• The Korea Journal of Herbology
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• v.34 no.4
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• pp.19-25
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• 2019

Objectives : Thymol (2-isopropyl-5-methylphenol), a natural monoterpenoid phenol, is one of the major odorant constituents found in natural essential oils of various herbal plants, such as Thymus quinquecostatus and Thymus vulgaris. Multiple biological activities of thymol, including antioxidative, antimicrobial, and anti-inflammatory effects, have been reported in numerous in vitro studies, and recently it was suggested that thymol may could inhibit oxidization of L-dihydroxyphenylalanine (L-DOPA) to dopaquinone required in melanogenesis pathway, as an antioxidant. Methods : MTT assay was performed to test the cytotoxic effect of thymol in B16F10 cells. Inhibitory effect of thymol to tyrosinase activities were examined using both mushroom tyrosinase and intracellular tyrosinase. Expression level of tyrosinase in B16F10 cells were investigated by western blot analysis. Results : The cell viability was decreased by thymol treatment in dose-dependant manner, leading significant cytotoxicity in 500 and $1000{\mu}M$ thymol-treated groups. In the alpha-melanocyte stimulating hormone (${\alpha}$-MSH)-induced melanogenesis, administration of thymol significantly decreased extracellular (secreted) melanin content in dose-dependent manner. Cellular tyrosinase activity assay and western blot analysis of intracellular tyrosinase showed that thymol has a strong anti-melanogenic effect by inhibition of tyrosinase activity and by decreasing expression of tyrosinase that contribute to melanin synthesis in the B1610 cells. Conclusions : As the first functional study that prove anti-melanogenic effect of thymol and its underlying mechanism in the living cells, our study suggests the applicability of fragrance as the functional materials of cosmetics or health supplement, not as just an additive.

• Journal of Microbiology and Biotechnology
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• v.33 no.1
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• pp.43-50
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• 2023

Fungal keratitis is a refractory kind of keratopathy. We attempted to investigate the antiinflammatory role of thymol on Aspergillus fumigatus (A. fumigatus) keratitis. Wound healing and fluorescein staining of the cornea were applied to verify thymol's safety. Mice models of A. fumigatus keratitis underwent subconjunctival injection of thymol. The anti-inflammatory roles of thymol were verified by hematoxylin-eosin (HE) staining, slit lamp observation, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting. In contrast with the DMSO group, more transparent corneas and less inflammatory cells infiltration were detected in mice treated with 50 ㎍/ml thymol. Thymol downregulated the synthesis of TLR4, MyD88, NF-kB, IL-1β, NLRP3, caspase 1, caspase 8, GSDMD, RIPK3 and MLKL. In summary, we proved that thymol played a protective part in A. fumigatus keratitis by cutting down inflammatory cells aggregation, downregulating the TLR4/ MyD88/ NF-kB/ IL-1β signal expression and reducing necroptosis and pyroptosis.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.201-209
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• 2006

Antifungal activities of 43 different plant oils were evaluated against different phytopathogenic fungi. Thyme oil showed highest antifungal activity among the tested oils. The major of thyme oil were found to be thymol, carvacrol, bomeol, p-cymene and linalool. Thymol and carvacrol were found to be responsible for thyme's antifungal activity. The spore germination assay was conducted on Alternaria mail and Botrytis cinerea. Thymol and carvacrol strongly inhibited spore germination in the fungi test. In addition, thymol and carvacrol showed a curative effectiveness to gray mold disease on cucumber crop. The antifungal activities of alkylphenol and alkylaniline compounds, which has similar molecular structure to that of thymol or cavacrol, were also tested. It was found that alkylphenol compounds also show higher inhibition to spore germination. Thus, thymol, carvacrol and alkylphenol compounds can be used an potent antifungal agents.

