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PubMed2005

Analysis of the essential oil from aerial parts of Eupatorium cannabinum subsp. corsicum (L.) by gas chromatography with electron impact and chemical ionization mass spectrometry.

Eupatorium cannabinum subsp. corsicum (L.), an aromatic plant, is an endemic subspecies from Corsica. The essential oil from aerial parts of E. cannabinum subsp. corsicum was studied by GC, GC/MS and 13C NMR. One hundred and forty-seven components were identified representing 93.6% of the total amount. The main constituents are germacrene D (28.5%), alpha-phellandrene (19.0%) and para-cymene (5.2%). A particularity of this essential oil is the presence of monoterpene esters derived from nerol, lavandulol, borneol, thymol and 8,9-dehydrothymol. These compounds have been investigated using GC/MS in different ionization modes like electron impact (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI).

Esters↗

PubMed2004

Isopanduratin A from Kaempferia pandurata as an active antibacterial agent against cariogenic Streptococcus mutans.

An antibacterial compound active against Streptococcus mutans was isolated from Kaempferia pandurata and identified as isopanduratin A using 1H NMR, 13C NMR and EI-MS. The minimum inhibitory concentration (MIC) of isopanduratin A was 4 mg/l which was much lower than that of some other natural anticariogenic agents such as sanguinarine (12 mg/l), green tea extract and carvacrol (125 mg/l), thymol (250 mg/l) and isoeugenol and eucalyptol (500 mg/l). The bactericidal test showed that isopanduratin A completely inactivated S. mutans at 20 mg/l in 1 min. Significant inhibitory activity of isopanduratin A was also observed against S. sobrinus, S. sanguinis and S. salivarius with an MIC of 4 mg/l. Damage to the cell membrane and cell wall of S. mutans by isopanduratin A was shown using transmission electron microscopy (TEM). These results suggest that isopanduratin A could be employed as a potential antibacterial agent for preventing dental caries.

Anti-Bacterial Agents↗

PubMed2004

Essential oils: their antibacterial properties and potential applications in foods--a review.

In vitro studies have demonstrated antibacterial activity of essential oils (EOs) against Listeria monocytogenes, Salmonella typhimurium, Escherichia coli O157:H7, Shigella dysenteria, Bacillus cereus and Staphylococcus aureus at levels between 0.2 and 10 microl ml(-1). Gram-negative organisms are slightly less susceptible than gram-positive bacteria. A number of EO components has been identified as effective antibacterials, e.g. carvacrol, thymol, eugenol, perillaldehyde, cinnamaldehyde and cinnamic acid, having minimum inhibitory concentrations (MICs) of 0.05-5 microl ml(-1) in vitro. A higher concentration is needed to achieve the same effect in foods. Studies with fresh meat, meat products, fish, milk, dairy products, vegetables, fruit and cooked rice have shown that the concentration needed to achieve a significant antibacterial effect is around 0.5-20 microl g(-1) in foods and about 0.1-10 microl ml(-1) in solutions for washing fruit and vegetables. EOs comprise a large number of components and it is likely that their mode of action involves several targets in the bacterial cell. The hydrophobicity of EOs enables them to partition in the lipids of the cell membrane and mitochondria, rendering them permeable and leading to leakage of cell contents. Physical conditions that improve the action of EOs are low pH, low temperature and low oxygen levels. Synergism has been observed between carvacrol and its precursor p-cymene and between cinnamaldehyde and eugenol. Synergy between EO components and mild preservation methods has also been observed. Some EO components are legally registered flavourings in the EU and the USA. Undesirable organoleptic effects can be limited by careful selection of EOs according to the type of food.

Anti-Bacterial Agents↗

PubMed2005

Preservative effect of combined treatment with electrolyzed NaCl solutions and essential oil compounds on carp fillets during convectional air-drying.

