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Rapid method for simultaneous quantitative determination of four major essential oil components from oregano (Oreganumsp.) and thyme (Thymus sp.) using FT-Raman spectroscopy.

A simple and rapid method for the quantitative determination of four major components found in oregano and thyme essential oils is presented. The method correlates the Raman peak intensity in the spectral region from 1800 to 600 cm(-1) and the concentration percentage of each particular constituent in the sample. To achieve accurate quantification results and avoid the risk of overlapping peaks of unknown Raman-active substances in natural essential oils, the peaks must be analyzed. For this purpose, PEAKSOLVE software (Ver. 1.0.5) was used. Unknown samples were measured with the FT-Raman method, and the results were compared to those of the gas chromatographic (GC) analysis. The comparison was made at a confidence level of 99%, and the two methods scored equally in terms of repeatability and accuracy even at the edge of the method specifications. The new method can provide accurate results in very short times once the setup is complete and could be utilized in areas where vast amounts of samples must be analyzed.

Oils, Volatile↗

Effect of thyme essential oils (Thymus hyemalis and Thymus zygis) and monensin on in vitro ruminal degradation and volatile fatty acid production.

The effect of the essential oils of thyme on the in vitro ruminal degradability of a barley seed/alfalfa hay substrate was studied. Two essential oils were used, one from Thymus hyemalis (TH), rich in carvacrol, and the other from Thymus zygis (TZ), rich in thymol. Four experimental treatments of in vitro degradability, using the Daisy II(200/220) incubator, were conducted including a negative control (CO), a positive control at 7.5 microg/mL of monensin (MO), and two treatments with essential oils (TH or TZ) at 1.35 microL/mL. The material was incubated at 39.5 degrees C for various lengths of time. At each time, the disappearance of dry matter, crude protein, and neutral detergent fiber was measured. Volatile fatty acids (VFAs) were determined after 48 h of incubation. CO and MO provided (p < 0.01) higher values of potential degradability (a + b) of DM than the TH and TZ treatments (72.6 and 70.8 vs 53.2 and 48.2%, respectively). Also, crude protein degradability was lowest in the essential oil treatments. The CO treatment showed the highest potential degradability of NDF. The values of VFA production obtained (p < 0.001) with CO and MO treatments were higher than those obtained with TH and TZ treatments (21.0 and 19.1 vs 11.2 and 10.1 mM). The essential oils decreased the molar proportion of propionate, increasing the acetate/propionate ratio. In conclusion, the effects of essential oils at assayed doses would not be nutritionally beneficial to the ruminal energetic metabolism.

Animals↗

Acetophenone glycosides from thyme (Thymus vulgaris L.).

Four acetophenone glycosides were isolated from the butanol-soluble fraction of thyme extracts. Their structures were determined by spectral methods (MS, NMR, and 2D-NMR). Among them, two new compounds, 4-hydroxyacetophenone 4-O-[5-O-(3, 5-dimethoxy-4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D -gl ucopyranoside (1) and 4-hydroxyacetophenone 4-O-[5-O-(4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D-+ ++gluc opyranoside (2), were determined. Compound 1 showed weak cytotoxicity, inhibiting DNA synthesis of human leukemia cells.

Acetophenones↗

Oregano, thyme and clove-derived flavors and skin sensitizers activate specific TRP channels.

Carvacrol, eugenol and thymol are major components of plants such as oregano, savory, clove and thyme. When applied to the tongue, these flavors elicit a warm sensation. They are also known to be skin sensitizers and allergens. The transient receptor potential channel (TRPV3) is a warm-sensitive Ca2+-permeable cation channel highly expressed in the skin, tongue and nose. Here we show that TRPV3 is strongly activated and sensitized by carvacrol, thymol and eugenol. Tongue and skin epithelial cells respond to carvacrol and eugenol with an increase in intracellular Ca2+ levels. We also show that this TRPV3 activity is strongly potentiated by phospholipase C-linked, G protein-coupled receptor stimulation. In addition, carvacrol activates and rapidly desensitizes TRPA1, which may explain the pungency of oregano. Our results support a role for temperature-sensitive TRP channels in chemesthesis in oral and nasal epithelium and suggest that TRPV3 may be a molecular target of plant-derived skin sensitizers.