• Mycobiology
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• v.50 no.6
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• pp.475-486
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• 2022

The antifungal activity of thymol against Aspergillus awamori F23 and Botrytis aclada F15 in onions was examined through direct treatment with amended media and gaseous treatment with I-plates (plastic plates containing central partitions). The protective and curative control efficacy of thymol was examined 24 h before and after the inoculation of onion bulbs with the fungal isolates. Mycelial growth, sporulation, and spore germination of the isolates were inhibited on potato dextrose agar amended with various concentrations of thymol or acetic acid (positive control). Overall, thymol produced a stronger inhibitory effect on the mycelial growth and development of the isolates than acetic acid. Following gaseous treatment in I-plates, mycelial growth, sporulation, and spore germination of the isolates were inhibited at higher concentrations of thymol or acetic acid; however, acetic acid showed a little effect on the sporulation and spore germination of the isolates. Following the treatment of onion bulbs with 1000 mg L^-1 of thymol 24 h before and after fungal inoculation, lesion diameter was greatly reduced compared with that following treatment with 0.5% ethanol (solvent control). Onion bulbs sprayed with thymol 24 h before fungal inoculation generally showed reduced lesion diameters by isolate F23 but not in isolate F15 compared with those sprayed 24 h after fungal inoculation. Collectively, thymol effectively inhibited the growth and development of A. awamori and B. aclada on amended media and in I-plates. In addition, spraying or fumigation of thymol is more desirable for effectively controlling these postharvest fungal pathogens during long-term storage conditions.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.321-323
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• 2006

A combination of thymol and sodium bisulfate was found to be an effective biocidal agent against strains of Burkholderia cepacia and of Xanthomonas maltophilia that were found in the space shuttle water system. Potassium iodide (KI), the biocidal agent used in the past, had a minimum inhibitory concentration (MIC) of 50,000 ppm against the two B. cepacia (541 STS-81 and 1119 STS-91) strains, whereas that of thymol and sodium bisulfate was 2,400 and 950 ppm, which was 21 and 53 times lower than that of KI for B. cepacia, respectively. The MIC value for the combination of thymol and sodium bisulfate was 4 times lower than that for thymol or sodium bisulfate alone against B. cepacia (541 STS-81, 1119 STS-91) or Pseudomonas cepacia (ATCC 31941). The fractional inhibitory concentration (FIC) of the combination of thymol and sodium bisulfate for all organisms tested was less than 0.5, indicating a strong synergistic effect.

• Mycobiology
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• v.46 no.3
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• pp.242-253
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• 2018

Onion (Allium cepa L.) is one of the major vegetable crops in Korea that are damaged and lost by pathogenic fungal infection during storage due to a lack of proper storage conditions. The aim of this study was to determine an appropriate control measure using thymol to increase the shelf life of onions. To control fungal infections that occur during low-temperature storage, it is necessary to identify the predominant fungal pathogens that appear in low-temperature storage houses. Botrytis aclada was found to be the most predominant fungal pathogen during low-temperature storage. The antifungal activity of the plant essential oil thymol was tested and compared to that of the existing sulfur treatments. B. aclada growth was significantly inhibited up to 16 weeks with spray treatments using a thymol solution. To identify an appropriate method for treating onions in a low-temperature storage house, thymol was delivered by two fumigation treatment methods, either by heating it in the granule form or as a solution at low-temperature storage conditions (in vivo). We confirmed that the disease severity was reduced up to 96% by fumigating thymol solution compared to the untreated control. The efficacy of the fumigation of thymol solution was validated by testing onions in a low-temperature storage house in Muan, Jeollanam-do. Based on these results, the present study suggests that fumigation of the thymol solution as a natural preservative and fungicide can be used as an eco-friendly substitute for existing methods to control postharvest disease in long-term storage crops on a commercial scale.

• Journal of Microbiology and Biotechnology
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• v.26 no.1
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• pp.28-37
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• 2016

Numerous plants have been documented to contain phenolic compounds. Thymol is one among these phenolic compounds that possess a repertoire of pharmacological activities, including anti-inflammatory, anticancer, antioxidant, antibacterial, and antimicrobial effects. Despite of the plethora of affects elicited by thymol, its activity profile on gastric cancer cells is not explored. In this study, we discovered that thymol exerts anticancer effects by suppressing cell growth, inducing apoptosis, producing intracellular reactive oxygen species, depolarizing mitochondrial membrane potential, and activating the proapoptotic mitochondrial proteins Bax, cysteine aspartases (caspases), and poly ADP ribose polymerase in human gastric AGS cells. The outcomes of this study displayed that thymol, via an intrinsic mitochondrial pathway, was responsible for inducing apoptosis in gastric AGS cells. Hence, thymol might serve as a tentative agent in the future to treat cancer.