The antimicrobial and antioxidant effects on carp fillet samples of treatments with alkaline electrolyzed NaCl solution EW (-) prior to treatment with acidic electrolyzed NaCl solution EW (+) and 1% solutions of the essential oils consisting of 0.5% carvacrol and 0.5% thymol (1% Cv+Ty) were tested. First carp fillet samples were treated with EW (-), then EW (+), followed by 1% (C+T), represented as [EW (-)/EW (+)/1% (Cv+Ty)] for 15 min, during drying at 45 degrees C. Samples were subsequently evaluated by microbiological, chemical and sensory analyses. Microbiological analyses indicated that the initial total microbial counts of samples treated with EW (-)/EW (+), 1% (Cv+Ty) or EW (-)/EW (+)/1% (Cv+Ty) were significantly (p< or =0.05) reduced, compared with the control sample. Treatment with EW (-)/EW (+)/1% (Cv+Ty) gave the strongest overall inhibition of microbial growth when compared to all of the other treatments. The volatile basic nitrogen (VBN) value of samples treated with EW (-)/EW (+)/1% (Cv+Ty) was kept at low level (18.46+/-0.45) until the end of drying period (5 days), compared with control samples (40.33+/-0.58). Treatment with EW (-)/EW (+)/1% (Cv+Ty) during drying significantly reduced the peroxide values (PV) and thiobarbituric acid values (TBA). Sensory evaluation indicated that there were significant differences (p< or =0.05) in the color, odor, taste, flavor and texture, on the end of the 5-day drying period between samples treated with EW (-)/EW (+)/1% (Cv+Ty), as compared to all of the other treatments. We conclude that treatment with EW (-)/EW (+)/1% (Cv+Ty) had stronger antimicrobial and antioxidant effects than all of the other treatments on carp fillets during drying, and could be a good alternative to artificial preservatives in food industry.

Animals↗

PubMed2026

Vortex-assisted liquid-liquid microextraction based on natural deep eutectic solvents for the determination of pyrethroid pesticides in urine.

A novel, facile, and environmentally friendly analytical method was developed based on vortex-assisted liquid-liquid microextraction and high-performance liquid chromatography with diode-array detection for detecting pyrethroid pesticides (PPs) in urine. Natural deep eutectic solvents (NADESs) were prepared using plant essential oil-derived monoterpenoids (thymol, carvacrol, and menthol) combined with aromatic primary alcohols (benzyl alcohol, phenethyl alcohol, and phenylpropyl alcohol) as hydrogen bond donors and acceptors. These solvents served as environmentally benign extraction media, thereby avoiding the use of conventional volatile, toxic organic solvents. NADESs are naturally derived, easy to prepare, biodegradable, and environmentally friendly solvents. Hydrophobic and π-π interactions between the NADESs and PPs may contribute to enhancing the affinity of PPs toward the NADESs phase. Vortex technology, accelerating mass transfer between the sample and extractant phases, enables fast extraction of PPs. Under optimized conditions, the method achieved a low detection limit (0.002 mg L-1), satisfactory precision with relative standard deviations (0.3%-2.4%), and acceptable recovery (80.7%-86.2%). The method demonstrated excellent performance in urine analysis and was feasible as a facile and green strategy for monitoring the content of PPs in biological matrices and assessing exposure risk.

Liquid Phase Microextraction↗

PubMed2005

Acid-base equilibrium of anionic dyes partially bound to micelles of nonionic surfactants.

The acid-base equilibria of the sulfonephthalein dyes, namely, bromothymol blue, thymol blue, and cresol red, in aqueous nonionic micellar solutions of Triton X-100, Tween-20, Tween-40, Tween-60, and Tween-80 have been investigated. The equilibrium constants of the partition of the dyes between micellar and aqueous pseudophases have been determined spectrophotometrically at fixed pH. The K(ass) increased with the surfactants in the order Tween-80<Tween-60<Tween-40<Tween-20<TX-100. The effect of such associations on the pKa2 of the dyes at various concentrations of the nonionic surfactant has been studied. The pKa2 of the dyes as a function of the concentrations of the surfactant was predicted from the equilibrium constants using a method developed to fit nonionic surfactants and was compared with experimental values determined directly. The pKa2s of the dyes predicted according to the present method have been found to be in good agreement with the experimental values.

