Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “THYMOL”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed1994

Factors that interact with the antibacterial action of thyme essential oil and its active constituents.

The viable counts of Salmonella typhimurium on nutrient agar (NA) decreased upon the addition of either the essential oil of thyme or its constituent thymol, especially under anaerobic conditions. Antagonistic effects of thymol against Staphylococcus aureus were also greater under anaerobic conditions. In contrast to the phenolic constituents of the oil, thymol and carvacrol, the chemically related terpenes p-cymene and gamma-terpinene had no antagonistic effects against Salm. typhimurium. The addition of Desferal to NA counteracted the antibacterial effects of both thyme oil and thymol. No support was obtained, however, for a possible role of iron in the oxygen-related antibacterial action of the thyme oil and thymol or for the observed effect of Desferal. In the presence of thymol, the viable counts of Salm. typhimurium obtained on a minimal medium (MM) were lower than those obtained on NA. Addition of bovine serum albumin (BSA) neutralized the antibacterial action of thymol. It is suggested that the effects of BSA or Desferal are due to their ability to bind phenolic compounds through their amino and hydroxylamine groups, respectively, thus preventing complexation reactions between the oil phenolic constituents and bacterial membrane proteins. This hypothesis is supported by the marked decrease in the viable counts of Salm. typhimurium caused by either thyme oil or thymol when the pH of the medium was changed from 6.5 to 5.5 or the concentration of Tween 80 in the medium was reduced.

Aerobiosis↗
PubMed1999

Beneficial effects of thyme oil on age-related changes in the phospholipid C20 and C22 polyunsaturated fatty acid composition of various rat tissues.

The aim of this study was to determine any age-related changes in phospholipid polyunsaturated fatty acid composition, in particular C20 and C22 fatty acids in rat liver, brain, kidney and heart, and to assess and compare the effects of dietary supplementation (42.5 mg/kg body weight/day) of the natural antioxidant thyme oil and its major component thymol throughout the rat life span. The fatty acid composition in the various tissues from young (7 months) and aged (28 months) rats was determined and compared. Livers from aged control, thyme oil and thymol treated rats exhibited an increase in 22:6(n-3). In contrast, 22:6(n-3) content of brain, kidney and heart declined in aged rats in all three dietary groups. However, aged rats treated with thyme oil and thymol displayed significantly higher levels of 22:6(n-3) than the respective age-matched controls. Tissue compositions of 20:4(n-6) were found to be significantly lower in the liver and kidney from aged control rats but not those fed either thyme oil or thymol. In aged rats, the composition of 20:4(n-6) in all tissues was highest in rats fed either thyme oil or thymol. These results show that dietary supplementation with thyme oil tended to maintain higher PUFA levels in all tissues studied. The majority of protection provided by thyme oil was by virtue of its thymol component, which comprises 49% of the whole oil. Thymol administered alone did not provide significantly higher protection than the whole oil, suggesting that other components within thyme oil are also contributing antioxidant activity.

Aging↗
PubMed2005

Evaluation of residues of essential oil components in honey after different anti-varroa treatments.

Apiary trials on the use of three different treatments (Apilife Var, thymol solution in olive oil, and thymol solution in ethanol) for the control of Varroa destructor were conducted in Aragon (northeastern Spain). For the evaluation of the presence of residues of these treatments in honey an analytical method was developed. The method is applied to analyze honey samples before and after treatments with the acaricides mentioned. A solid-phase extraction on trifunctional silane SPE C18 cartridge and gas chromatography separation using a flame ionization detector allow reliable and precise determination of residues of thymol, menthol, eucalyptol, and camphor in honey. The results indicate that camphor is present in only low concentrations, residues of eucalyptol or menthol were not found at all, and only thymol left residues in high concentrations. Residues of thymol found in honey collected from the beehives ranged from 0.75 to 8.20 microg/g for Apilife Var, from 0.03 to 6.30 microg/g for thymol solution in olive oil, and from 0.05 to 6.20 microg/g for thymol solution in ethanol. Even so, natural treatments can be considered to be good alternatives for synthetic acaricides, especially because they do not represent a sanitary risk.

