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PubMed2003

Evaluation of cetylpyridinium chloride for infection control in storage solution.

Storage solution is used in in vitro experimental studies to prevent dehydration of teeth collected immediately after extraction and to prevent bacterial and fungal growth in the storage media. The chemical nature of the storing agent may affect the tooth structure and material properties at the tested interface. The aim of this study was to evaluate the use of 0.1% cetylpyridinium chloride (CPC) as a new storage solution and to assess the possible effect of 0.1% thymol on microleakage and bond strength. Forty extracted human teeth were collected from 10 different dental clinics. Immediately after extraction, the teeth were randomly divided and immersed in four different storage solutions. Two test solutions of 0.1% CPC (group C) and 0.1% thymol (group T) were compared with phosphate-buffered saline (Group S - positive control) and to 3% H2O2 (group H - negative control). Bond strength test and dye penetration evaluation were then carried out. The findings suggest that the use of 0.1% CPC as storage solution does not affect bond strength to enamel. However, it may increase dye penetration at the cervical margin. The effect of 0.1% thymol on shear bond strength and dye penetration is similar to the effect of phosphate-buffered saline.

Anti-Infective Agents, Local↗
PubMed2005

Antimicrobial effects of essential oils in combination with chlorhexidine digluconate.

The aim of the present study was to compare antimicrobial effects of essential oils alone and in combination with chlorhexidine digluconate against planktonic and biofilm cultures of Streptococcus mutans and Lactobacillus plantarum. The essential oils included cinnamon, tea-tree (Melaleuca alternifola), manuka (Leptospermum scoparium), Leptospermum morrisonii, arnica, eucalyptus, grapefruit, the essential oil mouthrinse Cool Mint Listerine and two of its components, menthol and thymol. Cinnamon exhibited the greatest antimicrobial potency (1.25-2.5 mg/ml). Manuka, L. morrisonii, tea-tree oils, and thymol also showed antimicrobial potency but to a lesser extent. The combination effect of the essential oil-chlorhexidine was greater against biofilm cultures of both S. mutans and L. plantarum than against planktonic cultures. The amount of chlorhexidine required to achieve an equivalent growth inhibition against the biofilm cultures was reduced 4-10-fold in combination with cinnamon, manuka, L. morrisonii, thymol, and Listerine. We conclude that there may be a role for essential oils in the development of novel anticaries treatments.

Anti-Infective Agents, Local↗
PubMed2005

Synergistic inhibitory effect of citral with selected phenolics against Zygosaccharomyces bailii.

Antifungal susceptibilities of Zygosaccharomyces bailii to individual and binary mixtures of citral with selected phenolics were evaluated to identify synergistic combinations. Individual effects of citral, vanillin, thymol, carvacrol, and eugenol concentrations and combined effects of citral with the other phenolic compounds on the growth of Z. bailii were evaluated in potato dextrose agar, adjusted with sucrose to a water activity of 0.99 or 0.95, and hydrochloric acid to pH 4.5 or 3.5. MICs for individual and binary antimicrobial mixtures were identified and then transformed to fractional inhibitory concentrations. Inhibitory concentrations of citral and vanillin were higher than 650 ppm, whereas for thymol, eugenol, and carvacrol, concentrations were lower than 250 ppm for several of the studied water activity-pH conditions. Combining citral with the other phenolic compounds, fractional inhibitory concentration (FIC) and FIC(Index) varied from 0.216 to 0.582. FIC(Index) demonstrated synergistic effects on Z. bailii inhibition when citral was used in combination with vanillin, thymol, carvacrol, or eugenol. Therefore, the relative amount of antimicrobials could be greatly reduced.

Acyclic Monoterpenes↗
PubMed2001

The chemical and physical stability of a 1:1 mixture of propofol and methohexital.

