Acaricidal Toxicities of 1-Hydroxynaphthalene from Scutellaria barbata and Its Derivatives against House Dust and Storage Mites

• Introduction
• Materials and Methods
• Compounds
• Preparation
• Gas chromatography-mass spectrometry (GC-MS)
• Test mites
• Fumigant toxicity bioassay
• Contact toxicity bioassay
• Statistical analysis
• Results
• Discussion
• Acknowledgements
• References

Abstract

The essential oil of Scutellaria barbata was extracted using a steam distillation and then evaluated via fumigant and contact toxicity bioassays against Dermatophagoides farinae, Dermatophagoides pteronyssinus, and Tyrophagus putrescentiae. The acaricidal toxicities of 1-hydroxynaphthalene from S. barbata oil and its derivatives were determined and compared with those of benzyl benzoate. Based on the LD₅₀ values of 1-hydroxynaphthalene derivatives against D. farinae, D. pteronyssinus, and T. putrescentiae, obtained using a fumigant toxicity bioassay, the acaricidal activity of 1-hydroxynaphthalene (2.11, 2.37, and 4.50 µg/cm²) was 4.76, 6.00, and 2.68 times higher than that of benzyl benzoate (10.05, 9.50, and 12.50 µg/cm²) in the corresponding order, which was followed by that of 2-hydroxynaphthalene (9.50, 9.00, and 11.50 µg/cm²). On the contact toxicity bioassay, the acaricidal activity of 1-hydroxynaphthalene (0.79, 0.92, and 2.50 µg/cm²) was 9.49, 6.52, and 3.76 times higher than that of benzyl benzoate (7.50, 6.00, and 9.41 µg/cm²), which was followed by that of 2-hydroxynaphthalene (4.21, 4.80, and 6.50 µg/cm²). In conclusion, our results indicate that S. barbata oil and 1-hydroxynaphthalene derivatives might be effective natural agents for the management of house dust and storage mites.

Introduction

Dermatophagoides farinae (Hughes) and Dermatophagoides pteronyssinus (Trouessart) have been known as the most important pyroglyphid mites because of their cosmopolitan occurrence and abundance in homes [1]. The storage mite, Tyrophagus putrescentiae (Schrank), has been also recognized as an etiologic factor that causes allergic diseases which affect farmers and food workers [2]. These arthropods are a major source of potent allergens [3] and have a causal relationship with sudden infant death syndrome (SIDS) [4], [5]. Recently, housing lifestyle, such as individual households in apartment houses, central heating, and fitted carpets, has consistently changed, and these changes caused the increase of house dust and storage mites [6]. The control of various mites has been principally achieved with the use of synthetic acaricides such as benzyl benzoate, N,N-diethyl-m-toluamide (DEET), pirimiphos-methyl, and pyrethroids [7]. Despite the effectiveness of synthetic acaricides, their repeated use has produced resistance, undesirable side effects on nontarget organisms, and human health problems [8]. These problems emphasize the need for the development of new strategies for the selection of acaricides. Therefore, studies on mite control products have focused on bioactive components derived from plants [9]. To date, many studies have reported that plants produce various bioactive compounds [10], [11]. Especially, certain essential oils have long been renowned as alternative materials for the management of house dust and storage mites based on their biodegradability to nontoxic products, fewer harmful effects on nontarget organisms and the environment, and selective toxicity [12].

Given the above background, we conducted this study to evaluate the acaricidal activity of S. barbata (Lamiaceae) oil using fumigant and contact toxicity bioassays against adults of D. farinae, D. pteronyssinus, and T. putrescentiae. In addition, we also compared the acaricidal toxicities of active compounds extracted from S. barbata oil and its derivatives with those of an acaricide (benzyl benzoate).

