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PubMed2002

Carvacrol and thymol reduce swine waste odor and pathogens: stability of oils.

An incomplete anoxic fermentation of livestock waste results in offensive odor emissions. Antimicrobial additives may be useful in controlling odor emissions and pathogens. Natural antimicrobial compounds, carvacrol or thymol at 16.75 mM (2.5 g/l) completely inhibited the production of the offensive odor compounds, isobutyrate, valerate, isovalerate, and cresol, and significantly reduced other short-chain volatile fatty acids and gas emissions from swine waste. Fecal coliforms were reduced from 6.3 x 10(6) to 1.0 x 10(3) cells per ml 2 days after treatment with carvacrol (13.3 mM) and were not detectable within 14 days. Total culturable anaerobic bacteria were reduced from 12.4 x 10(10) to 7.2 x 10(8) cells per ml after 2 days and were suppressed below this level for 28 days. Lactate production was not prevalent in untreated swine waste indicating that the microbial populations differ from those in cattle waste. Carvacrol and thymol were stable in swine waste under anoxic conditions for 62 days with 90 to 95% of the additive being recovered in the waste solids. In conclusion, carvacrol and thymol are not metabolized in anoxic swine waste and they are potentially useful in controlling odor emissions and pathogens in swine waste.

Animals↗
PubMed2006

Thymol derivatives from hairy roots of Arnica montana.

Five known thymol derivatives were isolated from roots of Arnica montana transformed with Agrobacterium rhizogenes LBA 9402. The compounds were characterized by spectral methods. The pattern of thymol derivatives in light-grown hairy roots was slightly different from that in dark-grown ones. This is the first report on the presence of thymol derivatives in hairy roots of the plant.

Arnica↗
PubMed1994

Activity of thymol, carvacrol, cinnamaldehyde and eugenol on oral bacteria.

The antimicrobial activity of thymol, carvacrol, cinnamaldehyde and eugenol alone or combined was tested by micromethods on eight oral bacteria. The compounds showed an inhibitory activity on seven microorganisms and a synergistic effect was observed with certain combinations. The four compounds can be used alone or combined, as eugenol and thymol, eugenol and carvacrol, thymol and carvacrol, during the treatment of oral infectious diseases.

Acrolein↗
PubMed1989

Determination of thymol in halothane anaesthetic preparations by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) procedure has been developed for the isolation and quantification of thymol, a stabilizing agent present in halothane anaesthetic preparations. The method offers improvements in specificity and simplicity with respect to a current official procedure for thymol in halothane. Results for commercial preparations obtained by the proposed procedure demonstrate excellent precision and accuracy with RSD values for replicate analysis ranging from 0.11 to 0.74% and recoveries via fortification from 99.6 to 100.1%. The HPLC method was compared to compendial procedures for thymol bulk substance and halothane products. Chromatographic separation of other related phenolic preservatives used in pharmaceuticals suggests a more extensive application of the proposed procedure.

Chromatography, High Pressure Liquid↗
PubMed2004

Susceptibility of methicillin-resistant staphylococci to oregano essential oil, carvacrol and thymol.

The aim of this study was to evaluate the susceptibility of methicillin-susceptible and methicillin-resistant staphylococci (MSS, MRS) to oregano essential oil, carvacrol and thymol. The commercial aerial parts of Origanum vulgare L. were hydrodistilled and the essential oil analysed by gas- chromatography/electron impact mass spectrometry. The inhibition efficacy of this essence and its major components was assayed against 26 MSS and 21 MRS, using an agar dilution method. The methicillin resistance was thoroughly typed by Epsilometer test (E-test), polymerase chain reaction for mecA gene detection and PBP2' latex agglutination test. The results clearly demonstrated that the comparison between the susceptibility of MSS and MRS to oregano oil, carvacrol and thymol showed no significant differences (Fisher's exact test, P > 0.05). The best minimum inhibitory concentration values were reported for carvacrol (0.015-0.03%, v/v) followed by thymol (0.03-0.06%, v/v) and oregano oil (0.06-0.125%, v/v).

Anti-Infective Agents↗
PubMed2003

Caries incidence in permanent first molars after discontinuation of a school-based chlorhexidine-thymol varnish program.

