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PubMed2005

In vitro inhibitory activities of essential oils from two Korean thymus species against antibiotic-resistant pathogens.

The in vitro inhibitory activities of essential oils from Thymus magnus and T. quinquecostatus as well as their main constituents were evaluated against susceptible and resistant species of Streptococcus pneumoniae, Staphylococcus aureus, Salmonella enteritidis, and Salmonella typhimurium. Notably, the essential oil fraction of T. magnus and its main components displayed significant inhibitory action against both antibiotic-susceptible and resistant strains of S. pneumoniae, S. aureus, and S. typhimurium with minimum inhibitory concentrations (MICs) ranging from 0.125 to 8 mg/mL. The differential MIC values imply that the oil fraction and its main components exhibit distinct patterns of activity against the tested bacterial species. Moreover, the disk diffusion test revealed that the inhibitory activities of oil fraction and components were dose-dependent. Data from the checkerboard titer test confirmed synergism between the antibiotic, norfloxacin, and T. magnus oil or thymol, particularly against the resistant strains of S. aureus.

Anti-Bacterial Agents↗
PubMed2004

Effect of monoterpenes on lipid oxidation in maize.

The monoterpenes 1,8-cineole, thymol, geraniol, menthol and camphor strongly inhibited the root growth of Zea mays L. seedlings. They induced an oxidative stress as measured by the production of malondialdehyde, conjugated dienes and peroxides. This oxidative stress depended on the length of the exposure and on the monoterpene applied. The total fatty acid content was measured and fatty acid composition was analyzed. Unsaturated fatty acids increased in the treated samples. The alcoholic and non-alcoholic monoterpenes appeared to have different modes of action.

Acyclic Monoterpenes↗
PubMed2001

Effect of an antibacterial varnish on lactic acid production in plaque adjacent to fixed orthodontic appliances.

The effect of an antibacterial varnish on lactic acid concentration in suspensions of early supragingival plaque collected adjacent to fixed orthodontic brackets was evaluated in 25 adolescents using a double-blind split-mouth design with a placebo varnish control. The test varnish contained 1% chlorhexidine and 1% thymol as active ingredients. Both varnishes were applied on two occasions within 3 days and plaque was subsequently collected at 3, 7 and 30 days after the first treatment. The samples were evaluated for total viable counts (TVC) and the proportion of mutans streptococci. Acid fermentation in suspensions was induced by glucose and L(+)-lactic acid concentrations were determined enzymatically after a 30-min incubation period. The test varnish did not affect TVC but reduced the proportion of mutans streptococci significantly at the 7-day follow-up (P<0.05). The concentration of lactic acid was reduced by approximately 20% on the 3- and 7-day follow-ups (P<0.05). The results suggest that the chlorhexidine/thymol-containing varnish may to some extent reduce the viability and metabolic activity of susceptible oral bacteria in suspensions of early supragingival plaque.

Adolescent↗
PubMed1975

The inhibition by bromothymol blue of anion translocation across the mitochondrial membrane.

1. In rat liver mitochondria bromothymol blue inhibited the exchange of [14C]succinate for succinate, malonate, L-malate and inorganic phosphate; the [14C]citrate/citrate and [14C]citrate/malate exchange reactions and the phosphate/hydroxyl exchange were also inhibited by this dye. The inhibition of the rate of succinate, citrate and phosphate uptake by bromothymol blue is found to be competitive. 2. The degree of inhibition by bromothymol blue of the ]14C]succinate/malonate exchange reaction was pH dependent. It has been shown that the inhibition increased linearly while the pH was increased from 6.0 to 8.2. However, the binding rate of bromothymol blue to the mitochondria decreased with the rising pH of the medium. It is concluded that the binding of acidic bromothymol blue was not essential for the inhibitory effect. 3. Other sulfonephthalein derivatives also inhibited [14C]succinate/malonate exchange reaction. At pH 7.2 the relative order of the strength of the inhibitory action of the sulfonephthalein compounds tested was: thymol blue greater than bronocresol green greater than bromothymol blue greater than phenol red greater than bromocresol purple. The results do not indicate any correlation between the pK values of pH values of pH indicators and their extents of inhibition. 4. It is suggested that the negatively charged bromothymol blue interacts with the positively charged centers of the anion carrier systems causing inhibition of membrane permeability for anions.