Animals↗
PubMed2003

Optical sensor for carbon dioxide combining colorimetric change of a pH indicator and a reference luminescent dye.

A new optical CO(2) sensor based on the luminescence intensity change of the europium(III) complex tris(thenoyltrifluoroacetonato) europium(III) dihydrate ([Eu(tta)(3)]) caused by the absorption change of various pH indicators-thymol blue, phenol red, or cresol red-with CO(2) was developed and its CO(2) sensing properties were investigated. For all the CO(2) sensors using pH indicators the observed luminescence intensity from [Eu(tta)(3)] at 613 nm increased with increasing CO(2) concentration. The linear calibration method based on the plot of (I(100)-I(0))/(I-I(0)) versus the inverse of CO(2) concentration was suggested, where I(0) and I(100) were luminescence intensities at 613 nm of the CO(2) sensor film in 100% nitrogen and 100% gaseous CO(2). In all cases the plots showed good linearity and the correlation factors of the plots, r(2), were 0.991 for thymol blue, 0.990 for phenol red, and 0.998 for cresol red. The slopes of the plots (A/B) for thymol blue, phenol red, and cresol red were 2.2, 5.2, and 9.0%, respectively. The response times of the CO(2) sensor film were 4.0 s for thymol blue, 4.4 s for phenol red, and 8.8 s for cresol red for switching from nitrogen to CO(2), and the recovery times of films were 36 s for thymol blue, 39.2 s for phenol red, and 56.6 s for cresol red for switching from CO(2) to nitrogen. The signal changes were fully reversible and hysteresis was not observed during the measurements. The highly sensitive CO(2) sensor was developed using thymol blue as an indicator for the CO(2)-sensing probe.

Journal Article↗
PubMed2001

Evaluation of volatile chemical treatments for lethality to Salmonella on alfalfa seeds and sprouts.

A study was done to evaluate natural volatile compounds for their ability to kill Salmonella on alfalfa seeds and sprouts. Acetic acid, allyl isothiocyanate (AIT), trans-anethole, carvacrol, cinnamic aldehyde, eugenol, linalool, methyl jasmonate, and thymol were examined for inhibitory and lethal activity against Salmonella by exposing inoculated alfalfa seeds to compounds (1,000 mg/liter of air) for 1, 3, and 7 h at 60 degrees C. Only acetic acid, cinnamic aldehyde, and thymol caused significant reductions in Salmonella populations (>3 log10 CFU/g) compared with the control (1.9 log10 CFU/g) after treatment for 7 h. Treatment of seeds at 50 degrees C for 12 h with acetic acid (100 and 300 mg/liter of air) and thymol or cinnamic aldehyde (600 mg/liter of air) significantly reduced Salmonella populations on seeds (>1.7 log10 CFU/g) without affecting germination percentage. Treatment of seeds at 50 degrees C with AIT (100 and 300 mg/liter of air) and cinnamic aldehyde or thymol (200 mg/liter of air) did not significantly reduce populations compared with the control. Seed germination percentage was largely unaffected by treatment with gaseous acetic acid, AIT, cinnamic aldehyde, or thymol for up to 12 h at 50 degrees C. The number of Salmonella on seeds treated at 70 degrees C for 80 min with acetic acid (100 and 300 mg/liter of air), AIT (100 mg/liter of air), and cinnamic aldehyde and thymol (600 mg/liter of air) at water activity (a(w)) 0.66 was not significantly different than the number inactivated on seeds at a(w) 0.49. Acetic acid at 200 and 500 mg/liter of air reduced an initial population of 7.50 log10 CFU/g of alfalfa sprouts by 2.33 and 5.72 log10 CFU/g, respectively, within 4 days at 10 degrees C. whereas AIT at 200 and 500 mg/liter of air reduced populations to undetectable levels; however, both treatments caused deterioration in sensory quality. Treatment of sprouts with 1 or 2 mg of AIT per liter of air adversely affected sensory quality but did not reduce Salmonella populations after 11 days of exposure at 10 degrees C.

Colony Count, Microbial↗
PubMed2005

Thyme (Thymus vulgaris L.) leaves and its constituents increase the activities of xenobiotic-metabolizing enzymes in mouse liver.