Materials and Methods

Compounds

2,6-Dibromo-1,5-dihydroxynaphthalene (99 %), 1,5-dihydroxynaphthalene (97 %), 2,3-dihydrobenzofuran (99 %), hexadecanoic acid (99 %), linoleic acid (93 %), and 2-methoxy-4-vinylphenol (98 %) were purchased from Aldrich Chemical Co. Benzyl benzoate (99 %), 1-hydroxynaphthalene (99 %), 2-hydroxynaphthalene (99 %), and stearic acid (98.5 %) were purchased from Fluka Chemical Co. Other chemicals were of reagent grade.

Preparation

The plants of Scutellaria barbata were collected in July 2011 in Jeonju (Korea) and dried at room temperature. A voucher specimen was authenticated by Prof. Jeong-Moon Kim and deposited in the herbarium at the Department of Landscape Architecture, College of Agriculture, Chonbuk National University (CNU 201157). The samples were washed 3 times with 500 mL of distilled water and dried in an oven at 40 °C for 2 days, then finely powdered. The essential oil of S. barbata was extracted using a steam distillation. It was added to anhydrous sodium sulfate in order to remove molecular H₂O and then concentrated by rotary evaporation (EYELA auto jack NAJ-100) at 30 °C. Subsequently, it was stored in a refrigerator at 4 °C to prevent the volatilization of compounds.

Gas chromatography-mass spectrometry (GC-MS)

The essential oil of S. barbata was analyzed by GC (HP 6890; Agilent)-MS (5973 IV; Agilent). The volatile compounds of S. barbata oil were separated using a DB-5 (0.25 mm film) fused silica capillary column (0.25 mm i. d. × 30 m; J&W Scientific). The GC conditions include the following parameters: injector temperature, 210 °C; column temperature, isothermal at 50 °C for 15 min, then increased to 200 °C at 2 °C/min and held at this temperature for 15 min; ion source temperature, 230 °C. Helium was used as the carrier gas at a rate of 0.8 mL/min. The effluent of the GC column was introduced directly into the source of the MS. Spectra were obtained in the electron impact (EI) mode with 70 eV ionization energy. The mass range was between 10 and 425 m/z, and the sector mass analyzer was set to scan from 50 to 600 amu for 2 s. Volatile compounds were identified by comparison of retention times, retention indices, and mass spectra to the mass spectra library (The Wiley Registry of Mass Spectral Data, 7th ed.).

Test mites

The respective cultures of D. farinae, D. pteronyssinus, and T. putrescentiae were maintained in the laboratory for ten years without external exposure to any known acaricides. These mites were bred in a container (15 cm × 12 cm × 6 cm) with 30 g of sterilized artificial diet (fry feed No. 1 and dried yeast, 1 : 1 by weight) at 25 ± 1 °C and 75 % relative humidity in darkness. The fry feed (Miropa) was purchased from Korea Special Feed Meal Co., Ltd. The feed consisted of crude protein (49.0 %), cellulose (4.0 %), crude lipid (3.0 %), phosphate (2.0 %), calcium (1.8 %), and others (40.2 %).

Fumigant toxicity bioassay

Experiments were performed to determine whether lethal activities of volatile constituents derived from S. barbata oil and benzyl benzoate toward adults (7–10 days old) of D. farinae, D. pteronyssinus, and T. putrescentiae were attributed to fumigant toxicity [5]. Briefly, groups of 30–40 adults were placed on the bottom of a Petri dish (50 × 15 cm) and covered with a lid that had a fine wire screen (200 meshes). Filter papers (5.5 cm diameter) were treated with 42.1, 21.05, 5.26, 2.63, and 1.32 µg/cm² of the compounds or benzyl benzoate in 80 µL of methanol. Filter paper treated with methanol was used as a negative control. The treated filter paper was placed on top of the wire screen, which prevented direct contact of mites with either the compounds or the acaricide. Petri dishes were sealed with Parafilm to investigate the potential fumigant toxicity of the test materials. Treated and control mites were held at the same conditions used for colony maintenance. Mortalities were determined at 24 h after treatment. All treatments were performed in triplicate.