Acid-Base Equilibrium↗

PubMed2005

A new method for gaining insight into the chemistry of drying mineral surfaces using ATR-FTIR.

Although it is understood that the chemical environment at a drying surface is likely to be quite different from that at a fully hydrated surface, the difficulty of quantitative measurement has meant that this potentially crucial aspect of surface chemistry has gone largely overlooked. As a result, most of our understanding comes from measurement before and after drying, with a gray region of speculation in between. An interesting natural example is the paradoxical reduction of Mn oxides in moist soils as they dry, because drying is usually considered an oxidative process. This phenomenon indicates that important chemical changes are occurring during drying and an approach is needed to probe the chemistry of drying surfaces. Here we show the suitability of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy for real-time, in situ investigation of the drying solid-water interface, using the change in surface pH as an example. This was achieved by adsorbing thymol blue pH indicator (pK(a)=1.65) onto a natural Mn-rich clay and observing the real-time pH change, which dropped from pH 5 to below pH 1.65 with the removal of free water from the surface.

Journal Article↗

PubMed2006

A rapid and simple HPLC method for the analysis of propofol in biological fluids.

A selective and sensitive high-performance liquid chromatographic method for the analysis of propofol in biological samples was developed. Propofol and thymol (internal standard) were analysed on a Purospher RP-18 endcapped (75 mmx4 mm, 3 microm) stationary phase using acetonitrile and water (65:35, v/v) as eluents at a flow rate of 0.6 mL/min. The excitation and emission wavelengths were 276 and 310 nm, respectively. Sample treatment consisted of deproteinization by acetonitrile containing the internal standard and direct injection of the supernatant. Mean analytical recovery were 105% (CV 2.0%) at concentrations ranging from 0.05 to 10 mg/L. The quantification limit was 3 ng/mL for a 500 microL sample plasma volume and 5 ng/mL for a 500 microL blood sample. The intra-day and inter-day precisions were lower than 5.5% for three concentrations assessed (0.05, 1.0 and 10.0 mg/L). Considering the column size and the flow rate, the separation was achieved with an analysis time less than 6 min with a reduced consumption of solvent. This rapid HPLC method using a simple treatment procedure is sensitive enough for monitoring propofol in human biological samples.

Acetonitriles↗

PubMed2005

Anticariogenic activity of macelignan isolated from Myristica fragrans (nutmeg) against Streptococcus mutans.

The occurrence of dental caries is mainly associated with oral pathogens, especially cariogenic Streptococcus mutans. Preliminary antibacterial screening revealed that the extract of Myristica fragrans, widely cultivated for the spice and flavor of foods, possessed strong inhibitory activity against S. mutans. The anticariogenic compound was successfully isolated from the methanol extract of M. fragrans by repeated silica gel chromatography, and its structure was identified as macelignan by instrumental analysis using 1D-NMR, 2D-NMR and EI-MS. The minimum inhibitory concentration (MIC) of macelignan against S. mutans was 3.9 microg/ml, which was much lower than those of other natural anticariogenic agents such as 15.6 microg/ml of sanguinarine, 250 microg/ml of eucalyptol, 500 microg/ml of menthol and thymol, and 1000 microg/ml of methyl salicylate. Macelignan also possessed preferential activity against other oral microorganisms such as Streptococcus sobrinus, Streptococcus salivarius, Streptococcus sanguis, Lactobacillus acidophilus and Lactobacillus casei in the MIC range of 2-31.3 microg/ml. In particular, the bactericidal test showed that macelignan, at a concentration of 20 microg/ml, completely inactivated S. mutans in 1 min. The specific activity and fast-effectiveness of macelignan against oral bacteria strongly suggest that it could be employed as a natural antibacterial agent in functional foods or oral care products.

