• The Plant Pathology Journal
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• v.25 no.2
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• pp.189-192
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• 2009

The effect of plant extracts of eucalyptus (Eucalyptus chamadulonsis), garlic (Allium sativium), marigold (Tagetes erecta) and neem (Azadirachta indica) and essential oils were tested on the suppression of root-knot nematode Meloidogyne incognita under greenhouse and field conditions. In vitro study, all tested treatments had nematicidal effect on nematode juveniles after 24 and 48 hours from exposures. The highest percentage of nematode mortality was achieved by application of neem extract (65.4%), essential oils (64.4%) and marigold extract (60.5%), followed by garlic and eucalyptus extracts (38.7-39.5%). Under greenhouse and field conditions, neem extract and essential oils treatments were more effective in reducing population numbers of the M. incognita in soil and root gall index compared to other treatments. In field experiments, the maximum protection of tomato plant against root-knot nematode was obtained by application of neem and essential oil treatments, 44.2 and 32.6%, respectively.

• Journal of the Korean Wood Science and Technology
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• v.46 no.2
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• pp.166-177
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• 2018

Plant essential oils are defined as fragrant volatile oils extracted from leaves, stems, fruits, flowers, and roots of a plant. Such oils are composed of multiple components and multiple functions. By accumulation of inductive information, various plant essential oils have been studied for using in therapeutic medicine for various diseases. Despite of the apparent advantages of essential oils as a source of therapeutic medicines, plant essential oils have many limitations, including cytotoxic side effects. Therefore, it is necessary to evaluate the toxicity and the mechanisms of cytotoxicity of such oils. In this study, we evaluated the cytotoxicity to human-derived cell lines of 10 plant essential oils provided by National Institute of Forest Science (i.e., Larix kaempferi; Abies holophylla; Zanthoxylum ailanthoides; Pinus parviflora; Tsuga sieboldti; Chamaecyparis pisifera; Cryptomeria japonica; Pinus densiflora; Illicium anisatum; Pinus thunbergii). Cytotoxicity evaluations were accomplished by using CCK-assays and PCR-based cytotoxicity-related marker gene analyses with A549 cell line, and the Detroit551 cell line which are lung and skin cell line. The genes were analyzed included caspase-3 has a role in cell apoptosis, and the other cyclinA, cyclinB, cyclinD, and cyclinE regulated cell cycling for the cell proliferation. By examining the five cytotoxicity-related marker genes by performing real-time PCR and examined the cytostatic gene regulation associated with the various essential oils. The results of this study showed that the degree of cytotoxicity and the cytostatic gene regulation which could give precious information for using the plant essential oil for the clinical usages.

• The Plant Pathology Journal
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• v.32 no.1
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• pp.16-24
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• 2016

In this study, antifungal activity of essential oils of Cymbopogon citratus and Ocimum basilicum and two fungicides Mancozeb and Metalaxyl-Mancozeb in six different concentrations were investigated for controlling three species of Phytophthora, including P. capsici, P. drechsleri and P. melonis on pepper, cucumber and melon under in vitro and greenhouse conditions, respectively. Under the in vitro condition, the median effective concen- tration ($EC_{50}$) values (ppm) of plant essential oils and fungicides were measured. In greenhouse, soil infested with Phytophthora species was treated by adding 50 ml of essential oils and fungicides (100 ppm). Disease severity was determined after 28 days. Among two tested plant essential oils, C. citratus had the lowest $EC_{50}$ values for inhibition of the mycelial growth of P. capsici (31.473), P. melonis (33.097) and P. drechsleri (69.112), respectively. The mean $EC_{50}$ values for Metalaxyl-Mancozeb on these pathogens were 20.87, 20.06 and 17.70, respectively. Chemical analysis of plant essential oils by GC-MS showed that, among 42 compounds identified from C. citratus, two compounds ${\beta}$-geranial (${\alpha}$-citral) (39.16%) and z-citral (30.95%) were the most abundant. Under the greenhouse condition, Metalaxyl-Mancozeb caused the greatest reduction in disease severity, 84.2%, 86.8% and 92.1% on melon, cucumber, and pepper, respectively. The C. citratus essential oil reduced disease severity from 47.4% to 60.5% compared to the untreated control ($p{\leq}0.05$). Essential oils of O. basilicum had the lowest effects on the pathogens under in vitro and greenhouse conditions. These results show that essential oils may contribute to the development of new antifungal agents to protect the crops from Phytophthora diseases.