Contact toxicity bioassay

A contact toxicity bioassay [6] was used to evaluate the toxicity of materials derived from S. barbata and the acaricide benzyl benzoate, applied to a filter paper, to adults (7–10 days old) of D. farinae, D. pteronyssinus, and T. putrescentiae. Various amounts (42.1, 21.05, 5.26, 2.63, 1.32, and 0.66 µg/cm²) of each material were dissolved in methanol and then applied to a filter paper (5 cm diameter, 55 µm thick) (Whatman Co.) with a control filter paper treated with methanol. Filter paper treated with methanol was used as a negative control. Each piece was placed in the bottom of a Petri dish (5 cm diameter × 0.8 cm deep) after the treated and control filter papers were dried in a fume hood for 15 min. Groups of 30–40 mites were separately placed in each Petri dish. This was followed by the sealing of the lid. Mortalities were determined after 24 h through examination under a binocular microscope (20×; Olympus). Mites were considered dead if their appendages did not move when prodded with a pin. All treatments were performed in triplicate, and the LD₅₀ values were calculated.

Statistical analysis

The percentage of mortality and LD₅₀ values of target mites to the tested samples were determined. The treatment means were compared and separated at the p < 0.05 level of significance. The relative toxicity (RT) was determined based on the ratio of the activities of benzyl benzoate LD₅₀/test compound LD₅₀, as previously described.

Results

The volatile constituents of the essential oil extracted from S. barbata were identified by GC-MS ([Table 1]). Thus, a total of 13 volatile constituents were identified by comparing retention times, retention indices, and mass spectra to a library (The Wiley Registry of Mass Spectral Data, 7th ed.). The total amount of identified compounds was 98.07 %. Hexadecanoic acid (58.52 %) was the most general volatile compound, followed by 1-hydroxynaphthalene (12.22 %), stearic acid (5.16 %), 6,10,14-trimethyl-2-pentadecanone (5.01 %), eugenol (3.74 %), 1-octen-3-ol (2.93 %), trans-caryophyllene (2.26 %), β-ionone (2.02 %), 2,3-dihydrobenzofuran (1.56 %), linoleic acid (1.43 %), methyl eugenol (1.13 %), (−)-spathulenol (1.08 %), and 2-methoxy-4-vinylphenol (1.01 %). Furthermore, these compounds were divided into five groups: alcohols (eugenol, 1-hydroxynaphthalene, 2-methoxy-4-vinylphenol, methyl eugenol, 1-octen-3-ol, and (−)-spathulenol), aldehyde (6,10,14-trimethyl-2-pentadecanone), aliphatic acids (hexadecanoic acid, linoleic acid, and stearic acid), benzene (2,3-dihydrobenzofuran), and terpenes (trans-caryophyllene and β-ionone).

In order to predict the active compound against Dermatophagoides spp. and T. putrescentiae, the acaricidal activities of 6 commercial available compounds (2,3-dihydrobenzofuran, hexadecanoic acid, 1-hydroxynaphthalene, linoleic acid, 2-methoxy-4-vinylphenol, and stearic acid) were evaluated using fumigant and contact toxicity bioassays. Previous studies have reported the LD₅₀ values of trans-caryophyllene, eugenol, methyl eugenol, and 1-octen-3-ol against D. farinae, D. pteronyssinus, and T. putrescentiae. We therefore excluded these compounds from the test samples in the current study [13], [14]. As a result, 1-hydroxynaphthalene was found to have powerful fumigant and contact toxicity against house dust and storage mites.

