Many indigenous plants of the Philippines, including essential oil-bearing species, remain phytochemically and pharmacologically unexplored. In this study, the chemical composition of leaf essential oils (EOs) hydrodistilled from Litsea leytensis (Lauraceae) and Piper philippinum (Piperaceae) was determined using dual-column (HP-5MS/DB-WAX)/dual-detector gas chromatography and mass spectrometry analysis. Caryophyllene oxide (15.751/16.018%) was identified as the main compound in L. leytensis EO, followed by β-caryophyllene (11.130/11.430%) and α-copaene (9.039/9.221%). Ishwarane (25.937/25.280%), nerolidol (9.372/10.519%) and 3-ishwarone (6.916/2.588%) were the most abundant constituents of P. philippinum EO. Additionally, the in vitro growth-inhibitory activity of the EOs in the liquid and vapour phases against Staphylococcus aureus was evaluated using the broth microdilution volatilisation assay. Although the results showed no anti-staphylococcal effect, the presence of various bioactive compounds in both EOs suggests their potential future use in industrial applications.

• Klíčová slova
• GC-MS, Lauraceae, Piperaceae, essential oil, hydrodistillation, volatile compounds,
• Publikační typ
• časopisecké články MeSH

Background: In recent years, significant resistance of microorganisms to antibiotics has been observed. A biofilm is a structure that significantly aids the survival of the microbial population and also significantly affects its resistance. Methods: Thyme and clove essential oils (EOs) were subjected to chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Furthermore, the antimicrobial effect of these EOs was tested in both the liquid and vapor phases using the volatilization method. The effect of the EOs on growth parameters was monitored using an RTS-8 bioreactor. However, the effect of the EOs on the biofilm formation of commonly occurring bacteria with pathogenic potential was also monitored, but for less described and yet clinically important strains of Arcobacter spp. Results: In total, 37 and 28 compounds were identified in the thyme and clove EO samples, respectively. The most common were terpenes and also derivatives of phenolic substances. Both EOs exhibited antimicrobial activity in the liquid and/or vapor phase against at least some strains. The determined antimicrobial activity of thyme and clove oil was in the range of 32-1024 µg/mL in the liquid phase and 512-1024 µg/mL in the vapor phase, respectively. The results of the antimicrobial effect are also supported by similar conclusions from monitoring growth curves using the RTS bioreactor. The effect of EOs on biofilm formation differed between strains. Biofilm formation of Pseudomonas aeruginosa was completely suppressed in an environment with a thyme EO concentration of 1024 µg/mL. On the other hand, increased biofilm formation was found, e.g., in an environment of low concentration (1-32 µg/mL). Conclusions: The potential of using natural matrices as antimicrobials or preservatives is evident. The effect of these EOs on biofilm formation, especially Arcobacter strains, is described for the first time.

• Klíčová slova
• Arcobacter, antimicrobial effect, biofilm formation, clove, essential oil, thyme,
• Publikační typ
• časopisecké články MeSH

Essential oils (EOs) have been gaining popularity in the past decades among researchers due to their potential to replace conventional chemicals used in the fight against pests, pathogenic and spoilage microbes, and oxidation processes. EOs are complex mixtures with many chemical components, the content of which depends on many factors-not just the plant genus, species, or subspecies, but also chemotype, locality, climatic conditions, phase of vegetation, method of extraction, and others. Due to this fact, there is still much to study, with antimicrobial effect being one of the key properties of EOs. There are many methods that have been frequently used by researchers for in vitro evaluation; however, although the research has been going on for decades, an internationally accepted standard is still missing. Most of methods are based on time-proven standards used for the testing of antibiotics. Due to the specific properties of EOs and their components, such as volatility and hydrophobicity, many modifications of these standard procedures have been adopted. The aim of this review is to describe the most common methods and their modifications for the testing of antimicrobial properties of EOs and to point out the most controversial variables which can potentially affect results of the assays.

