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Concept: Thymol

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ETHNOPHARMACOLOGICAL RELEVANCE: Zataria multiflora Boiss. (ZM) is a thyme-like plant belonging to the Lamiaceae family that grows wild only in Iran, Pakistan and Afghanistan. This plant with the vernacular name of Avishan-e-Shirazi (Shirazi thyme) in Iran is a valuable medicinal and condimental plant. It has several traditional uses as an antiseptic, carminative, stimulant, diaphoretic, diuretic, anesthetic, anti-spasmodic and analgesic. AIM OF THE STUDY: This paper reviews the ethnopharmacology, pharmacology, toxicology, modern pharmaceutical uses and phytochemistry of Zataria multiflora, and highlights the gaps in our knowledge deserving further research. METHODS: All relevant databases were searched for the terms “Zataria”, “Zataria multiflora”, “Shirazi thyme” and “Iranian thyme” without limitation up to 24th October 2012. Information on Zataria multiflora was collected via electronic search using Pubmed, Scopus, Web of Science and SID (for articles in Persian language), and local books on ethnopharmacology. RESULTS: ZM has played an important role in Iranian traditional medicine. In light of the modern pharmacological and clinical investigations, ZM is a valuable medicinal and condimental plant that has anti-microbial, antioxidative, anti-inflammatory, spasmolytic and anti-nociceptive properties. The oil of ZM contains high percentages of oxygenated monoterpenes, in particular thymol and carvacrol, and exhibits excellent anti-microbial properties. CONCLUSIONS: Overall, antimicrobial property appears to be the most interesting studied biological effect of ZM. The lack of a comprehensive phytochemical analysis of ZM is an important limitation that can be noted regarding most of the previous studies.

Concepts: Pharmacology, Medicine, Lamiaceae, Iran, Persian language, Afghanistan, Pharmacognosy, Thymol

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Thymus leucospermus Hartvig is a Greek endemic species of Section Teucrioides Jalas. The essential oils obtained from five populations growing wild in the National Park of Northern Pindhos (NW Greece) were studied. The oil content ranged between 1.1 and 2.0 mL per 100 g of dry plant weight. The oils were particularly rich in phenolic monoterpenes: they had a high thymol (64.7-92.0%) or carvacrol (93.4%) content, whereas in one of the oils considerable amount of both compounds was found (thymol 61.6% and carvacrol 26.4%). Our results show that T. leucospermus is a high-quality thyme species, with respect to both oil content and composition.

Concepts: Biodiversity, Phenols, Essential oil, Oil, Monoterpene, Thymol, Thyme, Thymus vulgaris

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Six samples of red thyme (Thymus zygis) and two samples of winter thyme (Thymus hyemalis) essential oils (EOs) were obtained from plants cultivated in south-eastern Spain and extracted by steam distillation. Analysis by gas chromatography coupled with mass spectrometry detection provided the relative (%) and absolute (mM) concentrations. Thymol (30-54%), p-cymene (14-27%) and γ-terpinene (8-28%) were the most abundant components of T. zygis EO, while 1,8-Cineole (3-37%), p-cymene (1-29%), linalool (8-13%) and thymol (0-19%) were the most abundant components in the case of T. hyemalis EO. Enantioselective gas chromatography identified (-)-linalool, (-)-borneol and (+)-limonene as the main enantiomers. Several methods to evaluate antioxidant capacities were applied to the EOs, concluding that their activities were mainly due to thymol and linalool. The inhibition of lipoxygenase activity, mainly due to thymol, p-cymene and linalool, suggested their possible use as anti-inflammatories. The high antibacterial and antifungal activities determined for the EOs means that they can be used as natural preservatives. The results support the potential use of Thymus sp. EOs as natural food, cosmetic and pharmaceutical ingredients.