As described earlier, we evaluated the acaricidal activities of the essential oil extracted from S. barbata against house dust and storage mites using fumigant and contact toxicity bioassays ([Table 2]). Then, we also analyzed them as compared with benzyl benzoate. Based on the LD₅₀ values using a fumigant toxicity bioassay, the essential oil (7.56, 7.40, and 11.50 µg/cm²) of S. barbata was 1.33, 1.28, and 1.09 times more active than benzyl benzoate (10.05, 9.50, and 12.50 µg/cm²) against D. farinae, D. pteronyssinus, and T. putrescentiae, respectively. Additionally, using a contact toxicity bioassay, the essential oil (2.55, 2.50, and 5.00 µg/cm²) of S. barbata was 2.94, 2.40, and 1.88 times more effective than benzyl benzoate (7.50, 6.00, and 9.41 µg/cm²) against D. farinae, D. pteronyssinus, and T. putrescentiae, respectively. There was no mortality in the negative control (methanol) using fumigant and contact toxicity bioassays. These results indicate that the acaricidal activity of S. barbata oil was higher than that of the positive control (benzyl benzoate) within the experimental set-up. Our results showed that Dermatophagoides spp. was more susceptible to the S. barbata oil than T. putrescentiae regardless of bioassays. This indicates that the acaricidal activity of plant-derived compounds would vary depending on the species of mites.

To establish the structure-activity relationships between the functional groups (brome and hydroxyl groups) and fumigant or contact activity, we selected 2-hydroxynaphthalene, 1,5-dihydroxynaphthalene, and 2,6-dibromo-1,5-dihydroxynaphthalene as the derivatives of 1-hydroxynaphthalene ([Fig. 1]). Then, we tested them using fumigant and contact toxicity bioassays. Furthermore, we also compared the acaricidal activities of 1-hydroxynaphthalene and its derivatives with those of benzyl benzoate against D. farinae, D. pteronyssinus, and T. putrescentiae ([Table 2]). Based on the LD₅₀ values of 1-hydroxynaphthalene derivatives against D. farinae, D. pteronyssinus, and T. putrescentiae, obtained using a fumigant toxicity bioassay, the acaricidal activity of 1-hydroxynaphthalene (2.11, 2.37, and 4.50 µg/cm²) was 4.76, 6.00, and 2.68 times higher than that of benzyl benzoate (10.05, 9.50, and 12.50 µg/cm²) in the corresponding order and was followed by that of 2-hydroxynaphthalene (9.50, 9.00, and 11.50 µg/cm²). On the contact toxicity bioassay, the acaricidal activity of 1-hydroxynaphthalene (0.79, 0.92, and 2.50 µg/cm²) was 9.49, 6.52, and 3.76 times higher than that of benzyl benzoate (7.50, 6.00, and 9.41 µg/cm²) and was followed by that of 2-hydroxynaphthalene (4.21, 4.80, and 6.50 µg/cm²). Nevertheless, 1,5-dihydroxynaphthalene and 2,6-dibromo-1,5-dihydroxynaphthalene did not exhibit fumigant or contact activity against the three species of mites.

[Table 3] shows the comparison of the acaricidal activities between 1-hydroxynaphthalene and its derivatives on fumigant and contact toxicity bioassays. Against Dermatophagoides spp., the degree of the contact toxicity of 1-hydroxynaphthalene was approximately 2.67 and 2.26 times higher as compared with the fumigant toxicity bioassay. In addition, against T. putrescentiae the acaricidal activity of 1-hydroxynaphthalene was 1.80 times higher in the contact toxicity bioassay as compared with the fumigant toxicity bioassay. There was no significant difference in the degree of the contact and fumigant toxicities between 2-hydroxynaphthalene, which is one of the derivatives, and 1-hydroxynaphthalene. Taken together, these results indicate that the degree of the contact toxicity of 1-hydroxynaphthalene and its derivatives was significantly higher on the fumigant toxicity bioassay.