Anesthetic drugs are frequently mixed or coadministered to optimize anesthetic effects while minimizing adverse effects. Methohexital advantages include its low cost and rapid onset, while propofol provides improved airway anesthesia and extremely rapid clearance from the plasma. Therefore, a mixture of these agents might well be superior to either drug given alone. We wished to determine whether a mixture of methohexital and propofol is chemically and physically stable. A 1:1 mixture of propofol 10 mg/ml and methohexital was prepared. At times varying from 0 to 48 hours, mixtures with an internal standard of thymol kept at room temperature were thrice extracted with a 2:1 v/v mixture of diethyl ether:pentane, dried under nitrogen, and treated overnight with bis-trimethylsilyl-trifluoroacetamide. The resultant derivatives were transferred to microsample vials and analyzed by GC-MS. Drug stability was quantified by electronic integration of peak areas representing characteristic ions for each drug. For each sample, the peak area of the methohexital ion (m/z 239) or propofol ion (m/z 235) relative to the corresponding thymol ion (m/z 207) served as an index of the concentration of the drug in the sample. At times varying from 0 to 48 hours, mixtures without thymol were used to determine mean droplet size of the particles. This was accomplished using both an Accusizer and a Nicomp 370 Particle Sizer. One way ANOVA tested for significant changes in drug concentrations and mean particle size as a function of time. There was no significant breakdown of propofol or methohexital when combined in a 1:1 mixture and allowed to stand for 48 hours, nor was there an increase in particle size suggestive of emulsion instability. We concluded that a 1:1 mixture of propofol and methohexital was stable up to 48 hours after mixing.

Analysis of Variance↗
PubMedDate not supplied

Determination of isopropylmethylphenols in black seed oil by differential pulse voltammetry.

A differential pulse voltammetric method is presented for the determination of isopropylmethylphenols (carvacrol and/or thymol) in phytotherapeutic black seed oils. The voltammetric behaviours of these phenols were examined in various buffer systems over the pH range 3.5-10.0. In Sörensen buffered methanol solution (3:7; v:v; pH 8.5), the differential pulse voltammograms exhibited reproducible peaks at Ep + 0.49 V vs. silver-silver chloride-potassium chloride 3 M for both carvacrol and thymol. Under these conditions, a plot of peak height against concentration of the isopropylmethylphenols was found to be linear over the range 0.25-2.5 microg/mL (r = 0.999). The detection limit was 0.04 microg/mL. The described voltammetric method was tested on two black seed oils available on the Austrian market.

Cymenes↗
PubMed2002

Insecticidal properties of essential plant oils against the mosquito Culex pipiens molestus (Diptera: Culicidae).

The insecticidal activities of essential oil extracts from leaves and flowers of aromatic plants against fourth-instar larvae of the mosquito Culex pipiens molestus Forskal were determined. Extracts of Myrtus communis L were found to be the most toxic, followed by those of Origanum syriacum L, Mentha microcorphylla Koch, Pistacia lentiscus L and Lavandula stoechas L with LC50 values of 16, 36, 39, 70 and 89 mg litre-1, respectively. Over 20 major components were identified in extracts from each plant species. Eight pure components (1,8-cineole, menthone, linalool, terpineol, carvacrol, thymol, (1S)-(-)-alpha-pinene and (1R)-(+)-alpha-pinene) were tested against the larvae. Thymol, carvacrol, (1R)-(+)-alpha-pinene and (1S)-(-)-alpha-pinene were the most toxic (LC50 = 36-49 mg litre-1), while menthone, 1,8-cineole, linalool and terpineol (LC50 = 156-194 mg litre-1) were less toxic.

Acyclic Monoterpenes↗
PubMed2004

Chemical analysis and antifungal activity of Thymus striatus.

The essential oil composition from Thymus striatus collected from Mountain Orjen (Montenegro) has been investigated by gas chromatography-mass spectrometry. Thymol, gamma-terpinene and p-cymene were found to be the major components. Furthermore, the oil and its major component, thymol, were analysed for potential antifungal activity against plant, animal and human pathogenic fungi from different genera by a macrodilution test. The oil exhibited a strong inhibitory effect against all fungi investigated.

Antifungal Agents↗
PubMed1991

The effects of storage after extraction of the teeth on human dentine permeability in vitro.