• Klíčová slova
• agar diffusion, agar dilution, antibacterial, biofilm, broth dilution, plant extracts, vapor phase,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Essential oil from Thymus vulgaris L. has valuable therapeutic potential that is highly desired in pharmaceutical, food, and cosmetic industries. Considering these advantages and the rising market demand, induced polyploids were obtained using oryzalin to enhance essential oil yield. However, their therapeutic values were unexplored. So, this study aims to assess the phytochemical content, and antimicrobial, antioxidant, and anti-inflammatory activities of tetraploid and diploid thyme essential oils. Induced tetraploids had 41.11% higher essential oil yield with enhanced thymol and γ-terpinene content than diploid. Tetraploids exhibited higher antibacterial activity against all tested microorganisms. Similarly, in DPPH radical scavenging assay tetraploid essential oil was more potent with half-maximal inhibitory doses (IC50) of 180.03 µg/mL (40.05 µg TE/mg) than diploid with IC50 > 512 µg/mL (12.68 µg TE/mg). Tetraploids exhibited more effective inhibition of in vitro catalytic activity of pro-inflammatory enzyme cyclooxygenase-2 (COX-2) than diploids at 50 µg/mL concentration. Furthermore, molecular docking revealed higher binding affinity of thymol and γ-terpinene towards tested protein receptors, which explained enhanced bioactivity of tetraploid essential oil. In conclusion, these results suggest that synthetic polyploidization using oryzalin could effectively enhance the quality and quantity of secondary metabolites and can develop more efficient essential oil-based commercial products using this induced genotype.

• MeSH
• dinitrobenzeny * MeSH
• fytonutrienty farmakologie   MeSH
• monoterpeny s cyklohexanovým kruhem * MeSH
• oleje prchavé * farmakologie   chemie   MeSH
• oleje rostlin * MeSH
• simulace molekulového dockingu MeSH
• sulfanilamidy * MeSH
• tetraploidie MeSH
• thymol farmakologie   MeSH
• Thymus (rostlina) * chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dinitrobenzeny * MeSH
• fytonutrienty MeSH
• gamma-terpinene MeSH Prohlížeč
• monoterpeny s cyklohexanovým kruhem * MeSH
• oleje prchavé * MeSH
• oleje rostlin * MeSH
• oryzalin MeSH Prohlížeč
• sulfanilamidy * MeSH
• thyme oil MeSH Prohlížeč
• thymol MeSH

Essential oils (EOs) have great potential in inhalation therapy for the treatment of respiratory infections. However, innovative methods for evaluation of antimicrobial activity of their vapors are still needed. The current study reports validation of the broth macrodilution volatilization method for assessment of the antibacterial properties of EOs and shows the growth-inhibitory effect of Indian medicinal plants against pneumonia-causing bacteria in liquid and vapor phase. Among all samples tested, Trachyspermum ammi EO exhibits the strongest antibacterial effect against Haemophilus influenzae, with minimum inhibitory concentrations of 128 and 256 µg/mL in the liquid and vapor phases, respectively. Furthermore, Cyperus scariosus EO is found to be nontoxic to normal lung fibroblasts assessed by modified thiazolyl blue tetrazolium bromide assay. Chemical analysis performed using gas chromatography-mass spectrometry identified α-citral, cyperotundone, and thymol as the main constituents of Cymbopogon citratus, C. scariosus, and T. ammi EOs, respectively. In addition, β-cymene is identified as the major compound of T. ammi EO vapors when analyzed using solid-phase microextraction and gas-tight syringe sampling techniques. This study demonstrates the validity of the broth macrodilution volatilization method for antimicrobial screening of volatile compounds in the vapor phase and suggests the therapeutic potential of Indian medicinal plants in inhalation therapy.

• Klíčová slova
• Cymbopogon citratus, Cyperus scariosus, GC/MS, MTT assay, Trachyspermum ammi, antimicrobial activity, headspace analysis, macrodilution, respiratory infections, vapor phase, volatiles,
• MeSH
• antibakteriální látky chemie   MeSH
• antiinfekční látky * analýza   MeSH
• léčivé rostliny * MeSH
• lidé MeSH
• mikrobiální testy citlivosti MeSH
• oleje prchavé * farmakologie   chemie   MeSH
• plynová chromatografie s hmotnostně spektrometrickou detekcí MeSH
• pneumonie * MeSH
• volatilizace MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• antiinfekční látky * MeSH
• oleje prchavé * MeSH

While the inhalation of Thymus vulgaris L. essential oil (EO) is commonly approved for the treatment of mild respiratory infections, there is still a lack of data regarding the antimicrobial activity and chemical composition of its vapours. The antibacterial activity of the three T. vulgaris EOs against respiratory pathogens, including Haemophilus influenzae, Staphylococcus aureus, and Streptococcus pyogenes, was assessed in both liquid and vapour phases using the broth microdilution volatilisation (BMV) method. With the aim of optimising a protocol for the characterisation of EO vapours, their chemical profiles were determined using two headspace sampling techniques coupled with GC/MS: solid-phase microextraction (HS-SPME) and syringe headspace sampling technique (HS-GTS). All EO sample vapours exhibited antibacterial activity with minimum inhibitory concentrations (MIC) ranging from 512 to 1024 μg/mL. According to the sampling technique used, results showed a different distribution of volatile compounds. Notably, thymol was found in lower amounts in the headspace-peak percentage areas below 5.27% (HS-SPME) and 0.60% (HS-GTS)-than in EOs (max. 48.65%), suggesting that its antimicrobial effect is higher in vapour. Furthermore, both headspace sampling techniques were proved to be complementary for the analysis of EO vapours, whereas HS-SPME yielded more accurate qualitative results and HS-GTS proved a better technique for quantitative analysis.

