Essential oils or phytochemicals that are naturally synthesized by plants have received much attention as alternative pest control strategy. They are composed of highly volatile compounds which are less toxic to human but highly toxic to pests such as insects, microorganisms and nematodes. Until now, many researchers have evaluated the toxicities of essential oils and phytochemicals in Korea. Among them some of essential oils are formulated as repellents against mosquitoes. However, even such a broad research, the mode of action of essential oils is still unclear. To develop more effective and environmental friendly natural pesticides and to help understand the mode of action of essential oils, we have investigated the structureactivity relationship (SAR) between the chemical components of bio-active essential oils and nematode as well as insect pests. SAR of short-chain aliphatic compounds and ester analogues and pine wood nematode, Brusaphelenchus xylophilus; and salicylate analogues and adzuki been weevil, Callosobruchus chinensis are discussed here.

본 연구의 목적은 RAW 264.7 세포에 산초 종자 정유 성분의 항염 및 항산화 효과에 대하여 알아보고자 하였다. 산초 종자로부터 정유를 추출하였으며, 추출물의 항산화 및 항염 활성에 대하여 평 가하였다. 추출물의 항산화 활성은 DPPH 라디칼 소거능과 SOD 유사 활성 평가법을 이용하였다. 또한 세포독성 평가를 위해 MTT를 이용하여 세포생존율을 측정하였다. LPS로 염증이 유도된 RAW 264.7 세포에 대하여 산초 정유가 NO생성과 PGE2 생성 정도에 미치는 영향을 측정하였다. 그 결과 산초 종 자 정유는 농도 의존적으로 DPPH 라디칼 소거능과 SOD 유사 활성이 증가하는 것으로 나타났다. 세포 생존율 평가에서는 40 μg/mL-1 이하의 농도에서 98% 이상의 낮은 세포독성을 나타냈으며, 항염 효능 평가에서는 LPS를 단독으로 처리한 양성대조군보다 산초 정유 성분을 처리한 군에서 NO와 PGE2 생성 이 현저하게 감소되는 것을 확인하였다. 이러한 결과는 산초 정유가 염증매개인자를 감소시키고 산화의 활성을 방지할 수 있는 기능성 식물소재로서의 가능성을 나타낸다.

This study investigates the chemical compositions of Aster koraiensis Nakai essential oils and the quantitative changes of major terpene compounds according to various harvesting times. The essential oils obtained by hydrodistillation from the aerial parts of Aster koraiensis Nakai are being analyzed by GC and GC-MS. The essential oil compositions of Aster koraiensis Nakai are characterized byhigher contents of sesquiterpene compounds. Ninety-seven volatile flavor compounds are being identified in the essential oils from Aster koraiensis Nakai harvested in 2010, and caryophyllene oxide (8.38%), aristolene (7.08%), epiglobulol (5.57%), and ethyl furanone (4.73%) are the most abundant compounds. Ninety-five compounds are identified in the essential oils from the plants harvested in 2011, and aristolene (11.56%), calarene (9.33%), phytol (8.28%), ethyl furanone (7.63%), and epiglobulol (7.18%) are the most abundant compounds. Ninety-five compounds are being identified in the essential oils from the plants harvested in 2012, and calarene (15.3%), aristolene (14.24%), ethyl furanone (7.21%), phytol (6.98%) are the major compounds. The contents of aristolene, α-caryophyllene, α-muurolene, α-calacorene, aromadendrene oxide, and calarene increase significantly from 2010 to 2012. The contents of α-cubebene, isocaryophyllene, and diepi-α-cedrene epoxide decrease significantly from 2010 to 2012. The quantitative changes of aristolene and calarene according to harvesting time can be served as a quality index of the Aster koraiensis Nakai essential oils.

The toxicity of cade oil (Juniperus oxycedrus), its constituents and structurally related compounds toward adult house dust mite Dermatophagoides farina was examined. Results were compared with two commercially available acaricides, benzyl benzoate and deet. The cade oil constituents were identified by GC-MS analysis. Citral (LC50, 1.13 μg cm–2) and methyleugenol (LC50, 5.78 μg cm–2) were the most toxic compounds, followed by eugenol (LC50,12.52 μg cm–2), nerol (LC50, 21.4 μg cm–2) and terpinen-4-ol (LC50, 29.55 μg cm–2) were shown significant mortality against adult of D. farina. Toxicity of citral, methyleugenol were higher than that of benzyl benzoate, and above listed compounds was all more toxic than deet. Given the result of vapour-phase mortality tests that these compounds were more toxic in closed containers than in open ones, we concluded that vapour action plays a great role in their mode of delivery. Cade applied as 3 and 4% experimental sprays provided 96 and 100% mortality against the mites respectively, whereas permethrin (cis:trans, 25:75) 2.5 g/l spray treatment resulted in 17% mortality. Cade oil, and its constituents shown their potentials as effective alternatives for harmful synthetic acaricides for the control of Dermatophagoides populations as fumigants in contact and therefore illustrated the need for further study of this essential oil.