Animals↗
PubMed1992

Effect of phenolic compounds on the polymerization of methyl methacrylate.

The inhibitory effects of six phenolic compounds and two analogues on the polymerization of methyl methacrylate (MMA) by azobisisobutyronitrile (AIBM) were examined. Differential scanning calorimetry was used to determine the induction period (IP) and initial rate of polymerization (IRP). The IP values (minutes) decreased in the order: eugenol > thymol > hydroquinone > cresol > guaiacol > phenol >>> safrole > methol. The IRP values of all compounds tested ranged from 0.8 to 1.2 percent per minute, except for hydroquinone (0.2 percent per minute). Phenolic compounds inhibited the polymerization of MMA by scavenging radicals, and eugenol was the most potent inhibitor.

Cresols↗
PubMedDate not supplied

Caries inhibition by a resin-modified and a conventional glass ionomer cement, in vitro.

OBJECTIVES: The aim of this study was to compare inhibition, in vitro, of a resin-modified and a conventional glass ionomer cement. METHODS: Standardized Class V cavities were prepared in extracted human molar teeth and restored with Fuji II LC (n = 14) or Chemfil II (n = 14) according to manufacturers' guidelines. The teeth were submerged in an acid gel (lactic acid, gelatin, thymol, pH 4.5) for 14 days and resin embedded. Photomicrographs of ground sections were examined for enamel surface lesions, dentine surface lesions, wall lesions and evidence of caries inhibition. RESULTS: There was no significant difference between the depths of enamel or dentine surface lesions between the two materials. No wall lesions were found. CONCLUSIONS: Fuji II LC proved more acid resistant than Chemfil II and both materials inhibited caries in vitro.

Cariostatic Agents↗
PubMed2005

Essential oil composition and antimicrobial activity of Oliveria decumbens.

The essential oil of Oliveria decumbens was investigated for its components and antimicrobial activity against six bacteria and two fungal strains. The essential oil was characterized by a high amount of oxygenated monoterpene components of which thymol (47.06%) and carvacrol (23.31%) were the major components. The oil exhibited high antimicrobial activity against all tested Gram+ and Gram- bacteria and fungal strains.

Anti-Infective Agents↗
PubMed2005

Chemical composition and antibacterial activity of essential oil of Pulicaria odora L.

The chemical composition of the volatile oil constituent from Pulicaria odora L. roots has been analyzed by GC/MS. Twenty-seven components were identified, being thymol (47.83%) and its derivative isobutyrate (30.05%) the main constituents in the oil. Furthermore, the oil was tested against seven bacteria at different concentrations. Results showed that the oil exhibited a significant antibacterial activity.

Anti-Bacterial Agents↗
PubMed2004

Analysis of the fetal placental vascular tree by X-ray micro-computed tomography.

The current understanding of the placental vascular tree largely derives from time-consuming morphometric analyses performed by conventional histology, electron microscopy of corrosion casts and three-dimensional reconstructions based on physical tissue sections. In the present study, we demonstrate for the first time that micro-computed tomography (micro-CT) emerges as a new, non-destructive and fast tool for imaging and quantifying fetoplacental vasculature. Term placentae (n=5) were perfused with contrast agent consisting of barium-sulfate, gelatine and thymol shortly after Caesarean-section-delivery. Samples (1 cm(3)) from eight different regions of the placenta were subsequently scanned in a micro-CT. Using tomographic reconstruction algorithms, three dimensional images were obtained by micro-CT allowing total stereoscopic visualization and continuous quantitative analysis of the vascular structure of the investigated samples. These samples were compared regarding vascular surface (VS) and vascular density (vascular volume fraction, TCVF). Quantitative assessment showed an average vascular density of 16 per cent (SD+/-0.4) and a vascular surface of 475 mm(2)(SD+/-8) per total tissue volume (including intervillous space) of 125 mm(3). Micro-CT image-analysis showed no significant differences in the fetal vascularization among term placentae. Micro-CT imaging is feasible for imaging and analysis of the villous vascular tree, allows further morphologic studies and immunohistochemistry of the placental specimens and may emerge as an additional tool in the investigation of the physiology and pathophysiology of the placental vasculature.