• Journal of Environmental Science International
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• v.33 no.5
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• pp.333-343
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• 2024

This study aimed to investigate whether inhaling the aroma of essential oils could alleviate physiological stress responses and mimic the effects of forest therapy in urban settings. Briefly, 31 participants underwent stress index assessments for two days and inhaled the selected plant essential oils. The effects of this treatment on physiological responses were determined through electroencephalogram (EEG) and heart rate variability (HRV) measurements taken before and after inhaling the aroma of essential oils, extracting results for low frequency (LF) and high frequency (HF) components of HRV, as well as 𝜃 and 𝛼 brainwave activities. The results indicated that lavender oil did not yield significant differences, whereas pine, chamomile, and cypress oils exhibited significant differences in effects. Overall, stress relief was associated with enhanced 𝜃 and 𝛼 brainwave activities, a decrease in the LF component and an increase in the HF component of HRV. Among the essential oils studied, pine oil was the most effective. These findings underscore the potential of plant essential oils in replicating the therapeutic benefits of forest therapy, even in urban environments. Further investigations into their utilization are warranted to better understand and harness their therapeutic potential.

• The Plant Pathology Journal
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• v.31 no.3
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• pp.269-277
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• 2015

Anthracnose caused by Colletotrichum gloeosporioides has been destructive during pepper fruit production in outdoor fields in Korea. In vitro antifungal activities of 15 different plant essential oils or its components were evaluated during conidial germination and mycelial growth of C. gloeosporioides. In vitro conidial germination was most drastically inhibited by vapour treatments with carvacrol, cinnamon oil, trans-cinnamaldehyde, citral, p-cymene and linalool. Inhibition of the mycelial growth by indirect vapour treatment with essential oils was also demonstrated compared with untreated control. Carvacrol, cinnamon oil, trans-cinnamaldehyde, citral and eugenol were among the most inhibitory plant essential oils by the indirect antifungal efficacies. Plant protection efficacies of the plant essential oils were demonstrated by reduced lesion diameter on the C. gloeosporioides-inoculated immature green pepper fruits compared to the inoculated control fruits without any plant essential oil treatment. In planta test showed that all plant essential oils tested in this study demonstrated plant protection efficacies against pepper fruit anthracnose with similar levels. Thus, application of different plant essential oils can be used for ecofriendly disease management of anthracnose during pepper fruit production.

• Mycobiology
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• v.31 no.2
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• pp.99-104
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• 2003

Bee propolis ethanolic extract with some plant essential oils was investigated for its antidermatophytic properties. The tested plant essential oils included jasmine, clove, lemon, Arabian jasmine, mint, rosa, olive and basil. The antidermatophytic activity has been compared to Naftifine-HCl and Clotrimazole used for dermatophyte treatment. Experimental model has been tested using sheep hoof plate for the in vitro tests to stimulate human nails. Mint, clove and basil with 4 mg/ml of bee propolis have a comparable efficacy to those of Naftifine-HCl and Clotrimazole. There is a great necessity for new effective low price and safe antidermatophyte agents to avoid recurrent infection. Propolis synergistic could be of great importance with essential oils of plants in dermatophyte therapy.

• The Plant Pathology Journal
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• v.23 no.2
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• pp.97-102
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• 2007

A total of 39 essential oils were tested for antifungal activities as volatile compounds against five phytopathogenic fungi at a dose of 1 ${\mu}l$ per plate. Five essential oils showed inhibitory activities against mycelial growth of at least one phytopathogenic fungus. Origanum vulgare essential oil inhibited mycelial growth of all of the five fungi tested. Both Cuminum cyminum and Eucalyptus citriodora oils displayed in vitro antifungal activities against four phytopathogenic fungi except for Colletotrichum gloeosporioides. The essential oil of Thymus vulgaris suppressed the mycelial growth of C. gloeosporioides, Fusarium oxysporum and Rhizoctonia solani and that of Cymbopogon citratus was active to only F. oxysporum. The chemical compositions of the five active essential oils were determined by gas chromatography-mass spectrometry. This study suggests that both E. citriodora and C. cyminum oils have a potential as antifungal preservatives for the control of storage diseases of various crops.

