[p-Cymol & its derivatives. 4. Further studies on carvacrol synthesis].
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Cymenes↗
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Thymol and carvacrol binding to DNA: model for drug-DNA interaction.
Thymol and carvacrol can bind to major and minor grooves of B-DNA. The aim of this study was to examine the interaction of calf thymus DNA with thymol and carvacrol in aqueous solution and physiological pH with thymol/DNA and carvacrol/DNA (phosphate) molar ratios of 1/20, 1/10, 1/5, and 1/1. Fourier transform infrared and UV-visible difference spectroscopy were used to determine the thymol and carvacrol binding mode, binding constant, sequence selectivity, DNA secondary structure, and structural variations of thymol/DNA and carvacrol/DNA complexes in aqueous solution. Spectroscopic evidence showed that the thymol and carvacrol interaction occurred mainly through H-bonding of the thymol and carvacrol OH group to the guanine N7, cytosine N3, and backbone phosphate group with overall binding constant of K(thymol-DNA) = 2.43 x 10(3) M(-1), K(carvacrol-DNA) = 1.55 x 10(3) M(-1). In thymol and carvacrol-DNA complexes, DNA remains in the B-family structure.
Animals↗
13C-CPMAS and 1H-NMR study of the inclusion complexes of beta-cyclodextrin with carvacrol, thymol, and eugenol prepared in supercritical carbon dioxide.
Beta-cyclodextrin (beta-CD) inclusion complexes with carvacrol (1), thymol (2), and eugenol (3) (components of essential oils of vegetable origin) were prepared by the supercritical CO2 technique, and their structural characterization was achieved by means of 1H-NMR in aqueous solution and 13C-CPMAS NMR in the solid state. Evidence of the formation of the inclusion complexes for all the examined systems was obtained by 1H-NMR in solution, while 2D-ROESY-NMR experiments were used to investigate the geometry of inclusion. In addition, the dynamics of these inclusion complexes in the kHz timescale was investigated by analysis of the 1H and 13C spin-lattice relaxation times in the rotating frame.
Carbon Dioxide↗
Dehydration products of o-thymotic acid.
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Cymenes↗
Sulfur derivatives of o-thymotic acid.
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Cymenes↗
Determination of isopropylmethylphenols in black seed oil by differential pulse voltammetry.
A differential pulse voltammetric method is presented for the determination of isopropylmethylphenols (carvacrol and/or thymol) in phytotherapeutic black seed oils. The voltammetric behaviours of these phenols were examined in various buffer systems over the pH range 3.5-10.0. In Sörensen buffered methanol solution (3:7; v:v; pH 8.5), the differential pulse voltammograms exhibited reproducible peaks at Ep + 0.49 V vs. silver-silver chloride-potassium chloride 3 M for both carvacrol and thymol. Under these conditions, a plot of peak height against concentration of the isopropylmethylphenols was found to be linear over the range 0.25-2.5 microg/mL (r = 0.999). The detection limit was 0.04 microg/mL. The described voltammetric method was tested on two black seed oils available on the Austrian market.
Cymenes↗
Insecticidal properties of essential plant oils against the mosquito Culex pipiens molestus (Diptera: Culicidae).
The insecticidal activities of essential oil extracts from leaves and flowers of aromatic plants against fourth-instar larvae of the mosquito Culex pipiens molestus Forskal were determined. Extracts of Myrtus communis L were found to be the most toxic, followed by those of Origanum syriacum L, Mentha microcorphylla Koch, Pistacia lentiscus L and Lavandula stoechas L with LC50 values of 16, 36, 39, 70 and 89 mg litre-1, respectively. Over 20 major components were identified in extracts from each plant species. Eight pure components (1,8-cineole, menthone, linalool, terpineol, carvacrol, thymol, (1S)-(-)-alpha-pinene and (1R)-(+)-alpha-pinene) were tested against the larvae. Thymol, carvacrol, (1R)-(+)-alpha-pinene and (1S)-(-)-alpha-pinene were the most toxic (LC50 = 36-49 mg litre-1), while menthone, 1,8-cineole, linalool and terpineol (LC50 = 156-194 mg litre-1) were less toxic.
Acyclic Monoterpenes↗
In vitro acetylcholinesterase inhibitory properties of thymol, carvacrol and their derivatives thymoquinone and thymohydroquinone.