Freshly extracted third molars were stored for one week in one of four solutions: 70% ethanol, 10% formalin, distilled water with thymol and phosphate-buffered saline with thymol. Crown segments were prepared and initial permeability measurements taken. Each specimen was placed in a fresh preparation of its original solution, and permeability was measured over two periods: 1, 4, 6 and 8 days or 1, 8, 15 and 22 days. Ten crown segments were used for each solution for each time sequence. Permeabilities were lower for those specimens stored in ethanol and formalin than in water/thymol and saline/thymol, but most specimens showed increased permeability with time. Both storage solution and storage time had statistically significant effects (p less than 0.05), with significant differences between specimens stored in water/thymol and saline/thymol and those stored in ethanol and formalin. Thus, type of storage solution effects dentine permeability over time.

Analysis of Variance↗
PubMed1993

Storage effects on dentin permeability and shear bond strengths.

The effects of duration of storage and selection of storage solution upon dentin permeability and bond strength were studied over a period of 8 days to 6 mon. Teeth were stored immediately after extraction in one of five commonly used solutions: 70% ethanol (E); 10% formalin (F); distilled water (W); distilled water with thymol (WT); or phosphate-buffered saline with thymol (ST). Permeability and lap shear bond strength measurements were evaluated in a repeated measures design (n = 20) after 8 days, 15 days and 6 mon. Dentin permeability varied with solution type and duration of storage as demonstrated by ANOVA, increasing F, E and the water-based solutions, respectively. Saline storage resulted in large significant decreases in permeability after prolonged storage, suggesting changes in dentin. Bond strengths were unaffected by duration of storage or by solution type, except for saline. Thus, permeability and bond strength values may be affected by storage conditions. The results of this study indicate that saline, the most commonly used solution in dental materials research, may be unsuitable for use as a result of its effect on dentin permeability and bond strength.

Analysis of Variance↗
PubMed1993

Effect of storage media on microleakage of five dentin bonding agents.

The objective of this study was to investigate the effect of different storage media on microleakage at the gingival margin of mixed Class V composite restorations. Human molars were either used immediately after extraction (control group) or after a 3-4 wk storage period in 1% chloramine, 70% ethanol, 10% formalin, or 0.1% thymol. Class V cavities with cervical margins in cementum or dentin were prepared and restored with a microfill composite using five different dentin bonding agents. After thermocycling (1440 x from 5 degrees C to 55 degrees C) and basic fuchsin staining, the depth of dye penetration at the gingival margins was determined and ranked on a scale of 0 to 4. Class V restorations in teeth stored in formalin showed significantly less microleakage (mean leakage score, MLS = 1.7) than restorations in freshly extracted teeth (control group; MLS = 3.1). Microleakage scores in teeth stored in chloramine (MLS = 2.7), ethanol (MLS = 3.0) or thymol (MLS = 3.2) were not significantly different from the microleakage scores in the control group. The improvement of in vitro efficacy of dentin bonding agents when using extracted teeth stored in formalin is probably a result of collagen cross-linking by formaldehyde. Since such an alteration of the dentin does not reflect the condition of the substrate in vivo, extracted teeth assigned for in vitro evaluation of dentin bonding agents should not be stored in formalin. In teeth stored in 1% chloramine, the sums of ranks and the rank orders of the dentin bonding agents were comparable to those in freshly extracted teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1988

Inhibitory effects of selected Turkish spices and oregano components on some foodborne fungi.

The inhibitory effects of 10 selected Turkish spices, oregano essential oil, thymol and carvacrol towards growth of 9 foodborne fungi were investigated in culture media with pH 3.5 and 5.5. The antifungal effects of sodium chloride, sorbic acid and sodium benzoate and the combined use of oregano with sodium chloride were also tested under the same conditions for comparison. Of the spices tested, only sodium chloride were also tested under the same conditions for comparison. Of the spices tested, only oregano at 1.0, 1.5, 2.0% (w/v) levels showed effect on all fungi. 8% (w/v) sodium chloride was less effective than oregano. Oregano essential oil, thymol or carvacrol at concentrations of 0.025% and 0.05% completely inhibited the growth of all fungi, showing greater inhibition than sorbic acid at the same concentrations. The combined use of oregano and sodium chloride exhibited a synergistic antifungal effect.

Antifungal Agents↗
PubMed1996

Spectroscopic changes in human dentine exposed to various storage solutions--short term.