Anti-Bacterial Agents↗

PubMed2005

Chemoprevention by thyme oils of Aspergillus parasiticus growth and aflatoxin production.

The essential oils from Thymus eriocalyx and Thymus X-porlock obtained by hydrodistillation were analyzed by GC/MS. The major components of T. eriocalyx and T. X-porlock oils were thymol (63.8, 31.7%), beta-phellandrene (13.30, 38.7%), cis-sabinene hydroxide (8.1, 9.6%), 1,8-cineole (2, 1.7%), and beta-pinene (1.31, 2%), respectively. Antifungal activities of the oils were studied with special reference to the inhibition of Aspergillus parasiticus growth and aflatoxin production. Minimal inhibitory (MIC) and minimal fungicidal (MFC) concentrations of the oils were determined. Static effects of the above oils against A. parasiticus were at 250 ppm and lethal effects of T. eriocalyx and T. X-porlock were 500 and 1000 ppm of the oils, respectively. Aflatoxin production was inhibited at 250 ppm of both oils with that of T. eriocalyx being stronger inhibitor. Transmission electron microscopy (TEM) of A. parasiticus exposed to MIC level (250 ppm) of the oils showed irreversible damage to cell wall, cell membrane, and cellular organelles. It is concluded that the essential oils could be safely used as preservative materials on some kinds of foods at low concentrations to protect them from fungal infections.

Aflatoxins↗

PubMed2006

Influence of cavity preparation design on fracture resistance of posterior Leucite-reinforced ceramic restorations.

STATEMENT OF PROBLEM: Controversy exists concerning the preferred cavity design for posterior ceramic restorations to improve their resistance to fracture under occlusal load. PURPOSE: The aim of this study was to assess the resistance to fracture of leucite-reinforced ceramic restorations placed on molars with different cavity preparation designs. MATERIAL AND METHODS: Ninety noncarious molars were selected, stored in 0.2% thymol solution, and divided into 9 groups (n = 10): IT, intact teeth; CsI, conservative inlay; ExI, extensive inlay; CsO/mb, conservative onlay with mesio-buccal cusp coverage; ExO/mb, entensive onlay with mesio-buccal cusp coverage; CsO/b, conservative onlay with buccal cusp coverage; ExO/b, entensive onlay with buccal cusp coverage; CsO/t, conservative onlay with total cusp coverage; ExO/t, extensive onlay with total cusp coverage. Teeth were restored with a Leucite-reinforced ceramic (Cergogold). The fracture resistance (N) was assessed under compressive load in a universal testing machine. The data were analyzed with 1-way and 2-way analyses of variance, followed by the Tukey HSD test (alpha = .05). Fracture modes were recorded, based on the degree of tooth structure and restoration damage. RESULTS: One-way analysis showed that intact teeth had the highest fracture resistance values. Two-way analyses showed no significant differences for the isthmus extention factor, but showed a significant difference for the preparation design type of fracture (P = .03), and also for the interaction between both factors (P = .013). The fracture mode observed in all groups tended to involve only restorations. CONCLUSION: Within the limitations of this study, it was observed that cuspal coverage does not increase fracture resistance of the posterior tooth-restoration complex restored with leucite-reinforced ceramics.

Aluminum Silicates↗

PubMed2006

Essential oils--their antimicrobial activity against Escherichia coli and effect on intestinal cell viability.