The effects of thyme (Thymus vulgaris L.) leaves and its phenolic compounds, thymol and carvacrol, on the activities of xenobiotic-metabolizing enzymes, i.e., phase I enzymes such as 7-ethoxycoumarin O-deethylase (ECOD) and phase II enzymes such as glutathione S-transferase (GST) and quinone reductase (QR), were investigated. Mice were fed with a diet containing thyme (0.5% or 2.0%) or treated orally with thymol (50-200 mg/kg) or carvacrol (50-200 mg/kg) once a day for 7 successive days, and then the enzyme activities in the livers were analyzed. Dietary administration of 2% thyme caused slightly but significantly higher ECOD, GST, and QR activities by 1.1-1.4-fold. Thymol (200 mg/kg) treatment resulted in significantly higher ECOD, GST, and QR activities by 1.3-1.9-fold, and carvacrol (200 mg/kg) treatment caused significantly higher ECOD, GST, and QR activities by 1.3-1.7-fold. Thymol-treated animals had significantly higher protein levels of GST alpha and GST micro, and carvacrol-treated animals had significantly higher levels of GST micro. These results imply that thyme contains bifunctional inducers (i.e., substances capable of inducing both phase I and phase II enzymes) and that thymol and carvacrol may account for the effects of thyme.

7-Alkoxycoumarin O-Dealkylase↗
PubMed2002

Comparison of release mechanisms for botanical oils to control Varroa destructor (Acari: Varroidae) and Acarapis woodi (acari: Tarsonemidae) in colonies of honey bees (Hymenoptera: Apidae).

Two major parasitic pests threaten honey bee populations, the external mite Varroa destructor and the internal mite Acarapis woodi (Rennie). Varroa are beginning to develop resistance to the main chemical defense fluvalinate, and alternative control methods are being pursued. Previous studies have shown that botanical oils, especially thymol, can be effective. Six release devices for either thymol or a blend of botanical oils known as Magic 3 were tested in beehives. The release devices were as follows: (1) low density polyethylene (LDPE) sleeves filled with Magic 3, (2) Magic 3-infused florist blocks, (3) thymol infused florist blocks, (4) a canola oil and thymol mixture wick release, (5) a plastic strip coated with calcium carbonate and Magic 3, and (6) an untreated control. There were significant decreases in varroa levels with the use of Magic 3 sleeves, but brood levels also decreased. Tracheal mite levels significantly decreased with the Magic 3 sleeve treatment, the Magic 3 florist block treatment, and the thymol canola wick treatment. A second experiment showed that changing the location of Magic 3 sleeves in the colony did not detrimentally effect brood levels, but also did not effectively control varroa mites.

Animals↗
PubMed2005

A novel approach for the management of the chalkbrood disease infesting honeybee Apis mellifera L. (Hymenoptera: Apidae) colonies in Egypt.

Except for, very few articles regarding the influence of some organic acids on the causative pathogen, Ascosphaera apis Maassen, no other studies pertaining to the management of the chalkbrood disease were performed, so far in Egypt. Laboratory investigations indicated that the fungicides, i.e (Galben C 46%, Radomil gold pluse WP 42.5% and Daconil 2787) at their recommended rates did not exert any effect on the mycelical growth of the fungus. Therefore, these fungicides were completely excluded from the subsequent apiary trials. As to the Mycostatin, it was found clearly that this mycostatic compound was effective at the rates of 50.000 and 100.000 IU. Regarding the essential oils (ceder, clove, peppermint, parsley, black cumin, garden rocket, and ricin), ceder oil surpassed the other oils and materials in controlling the subject disease. It is peculiar that no studies on the efficacy of ceder are available in the literature, so the present work using ceder oil is recorded for the first time worldwide. Thymol substance at the rate of 2% showed also a great success in managing the CHB disease. Baised on the obtained results, the promising materials in controlling the disease could be arranged according to their efficacy in a descending order as follows: ceder oil>thymol>mycostatin and oxalic acid, so these highly effective materials were again tested under the apiary conditions. Outdoors (apiary) studies revealed that ceder oil 4% gave 100% reduction in mummies numbers. Reductions in number of fallen mummies ranged from 63.22 to 96.94, 18.93 to 81.74, and 10.11 to 68.16%, on average, for thymol, mycostatin, and oxalic acid, respectively. From the practical point of view, thymol could be recommended for controlling the CHB disease, as it is the cheapest material and proved to increase the brood nest as well. In addition, thymol has other uses in the field of apiculture.