Concepts: Mass spectrometry, Chromatography, Preservative, Distillation, Essential oil, Thymol, Thyme, Thymus vulgaris

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A preliminary study to evaluate the effect of dietary supplementation with olive phenols (oleuropein, hydroxytyrosol and secoiridoids), thyme phenols and a combination of these (5 mg per kg rat weight per day) on the α-tocopherol concentrations in the muscle and liver of healthy adult Wistar rats over 21 days was conducted. In addition, the excretion of α-tocopherol through the faeces was examined. The results demonstrated that the diet supplemented with some phenolic compounds of olive and thyme increased α-tocopherol (P < 0.05) in the liver of female rats, although the α-tocopherol content in the diet of all groups was identical. In addition, a synergic effect between the olive phenols and thyme was observed. Therefore, our study indicates a protective effect of olive and thyme phenols supplemented in the diet on α-tocopherol, resulting in a higher concentration of endogenous α-tocopherol in the rat liver.

Concepts: Nutrition, Rat, Phenols, Phenolic compounds in wine, Oleuropein, Thymol

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The aim of this work is to explore the possibility of using the phenolic monoterpenes (PMs) as leading compounds with antifungal activity against plant disease. The in vitro antifungal activities of carvacrol and thymol against seven kinds of plant pathogenic fungi were evaluated on mycelium growth rate method, and the results showed that carvacrol and thymol exhibited broad spectrum antifungal activity. Structure requirement for the antifungal activity of PMs was also investigated. The preliminary conclusion was that phenolic hydroxyl and monoterpene were basic structures for the antifungal activity of PMs, and the position of phenolic hydroxyl showed less effect. Ester derivatives of carvacrol and thymol were more effective than carvacrol and thymol against plant pathogenic fungi. We suggested that carvacrol, thymol and their ester derivatives could potentially be used as new fungicide leading compounds.

Concepts: Microbiology, Fungus, Terpenes and terpenoids, Phenols, Mycelium, Monoterpene, Carvacrol, Thymol

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Allorhizobium (Agrobacterium) vitis is a host-specific pathogenic bacterium that causes grapevine crown gall disease, affecting vine growth and production worldwide. The antibacterial activities of different aromatic plant essential oils were tested in vitro and in planta against A. vitis. Among the essential oils tested, those of Origanum compactum and Thymus vulgaris showed the most significant in vitro antibacterial activities, with a MIC of 0.156 and 0.312 mg/mL, respectively. A synergistic effect of these two essential oils (1:1) was observed and confirmed by the checkerboard test. Carvacrol (61.8%) and thymol (47.8%) are, respectively, the major compounds in the essential oils of O. compactum and T. vulgaris and they have been shown to be largely responsible for the antibacterial activities of their corresponding essential oils. Results obtained in vitro were reinforced by an in planta pathogenicity test. A mixture of O. compactum and T. vulgaris essential oils (1:1), inoculated into the injured stem of a tomato plant and a grapevine at 0.312 mg/mL as a preventive treatment, reduced both the number of plants developing gall symptoms and the size of the tumors.

Concepts: Bacteria, Plant, Agrobacterium tumefaciens, Essential oil, Grape, Thymol

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The antioxidative compounds were extracted by ultrasonic treatment of bran extracts of seven pigmented (completely) and non pigmented (sparsely) colored rice cultivars followed by assessment of their in vitro antioxidative capacity by LC-MS and oxidation/reduction assay based methods. A total of 40-compounds, 7-phenolic, 9-flavonoids, 9-hydroxycinammic acid derivatives, 3-hydroxybenzoic acid derivatives and other glucosides specifically, pro-anthocyanidin trimer and procyanidin-B1 (dimer) were indentified in completely colored rice cultivars. Higher DPPH radical scavenging activity of pigmented cultivars was due to higher percentage of phenolics like thymol, quinicquinic-caffeicacid ester and polar dicaffeoylquinic acid; whereas higher lipid peroxidation inhibition was attributed to the presence of polar substances such as p-hydroxybenzoicacid, procyanidin B1 and quercetin-3-O-rutinoside. The phosphomolybdenum reduction capacity was attributed to luteolin-7-O-glucoside, apigenin-7-O-glucoside, caffeicacid, myrecitin and phloreticacid. Whereas, grater reducing power of pigmented bran was attributed to presence of multiple-OH groups containing phenols, flavonoid and hydracinammicacid depicting potential health and nutritional effects of these rice cultivars.