Discussion

Inconsistent with previous reports, our results showed that the main compounds in the essential oil of S. barbata were hexahydrofarnesylacetone (11.0 %), 3,7,11,15-tetramethyl-2-hexadecen-1-ol (7.8 %), menthol (7.7 %), and 1-octen-3-ol (7.1 %) [15]. According to another study, S. barbata oil consisted of hexadecanoic acid (28.6 %), 1-octen-3-ol (6.21 %), 2,6-dimethylocta-2,7-dien-6-ol (5.80 %), hexahydrofarnesylacetone (4.60 %), caryophyllene (4.39 %), and others [16]. In this regard, the plant-derived constituents are influenced by extrinsic or intrinsic factors, such as the extraction methods, harvest time, plant parts (stems, leaves, flowers, and roots), plant species, and geographical location of where the plants are raised [17], [18].

From the viewpoint of the acaricidal toxicity of functional groups (brome and hydroxyl groups), the degree of the acaricidal toxicity of 1-hydroxynaphthalene and 2-hydroxynaphthalene, both containing the hydroxyl group in the naphthalene skeleton, was significantly higher as compared with 2,6-dibromo-1,5-dihydroxynaphthalene including the brome group. Previous studies have shown that the acaricidal activities are related to chemicals containing the hydroxyl group [19]. The aliphatic alcohols (1-octen-3-ol and 3,7-dimethyl-1-octen-3-ol) containing the hydroxyl group were more effective than the alkenes (1-octene, 1-octen-3-yl acetate, 1-octen-3-yl butyrate, and 3,7-dimethyl-1-octene) with no hydroxyl group [6]. Overall, chemicals providing the hydroxyl group had potent acaricidal toxicity on fumigant and contact toxicity bioassays.

In East Asia, S. barbata has been traditionally used with medicinal purposes for the treatment of breast cancer, chorioepithelioma, digestive system cancer, liver cirrhosis, lung cancer, and other diseases [20], [21]. It has been reported to contain various compounds such as flavone compounds (carthamidin, isocarthamidin, scutellarein, and wogonin) and phenolic compounds (apigenin, apigenin 5-O-β-glucopyranoside, p-coumaric acid, 4′-hydroxywogonin, luteolin, and scutellarin) [22], [23]. Despite excellent pharmacological actions of S. barbata, very little information exists with respect to its use for managing house dust and storage mites. Additionally, biological activity of 1-hydroxynaphthalene has been widely known [24]. Therefore, the current study is the first to report the acaricidal activity of S. barbata oil, 1-hydroxynaphthalene, and its derivatives against adults of D. farinae, D. pteronyssinus, and T. putrescentiae.

According to the Materials Safety Data Sheet (MSDS) from Sigma-Aldrich [25], the oral LD₅₀ values of 1-hydroxynaphthalene and 2-hydroxynaphthalene in rats are 1870 mg/kg and 1960 mg/kg, respectively. This indicates that 1-hydroxynaphthalene derivatives have a relatively lower acute toxicity against mammals. Both our results and previous reports suggest that 1-hydroxynaphthalene derivatives containing the hydroxyl group would be useful in manufacturing a commercially available, eco-friendly acaricide for the management of house dust and storage mites. Further studies are warranted to evaluate the acaricidal activities of naphthalene derivatives containing other functional groups (except for brome and hydroxyl groups) based on the naphthalene skeleton.

Acknowledgements

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A4A01002124).

Conflict of Interest

None.