Barium Sulfate↗
PubMed2003

Efficacy of differently concentrated chlorhexidine varnishes in decreasing Mutans streptococci and lactobacilli counts.

The objective of the present prospective trial was to compare the efficacy of differently concentrated chlorhexidine varnishes (EC40) = 40% chlorhexidine and Cervitec = 1% chlorhexidine + 0.1% thymol) on levels of Mutans streptococci (ms), lactobacilli (lb) and plaque formation in interproximal plaque and saliva. Twenty-four volunteers with a high level of ms in saliva were randomized into two groups and treated with the experimental varnishes. Varnish applications were performed in accordance with literature. Over a period of 2 weeks Cervitec was applied three times and EC40 once or twice, depending on ms counts after first application. Four and 12 weeks after final varnish application ms in plaque and saliva were evaluated. Furthermore, lactobacilli (lb) counts in saliva and the effect on plaque formation were recorded. Both varnishes revealed a reduction of ms in interproximal plaque and saliva after 4 and 12 weeks. The highly concentrated varnish revealed a significantly stronger reduction of ms in plaque and saliva compared with the lowly-concentrated varnish. No effect could be demonstrated on lb counts and plaque formation. The results indicate that the chlorhexidine varnishes tested may reduce ms in both interproximal plaque and saliva. However, the application of the highly concentrated varnish EC40 results in a higher decrease of ms in plaque sites and saliva.

Adult↗
PubMed1973

Observations relating to the efficiency of mixing in rapid reaction flow devices.

The principle of dimensional analysis of liquid flow has been applied to the problem of rapid mixing in flow apparatus. A model of the Hartridge-Roughton mixing chamber and observation tube has been scaled approximately 1/1.000 so that the times after mixing are approximately 6 s, the flow velocities are the order of 2 cm/s, and the distance from mixing to observation is 120 mm. Visual observation is employed to observe the end point of the mixing of acid-base with a color indicator, thymol blue. Quantitative estimates of the effect of the number of jets, the effect of screens placed in the flow stream, and the angle of jets, one with respect to another, lead to quantitative evaluations of these parameters for the scale model. The extent to which these parameters apply to the full-scale apparatus at faster flow velocities suggest that the general principles employed in the scale model are valid, although more emphasis is placed upon turbulence generation at the low flow velocities employed in this experiment than at the faster flow velocities employed in the full-scale apparatus.

Indicators and Reagents↗
PubMed1982

Screening for multiple myeloma using routine laboratory test results.

Characteristics of myeloma protein can be best detected through serum electrophoresis, and are also detected as abnormal results of flocculation tests or hyperglobulinemia by routine laboratory work. The authors identified 38 cases of multiple myeloma in 5 years, actively making use of the available informations in the laboratory. The number screened was 7 times as many as the incidence previously observed, and most of them were screened in subclinical conditions. A formula to discriminate multiple myeloma from other diseases was obtained referring to the thymol turbidity test (TTT) and zinc sulfate turbidity test (ZTT) results through analytical processing the data from the first examination of the 38 patients. The most efficient and practical screening method for multiple myeloma was then developed by combining the formula by which suspicious serum specimens in routine tests are screened, with electrophoresis which confirms the disease.

Blood Protein Electrophoresis↗
PubMed2001

Structural requirements of phenol derivatives for direct activation of chloride currents via GABA(A) receptors.