• Mycobiology
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• v.42 no.3
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• pp.262-268
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• 2014

Several postharvest diseases of table grapes (Vitis vinifera) occur during storage, and gray mold rot is a particularly severe disease because the causal agent, Botrytis cinerea, grows at temperatures as low as $0^{\circ}C$. Other postharvest diseases, such as those caused by Penicillium spp. and Aspergillus spp., also often lead to deterioration in the quality of table grapes after harvest. The use of plant essential oils such as thymol and linalool, to reduce postharvest diseases in several kinds of fruits, including table grapes and oranges, has received much attention in European countries. However, to the best of our knowledge there has been no report of the use of thymol fumigation to control gray mold in table grapes in Korea. Thymol ($30{\mu}g/mL$) and linalool ($120{\mu}g/mL$) significantly inhibited mycelial growth and conidia germination of B. cinerea. The occurrence rate of gray mold rot of B. cinerea and other unknown fungi was significantly reduced by fumigation with $30{\mu}g/mL$ thymol in several table grape cultivars, such as Campbell early, Muscat Bailey A, Sheridan, and Geobong. In this study, fumigation with $30{\mu}g/mL$ thymol, had no influence on the sugar content and hardness of grapes, but reduced fungal infection significantly. This suggests that $30{\mu}g/mL$ thymol could be utilized to reduce deterioration of grapes due to gray mold and other fungal infections during long-term storage.

• Journal of Animal Science and Technology
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• v.51 no.6
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• pp.511-520
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• 2009

The purpose of this study was to investigate effects of increased levels of eugenol, thymol and malate on pH and the concentrations of VFA, lactate and ammonia-N during in vitro ruminal incubation. One Hanwoo beef steer (741 kg) fitted with a rumen cannula was used and fed 0.5 kg/day rice straw and 10 kg/day corn-based concentrate (ratio of concentrate to rice straw = 95 : 5 on DM basis). Three different doses of thymol, eugenol and malate were used. Treatments of the experiment were as follows: Treatments of thymol were control (1g D-glucose/40ml), T1 (1g D-glucose + 40 mg thymol/40 ml), T2 (1g D-glucose + 50 mg thymol/40 ml) and T3 (1g D-glucose + 60 mg thymol/40 ml). Treatments of eugenol were control (1g D-glucose/40 ml), E1 (1g D-glucose + 55 mg eugenol/40 ml), E2 (1g D-glucose + 65 mg eugenol/40 ml) and E3 (1g D-glucose + 75 mg eugenol/40 ml). Treatments of malate were control (1g D-glucose/40ml), M1 (1g D-glucose + 25 mg malate/40ml), M2 (1g D-glucose + 50 mg malate/40 ml) and M3 (1g D-glucose + 100 mg malate/40 ml). The results of this study showed that eugenol and thymol have improved stability of the ruminal fermentation by decreasing lactic acid concentration and increasing ruminal pH. However, it inhibited the production of total VFA, acetate and propionate. Malate also improved stability of the ruminal fermentation by decreasing lactic acid concentration and increasing ruminal pH, but it had a very little effect on ruminal lactate concentrations and pH. On the other hand, malate did not decrease the concentrations of total VFA, acetate and propionate. Therefore, at the low ruminal pH expected in high-concentrate diets, thymol, eugenol, and malate are potentially useful in Hanwoo finishing diets. Further studies are necessary for determining the effectiveness of these additives on in vivo rumen fermentation and animal performance in Hanwoo finishing steers.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.363-370
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• 2017

In this study, we stored frozen shrimp (Litopenaeus vannamei) at $4^{\circ}C$ during 12 days and investigated the effect of chitosan coating with natural preservatives (0.05% carvacrol, 0.05% thymol) on the growth of microorganism (mesophilic bacteria, psychrophilic bacteria, Pseudomonas spp., $H_2S$ producing bacteria) and physiological characteristics (total volatile basic nitrogen and pH) and sensory evaluation (appearance, odor and general acceptance). Chitosan coating with natural antimicrobial compounds (0.05% carvacrol and 0.05% thymol) had inhibited the growth of all the target microorganism and showed the significant antimicrobial activity (p < 0.05) to mesophilic bacteria, psychrophilic bacteria and $H_2S$ producing bacteria until 12 day (the last day of this study). These treated groups had showed the significant difference (p < 0.05) in total volatile basic nitrogen and all the sensory characteristics but not in pH. Therefore, chitosan coating combined with natural antimicrobial compounds (0.05% carvacrol and 0.05% thymol) showed the effective antimicrobial activity on major spoilage microorganism on shrimp and could be used to elongate the shelf life of refrigerated shrimp.