• References

• 1 Arlian LG. Arthropod allergens and human health. Annu Rev Entomol 1987; 7: 447-461
  PubMedSearch in Google Scholar
• 2 Gulati R, Mathur S. Effect of Eucalyptus and Mentha leaves and Curcuma rhizomes on Tyrophagus putrescentiae (Schrank) (Acarina: Acaridae) in wheat. Exp Appl Acarol 1995; 19: 511-518
  CrossrefPubMedSearch in Google Scholar
• 3 Platts-Mills TAE, Thomas WR, Aalberse RC, Vervloet D, Chapman MD. Dust mite allergens and asthma: report of a second international workshop. J Allergy Clin Immunol 1992; 89: 1046-1062
  CrossrefPubMedSearch in Google Scholar
• 4 Helson GAH. House-dust mites and possible connection with sudden infant death syndrome. N Z Med J 1971; 74: 209
  PubMedSearch in Google Scholar
• 5 Kang SW, Kim HY, Lee WJ, Ahn YJ. Toxicity of bisabolangelone from Ostericum koreanum roots to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae). J Agric Food Chem 2006; 54: 3547-3550
  CrossrefPubMedSearch in Google Scholar
• 6 Yang JY, Lee HS. Acaricidal activities of the active component of Lycopus lucidus oil and its derivatives against house dust and stored food mites (Arachnida: Acari). Pest Manag Sci 2012; 68: 564-572
  CrossrefPubMedSearch in Google Scholar
• 7 Schober G, Kniest FM, Kort HS, De Saint Georges Gridelet DM, van Bronswijk JE. Comparative efficacy of house dust mite extermination products. Clin Exp Allergy 1992; 22: 618-626
  CrossrefPubMedSearch in Google Scholar
• 8 Pollart SM, Chapman MD, Platts-Mills TA. House dust sensitivity and environmental control. Immunol Allergy Clin North Am 1987; 14: 591-603
  PubMedSearch in Google Scholar
• 9 Park IL, Lee HS, Lee SG, Park JD, Ahn YJ. Insecticidal and fumigant activities of Cinnamomum cassia bark-derived materials against Mechoris ursulus (Coleoptera: Attelabidae). J Agric Food Chem 2000; 48: 2528-2531
  CrossrefPubMedSearch in Google Scholar
• 10 Lee HS, Sturm A. Purification and characterization of neutral and alkaline invertase from carrot. Plant Physiol 1996; 112: 1513-1522
  CrossrefPubMedSearch in Google Scholar
• 11 Kim JJ, Lee MY. Isolation and characterization of edestin from cheungsam hempseed. J Appl Biol Chem 2011; 54: 84-88
  CrossrefPubMedSearch in Google Scholar
• 12 Isman MB. Plant essential oils for pest and disease management. Crop Prot 2000; 19: 603-608
  CrossrefPubMedSearch in Google Scholar
• 13 Sung BK, Lee HS. Chemical composition and acaricidal activities of constituents derived from Eugenia caryophyllata leaf oils. Food Sci Biotechnol 2005; 14: 73-76
  PubMedSearch in Google Scholar
• 14 Yang JY. Acaricidal activities of bioactive components isolated from Lycopus lucidus and structure-activity relationships of their derivatives. Chonbuk: Chonbuk National University; 2012: 65-71
  CrossrefSearch in Google Scholar
• 15 Yu J, Lei J, Yu H, Cai X, Zou G. Chemical composition and antimicrobial activity of the essential oil of Scutellaria barbata . Phytochemistry 2004; 65: 881-884
  CrossrefPubMedSearch in Google Scholar
• 16 Pan R, Guo F, Lu H, Feng WW, Iiang YZ. Development of the chromatographic fingerprint of Scutellaria barbata D. Don by GC-MS combined with chemometrics methods. J Pharm Biomed 2011; 55: 391-396
  CrossrefPubMedSearch in Google Scholar
• 17 Mostafa K, Yadollah Y, Fatemeh S, Naader B. Comparison of essential oil composition of Carum copticum obtained by supercritical carbon dioxide extraction and hydrodistillation methods. Food Chem 2004; 86: 587-591
  CrossrefPubMedSearch in Google Scholar
• 18 Felice S. Influence of harvesting time on yield and composition of the essential oil of a thyme (Thymus pulegioides L.) growing wild in Campania (Southern Italy). J Agric Food Chem 1996; 44: 1327-1332
  CrossrefPubMedSearch in Google Scholar
• 19 Jeong EY, Kim MG, Lee HS. Active compound isolated from Dipscorea japonica roots with fumigant activity against house dust and stored food mites. J Korean Soc Appl Biol Chem 2011; 54: 806-810
  CrossrefPubMedSearch in Google Scholar
• 20 Qian B. Clinical effects of anticancer Chinese medicine. Shanghai: Shanghai Translation Publishing House; 1987: 6-7
  Search in Google Scholar
• 21 Yin XL, Zhou JB, Jie CF, Xing DM, Zhang Y. Anticancer activity and mechanism of Scutellaria barbata extract on human lung cancer cell line A549. Life Sci 2004; 75: 2233-2244
  CrossrefPubMedSearch in Google Scholar
• 22 Goh D, Lee YH, Ong ES. Inhibitory effects of a chemically standardized extract from Scutellaria barbata in human colon cancer cell lines, LoVo. J Agric Food Chem 2005; 53: 8197-8204
  CrossrefPubMedSearch in Google Scholar
• 23 Yao H, Li SG, Hu JA, Chen Y, Huang LY, Lin JH, Li HW, Lin XH. Chromatographic fingerprint and quantitative analysis of seven bioactive compounds Scutellaria barbata . Planta Med 2011; 77: 288-293
  PubMedSearch in Google Scholar
• 24 Song HY, Lee HS. Antibacterial activity of naphthalin and its derivatives against oral bacteria. J Korean Soc Appl Biol Chem 2012; 55: 183-187
  CrossrefPubMedSearch in Google Scholar
• 25 Sigma-Aldrich. Material safety data sheet (version 4.1). Seoul: Sigma-Aldrich Korea Ltd.; 2010
  Search in Google Scholar