OBJECTIVES: To determine whether the cessation for 3 years of a 24-month program of chlorhexidine-thymol varnish applications would affect caries incidence in the first permanent molars of a population of schoolchildren of middle and lower-middle socioeconomic level. METHODS: Two groups of 6-7-year-old schoolchildren, randomized by school-class, were followed up in a clinical trial. One group received applications of chlorhexidine-thymol varnish every 3 months and the other group acted as controls. The program ended after 24 months and its effects were evaluated. Three years later, 55.5% of the schoolchildren were re-examined and the caries increments were documented. RESULTS: At the end of the 24-month program, the treated children had significantly fewer decayed and filled surfaces in permanent molars (lower DFS index) versus the controls. At 3 years after the discontinuation of the program, this difference had disappeared; there were no differences in the incidence of decayed, missing and filled surfaces (DMFS) index in permanent molars between the treated children and the controls. CONCLUSION: The cessation for 3 years of a 3-month program of chlorhexidine-thymol varnish applications resulted in a nonsignificant increase in the prevalence of dental caries in the permanent first molar.

Anti-Infective Agents, Local↗
PubMed2005

In vitro inhibitory effects of thymol and quinones of Nigella sativa seeds on cyclooxygenase-1- and -2-catalyzed prostaglandin E2 biosyntheses.

Dithymoquinone, thymohydroquinone, thymol and thymoquinone, compounds derived from N. sativa seeds, were investigated for their in vitro anti-inflammatory activities using cyclooxygenase-1 (COX-1) and -2 (COX-2) assays. Our results show that all substances tested possess significant inhibitory activity against at least one COX form at concentrations comparable to the active one of indomethacin. Thymol was the most active against COX-1 with an IC (50) value of 0.2 microM while thymohydroquinone and thymoquinone exhibited the strongest inhibitory effect on COX-2 with IC (50) values of 0.1 and 0.3 microM, respectively. Moreover, dithymoquinone and thymoquinone showed a limited COX-2-specific inhibition. We conclude that dithymoquinone, thymohydroquinone, thymol and thymoquinone can participate in the general anti-inflammatory activity of N. sativa and suggest that these agents should be further studied for possible use as non-steroidal anti-inflammatory drugs.

Cyclooxygenase 1↗
PubMed2004

Comparison between two thymol formulations in the control of Varroa destructor: effectiveness, persistence, and residues.

An apiary trial on the use of two acaricide formulations (gel-Apiguard and vermiculite and Api Life VAR) in the control of Varroa destructor (Anderson & Trueman) was conducted in summer 2001 in Sardinia (Italy). The main goals were 1) to determine their effectiveness against V. destructor, taking into account natural mite mortality in control hives; and simultaneously 2) to determine the persistence of both formulations and residues in honey and wax, by using a new extraction method. Both thymol formulations, after the treatments, reduced significantly the levels of mite infestations of adult bees and sealed brood, but their efficacy, expressed as percentage of mortality, was lower for both products (Api Life VAR 74.8 +/- 13.1 and 81.3 +/- 15.5, Apiguard 90.4 +/- 8.3 and 95.5 +/- 8.7 for sealed brood and adult bees, respectively) than the efficacy previously obtained with the same products in other experimental conditions. Moreover, a considerable colony-to-colony variability was recorded, and a significant negative effect of the thymol treatments on colony development was observed. During 2 wk of treatment, the bees removed nearly 95% of all the applied product (gel or vermiculite). Residues found in honey collected from the nest varied from 0.12 to 4.03 mg/kg for Api Life VAR and from 0.40 to 8.80 mg/kg for Apiguard. The residues were relatively higher in wax (Api Life VAR = 21.6 +/- 13.0; Apiguard = 147.7 +/- 188.9) than in honey, because thymol is a fat-soluble ingredient.

Animals↗
PubMed2000

Synergistic effects of nisin and thymol on antimicrobial activities in Listeria monocytogenes and Bacillus subtilis.

Nisin Z and thymol were tested, alone and in combination, for antibacterial activity against Listeria monocytogenes ATCC 7644 and Bacillus subtilis ATCC 33712. The antibacterial effect of nisin Z, produced by Lactococcus lactis KE3 isolated from the traditional Moroccan fermented milk, was greatly potentiated by sub-inhibitory concentrations of thymol in both bacterial strains. Our data showed that the concentration of nisin required for effective control of food-borne pathogenic bacteria could be considerably lowered by the use of thymol in combination. The use of low concentrations of nisin could lead to a less favourable condition for the occurrence of nisin-resistant bacterial sub-populations.

Anti-Bacterial Agents↗
PubMed1982

Difference in the mechanism of the action of caffeine and thymol on the calcium sequestering property of sarcoplasmic reticulum of frog skinned muscle fibers.