OBJECTIVES: Tooth storage conditions in studies of dentine have not been standardized. The objective of this investigation was to determine the effects of storage solution and time on dentine, using spectroscopic methods. METHODS: Twenty-seven dentine disks (0.75 mm thick) were prepared from freshly extracted third molars with documented histories. The teeth were sectioned parallel to the occlusal plane using a diamond saw. Specimens were analysed non-destructively for surface chemical changes using specular reflectance infra-red Fourier transform spectroscopy (SRIFTS), and changes in optical properties were measured in the ultraviolet, visible and near-infra-red spectral ranges with an integrating sphere spectrophotometer (UV/VIS/NIR) before and after storage. A minimum of five specimens were stored in distilled water with 0.02% thymol, purified and filtered water, phosphate buffered saline with 0.02% thymol, 70% ethanol or 10% buffered formalin and evaluated at 0, 1, 2, 7, 14, 21 and 28 days. After each measurement, specimens were stored in fresh solutions. IR spectra were obtained from 4400 to 400 wave-numbers (cm-1). Optical properties of reflectance and transmittance were determined from 200 to 2500 nm, and absorbance was calculated. RESULTS: Analysis of the IR spectra indicated no significant differences in collagen or mineral peak positions for any solution at any time period. There were significant differences in peak intensities of dentine stored in distilled water, purified and filtered water and phosphate-buffered saline over time in the IR spectra. Furthermore, differences in optical properties of dentine disks were detected by UV/VIS/NIR. CONCLUSION: It was concluded that changes in surface chemistry and optical properties of dentine occur as a function of storage solution and time, which must be considered when studying dentine.

Anti-Infective Agents↗
PubMed2002

Aspergillus flavus dose-response curves to selected natural and synthetic antimicrobials.

The effects of selected concentrations of antimicrobials from natural (vanillin, thymol, eugenol, carvacrol or citral) or synthetic (potassium sorbate or sodium benzoate) origin on Aspergillus flavus lag time inoculated in laboratory media formulated at water activity (a(w)) 0.99 and pH 4.5 or 3.5, were evaluated. Time to detect a colony with a diameter > 0.5 mm was determined. Mold response was modeled using the Fermi function. Antimicrobial minimal inhibitory concentration (MIC) was defined as the minimal required inhibiting mold growth for 2 months. Fermi function successfully captured A. flavus dose-response curves to the tested antimicrobials with a highly satisfactory fit. Fermi equation coefficients, Pc and k, were used to compare antimicrobials and assess the effect of pH. Important differences in Pc and k were observed among antimicrobials, being natural antimicrobials less pH dependent than synthetic antimicrobials. A large Pc value represents a small antimicrobial effect on A. flavus lag time; thus, high concentrations are needed to delay growth. A. flavus exhibited higher sensitivity to thymol, eugenol, carvacrol, potassium sorbate (at pH 3.5), and sodium benzoate (at pH 3.5) than to vanillin or citral. MICs varied from 200 ppm of sodium bcnzoate at pH 3.5 to 1800 ppm of citral at both evaluated pHs.

Anti-Infective Agents↗
PubMed1998

In vitro percutaneous absorption enhancement of a lipophilic drug tamoxifen by terpenes.

Tamoxifen is a highly lipophilic drug that is widely used in breast malignancies and also as a prophylactic therapy in women at high risk for the development of this disease. Recently, the terpenes have been reported to show an enhancement effect on percutaneous drug absorption. The effect of terpenes (e.g. carvone, 1,8-cineole, menthol, and thymol) was studied on the in vitro percutaneous absorption of tamoxifen through porcine epidermis. The above terpenes (5% w/v) in combination with 50% ethanol significantly (P < 0.01) increased the permeability coefficient of tamoxifen in comparison to the control (50% ethanol). The solubility of tamoxifen was determined in the control and enhancer solutions to correct the permeability enhancement by way of fractional solubility adjustment. Binding of tamoxifen to powdered stratum corneum from control and enhancer solutions was also determined. Binding studies reveal that the enhancement in the permeability coefficient of tamoxifen by menthol and thymol is due at least in part, to improvement in the partitioning of the drug to the stratum corneum. In conclusion, terpenes in combination with ethanol can be used to enhance the percutaneous absorption of the highly lipophilic drug tamoxifen.

Animals↗
PubMed2001

Inhibition of malonaldehyde formation from blood plasma oxidation by aroma extracts and aroma components isolated from clove and eucalyptus.