Essential oils are known to possess antimicrobial activity against a wide spectrum of bacteria. The main objective of this study was to evaluate possible harmful effects of four commonly used essential oils and their major components on intestinal cells. Antimicrobial activity of selected plant extracts against enteroinvasive Escherichia coli was dose dependent. However, doses of essential oils with the ability to completely inhibit bacterial growth (0.05%) showed also relatively high cytotoxicity to intestinal-like cells cultured in vitro. Lower doses of essential oils (0.01%) had only partial antimicrobial activity and their damaging effect on Caco-2 cells was only modest. Cell death assessment based on morphological and viability staining followed by fluorescence microscopy showed that essential oils of cinnamon and clove and their major component eugenol had almost no cytotoxic effect at lower doses. Although essential oil of oregano and its component carvacrol slightly increased the incidence of apoptotic cell death, they showed extensive antimicrobial activity even at lower concentrations. Relatively high cytotoxicity was demonstrated by thyme oil, which increased both apoptotic and necrotic cell death incidence. In contrast, its component thymol showed no cytotoxic effect as well as greatly-reduced ability to inhibit visible growth of the chosen pathogen in the doses used. On the other hand, the addition of all essential oils and their components at lower doses, with the exception of thyme oil, to bacterial suspension significantly reduced the cytotoxic effect of E. coli on Caco-2 cells after 1h culture. In conclusion, it is possible to find appropriate doses of essential oils showing both antimicrobial activity and very low detrimental effect on intestinal cells.

Caco-2 Cells↗

PubMed2000

Benefits of magnesium in acute myocardial infarction: timing is crucial.

OBJECTIVE: To evaluate magnesium deficiency during and after acute myocardial infarction (AMI) and the role of intravenous magnesium therapy given in the early postinfarction period. METHODS: One hundred patients with AMI were randomly assigned to 2 equal groups and monitored over a 4-week period. The placebo group received intravenous dextrose solution and the trial group was given 15 g intravenous magnesium (62 mmol) over a 48-hour period. Serum magnesium levels were measured on days 1, 2, 4, and 6 after admission by calorimetry with methyl thymol blue. RESULTS: The groups were comparable in prevalence of risk factors for coronary artery disease and other acute parameters of AMI. The serum magnesium levels of a group of 50 controls were higher (1.61 +/- 0. 21 vs 1.23 +/- 0.27mEq/L) than in patients with AMI (P <.001). There was an increase in serum magnesium levels in the trial group on day 2 (1.73 +/- 0.27 vs 1.29 +/- 0.28 mEq/L; P <.001) as well as on day 4 (1.62 +/- 0.25 vs 1.38 +/- 0.36 mEq/L; P <.001). The trial group also showed significantly lower incidence of arrhythmias (8% vs 34%) and death (4% vs 20%). The mortality rate from pump failure was reduced in the trial group (4% vs 14%). CONCLUSIONS: The serum magnesium levels in patients with AMI were lower compared with controls. The administration of intravenous magnesium to patients in the immediate postinfarction period is cardioprotective and decreases the incidence of arrhythmia, pump dysfunction, and death. Thus intravenous magnesium is a safe, effective, and inexpensive modality of treatment in AMI.

Drug Administration Schedule↗

PubMed1998

The effect of various storage methods and media on shear-bond strengths of dental composite resin to bovine dentine.

A variety of media and methods have been used to store teeth used in bond-strength studies of resin restorative materials to dentine. This study examined the effect of 2 months of storage using 11 different methods and media on the shear-bond strength of Z100 resin composite to bovine dentine mediated by Scotchbond Multi Purpose adhesive. Freshly harvested teeth were used as controls. The results showed that 7 of the l1 storage methods or media were similar in shear-bond strengths and bond-failure characteristics. Four of the 11 methods (irradiation, or storage in thymol, methanol, and glutaraldehyde) resulted in significantly lower shear-bond strengths and atypical shear-bond failure, indicating that these are the least desirable methods of tooth storage for studies of this type. This study has further shown that if insufficient numbers of fresh teeth are available for studies of shear-bond strength, then freezing is the preferred method of storage for the registration of high shear-bond strengths. It is also apparent that further investigations are needed to examine what post mortem changes occur in dentine, whether these changes are modified by various storage conditions, and whether they have any significant effect on bonding of resin composites.

Analysis of Variance↗

PubMed2000

Chromatographic study of terpene derivatives on porous graphitic carbon stationary phase with beta-cyclodextrin as mobile phase modifier.

