With aim to develop effective proof-of-concept approach which can be used in a development of new preparations for the inhalation therapy, we designed a new screening method for simple and rapid simultaneous determination of antibacterial potential of plant volatiles in the liquid and the vapour phase at different concentrations. In addition, EVA (ethylene vinyl acetate) capmat™ as vapour barrier cover was used as reliable modification of thiazolyl blue tetrazolium bromide (MTT) assay for cytotoxicity testing of volatiles on microtiter plates. Antibacterial activity of carvacrol, cinnamaldehyde, eugenol, 8-hydroxyquinoline, thymol and thymoquinone was determined against Haemophilus influenzae, Staphylococcus aureus, and Streptococcus pneumoniae using new broth microdilution volatilization method. The cytotoxicity of these compounds was evaluated using MTT test in lung fibroblast cells MRC-5. The most effective antibacterial agents were 8-hydroxyquinoline and thymoquinone with the lowest minimum inhibitory concentrations (MICs) ranging from 2 to 128μg/mL, but they also possessed the highest toxicity in lung cell lines with half maximal inhibitory concentration (IC50) values 0.86-2.95μg/mL. The lowest cytotoxicity effect was identified for eugenol with IC50 295.71μg/mL, however this compound produced only weak antibacterial potency with MICs 512-1024μg/mL. The results demonstrate validity of our novel broth microdilution volatilization method, which allows cost and labour effective high-throughput antimicrobial screening of volatile agents without need of special apparatus. In our opinion, this assay can also potentially be used for development of various medicinal, agricultural, and food applications that are based on volatile antimicrobials.
- MeSH
- Acrolein analogs & derivatives chemistry MeSH
- Anti-Bacterial Agents chemistry MeSH
- Benzoquinones chemistry MeSH
- Cell Line MeSH
- Eugenol chemistry MeSH
- Phytochemicals chemistry MeSH
- Haemophilus influenzae drug effects MeSH
- Humans MeSH
- Microbial Sensitivity Tests methods MeSH
- Monoterpenes chemistry MeSH
- Oxyquinoline chemistry MeSH
- Staphylococcus aureus drug effects MeSH
- Streptococcus pneumoniae drug effects MeSH
- Volatile Organic Compounds chemistry MeSH
- Tetrazolium Salts MeSH
- Thiazoles MeSH
- Thymol chemistry MeSH
- Volatilization * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Carvacrol and thymol, both plant-derived volatile compounds, have extensively been studied individually as well as in combination with other agents for their antimicrobial activity in liquid phase. However, in contrast to well-established assays for testing of antimicrobial combinatory effects in liquid media, there are no standardized methods for evaluation of interactions between volatile compounds in vapour phase. The objective of this study was to verify new broth volatilization chequerboard method by testing the combination of carvacrol and thymol and to determine in vitro inhibitory effect of these compounds in liquid and vapour phase against twelve Staphylococcus aureus strains. The new method, based on combination of standard microdilution chequerboard and new broth volatilization tests allowing calculation of fractional inhibitory concentrations (FICs), was used. Combination of carvacrol and thymol produced the additive antimicrobial effect against all strains tested. In several cases, they reached ΣFIC values lower than 0.6, which can be considered as a strong additive interaction. The best result was found in vapour phase against one standard strain at combination of 128 μg/mL of carvacrol and 16-256 μg/mL of thymol (ΣFIC = 0.51) and in liquid phase against one clinical isolate at combination of 256 μg/mL of carvacrol and 256 μg/mL of thymol (ΣFIC = 0.53). The study verified that the new technique is suitable for simple and rapid high-throughput combinatory antimicrobial screening of volatile compounds simultaneously in vapour and liquid phase and that it allows determination and comparison of MIC and FIC values in both, liquid and solid media.
This review summarizes data on the in vitro antimicrobial effectiveness of volatile agents of plant origin and in vitro methods for evaluating their activity in the vapour phase. As a result of literature analysis, the antimicrobial efficacy of vapours from 122 different plant species and 19 pure compounds examined in 61 studies using different in vitro tests against a broad spectrum of microorganisms was identified and summarized. In addition, 11 different techniques found in the literature are described in detail. An original classification of methods based on the solid and liquid matrix volatilization principle is proposed because carrier medium/matrix selection is crucial for the volatilization of any agents tested. This review should be useful for medicinal, pharmaceutical, food, and agricultural experts working in areas related to the management of infectious diseases (especially respiratory and skin infections), food preservation (active packaging), and protection of agriculture products (controlled atmosphere). It may also stimulate the interest of pharmaceutical, cosmetic, food, and agriculture industries in the research and development of new antimicrobial agents of natural origin. Since several original apparatuses previously developed for antimicrobial susceptibility testing in the vapour phase are described in this review, labware manufacturers may also be interested in this topic. The review also provides specific guidelines and recommendations for researchers studying the antimicrobial activity of volatile agents. The article will therefore appeal to communities of industrial stakeholders, pharmacists, physicians, food experts, agriculturists, and researchers in related areas such as pharmacology, medicinal chemistry, microbiology, natural product chemistry, food preservation and plant protection.