Concepts: Alcohol, Nutrition, Antioxidant, Redox, Resveratrol, Phenols, Rice, Thymol

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Thymol (THY)/γ-Cyclodextrin(γ-CD) inclusion complex (IC) encapsulated electrospun zein nanofibrous webs (zein-THY/γ-CD-IC-NF) were fabricated as a food packaging material. The formation of THY/γ-CD-IC (1:1 and 2:1) was proved by experimental (X-ray diffraction (XRD), thermal gravimetric analysis (TGA), (1)H NMR) and computational techniques. THY/γ-CD-IC (2:1) exhibited higher preservation rate and stability than THY/γ-CD-IC (1:1). It is worth mentioning that zein-THY/γ-CD-IC-NF (2:1) preserved much more THY as observed in TGA and stability of THY/γ-CD-IC (2:1) was higher, as shown by a modelling study. Therefore, much more THY was released from zein-THY/γ-CD-IC-NF (2:1) than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). Similarly, antibacterial activity of zein-THY/γ-CD-IC-NF (2:1) was higher than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). It was demonstrated that zein-THY/γ-CD-IC-NF (2:1) was most effective in inhibiting the growth of bacteria on meat samples. These webs show potential application as an antibacterial food packaging material.

Concepts: Diffraction, X-ray, Antiseptic, X-ray scattering techniques, Packaging, Preservation, Thymol, Packaging and labeling

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A new monoterpenoid, 7-acetyl-8,9-dihydroxy thymol (1), together with a known one 7,8-dihydroxy-9-buyryl thymol (2), were isolated from the dried flower buds of Lonicera japonica Thunb. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analyses. The potential antibacterial effects of these compounds on Staphylococcus aureus, Escherichia coli, Micrococcus luteus, and Bacillus cereus were evaluated. Interestingly, both compounds 1 and 2 exhibited significant antibacterial activities with IC50 values range from 27.64 ± 2.26 to 128.58 ± 13.26 μg/mL.

Concepts: Bacteria, Microbiology, Staphylococcus aureus, Bud, Escherichia coli, Activity, Honeysuckle, Thymol

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The antibacterial activity of thyme essential oil (TEO) was evaluated against four serovars of Salmonella (S. Enteritidis, S. Typhimurium, S. Montevideo and S. Infantis), experimentally inoculated (10(6)CFU/g) in minced pork, which was treated with different concentrations of the TEO (0.3%, 0.6% and 0.9%) packaged under vacuum or MAP (30%O2/50%CO2/20% N2) and stored at 3±1°C for 15days. GC-MS analysis of the TEO was performed in order to determine composition, and the predominant constituent was thymol (50.48%), followed by p-cymene and linalool. The minimum inhibitory concentration was determined for each Salmonella serovar studied. Among the tested active compounds, thymol and carvacrol exhibited the greatest inhibitory effect followed by TEO, with minimum inhibitory concentrations of 320 to 640μg/ml. S. Enteritidis was the most sensitive serovar. During the storage period, Salmonella counts in pork were reduced by 1.69-4.05logCFU/g. The influence of TEO on Enterobacteriaceae, lactic acid bacteria and total viable count was determined in control mince with no added Salmonella. The most pronounced antibacterial effect was achieved by the combination MAP and 0.9% TEO. Although the antibacterial activities of all studied concentrations of TEO in pork were evident and significant (P<0.05), sensory analysis showed that 0.3% TEO was the most acceptable to trained panellists.

Concepts: Bacteria, Acid, Microbiology, Lactic acid, Lactobacillus, Salmonella enterica, Pork, Thymol