• Klíčová slova
• antimicrobial activity, broth microdilution, headspace analysis, respiratory infections, thyme, vapour phase,
• MeSH
• antibakteriální látky chemie   izolace a purifikace   farmakologie   MeSH
• Haemophilus influenzae účinky léků   MeSH
• mikrobiální testy citlivosti MeSH
• mikroextrakce na pevné fázi * MeSH
• oleje prchavé chemie   izolace a purifikace   farmakologie   MeSH
• plynová chromatografie s hmotnostně spektrometrickou detekcí MeSH
• Staphylococcus aureus účinky léků   MeSH
• Streptococcus pyogenes účinky léků   MeSH
• Thymus (rostlina) chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• oleje prchavé MeSH

This commentary critically examines the modern paradigm of natural volatiles in 'medical aromatherapy', first by explaining the semantics of natural volatiles in health, then by addressing chemophenetic challenges to authenticity or reproducibility, and finally by elaborating on pharmacokinetic and pharmacodynamic processes in food, therapy, and disease prophylaxis. Research over the last 50 years has generated substantial knowledge of the chemical diversity of volatiles, and their strengths and weaknesses as antimicrobial agents. However, due to modest in vitro outcomes, the emphasis has shifted toward the ability to synergise or potentiate non-volatile natural or pharmaceutical drugs, and to modulate gene expression by binding to the lipophilic domain of mammalian cell receptors. Because essential oils and natural volatiles are small and lipophilic, they demonstrate high skin penetrating abilities when suitably encapsulated, or if derived from a dietary item they bioaccumulate in fatty tissues in the body. In the skin or body, they may synergise or drive de novo therapeutic outcomes that range from anti-inflammatory effects through to insulin sensitisation, dermal rejuvenation, keratinocyte migration, upregulation of hair follicle bulb stem cells or complementation of anti-cancer therapies. Taking all this into consideration, volatile organic compounds should be examined as candidates for prophylaxis of cardiovascular disease. Considering the modern understanding of biology, the science of natural volatiles may need to be revisited in the context of health and nutrition.

• Klíčová slova
• anti-inflammatory, antimicrobial, aromatherapy, gas chromatography, headspace, pathogen, pharmacodynamics, pharmacokinetics,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Due to its large surface area, the skin is susceptible to various injuries, possibly accompanied by the entrance of infective agents into the body. Commensal organisms that constitute the skin microbiota play important roles in the orchestration of cutaneous homeostasis and immune competence. The opportunistic pathogen Staphylococcus aureus is present as part of the normal biota of the skin and mucous membranes in both humans and animals, but can cause disease when it invades the body either due to trauma or because of the impaired immune response of the host. Colonization of livestock skin by S. aureus is a precursor for majority of bacterial skin infections, which range from boils to sepsis, with the best-characterized being bovine mastitis. Antibiotic treatment of these infections can contribute to the promotion of resistant bacterial strains and even to multidrug resistance. The development of antibiotic resistance to currently available antibiotics is a worldwide problem. Considering the increasing ability of bacteria to effectively resist antibacterial agents, it is important to reduce the livestock consumption of antibiotics to preserve antibiotic effectiveness in the future. Plants are recognized as sources of various bioactive substances, including antibacterial activity towards clinically important microorganisms. This review provides an overview of the current knowledge on the major groups of phytochemicals with antibacterial activity and their modes of action. It also provides a list of currently known and used plant species aimed at treating or preventing bacterial skin infections in livestock.

• Klíčová slova
• Staphylococcus aureus, antibiotic resistance, phytochemicals, wounds,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

In this study, a new broth macrodilution volatilization method for the simple and rapid determination of the antibacterial effect of volatile agents simultaneously in the liquid and vapor phase was designed with the aim to assess their therapeutic potential for the development of new inhalation preparations. The antibacterial activity of plant volatiles (β-thujaplicin, thymohydroquinone, thymoquinone) was evaluated against bacteria associated with respiratory infections (Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes) and their cytotoxicity was determined using a modified thiazolyl blue tetrazolium bromide assay against normal lung fibroblasts. Thymohydroquinone and thymoquinone possessed the highest antibacterial activity against H. influenzae, with minimum inhibitory concentrations of 4 and 8 µg/mL in the liquid and vapor phases, respectively. Although all compounds exhibited cytotoxic effects on lung cells, therapeutic indices (TIs) suggested their potential use in the treatment of respiratory infections, which was especially evident for thymohydroquinone (TI > 34.13). The results demonstrate the applicability of the broth macrodilution volatilization assay, which combines the principles of broth microdilution volatilization and standard broth macrodilution methods. This assay enables rapid, simple, cost- and labor-effective screening of volatile compounds and overcomes the limitations of assays currently used for screening of antimicrobial activity in the vapor phase.