- MeSH
- Anti-Bacterial Agents MeSH
- Anti-Infective Agents * MeSH
- Food Preservation MeSH
- Volatilization MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Magnetron sputtering was employed for the deposition of cobalt oxide thin films on stainless steel meshes. Catalysts prepared by sputtering in inert and oxidation atmosphere were compared with those obtained by electrochemical deposition and hydrothermal synthesis. Systematic characterization using X-ray diffraction, scanning electron microscopy, N2 physisorption, infrared spectroscopy, Raman spectroscopy, and temperature-programmed reduction by hydrogen allowed detailed monitoring of their physicochemical properties. Ethanol gas-phase oxidation was employed as a model reaction to reveal the catalytic performance of the catalysts. It was shown that the catalyst prepared by magnetron sputtering in oxidation atmosphere exhibited the best mechanical stability among all studied catalysts. Moreover, its catalytic activity was 18 times higher than that of pelletized commercial cobalt oxide.
- MeSH
- Catalysis MeSH
- Cobalt * MeSH
- Oxides * MeSH
- Volatile Organic Compounds * MeSH
- Publication type
- Journal Article MeSH
A method employing the direct immersion solid-phase microextraction followed by GC-MS analysis is presented for the determination of essential oils components in herbal tea infusions, i.e. their direct content in the liquid phase. The extraction performances were compared using five different microextraction fibres. Significant parameters affecting sorption process such as sample amount, sorption and desorption time and temperature, stirring speed, pH adjustment and effect of ionic strength were optimised and discussed. By optimising the key parameters, a detection limits (LOD = S/N × 3) for ten target marker compounds were obtained in the range from 5.3 to 48.2 ng/mL with recoveries ranged between 93.03 and 100.50%. Intra-day and inter-day repeatability at three concentration levels were found to be 1.1-15.3 and 7.2-15.5% RSD, respectively. Finally, the optimised procedure enabling a rapid and simple analysis of essential oils was applied for the direct determination of these compounds in ten herbal tea infusions.
Volatile aromatic compounds have a major impact on the final organoleptic properties of cider, and their profiles are influenced by a number of parameters that are closely related to production technologies, especially with regard to the raw material, the microorganism used and the fermentation process. In this work, the profiles of volatile compounds (4 fatty acids, 6 higher alcohols and 12 esters) from 34 European ciders were studied using HS-SPME-GC-MS. Volatiles were isolated by HS-SPME using a CAR/PDMS fiber. Analytical data were statistically evaluated using principal component analysis, and differences in composition of volatiles between cider produced using "intensified" technologies and that of ciders produced by traditional production processes were demonstrated. This difference was mainly due to varying contents of some higher alcohols (2-methylpropanol, isoamyl alcohols, hexanol, and butane-2,3-diol) and esters (ethyl 2-methylbutanoate, butylacetate, and hexyl acetate).
The broth microdilution (BMD) method is widely used for the determination of minimum inhibitory concentrations of antimicrobial agents, including volatile oils and their components. In this series of various experiments, we have demonstrated the influence of thymoquinone (TQ) vapor on the results of the BMD test performed with Staphylococcus aureus as a model organism. The spread of vapor from the TQ containing wells (32-512 μg/mL) caused the complete inhibition of staphylococcal growth in adjoining wells initially containing bacterium-inoculated pure Mueller-Hinton broth only and thus produced false positive results of the test. The ability of TQ to pass into the adjoined wells was subsequently confirmed by gas chromatography-mass spectrometry, whereas TQ at concentrations up to 84 μg/mL was detected in these wells after five hours. Based on these results, we suppose that vapors of TQ as well as of other naturally occurring volatile compounds and their mixtures (for example essential oils and plant extracts) can significantly influence results of the standard BMD assay. These observations, therefore, call for development of new appropriate BMD method suitable for assessment of antimicrobial activity of volatile substances.