강원도 홍천을 비롯한 중북부지역의 단호박 재배지를 중심으로 호박과실파리 [Bactrocera depressa (Shiraki)]의 피해가 매년 증가하고 있는 추세다. 호박과실파 리의 피해 방지를 위해 Essential oil을 이용한 산란 기피물질을 탐색하였다. 3일간 의 실내 기피 시험에서 유칼립투스와 피톤치드는 각 1.0회 산란을 보였고 카놀라유 와 피톤볼에서는 조사 기간 동안 산란 피해가 발견되지 않았다. 야외 포장시험에서 essential oil에 대한 호박과실파리 암컷의 산란율은 피톤치드 16.7%, 유칼립투스 10.0% ,카놀라유 13.3%이었고 피톤볼은 0.0%이었다.

This study was investigated the chemical composition from Syneilesis palmata essential oil and the tendency of variation of the sesquiterpene compounds according to the harvesting time. The essential oils obtained by hydro distillation from the aerial parts of Syneilesis palmata were analyzed by GC and GC-MS. Ninety-eight compounds consisting of 9 aliphatic hydrocarbons, 17 sesquiterpene hydrocarbons, 11 aliphatic aldehydes, 1 terpene aldehyde, 8 aliphatic alcohols, 4 monoterpene alcohols, 16 sesquiterpene alcohols, 3 diterpene alcohols, 6 ketones, 11 esters, 8 oxides and epoxides, 3 acids and 1 miscellaneous one were identified from the oil. Spathulenol (22.33%) was the most abundant compound, followed by β- caryophyllene (6.23%), germacrene D (5.57%), longipinane (4.10%), and epiglobulol (3.65%). The volatile composition of Syneilesis palmata was characterized by higher contents of sesquiterpene compounds, especially sesquiterpene alcohols. The total content of 13 sesquiterpene compounds was decreased significantly from 2010 to 2012. α-Caryophyllene, β-bisabolene, elemol, germacrene D, β-zingiberene, longipinane, and β-caryophyllene alcohol contents decreased, while β-bisabolol content increased during 3 years. The ecological responses to recent climate change may be influenced in the chemical components of natural plant terpenoids.

Repellency of 20 plant essential oils to malaria main vector in the Republic of Korea (ROK), Anopheles kleini, was evaluated using skin direct contact bioassay. Anopheles kleini showed the highest repellency to Pelargonium graveolens with EC50 value of 0.244 mg/cm2, followed by Pinus sylvestris and Cinnamomum camphora with EC50 values of 0.484 mg/cm2 and 0.862 mg/cm2. The lowest repellency of An. kleini was revealed from Clary sage oil with EC50 value of 4.665 mg/cm2. Anopheles kleini did not demonstrated any repellency to Lemon, Orange, Neem, Coconut and Olive oil over 20 mg/cm2. Major repellent constituents of Geranium, Pine and Camphora oil were analyzed and identified using Mass-data, GC and GC-Mass. Major constituent of Geranium were β-citronellol (37.0%) and Camphora, 1,8-cineole (35.8%) and Pine, α-terpineol (39.5%). Anopheles kleini showed higher repellency to β-citronellol and 1,8-cineole than to DEET and IR3535 and did not showed any repellency to sabinene and γ-eudesmol over 20 mg/cm2. Residual repellent time of 1,8-cineole and β-citronellol were 26 and 41 min, respectively and DEET, 84 min and IR3535, 102 min. In the light of global efforts to reduce the level of highly toxic synthetic repellents, the three essential oils and their major constituents described merit further study as potential biorepellents for the control of An. kleini populations