The aim of this study was to examine in vitro the inhibitory activity exerted by the main constituents of essential oil obtained from the aromatic plant Thymus vulgaris L. on acetylcholinesterase (AChE). The total essential oil and selected compounds, specifically linalool and thymol, carvacrol and their derivatives thymoquinone and thymohydroquinone, were tested for AChE inhibition. Thymohydroquinone exhibited the strongest AChE inhibitory effect over the range of concentrations. The AChE inhibitory potential decreased in the following order: thymohydroquinone > carvacrol > thymoquinone > essential oil > thymol > linalool. It is interesting that the AChE inhibitory effect exerted by carvacrol was 10 times stronger than that exerted by its isomer thymol, although thymol and carvacrol have a very similar structure.
Acetylcholinesterase↗
Induction of geranyl pyrophosphate pyrophosphatase activity by cholesterol-suppressive isoprenoids.
Diets supplemented (1 mmol/kg) with thymol, carvacrol, and beta-ionone significantly decreased the serum cholesterol levels of cockerels. These mevalonate-derived end products of plant secondary metabolism (isoprenoids) had no impact on two cytosolic prenyl alcohol (and ethanol) dehydrogenase activities; each treatment increased microsomal geranyl pyrophosphate pyrophosphatase activity by greater than twofold. The structural diversity of the isoprenoids which suppress cholesterol synthesis may be reconciled by their ability to increase pyrophosphatase activity, thus leading to the production of the endogenous, post-transcriptional regulator of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity.
Animals↗
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↗
Adaptation of the food-borne pathogen Bacillus cereus to carvacrol.
Carvacrol, a natural antimicrobial compound present in the essential oil fraction of oregano and thyme, is bactericidal towards Bacillus cereus. A decrease of the sensitivity of B. cereus towards carvacrol was observed after growth in the presence of non-lethal carvacrol concentrations. A decrease of the melting temperature (Tm) of membranes from 20.5 degrees C to 12.6 degrees C was the immediate effect of the addition of carvacrol. Cells adapted to 0.4 mM carvacrol showed a lower membrane fluidity than nonadapted cells. Adaptation of 0.4 mM carvacrol increased the Tm from 20.5 degrees C to 28.3 degrees C. The addition of carvacrol to cell suspensions of adapted B. cereus cells decreased Tm again to 19.5 degrees C, approximately the same value as for the non-adapted cells in the absence of carvacrol. During adaptation, changes in the fatty acid composition were observed. The relative amount of iso-C13:0, C14:0, and iso-C15:0 increased and cis-C16:1 and C18:0 decreased. The head-group composition also changed, two additional phospholipids were formed and one phospholipid was lacking in the adapted cells. It could be concluded that B. cereus adapts to carvacrol when present at non-lethal concentrations in the growth medium by lowering its membrane fluidity by changing the fatty acid and headgroup composition.
Adaptation, Physiological↗
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↗
Changes in heartwood chemistry of dead yellow-cedar trees that remain standing for 80 years or more in southeast Alaska.
We measured the concentrations of extractable bioactive compounds in heartwood of live yellow-cedar (Chamaecyparis nootkatensis) trees and five classes of standing snags (1-5, averaging 4, 14, 26, 51, and 81 years-since-death, respectively) to determine how the concentrations changed in the slowly deteriorating snags. Three individuals from each of these six condition classes were sampled at four sites spanning a 260-km distance across southeast Alaska, and the influence of geographic location on heartwood chemistry was evaluated. Cores of heartwood were collected at breast height and cut into consecutive 5-cm segments starting at the pith. Each segment was extracted with ethyl acetate and analyzed by gas chromatography. Concentrations of carvacrol, nootkatene, nootkatol, nootkatone, nootkatin, and total extractives (a sum of 16 compounds) for the inner (0-5 cm from pith), middle (5-10 cm from pith), and surface (outer 1.1-6.0 cm of heartwood) segments from each core were compared within each tree condition class and within segments across condition classes. Heartwood of class 1 and 2 snags had the same chemical composition as live trees. The first concentration changes begin to appear in class 3 snags, which coincides with greater heartwood exposure to the external environment as decaying sapwood sloughs away, after losing the protective outer bark. Within core segments, the concentrations of all compounds, except nootkatene, decrease between snag classes 2 and 5, resulting in the heartwood of class 5 snags having the lowest quantities of bioactive compounds, although not different from the amounts in class 4 snags. This decline in chemical defense is consistent with heartwood of class 5 snags being less decay-resistant than heartwood of live trees, as observed by others. The unique heartwood chemistry of yellow cedar and the slow way it is altered after death allow dead trees to remain standing for up to a century with a profound impact on the ecology of forests in southeast Alaska where these trees are in decline.