• Klíčová slova
• antimicrobial, cytotoxicity, macrodilution method, respiratory infections, thymohydroquinone, thymoquinone, vapor phase, volatile compound, β-thujaplicin,
• MeSH
• antibakteriální látky analýza   chemie   farmakologie   MeSH
• aplikace inhalační MeSH
• Bacteria účinky léků   MeSH
• benzochinony aplikace a dávkování   farmakologie   MeSH
• Haemophilus influenzae účinky léků   MeSH
• mikrobiální testy citlivosti MeSH
• monoterpeny aplikace a dávkování   farmakologie   MeSH
• oleje prchavé chemie   farmakologie   MeSH
• Staphylococcus aureus účinky léků   MeSH
• Streptococcus pneumoniae účinky léků   MeSH
• Streptococcus pyogenes účinky léků   MeSH
• těkavé organické sloučeniny chemie   farmakologie   MeSH
• thymol aplikace a dávkování   analogy a deriváty   farmakologie   MeSH
• tropolon aplikace a dávkování   analogy a deriváty   farmakologie   MeSH
• volatilizace MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• benzochinony MeSH
• beta-thujaplicin MeSH Prohlížeč
• monoterpeny MeSH
• oleje prchavé MeSH
• těkavé organické sloučeniny MeSH
• thymohydroquinone MeSH Prohlížeč
• thymol MeSH
• thymoquinone MeSH Prohlížeč
• tropolon MeSH

Volatile plant-derived products were observed to exhibit broad spectrum of biological effects. However, due to their volatility, results of conventional microplate-based bioassays can be significantly affected by the vapors. With aim to demonstrate this phenomenon, antimicrobial, antioxidant, and cytotoxic activities of three essential oils (Alpinia elegans, Cinnamomum iners, and Xanthostemon verdugonianus), one supercritical CO2 extract (Nigella sativa), and four plant-derived compounds (capsaicin, caryophyllene oxide, 8-hydroxyquinoline, and thymoquinone) were evaluated in series of experiments including both ethylene vinyl acetate (EVA) Capmat sealed and nonsealed microplates. The results clearly illustrate that vapor transition to adjoining wells causes false-positive results of bioassays performed in nonsealed microtiter plates. The microplate layout and a duration of the assay were demonstrated as the key aspects defining level of the results affection by the vapors of volatile agents. Additionally, we reported biological activities and chemical composition of essential oils from A. elegans seeds and X. verdugonianus leaves, which were, according to our best knowledge, analyzed for the first time. Considering our findings, certain modifications of conventional microplate-based assays are necessary (e.g., using EVA Capmat as vapor barrier) to obtain reliable results when biological properties of volatile agents are evaluated.

• Klíčová slova
• DPPH, MTT, bioassay, broth microdilution, essential oil, microtiter plate, plant compounds, supercritical CO2 extract, volatilization,
• MeSH
• antiinfekční látky chemie   izolace a purifikace   farmakologie   MeSH
• antioxidancia chemie   izolace a purifikace   farmakologie   MeSH
• bifenylové sloučeniny antagonisté a inhibitory   MeSH
• biologické přípravky chemie   izolace a purifikace   farmakologie   MeSH
• Candida albicans účinky léků   MeSH
• galgán chemie   MeSH
• mikrobiální testy citlivosti MeSH
• Myrtaceae chemie   MeSH
• Nigella chemie   MeSH
• oleje prchavé chemie   izolace a purifikace   farmakologie   MeSH
• pikráty antagonisté a inhibitory   MeSH
• rostlinné extrakty chemie   izolace a purifikace   farmakologie   MeSH
• skořicovník chemie   MeSH
• Staphylococcus aureus účinky léků   MeSH
• těkavé organické sloučeniny chemie   izolace a purifikace   farmakologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 1,1-diphenyl-2-picrylhydrazyl MeSH Prohlížeč
• antiinfekční látky MeSH
• antioxidancia MeSH
• bifenylové sloučeniny MeSH
• biologické přípravky MeSH
• oleje prchavé MeSH
• pikráty MeSH
• rostlinné extrakty MeSH
• těkavé organické sloučeniny MeSH