Animals↗
PubMed2006

Molluscicidal effect of three monoterpenes oils on schistosomiasis and fascioliasis vector snails in Egypt.

Thymol, Linalool and Eugenol showed considerable molluscicidal effect against Biomphalaria alexandrina, Bulinus truncatus and Lymnneae natalensis. The thymol was the potent one at least LC50 and LC90) followed by euganol then linalool. L. natalensis were more sensitive to these compounds followed by B. truncatus and then B. alexandrina. The LC50 & LC90) of thymol were 22 and 34 ppm against B. alexaldrina, 20 and 30 ppm for B. truncatuts and 18 and 29 ppm for L. nalalensis. These values were higher with Eugenol, 28 and 48 ppm for B. alexuadrina, 24 and 44 ppm for B. truncatus and 22 and 40 ppm for L. natalensis. Linalool showed highest values of LCs5 and LC90 against B. alexandrina, 34 and 56 ppm, against B. truncatus 30 and 52 ppm and for L. natalensis 28 and 48 ppm, respectively. Maintaining of B. alexandrina at LC10 of Thymol for one week induced an inhibitory effect in the level of some enzymes (AchE, SDH). It led to increase in the activity of other enzymes (ACP, ALP & G-6-PD). Acetylcholine-sterase activity (AchE) of treated B. alexandrina was significantly reduced by 45.9% when compared to control. The results showed a significant decrease in succinate dehydrogenase activity (SDH) by 46.4% together with a concomitant increase in glucose-6-phosphate dehydrogenase activity level (G-6-PD) by 47.5% in comparison with control. The activities of acid phosphatase and alkaline phosphatase enzymes were found to be higher in the treated snails than in control ones. The percentage increases were 47.2% & 73.2% respectively. The results also showed an elevation in the hemolymph glucose content of treated snails by 51.9% while the tissue glycogen content was reduced by 48.1%. The infection of B. alexandrina with S. mansoni miracidia was greatly reduced by thymol LC10 (sublethal dose). The infection rate reduction was 43.1%. The treated snails' prepatent period was prolonged (34.2 +/- 3.3 days) compared to control (28.4 +/- 1.2 days). A highly significant reduction of total cercarial production per snail occurred in experimental snails as compared to control.

Acyclic Monoterpenes↗
PubMed2006

Study of cytotoxic, genotoxic and DNA-protective effects of selected plant essential oils on human cells cultured in vitro.

OBJECTIVES: To investigate cytotoxic, genotoxic and DNA-protective effects of carvacrol and thymol on human hepatoma HepG2 and colonic Caco-2 cells cultured in vitro. METHODS AND RESULTS: Cytotoxicity testing was performed by the trypan blue exclusion technique. Level of DNA lesions induced in human cells with carvacrol, thymol or their combinations with hydrogen peroxide (H(2)O(2)) were measured by alkaline single cell gel electrophoresis (comet assay). The trypan blue exclusion technique showed that though the metabolically more competent human hepatoma HepG2 cells were more sensitive to the toxic effects of carvacrol or thymol than colonic Caco-2 cells, which contained lower levels of metabolizing enzymes, the observed differences were not very expressive. The comet assay technique showed that at concentrations <IC(50) the compounds studied did not induce DNA strand breaks either in hepatoma HepG2 or in colonic Caco-2 cells. On the other side, 24-h incubation of cells in the presence of carvacrol or thymol led to a significant protection of the cells studied toward DNA damage induced by H(2)O(2). CONCLUSIONS: Based on our results it can be concluded that the cytotoxic effects of selected components of essential plant oils on human hepatoma HepG2 and colonic Caco-2 cells were not associated with a DNA-damaging effect. Carvacrol and thymol reduced the level of DNA lesions induced by H(2)O(2). We assume that the observed DNA-protective effects of these plant volatiles can be associated with their antioxidative activity.