• Journal of Life Science
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• v.14 no.6 s.67
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• pp.1003-1008
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• 2004

11 plant essential oils are screened in vitro for their antifungal activities against Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani, which are causative agents of serious plant diseases. The radial growth of the test fungi were reduced in response to the oils. Among them, the essential oil from the bark of Cinnamomum zeylanicum inhibited 3 tested fungi growth, strongly, followed by those of oregano and thyme. The major constituents of the three essential oils, cinnaldehyde, carvacrol and thymol were tested for their effects on the fungi. From the results obtained, cinnamaldehyde, the major constituents of C. zeylanicum bark esential oil, has potential to be developed as a biopesticide for controlling phytopathogenic fungi causing serious damages on the important crops cultivated in Korea.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.207-224
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• 2011

Diseases caused by plant pathogenic bacteria constitute an emerging threat to global food security. Xanthomonas is a large genus of Gram-negative bacteria that cause disease in several host plants leading to considerable losses in productivity and quality of harvests. Despite the ranges of controlling techniques available, the microbiological safety of economically important crops and crop plants including fruits and vegetables continues to be a major concern to the agriculture industry. On the other hand, many of the currently available antimicrobial agents for agriculture are highly toxic, non-biodegradable and cause extended environmental pollution. Besides, the use of antibiotics has provoked an increased resistance among the bacterial pathogens and their pathovars. Thus, novel efficient and safe remedies for controlling plant bacterial diseases are necessary. There has been an increasing interest worldwide on therapeutic values of natural products such as essential oils, hence the purpose of this review is to provide an overview of the published data on the antibacterial efficacy of essential oils that could be considered suitable for application in agriculture as biocontrol measures against plant pathogenic bacteria of Xanthomonas species. The current knowledge on the use of essential oils to control Xanthomonas bacteria in vitro and in vivo models has been discussed. A brief description on the legal aspects on the use of essential oils against bacterial pathogens has also been presented. Through this review, a mode of antibacterial action of essential oils along with their chemical nature and the area for future research have been thoroughly discussed.

• Journal of Microbiology and Biotechnology
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• v.23 no.6
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• pp.771-778
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• 2013

Essential oils are increasingly of interest for use as novel drugs acting as antimicrobial and antiviral agents. In the present study, we report the in vitro antiviral activities of 29 essential oils, extracted from Chinese indigenous aromatic plants, against the tobacco mosaic virus (TMV). Of these essential oils, those oils from ginger, lemon, tea tree, tangerine peel, artemisia, and lemongrass effected a more than 50% inhibition of TMV at 100 ${\mu}g/ml$. In addition, the mode of antiviral action of the active essential oils was also determined. Essential oils isolated from artemisia and lemongrass possessed potent inactivation and curative effects in vivo and had a directly passivating effect on TMV infection in a dose-dependent manner. However, all other active essential oils exhibited a moderate protective effect in vivo. The chemical constitutions of the essential oils from ginger, lemon, tea tree, tangerine peel, artemisia, and lemongrass were identified by gas chromatography and gas chromatography-mass spectrometry. The major components of these essential oils were ${\alpha}$-zingiberene (35.21%), limonene (76.25%), terpinen-4-ol (41.20%), limonene (80.95%), 1,8-cineole (27.45%), and terpinolene (10.67%). The curative effects of 10 individual compounds from the active essential oils on TMV infection were also examined in vivo. The compounds from citronellal, limonene, 1,8-cineole, and ${\alpha}$-zingiberene effected a more than 40% inhibition rate for TMV infection, and the other compounds demonstrated moderate activities at 320 ${\mu}g/ml$ in vivo. There results indicate that the essential oils isolated from artemisia and lemongrass, and the individual compound citronellal, have the potential to be used as an effective alternative for the treatment of tobacco plants infected with TMV under greenhouse conditions.