Animals↗

A new hydroxyjasmone glucoside and its related compounds from the leaf of thyme.

From the polar portion of the methanol extract of thyme (leaf of Thymus vulgaris; Labiatae), which has been used as a stomachic, carminative, a component of prepared cough tea, and as a spice, a new hydroxyjasmone glucoside, (Z)-5'-hydroxyjasmone 5'-O-beta-D-glucopyranoside was isolated together with five related compounds and four aromatic compounds. The structures of the new compound was clarified by spectral investigation.

Glucosides↗

Protein glycation inhibitors from thyme (Thymus vulgaris).

Nonenzymatic glycation of bovine serum albumin (BSA) was inhibited in vitro by some extracts of 34 kinds of spices. The methanol extract of thyme (Thymus vulgaris) had the most potent inhibitory activity among them. Chromatographic purification yielded four flavonoids, quercetin (1), eriodictyol (2), 5,6,4'-trihydroxy-7,8,3'-trimethoxyflavone (3), and cirsilineol (4). These known flavonoids suppressed the levels of advanced glycation end products (AGEs) and fructosamines, shown by the measurement of specific fluorescent groups and the reduction of nitroblue tetrazolium (NBT), respectively. The inhibitory activities were compared with those of other structure-related flavonoids and aminoguanidine.

Flavonoids↗

New monoterpene glucoside from the aerial parts of thyme (Thymus vulgaris L.).

A new monoterpene glucoside (1) was isolated from a methanol extract of the dried aerial parts of thyme (Thymus vulgaris L.), together with known 2- and 5-beta-D-glucopyranosylthymoquinols (2 and 3, respectively), and (-)-angelicoidenol-beta-D-glucopyranoside (4). The structure of 1 was elucidated to be (R)-p-cymen-9-yl beta-D-glucopyranoside by spectral evidence and enantioselective synthesis from (R)- and (S)-p-cymen-9-ol derived from p-cymen-8-ol.

Glucosides↗

Monoterpenes from thyme (Thymus vulgaris) as potential mosquito repellents.

Five monoterpenes (carvacrol, p-cymene, linalool, alpha-terpinene, and thymol) derived from the essential oil of thyme (Thymus vulgaris) were examined for their repellency against the mosquito Culex pipiens pallens. All 5 monoterpenes effectively repelled mosquitoes based on a human forearm bioassay. Alpha-terpinene and carvacrol showed significantly greater repellency than a commercial formulation, N,N-diethyl-m-methylbenzamide (deet), whereas thymol showed similar repellency to that of deet. The duration of repellency after application for all these monoterpenes was equal to or higher than that of deet. These findings indicate that a spray-type solution containing 2% alpha-terpinene may serve as an alternative mosquito repellent.

Acyclic Monoterpenes↗

[The elevation of the leucocyte and thrombocyte counts produced by a thyme extract in the peripheral blood as compared to that caused by 2-cyanoethylurea (author's transl)].

A thyme extract, the preparation of which is described, produced a considerable stimulation of leucopoiesis and also an elevation of the thrombocyte count in the blood. In a comparative trial, the immunopotentiator 2-cyanoethylurea (BA1-4) has been found to be even more effective. The elevation of the leucocyte count is of importance not only to the various possibilities of immunostimulation, but also directly, in connexion with an elevation of the thrombocyte count, to the tumour-damaging process in the cancer multistage therapy, due to the promotion of the selective haemostasis set up on this occasion in the tumour tissue. The activation of immunological processes by intensive variants of the oxygen multistage therapy (O2-MT) increases in particular the efficiency of immunopotentiators so the latter should be used, in connexion with O2-MT, in any cancer therapy.

Animals↗

Spectrophotometric determination of certain volatile oils. Part 1: Assay for phenols in volatile oils of clove and thyme.

A differential spectrophotometric method was described for the assay of thyme and clove oils. The method is based on the relative absorbance measurement of the thymate or eugenate anions to the respective molecular thymol or eugenol in alcoholic medium. The results of the differential method, compared with those of the conventional method, are more accurate.

Condiments↗