Correspondence

• References

• 1 Arlian LG. Arthropod allergens and human health. Annu Rev Entomol 1987; 7: 447-461
  PubMedSearch in Google Scholar
• 2 Gulati R, Mathur S. Effect of Eucalyptus and Mentha leaves and Curcuma rhizomes on Tyrophagus putrescentiae (Schrank) (Acarina: Acaridae) in wheat. Exp Appl Acarol 1995; 19: 511-518
  CrossrefPubMedSearch in Google Scholar
• 3 Platts-Mills TAE, Thomas WR, Aalberse RC, Vervloet D, Chapman MD. Dust mite allergens and asthma: report of a second international workshop. J Allergy Clin Immunol 1992; 89: 1046-1062
  CrossrefPubMedSearch in Google Scholar
• 4 Helson GAH. House-dust mites and possible connection with sudden infant death syndrome. N Z Med J 1971; 74: 209
  PubMedSearch in Google Scholar
• 5 Kang SW, Kim HY, Lee WJ, Ahn YJ. Toxicity of bisabolangelone from Ostericum koreanum roots to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae). J Agric Food Chem 2006; 54: 3547-3550
  CrossrefPubMedSearch in Google Scholar
• 6 Yang JY, Lee HS. Acaricidal activities of the active component of Lycopus lucidus oil and its derivatives against house dust and stored food mites (Arachnida: Acari). Pest Manag Sci 2012; 68: 564-572
  CrossrefPubMedSearch in Google Scholar
• 7 Schober G, Kniest FM, Kort HS, De Saint Georges Gridelet DM, van Bronswijk JE. Comparative efficacy of house dust mite extermination products. Clin Exp Allergy 1992; 22: 618-626
  CrossrefPubMedSearch in Google Scholar
• 8 Pollart SM, Chapman MD, Platts-Mills TA. House dust sensitivity and environmental control. Immunol Allergy Clin North Am 1987; 14: 591-603
  PubMedSearch in Google Scholar
• 9 Park IL, Lee HS, Lee SG, Park JD, Ahn YJ. Insecticidal and fumigant activities of Cinnamomum cassia bark-derived materials against Mechoris ursulus (Coleoptera: Attelabidae). J Agric Food Chem 2000; 48: 2528-2531
  CrossrefPubMedSearch in Google Scholar
• 10 Lee HS, Sturm A. Purification and characterization of neutral and alkaline invertase from carrot. Plant Physiol 1996; 112: 1513-1522
  CrossrefPubMedSearch in Google Scholar
• 11 Kim JJ, Lee MY. Isolation and characterization of edestin from cheungsam hempseed. J Appl Biol Chem 2011; 54: 84-88
  CrossrefPubMedSearch in Google Scholar
• 12 Isman MB. Plant essential oils for pest and disease management. Crop Prot 2000; 19: 603-608
  CrossrefPubMedSearch in Google Scholar
• 13 Sung BK, Lee HS. Chemical composition and acaricidal activities of constituents derived from Eugenia caryophyllata leaf oils. Food Sci Biotechnol 2005; 14: 73-76
  PubMedSearch in Google Scholar