Caco-2 Cells↗
PubMed2003

Development of bacterial resistance to several biocides and effects on antibiotic susceptibility.

The aims of this study were to investigate the development of bacterial resistance to eugenol, thymol, trichlorocarbanalide (TCC), didecyldimethylammonium chloride (DDDMAC) and C10-16-alkyldimethyl, N-oxides (ADMAO) and subsequent effects on antibiotic susceptibility. An agar minimum inhibitory concentration (MIC) method was used to assess the activity of the biocides against standard bacterial strains and laboratory mutants. A range of techniques including disk diffusion and gradient plate experiments were used to attempt to develop bacterial 'resistance' or tolerance to the biocides. The mutants produced were examined for cross-resistance to the other biocides and to antibiotics via disk diffusion and gradient plate MIC methods. Outer membrane proteins of the mutants were extracted and examined using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Escherichia coli triclosan-resistant mutants were not cross-resistant to eugenol, thymol, TCC, DDDMAC and ADMAO. Mutants with elevated MICs to DDDMAC (E. coli and Pseudomonas aeruginosa), thymol (E. coli) and eugenol (E. coli) were isolated, but all remained sensitive to higher concentrations of the agents. Bacteria with elevated MICs to TCC and ADMAO were not obtained. Some low-level cross-resistance between DDDMAC, eugenol and thymol was observed with the E. coli gradient plate mutants, as well as reduced susceptibility to antibiotics, most notably chloramphenicol. The lack of cross-resistance of the triclosan mutants suggested that the mode of action of triclosan is not shared with the other biocides studied. SDS-PAGE results indicated that the DDDMAC P. aeruginosa mutant had a reduced amount (or absence) of one outer membrane protein in comparison with the standard strain. In conclusion, under laboratory conditions, bacterial exposure to thymol, eugenol and DDDMAC can lead to reduced susceptibility between selected biocidal agents and antibiotics, more specifically, chloramphenicol. However, further studies are required to determine if this is of clinical significance.

Anti-Infective Agents, Local↗
PubMed2001

Genetic diversity of Ocimum gratissimum L. based on volatile oil constituents, flavonoids and RAPD markers.

Morphological, chemical and genetic differences of 12 tree basil (Ocimum gratissimum L.) accessions were studied to determine whether volatile oils and flavonoids can be used as taxonomical markers and to examine the relationship between RAPDs to these chemical markers. Eugenol, thymol, and geraniol were the major volatile oil constituents found in Ocimum gratissimum. Xantomicrol and cirsimaritin were the major external flavones. The accessions morphologically described as O. gratissimum var. gratissimum contained eugenol as the major volatile oil constituent, and cirsimaritin as the major flavone. Ocimum gratissimum var. macrophyllum accessions contained thymol as the major volatile oil constituent, and xantomicrol as the major flavone. A distinct essential oil and flavone chemotype (producing geraniol and a mixture of the flavones cirsimaritin, isothymusin, xanthomicrol, and luteolin) was found in an accession genetically more distant from the other two groups when analyzed by molecular markers. The accessions could be divided based on volatile oil constituents into six groups: (1) thymol: alpha-copaene (ot24, ot25, ot26, and ot28); (2) eugenol:spathulenol (ot17, ot63, and ot52); (3) thymol:p-cymene (ot65); (4) eugenol:gamma-muurolene (ot27 and ot29); (5) eugenol:thymol: spathulenol (ot85); and (6) geraniol (ot84). Cluster analysis of RAPD markers showed that there are three groups that are distinct genetically and highly correlated (r=0.814) to volatile oil constituents.

Journal Article↗
PubMed2004

Effect of some volatile oils on the affinity of intact and oxidized low-density lipoproteins for adrenal cell surface receptors.