An assessment was made of the toxicity of 12 insecticides, three essential oils and Bacillus thuringiensis var. israelensis (Bti) alone or in combination with the oil major constituents, (E)-anethole (AN), (E)-cinnamaldehyde (CA) and eugenol (EU), to third instars from bamboo forest collected Aedes albopictus and rice paddy field collected Anopheles sinensis resistant to various groups of insecticides. The toxicity of the test insecticides, essential oils and binary mixtures of Bti and the oil constituents (1:1 ratio) was evaluated using a direct-contact mortality bioassay. Binary mixtures of B.t.i. and CA, AN or EU were significantly more toxic against Ae. albopictus larvae (LC50, 0.0084, 0.0134 and 0.0237 mg/l) and An. sinensis larvae (0.0159, 0.0388 and 0.0541 mg/l) than either B.t.i. (1.7884 and 2.1681 mg/l) or CA (11.46 and 19.43 mg/l), AN (16.66 and 25.11 mg/l) or EU (24.60 and 32.14 mg/l) alone. Based on the co-toxicity coefficient (CC) and synergistic factor (SF), the three binary mixtures operated in a synergy pattern (CC, 140.7–368.3 and SF, 76–213 for Ae. albopictus CC, 75.1–245.3 and SF, 40–136 for An. sinensis).The binary mixtures of Bti and essential oil constituents described, particularly (E)-cinnamaldehyde, merit further study as potential mosquito larvicides for the control of malaria vector mosquito populations in light of global efforts to reduce the level of highly toxic synthetic insecticides in the aquatic environment.

The black cutworm, Agrotis ipsilon (Hufnagel), damages various cultivated crops and is also occasionally a serious pest of turfgrass, especially on golf courses. Essential oils have potential as alternative control agents for insect pests. Sixteen essential oils (anise, camphor, cinnamon, citronella, clove, fennel, geranium, lavender, lemongrass, linseed, neem, peppermint, pine, thyme, turpentine and tea saponin) and paraffin oil were assessed in the laboratory and the green house for their efficacy against black cutworm larvae. Treatment of potted perennial ryegrass with anise, cinnamon, neem, paraffin or turpentine reduced black cutworm damage in a greenhouse trial. Neem oil (2000 ppm) reduced growth of black cutworms feeding on treated clippings within 3 and 5 days. Treatment of perennial ryegrass in pots resulted in 100, 100 and 46% mortality of black cutworm at 4000, 2000 and 1000 ppm, respectively. Weight of survivors at the 1000 ppm rate was 5 fold less than weight of comparably-aged controls.

본 연구는 친환경적으로 시금치 노균병을 방제하기 위하여 식물정유, 길항미생물 및 난황유의 병발생 억제효과를 검정하여 화학농약 대신에 이용할 수 있는 친환경제제로서의 가능성을 검토하였다. 5종의 식물정유 가운데 노균병 방제효과는 1회 처리구와 1주 간격 2회 처리구 모두 Eucalyptus approximans 오일의 병원균 억제효과가 60% 정도로 가장 높은 것으로 나타났다. 반면에 토양에서 선발된 길항균 세 종류의 시금치 노균병 방제효과는 모두 20% 이하로 식물정유 처리보다 낮게 나타났다. 난황유 0.3%와 0.5%농도에서 1주일간격 2회 처리구에서 병원균 억제율이 각각 84.5%와 91.5%로 억제되어 가장 효과가 우수한 것으로 나타났다.

The larvicidal activity of 104 plant essential oils and their major constituents against third instar larvae of mushroom fly Camptomyia corticalis was examined using a vapor-phase mortality bioassay. Results were compared with those of the conventional insecticides dichlorvos. Over ten plant essential oils exhibited showed more than 90% mortality. At a rate of 0.2 mg/cm3 air, pulegone, and thujone, exhibited 100% morality whereas camphor, 1,8-cineole, α-pinene, thymol and menthol showed 90% mortality at 0.6 mg/cm3 air. Global efforts to reduce the level of highly toxic synthetic insecticides in the agricultural environment justify further studies on the essential oils and their constituents described as potential insecticides for the control of the mushroom fly as fumigants with contact action.

Origanum essential oil [Origanum acutidens (Hand.-Mazz.)] showing insecticidal activity and repellency against red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae) adults was analysed by GC-MS. All constituents of the oil were identified, and the main components were carvacrol (67.2%), p-cymene (16.2%), γ-terpinene (5.5%), thymol (4.9%),and linalool(2.1%). In vapor phase fumigant assay, the origanum oil was more effective in closed condition (LD50 = 0.555 mg/cm3) than in open one (LD50 = 0.353 mg/cm3).This result suggests that the toxicity of the oil to red flour beetle is exerted largely by vapor phase. Based on 24-h LD50 values, the toxicity of caryophyllene oxide (0.00018 mg/cm3) was comparable with that of dichlorvos (0.00007mg/cm3) as a positive insecticide. In addition, thymol, camphene, α-pinene, p-cymene, and γ-terpinene gave good insecticidal activity (LD50 = 0.012 - 0.195 mg/cm3). In repellent test using 9 constituents of origanum oil, caryophyllene oxide showed 100% repellent activity at 0.0158 and 0.0032 mg/cm2. These results indicate that the origanum oil and its some components could be potential candidates as a fumigant and repellent for managing T. castaneum adults. Potential molecular target of repellents will be discussed.