• 14 Yang JY. Acaricidal activities of bioactive components isolated from Lycopus lucidus and structure-activity relationships of their derivatives. Chonbuk: Chonbuk National University; 2012: 65-71
  CrossrefSearch in Google Scholar
• 15 Yu J, Lei J, Yu H, Cai X, Zou G. Chemical composition and antimicrobial activity of the essential oil of Scutellaria barbata . Phytochemistry 2004; 65: 881-884
  CrossrefPubMedSearch in Google Scholar
• 16 Pan R, Guo F, Lu H, Feng WW, Iiang YZ. Development of the chromatographic fingerprint of Scutellaria barbata D. Don by GC-MS combined with chemometrics methods. J Pharm Biomed 2011; 55: 391-396
  CrossrefPubMedSearch in Google Scholar
• 17 Mostafa K, Yadollah Y, Fatemeh S, Naader B. Comparison of essential oil composition of Carum copticum obtained by supercritical carbon dioxide extraction and hydrodistillation methods. Food Chem 2004; 86: 587-591
  CrossrefPubMedSearch in Google Scholar
• 18 Felice S. Influence of harvesting time on yield and composition of the essential oil of a thyme (Thymus pulegioides L.) growing wild in Campania (Southern Italy). J Agric Food Chem 1996; 44: 1327-1332
  CrossrefPubMedSearch in Google Scholar
• 19 Jeong EY, Kim MG, Lee HS. Active compound isolated from Dipscorea japonica roots with fumigant activity against house dust and stored food mites. J Korean Soc Appl Biol Chem 2011; 54: 806-810
  CrossrefPubMedSearch in Google Scholar
• 20 Qian B. Clinical effects of anticancer Chinese medicine. Shanghai: Shanghai Translation Publishing House; 1987: 6-7
  Search in Google Scholar
• 21 Yin XL, Zhou JB, Jie CF, Xing DM, Zhang Y. Anticancer activity and mechanism of Scutellaria barbata extract on human lung cancer cell line A549. Life Sci 2004; 75: 2233-2244
  CrossrefPubMedSearch in Google Scholar
• 22 Goh D, Lee YH, Ong ES. Inhibitory effects of a chemically standardized extract from Scutellaria barbata in human colon cancer cell lines, LoVo. J Agric Food Chem 2005; 53: 8197-8204
  CrossrefPubMedSearch in Google Scholar
• 23 Yao H, Li SG, Hu JA, Chen Y, Huang LY, Lin JH, Li HW, Lin XH. Chromatographic fingerprint and quantitative analysis of seven bioactive compounds Scutellaria barbata . Planta Med 2011; 77: 288-293
  PubMedSearch in Google Scholar
• 24 Song HY, Lee HS. Antibacterial activity of naphthalin and its derivatives against oral bacteria. J Korean Soc Appl Biol Chem 2012; 55: 183-187
  CrossrefPubMedSearch in Google Scholar
• 25 Sigma-Aldrich. Material safety data sheet (version 4.1). Seoul: Sigma-Aldrich Korea Ltd.; 2010
  Search in Google Scholar