- MeSH
- Anti-Infective Agents chemistry pharmacology MeSH
- Benzoquinones chemistry pharmacology MeSH
- Microbial Sensitivity Tests methods MeSH
- Oils, Volatile chemistry pharmacology MeSH
- Plant Oils chemistry pharmacology MeSH
- Oxacillin chemistry pharmacology MeSH
- Staphylococcus aureus drug effects growth & development MeSH
- Dose-Response Relationship, Drug MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The true bugs (Hemiptera: Heteroptera) have evolved a system of well-developed scent glands that produce diverse and frequently strongly odorous compounds that act mainly as chemical protection against predators. A new method of non-lethal sampling with subsequent separation using gas chromatography with mass spectrometric detection was proposed for analysis of these volatile defensive secretions. Separation was performed on Rtx-200 column containing fluorinated polysiloxane stationary phase. Various mechanical irritation methods (ultrasonics, shaking, pressing bugs with plunger of syringe) were tested for secretion sampling with a special focus on non-lethal irritation. The preconcentration step was performed by sorption on solid phase microextraction (SPME) fibers with different polarity. For optimization of sampling procedure, Pyrrhocoris apterus was selected. The entire multi-parameter optimization procedure of secretion sampling was performed using response surface methodology. The irritation of bugs by pressing them with a plunger of syringe was shown to be the most suitable. The developed method was applied to analysis of secretions produced by adult males and females of Pyrrhocoris apterus, Pyrrhocoris tibialis and Scantius aegyptius (all Heteroptera: Pyrrhocoridae). The chemical composition of secretion, particularly that of alcohols, aldehydes and esters, is species-specific in all three pyrrhocorid species studied. The sexual dimorphism in occurrence of particular compounds is largely limited to alcohols and suggests their epigamic intraspecific function. The phenetic overall similarities in composition of secretion do not reflect either relationship of species or similarities in antipredatory color pattern. The similarities of secretions may be linked with antipredatory strategies. The proposed method requires only a few individuals which remain alive after the procedure. Thus secretions of a number of species including even the rare ones can be analyzed and broadly conceived comparative studies can be carried out.
- MeSH
- Heteroptera metabolism MeSH
- Gas Chromatography-Mass Spectrometry methods MeSH
- Volatile Organic Compounds analysis metabolism MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Comparative Study MeSH
Profily těkavých karboxylových kyselin byly stanoveny plynovou chromatografií v souboru 287 mikrobiologicky pozitivních i negativních hemokultur, kultivovaných na svépomocí připravených médiích a v systému BacT/Alert. Některé aerobní bakterie poskytovaly málo chaharakteristické profily s malým obsahem kyselin, některé byly chromatograficky negativní, anaerobní bakterie poskytovaly profily s větším obsahem kyselin. v 11 % hemokultur umožnila tato metoda během 30 minut detekci mikrobů nenalezených kultivačním vyšetřením, obvykle anaerobních. V některých případech je možná i orientační přibližná identifikace etiologického agens.
The volatile fatty acid profiles were determined by gas chromatography in 287 microbiologically positive and negative blood cultures, evaluated in homemade media and by the BacT/Alert system. Some aerobic bacteria yielded less characteristic profiles with low content of acids, some of them were chromatographically negative, anaerobic bacteria yielded profiles with larger acid content. Addirional bacteria, mostly anaerobic, were detected by this method within 30 minutes in 11 % of evaluated blood cultures as compared with cultivation. In some cases, the tentative identification of etiologic agents was also possible.
Mikročástice se sníženou velikostí částic byly úspěšně připraveny metodou odpařování rozpouštědla. Pro přípravu každého vzorku byly použity různé parametry a byl hodnocen jejich vliv na výsledné mikročástice. Jako modelové léčivo byl pro enkapsulaci do částic na bázi Eudragit? RS vybrán nerozpustný ibuprofen. Získané mikročástice byly zhodnoceny pomocí optické mikroskopie a skenovací elektronové mikroskopie. Byl sledován vliv objemu vodné fáze (600, 400, 200 ml) a koncentrace polyvinyl alkoholu (1% a 0,1%) na vlastnosti mikročástic, jako je enkapsulační účinnost, drug loading, burst effect a morfologie mikročástic. Bylo zjištěno, že vzorek připravený s 600 ml vodné fáze a 1% koncentrací PVA poskytoval nejpříznivější výsledky.
Size-reduced microparticles were successfully obtained by solvent evaporation method. Different parameters were applied in each sample and their influence on microparticles was evaluated. As a model drug the insoluble ibuprofen was selected for the encapsulation process with Eudragit? RS. The obtained microparticles were inspected by optical microscopy and scanning electron microscopy. The effect of aqueous phase volume (600, 400, 200 ml) and the concentration of polyvinyl alcohol (PVA; 1.0% and 0.1%) were studied. It was evaluated how those variations and also size can affect microparticle characteristics such as encapsulation efficiency, drug loading, burst effect and microparticle morphology. It was observed that the sample prepared with 600 ml aqueous phase and 1% concentration of polyvinyl alcohol gave the most favorable results.
- Keywords
- mikročástice, charakteristiky mikročástic, Eudragit RS®,
- MeSH
- Ibuprofen pharmacokinetics MeSH
- Drug Delivery Systems * MeSH
- Delayed-Action Preparations * pharmacokinetics MeSH
- Microscopy classification methods MeSH
- Particulate Matter MeSH
- Polyvinyl Alcohol MeSH
- Drug Compounding * methods MeSH
- Solvents MeSH
- In Vitro Techniques MeSH
- Drug Liberation MeSH
- Particle Size MeSH
- Water MeSH
- Volatilization MeSH
- Research MeSH