Extensive research has shown that a high plasma concentration and oxidation of low-density lipoproteins (LDL) has an important role in atherogenesis. The affinity of LDL to its classic receptor is reduced due to oxidation. Instead, it is taken up by scavenger molecules in macrophages, as a result of which foam cells are formed that have a major role in increasing the subendothelial fat layers of the blood vessels. In the present study the antioxidant effect of eight volatile compounds in plant essences, namely, anethol, eugenol, limonen, linalool, p-cymol, pulegon, thymol, and geraniol, and their effect on the affinities of intact and oxidized (with Cu(+2)) LDL for LDL receptor in sheep adrenal tissue cells in the presence of labeled LDL with fluorescein isothiocynate (FITC) were investigated. The results obtained show that eugenol and thymol have the highest antioxidant effect, on the uptake of LDL (intact and oxidized) by the adrenal cells. The order of the compounds studied with regard to their antioxidant effect on intact and oxidized LDL is as follows: On intact LDL: eugenol > or = thymol > linalool > p-cymol > limonen > geraniol > anethol; on oxidized LDL: thymol > or = eugenol > geraniol > p-cymol > linalool > pulegon. Our findings also show that the compounds, particularly thymol and eugenol, have an antioxidant property and can change the affinity of the LDL particles for the LDL receptor probably due to their lipophylic property. Further research may prove that these compounds can be used clinically, especially in atherosclerotic and hypercholesterolemic cases.

Adrenal Glands↗
PubMed2000

Effective fall treatment of Varroa jacobsoni (Acari: Varroidae) with a new formulation of formic acid in colonies of Apis mellifera (Hymenoptera: Apidae) in the northeastern United States.

New formulations of formic acid and thymol, both individually and in combination with various essential oils, were compared with Apistan to determine their efficacy as fall treatments for control of Varroa jacobsoni (Oudemans), a parasitic mite of the honey bee, Apis mellifera L. Percent mite mortality in colonies treated with 300 ml of 65% formic acid averaged 94.2 +/- 1.41% (least square means +/- SE, n = 24), equivalent to those receiving four, 10% strips of Apistan (92.6 +/- 1.79%, n = 6). Treatment with thymol (n = 24) resulted in an average mite mortality of 75.4 +/- 5.79%, significantly less than that attained with Apistan or formic acid. The addition of essential oils did not affect treatment efficacy of either formic acid or thymol. The ratio of the coefficients of variation for percentage mortality for the formic acid (CVFA) and Apistan (CVA) groups was CVFA/CVA = 0.66. This indicates that the formic acid treatment was as consistent as the Apistan treatment. Thymol treatments did not provide as consistent results as Apistan or formic acid. Coefficient variation ratios for percentage mortality for the thymol group (CVT) with the Apistan and formic acid groups were CVT/CVA = 4.47 and CVT/CVFA = 6.76, respectively. In a second experiment, colonies received a 4-wk fall treatment of either 300 ml of 65% formic acid (n = 24) or four, 10% strips of Apistan (n = 6). The next spring, mite levels in the formic acid group (554.3 +/- 150.20 mites) were similar to those in the Apistan treatment group (571.3 +/- 145.05 mites) (P = 0.93). Additionally, the quantities of bees, brood, pollen, and nectar/honey in the two treatment groups were not significantly different (P > or = 0.50 each variable). These results suggest that formic acid is an effective alternative to Apistan as a fall treatment for varroa mites in temperate climates.

Animals↗
PubMed1999

Toxicity of selected plant volatiles in microbial and mammalian short-term assays.

In this study, several short-term microbial and mammalian in vitro assays were used to evaluate cytotoxicity and genotoxicity of four plant volatiles showing antifungal activity: cinnamaldehyde, carvacrol, thymol and S(+)-carvone. All inhibited viability and proliferation of Hep-2 cells in a dose-dependent manner. IC50 ranged from 0.3 mM (cinnamaldehyde) to 0.7 mM (thymol) in viability tests and from 0.2 mM (carvacrol) to 0.9 mM (carvone) in the proliferation test. The morphological analysis suggested an involvement of apoptosis in the cases of carvone, carvacrol and cinnamaldehyde. At nontoxic doses, carvacrol and thymol increased the number of revertants in the Ames test by 1.5-1.7 times, regardless of metabolic activation. In the SOS-chromotest, none of the four plant volatiles caused DNA damage at non-toxic doses. In the DNA repair test, a marked dose-dependent differential toxicity was observed with carvone and, to a lesser extent, with cinnamaldehyde, while with thymol and carvacrol, this effect was less pronounced. In conclusion, the considered in vitro cytotoxicity assays have shown to be sensitive enough to highlight a variety of toxic effects at the cellular level, which can be rather different between chemically closely related compounds, such as isomers.