The inhibitory effect of aroma extracts isolated from clove buds [Syzygium aromaticum (L.) Merr. et Perry] and eucalyptus leaves (Eucalyptus polyanthemos Schauer) on malonaldehyde (MA) formation from horse blood plasma oxidized with Fenton's reagent was determined by gas chromatography. Aroma chemicals such as eugenol, thymol and benzyl alcohol, identified in the aroma extracts, were examined for their inhibitory effect on the same system. Between the two aroma extracts tested, clove exhibited the most potent antioxidant activities. Extracts of eucalyptus and clove inhibited MA formation by 23 and 48%, respectively, at the level of 400 microg/ml, whereas, alpha-tocopherol and BHT inhibited MA formation by 52 and 70%, respectively, at the same level. Eugenol, thymol and benzyl alcohol inhibited MA formation by 57, 43 and 32%, respectively, at the level of 400 microg/ml.

Animals↗
PubMed2006

Composition of the essential oils of Thymus and Origanum species from Algeria and their antioxidant and antimicrobial activities.

The composition of the essential oils of Origanum and Thymus species restricted to Algeria and the North Africa region was determined. Antioxidant and antibacterial activities of the isolated essential oils were also determined. The oils of oregano plants were strongly characterized by p-cymene (16.8-24.9%), gamma-terpinene (16.8-24.9%), thymol (8.4-36.0%), and carvacrol (1.1-29.7%), a thymol chemotype for Origanum floribundum and a alpha-terpineol chemotype for Thymus numidicus being described for the first time. The strains of Listeria monocytogenes tested were relatively resistant to the action of essential oils of either Origanum or Thymus species. All essential oils possessed antioxidant activity, but this was dependent on the specific chemical composition and the method employed to determine such activity.

Algeria↗
PubMed2006

Oregano, thyme and clove-derived flavors and skin sensitizers activate specific TRP channels.

Carvacrol, eugenol and thymol are major components of plants such as oregano, savory, clove and thyme. When applied to the tongue, these flavors elicit a warm sensation. They are also known to be skin sensitizers and allergens. The transient receptor potential channel (TRPV3) is a warm-sensitive Ca2+-permeable cation channel highly expressed in the skin, tongue and nose. Here we show that TRPV3 is strongly activated and sensitized by carvacrol, thymol and eugenol. Tongue and skin epithelial cells respond to carvacrol and eugenol with an increase in intracellular Ca2+ levels. We also show that this TRPV3 activity is strongly potentiated by phospholipase C-linked, G protein-coupled receptor stimulation. In addition, carvacrol activates and rapidly desensitizes TRPA1, which may explain the pungency of oregano. Our results support a role for temperature-sensitive TRP channels in chemesthesis in oral and nasal epithelium and suggest that TRPV3 may be a molecular target of plant-derived skin sensitizers.

Animals↗
PubMed2003

Activity of natural antimicrobial compounds against Escherichia coli and Salmonella enterica serovar Typhimurium.

AIMS: The objective of this study was to evaluate the inhibitory activity of several natural organic compounds alone or in combination with nisin against Escherichia coli and Salmonella Typhimurium. METHODS AND RESULTS: The minimum inhibitory concentration (MIC) of five natural organic compounds were determined, and the effect of their combinations with nisin was evaluated by the checkerboard assay using the Bioscreen C. As expected, nisin by itself showed no inhibition against either of the Gram-negative bacteria. Thymol was found to be the most effective with the lowest MIC values of 1.0 and 1.2 mmol 1-1 against Salm. Typhimurium and E. coli, respectively. After thymol, the antimicrobial order of the natural organic compounds was carvacrol > eugenol > cinnamic acid > diacetyl. However, the combination of nisin with the natural organic compounds did not result in the enhancement of their antimicrobial activities. On the contrary, combination of nisin with diacetyl against Salm. Typhimurium resulted in an antagonism of diacetyl activity. CONCLUSIONS: While the individual natural organic compounds showed inhibitory activity against the two Gram-negatives, their combinations with nisin showed no improvement of antimicrobial activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows the potential of the natural organic compounds to control E. coli and Salm. Typhimurium.

Anti-Bacterial Agents↗