> <p>Background</p> <p>Plants have long been investigated as a source of antibiotics and other bioactives for the treatment of human disease. New Zealand contains a diverse and unique flora, however, few of its endemic plants have been used to treat tuberculosis. One plant, <it>Laurelia novae-zelandiae</it>, was reportedly used by indigenous Maori for the treatment of tubercular lesions.</p> <p>Methods</p> <p><it>Laurelia novae-zelandiae </it>and 44 other native plants were tested for direct anti-bacterial activity. Plants were extracted with different solvents and extracts screened for inhibition of the surrogate species, <it>Mycobacterium smegmatis</it>. Active plant samples were then tested for bacteriostatic activity towards <it>M. tuberculosis </it>and other clinically-important species.</p> <p>Results</p> <p>Extracts of six native plants were active against <it>M. smegmatis</it>. Many of these were also inhibitory towards <it>M. tuberculosis </it>including <it>Laurelia novae-zelandiae </it>(Pukatea). <it>M. excelsa </it>(Pohutukawa) was the only plant extract tested that was active against <it>Staphylococcus aureus</it>.</p> <p>Conclusions</p> <p>Our data provide support for the traditional use of Pukatea in treating tuberculosis. In addition, our analyses indicate that other native plant species possess antibiotic activity.</p