Acrolein↗
PubMed2001

Preparation and characterization of two-phase melt systems of lidocaine.

The melting point of lidocaine was significantly lowered when mixed with thymol and/or aqueous ethanol. Mixtures of lidocaine and thymol at ratios within the range of 30:70-70:30 (w:w) became homogeneous oils at 25 degrees C. In a pH 9.2 carbonate buffer containing 25% ethanol, lidocaine (5%, w:w) also liquefied at 25 degrees C. The studies led to the development of novel two-phase melt systems of lidocaine (TMS) which consisted of a highly concentrated oil phase of lidocaine and an alcoholic aqueous phase. A compositional phase diagram showed that in aqueous dispersions of lidocaine, concurrent use of thymol and ethanol depressed the melting point of lidocaine more effectively than when they were used individually. Both thymol and aqueous ethanol were necessary as melting point depressing agents to achieve the highest possible lidocaine concentration of 87% (w:w) in the oil phase of a TMS at 25 degrees C. Containing an internal oil phase and an external aqueous phase at ambient temperature, such a TMS can be readily formulated into topical O/W cream after addition of proper surfactants and thickening agents. In an anesthetic activity test using mouse tail-flick model, a 5% lidocaine cream prepared was highly effective as shown by the prolonged latency time of the mice to a heat stimulus as compared with a placebo (P<0.05).

Analgesia↗
PubMed2001

Validation of DIAGNOdent for quantification of smooth-surface caries: an in vitro study.

The aims were 1) to validate a laser-based device, KaVo DIAGNOdent, for quantification of caries lesions on smooth surfaces, using histopathologic and microradiographic analyses as the gold standard, and 2) to test inter- and intra-observer agreements. We also investigated the influence on DIAGNOdent readings of the storage medium used for extracted teeth. Two observers measured independently the tooth surfaces of 40 extracted premolars that had been stored in thymol-saturated saline. After subsequent storage in neutral-buffered formalin for 14 days they were re-measured. The teeth were then sectioned for histopathologic and microradiographic analysis. The Spearman rank correlation coefficients between lesion depth and DIAGNOdent readings were 0.78-0.83 and 0.85 for teeth stored in thymol-saturated saline and formalin, respectively. Inter- and intra-observer agreements were 0.94 and 0.95 when the teeth were stored in thymol-saturated saline. The DIAGNOdent reading was almost 1.5 times higher for teeth stored in formalin than for those stored in thymol saline. The Spearman rank correlation coefficient between mineral loss in enamel (deltaZ) and DIAGNOdent readings ranged from 0.64 to 0.68. It was concluded that DIAGNOdent may be helpful for assessing smooth-surface caries, but the cut-off points need to be assessed under clinical conditions. The increase in fluorescence associated with storage of teeth in formalin warrants further investigation.

Analysis of Variance↗
PubMed2005

Insecticidal activity of selected monoterpenoids and rosemary oil to Agriotes obscurus (Coleoptera: Elateridae).

Acute toxicities of three naturally occurring monoterpenoid essential oil constituents and the essential oil of rosemary were tested against late instars of Agriotes obscurus (L.) (Coleoptera: Elateridae). Both contact and volatile toxicities of thymol, citronellal, eugenol, and rosemary oil were determined. Also, phytotoxicity of these compounds was evaluated on corn germination and seedling development. Thymol had the greatest contact toxicity (LD50 = 196.0 microg/larva), whereas citronellal and eugenol were less toxic (LD50 = 404.9 and 516.5 microg/larva, respectively). Rosemary oil did not show any significant contact toxicity, even at 1,600 microg/larva. In terms of volatile toxicity, citronellal was the most toxic to wireworm larvae (LC50 = 6.3 microg/cm3) followed by rosemary oil (LC50 = 15.9 microg/cm3), thymol (LC50 = 17.1 microg/cm3), and eugenol (LC50 = 20.9 microg/cm3). Thymol, eugenol, and citronellal significantly inhibited corn seed germination and development, whereas rosemary oil had only minimal phytotoxic effects.

Animals↗