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

Eyebright, Euphrasia rostkoviana Hayne (Scrophulariaceae), is a medicinal plant traditionally used in Europe for the treatment of various health disorders, especially as eyewash to treat eye ailments such as conjunctivitis and blepharitis that can be associated with bacterial infections. Some Euphrasia species have been previously reported to contain essential oil. However, the composition and bioactivity of E. rostkoviana oil are unknown. Therefore, in this study, we investigated the chemical composition and antimicrobial activity of the eyebright essential oil against some organisms associated with eye infections: Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, and Candida albicans. GC-MS analysis revealed more than 70 constituents, with n-hexadecanoic acid (18.47%) as the main constituent followed by thymol (7.97%), myristic acid (4.71%), linalool (4.65%), and anethole (4.09%). The essential oil showed antimicrobial effect against all organisms tested with the exception of P. aeruginosa. The best activity was observed against all Gram-positive bacteria tested with the minimum inhibitory concentrations of 512 µg/mL. This is the first report on the chemical composition of E. rostkoviana essential oil and its antimicrobial activity.

• Publikační typ
• časopisecké články MeSH