The effects of caffeine and thymol on the release of calcium from sarcoplasmic reticulum (SR) of mechanically skinned fibers isolated from semitendinosus muscle of frog, Xenopus laevis, are studied. Calcium release caused by caffeine is composed of two processes, a fast and a slow ones. The fast process is observable only when the amount of calcium stored in SR is above a "threshold" value while the slow one detectable only below the threshold value. The rate of these two processes does not depend on the concentration of caffeine so strongly, but the threshold value decreased as caffeine concentration is increased. On the contrary to this, calcium release produced by thymol is observed as a single rate process. More thymol results in increase in the rate of this process. The effects of these two kinds of drug on the uptake of calcium to SR are also studied. These two drugs give different effects on the calcium uptake, which are consistent with those actions of drugs on the calcium release. Procaine weakens the effects of these drugs. A simple model is given to explain the action of these two drugs on SR. The mechanisms of the drug action are also discussed in relation to the results obtained with the spin-label study.

Animals↗
PubMedDate not supplied

Thymol derivatives from a root culture of Inula helenium.

A root culture of Inula helenium L. was established from leaf explants of aseptic seedlings. An ethanol extract from the lyophilised roots was fractionated using different chromatographic techniques (CC, TLC). The main secondary metabolites found in the root culture were two thymol derivatives: 10-isobutyryloxy-8,9-epoxy-thymol isobutyrate (1) and 10-isobutyryloxy-6-methoxy-8,9-epoxy-thymol isobutyrate (2). The compounds were identified by spectral methods. Quantification of compound 1 in plant material was done by analytical RP-HPLC.

Biomass↗
PubMed2000

Effect of thyme oil and thymol dietary supplementation on the antioxidant status and fatty acid composition of the ageing rat brain.

The present study measured changes in antioxidant enzyme activity in, and the phospholipid fatty acid composition of the ageing rat brain and tested whether dietary supplementation with thyme oil or thymol could provide beneficial effects. There were significant declines in superoxide dismutase (EC 1.15.1.1) and glutathione peroxidase (EC 1.11.1.9) activities and the total antioxidant status in the untreated rats with age, while thyme-oil- and thymol-fed rats maintained significantly higher antioxidant enzyme activities and total antioxidant status. The proportions of 18:2n-6, 20:1n-9, 22:4n-6 and 22:5n-3 in the brain phospholipids resulting from all three dietary treatments were significantly higher in 28-month-old rats than in 7-month-old rats. Only 20:1n-9 levels in 28-month-old thyme-oil- and thymol-treated rats were significantly higher than in the age-matched control. The proportion of 22:6n-3 in brain phospholipids, which declined with age in control rats, was also significantly higher in rats given either supplement. This latter finding is particularly important as optimum levels of 22:6n-3 are required for normal brain function. These results highlight the potential benefit of thyme oil as a dietary antioxidant.

Aging↗
PubMedDate not supplied

Effectiveness of chlorhexidine-thymol varnish in preventing caries lesions in primary molars.

PURPOSE: The objective of this study was to evaluate the effect of chlorhexidine-thymol varnish on the prevention of caries lesions in primary molars among schoolchildren ages 6 to 7 in relation to their previous experience with caries. METHODS: Two groups of schoolchildren of lower-middle socioeconomic level were followed up in a clinical trial: one group of 86 children, treated with a chlorhexidine-thymol varnish (Cervitec) and another group of 95 children who served as controls. The varnish was reapplied every 3 months, and the caries lesion increments were compared at 24 months. RESULTS: There was no statistically significant difference between these 2 groups in the increment in decayed and filled primary molars. The children in the varnish group with no decayed or filled primary teeth at baseline showed a significantly lower (P<.05) incidence of caries lesions in primary molars (at 24 months) compared with the control group. CONCLUSIONS: Chlorhexidine-thymol varnish can be said to reduce caries lesions in the primary molars of schoolchildren ages 6 to 7 with no previous caries lesion experience.

Anti-Infective Agents, Local↗
PubMedDate not supplied

The use of Thymi Herba as feed additive (0.1%, 0.5%, 1.0%) in weanling piglets with assessment of the shedding of haemolysing E. coli and the detection of thymol in the blood plasma.