Propofol directly activates gamma-aminobutyric acid (GABA(A)) receptors in the absence of the natural agonist. This mechanism is supposed to contribute to its sedative-hypnotic actions. We studied the effects of seven structurally related phenol derivatives on chloride inward currents via rat alpha1beta2gamma2 GABA(A) receptors, heterologously expressed in HEK 293 cells in order to find structural determinants for this direct agonistic action. Only compounds with the phenolic hydroxyl attached directly to the benzene ring and with aliphatic substituents in ortho position to the phenolic hydroxyl activated chloride currents in the absence of GABA. Concentrations required for half-maximum effect were 980 microM for 2-methylphenol, 230 microM for 2,6-dimethylphenol, 200 microM for thymol, and 23 microM for propofol. Drug-induced chloride currents showed no desensitisation during the 2-s application. These results show that the position of the aliphatic substituents with respect to the phenolic hydroxyl group is the crucial structural feature for direct GABA(A) activation by phenol derivatives.

Animals↗
PubMed2003

Synthesis, beta-adrenergic blocking activity and beta-receptor binding affinities of 1-substituted-3-(2-isopropyl-5-methyl-phenoxy)-propan-2-ol oxalates.

The compounds 1-isopropylamino-3-(2-isopropyl-5-methyl-phenoxy)-propan-2-ol oxalate (5) and 1-tert-butylamino-3-(2-isopropyl-5-methyl-phenoxy)-propan-2-ol oxalate (6) were synthesized from thymol (1), a naturally occurring agent in Thymus vulgaris L. Pharmacological evaluation of 5 and 6 were carried out using mouse ECG and isolated rat uterus models. Pretreatment of 5 (100 microg/kg, i.v.) and 6 (50 microg/kg, i.v.) antagonized isoprenaline (2 microg/kg, i.v.) induced tachycardia, similar to that of atenolol (CAS 29122-68-7, 20 microg/kg, i.v.) pretreatment in mouse ECG experiments as measured by R-R interval. Pretreatment of 5 and 6 blocked isoprenaline and adrenaline induced relaxation of isolated rat uterus (unprimed). Also the compounds 5 and 6 were subjected to in vitro beta1- and beta2-adrenergic receptor binding assay using turkey erythrocyte membrane (beta1) and lung homogenate of rats (beta2). Both 5 and 6 showed beta-adrenergic receptor affinity comparable with that of propranolol (propranolol hydrochloride, CAS 318-98-9) with out selectivity to any one beta-adrenergic receptor. These results suggest that both the compounds possess non-selective beta-adrenergic blocking activity, with the tert-butyl derivative 6 being more active than the isopropyl derivative 5.

Adrenergic beta-1 Receptor Antagonists↗
PubMed2001

Prevention of pit and fissure caries using an antimicrobial varnish: 9 month clinical evaluation.

OBJECTIVE: The purpose of this study was to determine whether Cervitec--a chlorhexidine--containing varnish could reduce the development of pit and fissure caries in children. METHODS: One hundred children each in age groups 7-8 and 12-14 years were selected from schools in Riyadh, Saudi Arabia. To be included in the study, each child had to have at least two sound contra-lateral first or second permanent molars with deep fissures. A split mouth method was used with one test tooth and one control within the same jaw. The left or the right side was selected randomly for test or control. The plaque samples from the occlusal surfaces of the test and control and the saliva samples were collected at baseline examination and after 9 months to estimate the number of Streptococcus mutans by the strip mutans method of Jensen and Bratthall (Jensen B, Bratthall D. A new method for the estimation of mutans streptococci in human saliva. Journal of Dental Research 1989;68:468-471). Cervitec varnish containing 1% chlorhexidine (CHx) and thymol was applied at baseline, at 3-4 months and at 6 months to the test tooth after isolation while the control had prophylaxis using cotton pellet in water each time the varnish was applied to the test tooth. Caries examination of the test and control followed after 9 months, according to the criteria and methods of WHO (World Health Organization. Oral Health Surveys. Basic Methods 4th ed., Geneva, WHO 1997). The blind technique was used in the diagnosis of caries and in the examination of the S. mutans count at the end of the study. RESULTS: Ninety four of the 7-8 year old and 86 of the 12-14 year old children completed the study. The results showed that the caries increment in both control groups of teeth after 9 months is significantly higher than in the test teeth (McNemar test: chi2 = 11.60, P < 0.001). The rate of caries development in a fissure was significantly correlated to the plaque mutans score of that fissure and there was considerable reduction in the S. mutans count of the plaque in the test teeth compared with the control (Spearman Rank Correlation: P < 0.001). CONCLUSION: It is concluded that the CHx varnish reduced the development of fissure caries significantly.