Acetates↗
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↗
Antioxidant actions of thymol, carvacrol, 6-gingerol, zingerone and hydroxytyrosol.
Antioxidants minimize oxidation of the lipid components in foods. There is an increasing interest in the use of natural and/or synthetic antioxidants in food preservation, but it is important to evaluate such compounds fully for both antioxidant and pro-oxidant properties. The properties of thymol, carvacrol, 6-ginerol, hydroxytyrosol and zingerone were characterized in detail. Thymol, carvacrol, 6-gingerol and hydroxytyrosol decreased peroxidation of phospholipid liposomes in the presence of iron(III) and ascorbate, but zingerone had only a weak inhibitory effect on the system. The compounds were good scavengers of peroxyl radicals (CCl3O2; calculated rate constants > 10(6) M-1 sec-1) generated by pulse radiolysis. Thymol, carvacrol, 6-gingerol and zingerone were not able to accelerate DNA damage in the bleomycin-Fe(III) system. Hydroxytyrosol promoted deoxyribose damage in the deoxyribose assay and also promoted DNA damage in the bleomycin-Fe(III) system. This promotion was inhibited strongly in the deoxyribose assay by the addition of bovine serum albumin to the reaction mixtures. Our data suggest that thymol, carvacrol and 6-gingerol possess useful antioxidant properties and may become important in the search for 'natural' replacements for 'synthetic' antioxidant food additives.
Antioxidants↗
Extracts and fractions of Thymus capitatus exhibit antimicrobial activities.
Preliminary phytochemical screening of the plant Thymus capitatus exhibited the presence of saponins, resins, flavonoids, essential and fixed oils. Aqueous and ethanolic extracts (10-200 mg/ml) as well as saponin, resin and essential oil of the plant (10-5000 micrograms/ml inhibited the growth of several bacteria and fungi.
Anti-Bacterial Agents↗
Automated post-collection concentration for purified preparative fractions via solid phase extraction.
Recent advancements in preparative HPLC have improved and streamlined compound purification. However, fraction evaporation remains a bottleneck within the process. An alternative to fraction evaporation is to remove the water and reduce the overall volume of the collection by trapping the fraction onto a solid phase extraction (SPE) cartridge. This method (as opposed to analytical applications involving SPE) works by collecting and then diluting the fraction(s), passing the fraction(s) through a SPE, drying the SPE with nitrogen and ultimately eluting the concentrated fraction(s) in a small amount of 100% organic solvent. An appreciable breakthrough is not observed using this method. In addition, recovery from the SPE for the tested compounds rosmarinic acid and carvacrol, two naturally occurring antioxidants in oregano, was found to be 95-98% for a 100mg injection via preparative HPLC purification at 50mg/compound.
Antioxidants↗
Effects of terpenoid phenol derivatives on calcium current in canine and human ventricular cardiomyocytes.
Concentration-dependent (10-1000 microM) effects of terpenoid phenol derivatives were studied on L-type Ca(2+) current in isolated canine and human ventricular cardiomyocytes using the whole-cell configuration of patch clamp technique. Carvacrol, thymol and eugenol suppressed peak Ca(2+) current at +5 mV, having EC(50) values and Hill coefficients of 98+/-11, 158+/-7 and 187+/-15 microM and 1.42+/-0.05, 2.96+/-0.43 and 1.6+/-0.1, respectively, in canine myocytes. Zingerone displayed a weak effect (estimated EC(50): 2+/-0.37 mM, Hill coefficient: 0.73+/-0.07), while vanillin and guaiacol failed to substantially modify Ca(2+) current up to the concentration of 1 mM. In addition to tonic block, thymol and carvacrol, but not eugenol, evoked marked rate-dependent block at 2 Hz. Carvacrol and eugenol accelerated inactivation of Ca(2+) current and caused leftward shift in the voltage dependence of steady-state inactivation without altering activation kinetics. Carvacrol, but not eugenol, increased the time constant of recovery from inactivation. These effects of carvacrol and eugenol developed rapidly and were largely reversible. In myocytes isolated from undiseased human hearts, the effect of carvacrol was similar to that observed in canine cells. It is concluded that suppression of cardiac Ca(2+) currents by phenol derivatives is influenced by the substituent in the benzene ring, and the blocking effect of these drugs may involve interactions with the inactivation machinery of the channel.
Animals↗