Thymi Herba (Thymus vulgaris, rubbed) was given as feed additive to weanling piglets. 3 concentrations (0.1%, 0.5%, 1%) were tested against a control group. Rectal swabs were collected weekly and were sent in for bacterial testing. The shedding of haemolysing E. coli was evaluated. There was no significant difference in the shedding of haemolysing E. coli between the 4 groups. Neither was there a difference in the distribution of the various serotypes. Thymol was detected in the blood plasma in all thyme groups. The increase in thymol level with greater amounts of thyme herb was significant. Three days after withdrawal of the feed additive no thymol levels were detected. The study results did not reveal any effects on haemolysing E. coli in the gut.

Animals↗
PubMed1993

[Antibacterial activity of thymol, carvacrol and cinnamaldehyde alone or in combination].

The antimicrobial activity of thymol, carvacrol and cinnamaldehyde was tested by several methods on bacteria involved in upper respiratory tract infections. Their combinations were investigated too. The broad spectrum of activity and the synergistic effect observed with some combinations (specially thymol and carvacrol) could allowed the use of the three compounds alone or, like thymol an carvacrol, combined during the treatment of respiratory infections.

Acrolein↗
PubMed2005

Novel mesoporous solid superacidic catalysts: activity and selectivity in the synthesis of thymol by isopropylation of m-cresol with 2-propanol over UDCaT-4, -5, and -6.

The alkylation of m-cresol with isopropyl alcohol in the presence of novel superacidic catalysts named as UDCaT-4, UDCaT-5, and UDCaT-6 was investigated. The catalysts are modified versions of zirconia showing high catalytic activity, stability, and reusability in the presence of water as compared to conventional sulfated zirconia. The objective of the present investigation was to explore the potential of these catalysts in this alkylation of m-cresol with isopropyl alcohol to thymol, which has widescale applications. The reactions were conducted in liquid phase in the temperature range of 433-473 K. Both, O- and C-alkylated products were obtained at lower temperatures, while at higher temperatures, thymol was the main product of the reaction. The catalytic activity increases in the order UDCaT-5 > UDCaT-6 >UDCaT-4 > sulfated zirconia. Thymol could be efficiently obtained with selectivity reaching up to 79% at an isopropyl alcohol conversion of 92% with UDCaT-5. This process can be a replacement for the existing process based on zeolites where high temperature and pressure are required. Synergistic effects of very high sulfur content present (9% S) and preservation of the tetragonal phase in UDCaT-5, in comparison with sulfated zirconia (4% S), were responsible for higher catalytic activity. A systematic investigation of the effects of various operating parameters was accomplished, and a mathematical model is developed to describe the reaction pathway and validated with experimental results. The reaction was carried out without using solvent, and the process subscribes to the principles of green chemistry.

Journal Article↗
PubMedDate not supplied

Spectrophotometric determination of sulfur dioxide in air, using thymol blue.

A simple and sensitive spectrophotometric method was developed for the determination of trace amounts of sulfur dioxide. The method is based on the reaction of SO2 with a known excess of ICI as the oxidant. The unreacted ICI iodinates thymol blue under acidic conditions. The lambdamax of thymol blue is at 545 nm under acidic conditions, and on lodination lambdamax shifts to 430 nm. This shift results in a decrease in the absorbance at 545 nm. The amount of uniodinated thymol blue present depends on the concentration of unreacted ICI, which in turn depends on the SO2 concentration. The system obeys Beer's law in the range 0-30 microg SO2 in a final volume of 25 mL, having a molar absorptivity of 3.2 x 10(4) L/mol cm with a relative standard deviation (RSD) of 2% at 24 microg SO2 (n = 10). The uniodinated dye can be extracted into 5 mL isoamyl alcohol under acidic conditions for measurement of absorbance. The extraction method obeys Beer's law in the range 0-5 microg SO2, having a molar absorpitivity of 4.16 x 10(4) L/mol x cm with an RSD of 1.9% at 4 microg SO2 (n = 10). The method has been successfully applied to the determination of atmospheric SO2.

Air↗
PubMed1987

Differences of superoxide production in blood leukocytes stimulated with thymol between human and non-human primates.

Thymol induced superoxide production (O2-) by blood leukocytes was examined in various primates including man. Leukocytes of chimpanzee and hamadryas baboon cells showed only 35% of the maximal O2- production rate obtained in human cells, and those of the Japanese monkey and orang-utan failed to respond. In contrast, when cells were stimulated with 12-O-tetradecanoyl phorbol acetate, no significant difference in the O2- production rate was observed between human and monkey cells except for chimpanzee. These results showed that human leukocytes are the most sensitive to thymol among the primates tested. The responsiveness of non-human primate leukocytes could be classified into two types, African-type(chimpanzee and baboon) and Asian-type(orang-utan and macaque).

Animals↗