The stoichiometric coefficients and apparent formation constants (Kf) of alpha-terpineol, thymol, geraniol and linalool complexes with beta-cyclodextrin (beta-CD) were determined using HPLC with a porous graphitic carbon (PGC) chromatographic support. Measurements were performed with four different methanol-water mobile phases. All the terpene derivatives under study form 1:1 guest-CD complexes. Graphs of Kf as a function of the mobile phase composition appeared different from those classically described for RP-C18 and suggest that the PGC stationary phase could play an active role in the complexation process. Solute-CD inclusion and solute-stationary phase interactions may be involved in this specific behavior.

Chromatography, High Pressure Liquid↗

PubMed2002

Determination of acaricides in honey by high-performance liquid chromatography with photodiode array detection.

Rapid analytical methods are described to control quality of honeys, concerning residues of acaricides applied in hives to prevent Varroa jacobsoni infestation. A liquid-liquid extraction with hexane-propanol-2-ammonia (60 ml:30 ml:0.28%) was used for the simultaneous analysis of coumaphos, bromopropylate, amitraz and fluvalinate. For thymol, one clean up on a solid-phase extraction C18 (500 mg, 6 ml) column was performed; for rotenone, a liquid extraction with dichloromethane was realised. Quantitative recoveries obtained with honey were satisfactory and were superior to 80%. All acaricides are identified by reversed-phase high-performance liquid chromatography with photodiode array detection. Quantification limits obtained were below maximal residue limits when these exist.

Acari↗

PubMed1989

Marginal leakage of composite resin restorations in combination with dentinal and enamel bonding agents.

Marginal leakage is a cause of failure of composite resin restorations. The effect of two enamel and two dentin bonding agents on marginal leakage alongside composite resins was assessed and compared in enamel and dentinal cavities. Cavities, one in buccal enamel and the other in cervical dentin, were prepared in each of 350 extracted sound human premolar teeth and randomly assigned to combinations of bonding agents and composite resins. After insertion the restorations were polished and the restored teeth were stored in distilled water and thymol at 20 degrees C for 28 days. This was followed by thermal stressing (15 degrees C and 45 degrees C) for 24 hours with a dip cycle of 30 seconds, whereafter a marginal leakage test was performed. The results showed that in enamel cavities, the bonding agents Enamelbond, Heliobond, and Scotchbond significantly reduced marginal leakage compared with Dentin-Adhesit. In the dentinal cavities, Dentin-Adhesit and Scotchbond reduced marginal leakage compared with Enamelbond and Heliobond. No significant difference was noted in the sealing ability of Dentin-Adhesit and Scotchbond. In dentin the P10/Dentin-Adhesit, and Silar/Scotchbond combinations sealed significantly better than P10/Enamelbond.

Acrylic Resins↗

PubMed1992

Management of patients with sickle cell disease.

The ever-increasing body of information regarding the molecular pathogenesis of sickle cell disease has raised expectations that a specific and effective therapy could be devised to inhibit polymerization of hemoglobin S. Despite an intense international research effort, this goal has not yet been realized. Supportive care continues to be the mainstay in the management of patients with sickle cell anemia. Empiric measures were used in early attempts to treat sickle cell anemia. Herrick reported gratifying improvement after "rest, nourishing food, the administration of iodide, arsenic, thymol and the application of boric ointment to leg ulcers." Many of these suggestions are similar to those of today. Several factors have significantly improved the prognosis of patients with this disease. Improved medical care, genetic counseling, and universal neonatal screening have directly resulted in improved outcome. Molecular biologic techniques have allowed us to approach this disease in a pathophysiologic way. Now we can envision antenatal diagnosis with the use of molecular probes and treatment by gene amplification. Still, however, the most important and challenging link in the chain between the biology of the disease and the clinical sequelae is an astute and interested physician who must remain objective at all times.

Anemia, Sickle Cell↗