Adolescent↗
PubMed1998

In vitro caries inhibition by polyacid-modified composite resins ('compomers').

OBJECTIVES: The aim of this study was to compare the in-vitro caries inhibition of two polyacid-modified composite resins (PMCRs). METHODS: Three standardized class V cavities were prepared in eight extracted human molar teeth. Two of these cavities in each tooth were restored with Compoglass and Dyract according to manufacturers' guidelines. A conventional glass-ionomer cement restoration (Chemfil II) was placed in the third cavity in each tooth as a control. The teeth were submerged in an acid gel (lactic acid, gelatin, thymol, pH 4.5) for 28 days and then resin embedded. Ground sections were examined at x 160 magnification for enamel surface lesion depth, dentine surface lesion depth, wall lesions and evidence of caries inhibition. RESULTS: There was no significant difference between the depths of enamel or dentine surface lesions between the two compomer and conventional glass-ionomer materials. However, both PMCRs exhibited greater wall lesions than the conventional glass-ionomer material indicating less caries inhibition. CONCLUSIONS: These results suggest that PMCRs provide less caries inhibition than glass-ionomer cements.

Anti-Infective Agents, Local↗
PubMed2003

Influence of nitrogen fertilizers on the yield and composition of thyme (Thymus vulgaris).

The influence of nitrogen fertilizers on the yield of crop, as well as on the production and composition of the essential oil and some other chemical characteristics of thyme, was investigated. Different levels of fertilizers (N = 0, 45, 90, and 135 kg x ha(-)(1)) were applied. It was found that fertilizers increase thyme crop, but differences in the yield of essential oil were not remarkable. However, the use of certain amounts of nitrogen fertilizers resulted in higher yields of essential oil obtainable from the cultivation area unit (dm(3) ha(-)(1)). Totally, 61 constituents were identified in thyme essential oil by capillary GC and GC-MS. Thymol was the dominating compound in the all analyzed oils (44.4-58.1%), followed by p-cymene (9.1-18.5%), gamma-terpinene (6.9-18.9%), and carvacrol (2.4-4.2%). Differences in the percentage of these and other compounds in thyme herb cultivated under different fertilization doses were not significant; very slight changes in the percentage composition were detected after drying. Some variations in the amount of individual constituents expressed in arbitrary units per kilogram of herb (which is almost equivalent to mg x kg(-)(1)) were observed. The highest amounts of sugars and sucrose, in particular, were determined in the second year of thyme cultivation. Differences in the content of dry soluble substances were not meaningful, and there was no effect of nitrogen fertilizers on this chemical characteristic. Some effect of fertilization on the content of vitamin C and carotenes was observed in the first year of thyme cultivation. It was determined that nitrogen fertilizers influence the amount of nitrates, which was highest in the second-year-first-harvest.

Ascorbic Acid↗
PubMed2004

Chemical composition and extraction yield of the extract of Origanum vulgare obtained from sub- and supercritical CO2.

In this work sub- and supercritical CO(2) were used to obtain extracts from two origanum samples, one commercial, and another cultivated under agronomic control. The experiments were performed in the temperature range of 293-313 K and from 100 to 200 bar in pressure, employing around 26 g of origanum samples. Results show that the commercial sample provides a higher yield of extract if compared to the other sample. It is also achieved that a raise in temperature at constant pressure leads to an increase in the extraction yield despite solvent density changes. Chemical analyses were carried out in a GC-MSD, allowing the identification of around 24 compounds by use of the library of spectra of the equipment and injection of some standard compounds for both commercial and cultivated origanum samples. It was also found that the distribution of chemical components as a function of extraction time differs appreciably between the origanum species. The chromatographic analysis permitted the identification of thymol and cis-sabinene hydrate as the most prominent compounds present in commercial oregano sample and carvacrol and cis-sabinene hydrate in the cultivated Origanum vulgare.

Carbon Dioxide↗