The toxicity of melissa and savory essential oil constituents against adult Bemisia tabaci was examined using vapor-phase toxicity bioassay. Results were compared with those following the treatment with currently used insecticide dichlorvos. As judged by 24 h LC50 values, thymol (0.59×10-3 mg/cm3) was the most toxic constituent, followed by cavacrol (0.60×10-3 mg/cm3). These compounds were slightly less toxic than dichlorvos (LC50, 0.20×10-3 mg/cm3). Strong activity was also obtained from borneol (LC50, 1.06×10-3 mg/cm3), α-terpineol (1.22×10-3 mg/cm3), geraniol (1.23×10-3 mg/cm3), linalool (1.33×10-3 mg/cm3), lavendulol (1.44×10-3 mg/cm3), nerol (1.52×10-3 mg/cm3), β-citronellol (1.81×10-3 mg/cm3), terpinene-4-ol (1.87×10-3 mg/cm3), 1-octen-3-ol (2.06×10-3 mg/cm3), and citral (2.34×10-3 mg/cm3). The melissa and savory essential oil-derived compounds, particularly thymol and carvacrol, merit further study as potential insecticides for the control of B. tabaci.

C. obtusa, an essential oil produced in Jeollanamdo Gangjin, is the most effective plant oil for easing Sick House Syndrome, having an effect similar to a therapeutic walk in the woods and acting as a sterilizer. In light of its medicinal importance, its composition, antibacterial activity and ability to mitigate an offensive odor have been analyzed. Through GC-MS, I confirmed that it contains approximately 50 components, 80.30% of which are various monoterpenes. It was effective at alleviating malodors from formaldehyde, ammonia, trimetylamine and methylmercaptan as determined in colorimetric gas detection tube tests in comparison with lemongrass and clove leaf essential oil. I obtained from Minimal Inhibition Concentration(MIC) of C. obtusa, higher concentrations will lead to increased antibacterial activity. Therefore it is estimated that utility value of it will be grow more and more.

The repellency to female Stomoxys calcitrans (L.) of 21 essential oils alone or in combination with Calophyllum inophyllum nut oil (tamanu oil) was examined using a skin bioassay. Results were compared with those following treatment with the commonly used repellent DEET (N,N-diethyl-3-methylbenzamide). As judged by the protection time (PT) to first bite at 0.5 mg cm-2, patchouli (3.67 h) was the most effective essential oil, followed by clove bud, lovage root, clove leaf and thyme white essential oils (3.50-2.12 h). Thyme red, oregano and geranium essential oils exhibited moderate protection time (PT, 1.24-1.11 h). At 0.25 mg cm-2, effective protection time of clove bud, clove leaf and lovage root essential oils was about 1 h. The protection times of DEET were 4.47 and 2.17h at 0.5 and 0.25 mg cm-2 respectively. The remarkable increase in the protection time were produced by binary mixtures of five essential oils (clove bud, clove leaf, thyme white, patchouli and savory) and tamanu oil (0.25:2.0 mg cm-2) compared with those of either the constituted essential oil, tamanu oil or DEET alone, indicating the involvement in synergy. These essential oils, tamanu oil and binary mixtures did not cause any adverse effects on the human volunteers at 0.5 mg cm-2 except savory oil. Thus binary mixtures of essential oils and tamanu oil described merit further study as potential insect repellents for protection from humans and domestic animals from biting and nuisance caused by S. calcitrans.

Artemisia scoparia (A. scoparia), perennial herb is indigenous to Korea and has been traditionally used in liver damage. We investigated the effect of the essential oil obtained from A. scoparia on apoptosis of KB cells. Cytotoxicity and cellular DNA content were analyzed by MTT assay and flow cytometry, agarose gel electrophoresis, and Hoechst 33258 staining. The caspase-3 and poly (ADP-ribose) polymerase (PARP) proteins were estimated by Western blotting method. We found that the essential oil induced the apoptosis of the KB cells by concentrations of 0.4 to 0.2 mg/ml which was verified by DNA fragmentation, apoptotic bodies, and the sub-G0/G1 ratio. The essential oil also transient caspase-9 and caspase-3 activity and cleavage of PARP in KB cells for 24 h. The essential oil-induced apoptotic cell death was accompanied by up-regulation of Bax and down-regulation of Bcl-2. In conclusion, we demonstrated that the essential oil of A. scoparia induces apoptosis in KB cells