Jun-Hwan Park

Evaluation of benzaldehyde derivatives from Morinda officinalis as anti-mite agents with dual function as acaricide and mite indicator.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTS virus with 12–30% fatality rate. Despite severity of the disease, any medication or treatment for SFTS has not developed yet. One approach to prevent SFTS spreading is to control the arthropod vector carrying SFTS virus. We report that 2–methylbenzaldehyde analogues from M. officinalis have a dual function as acaricide against Dermatophagoides spp. and Haemaphysalis longicornis and indicator (color change) against Dermatophagoides spp. Based on the LD50 values, 2,4,5–trimethylbenzaldehyde (0.21, 0.19, and 0.68 μg/cm3) had the highest fumigant activity against D. farinae, D. pteronyssinus, and H. longicornis, followed by 2,3–dimethylbenzaldehyde (0.46, 0.44, and 0.79 μg/cm3), 2,4–dimethylbenzaldehyde (0.66, 0.59, and 0.95 μg/cm3), 2,5–dimethylbenzaldehyde (0.65, 0.68, and 0.88 μg/cm3), 2–methylbenzaldehyde (0.95, 0.87, and 1.28 μg/cm3), 3–methylbenzaldehyde (0.99, 0.93, and 1.38 μg/cm3), 4–methylbenzaldehyde (1.17, 1.15, and 3.67 μg/cm3), and M. officinalis oil (7.05, 7.00, and 19.70 μg/cm3). Furthermore, color alteration of Dermatophagoides spp. was shown to be induced, from colorless to dark brown, by the treatment of 2,3–dihydroxybenzaldehyde. These finding indicated that 2–methylbenzaldehyde analogues could be developed as functional agent associated with the arthropod vector of SFTS virus and allergen.

Phototactic behavioral response of agricultural insects and stored-product insects to light-emitting diodes (LEDs)

Agricultural insects and stored-product insects are influenced by luminance intensities, exposure times, and wavelengths of light-emitting diodes (LEDs). Based on the phototactic behaviors of the agricultural insects, green or blue LEDs are most attractive for Bemisia tabaci, Trialeurodes vaporariorum, Myzus persicae, Liriomyza trifolii, Spodoptera exigua, and Spodoptera litura. Green LED attracts Plutella xylostella and Frankliniella occidentalis. Similarly, green or blue LEDs are more attractive to agricultural insects, such as Liriomyza sativae, Sogatella furcifera, and Nilaparvata lugens, than other wavelength LEDs. Concerning the phototactic behaviors of the stored-product insects, red LED is attractive for, in descending order Tribolium castaneum, Sitophilus zeamais, Lasioderma serricorne, and Tyrophagus putrescentiae. Blue LED captures most Sitophilus oryzae and Sitotroga cerealella. Red and blue LEDs are more attractive for stored-product insect pests rate than ultraviolet LED and green, yellow, white, and infrared LEDs. Based on the attraction rate of the stored-product insects on granary, red LED is most attractive for S. cerealella and Plodia interpunctella. These light sources are effective in controlling agricultural and stored-product insects. Applying LED technology for greenhouses and granaries along with conventional traps reduces crop loss due to moths, beetles, aphids, and weevils. LEDs have potential value in integrated pest management.

Isolation of 8-hydroxyquinoline from Sebastiania corniculata and antimicrobial activity against food-borne bacteria

Antimicrobial activities of the five fractions obtained from the methanol extract of Sebasticania corniculata plant were evaluated against five food poisoning bacteria using the agar diffusion method. The chloroform fraction possessed strong antimicrobial activities against five food poisoning bacteria. 8-Hydroxyquinoline was isolated from the chloroform fraction by the various chromatography analyses. When to the agar diffusion method was used, 8-hydroxyquinoline showed potent antimicrobial activities against five food poisoning bacteria. In the case of minimum bactericidal concentration or minimum inhibitory concentration, 8-hydroxyquinoline showed significantly higher antimicrobial activity against five food poisoning bacteria. Thus, the extract of S. corniculata and 8-hydroxyquinoline could be useful for the development of eco-friendly food supplemental agents.

2-isopropyl-5-methylphenol isolated from Ruta graveolens and its structural analogs show antibacterial activity against food-borne bacteria

The antimicrobial activities of the essential oil obtained from the aerial parts of Ruta graveolens and 2-isopropyl-5-methylphenol analogs were evaluated against six food-borne bacteria. The essential oil of R. graveolens aerial parts exhibited potent antimicrobial activity against six food-borne bacteria. 2-Isopropyl-5-methylphenol was isolated by chromatographic analyses. The structure-activity relationships of the 2-isopropyl-5-methylphenol analogs, 2-isopropyl-5-methylphenol, and its structural analogs (2-isopropylphenol, 2-methylphenol, phenol, and 2-isopropyl-5-methylbenzene) were determined against six food-borne bacteria. When employing the agar diffusion method, 2-isopropyl-5-methylphenol and 2-isopropylphenol had potent antimicrobial activities against the six food-borne bacteria. The minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) values of 2-isopropyl-5-methylphenol and its structural analogs were determined against the six food-borne bacteria. 2-Isopropyl-5-methylphenol exhibited the strongest activity (MIC, 5–6.25 μg/mL; MBC, 6.25–12.5 μg/mL) against the six food-borne bacteria. Therefore, the essential oil of R. graveolens and 2-isopropyl-5-methylphenol analogs should be useful as natural food preservatives.

Antimicrobial activities of 2,6-dimethoxy-1,4-benzoquinone and its structurally related analogues against seven food-borne bacteria

Antimicrobial activities of 2,6-dimethoxy-1,4-benzoquinone and its structurally related analogues (2,6-dichloro-, 2,6-dimethyl-, 2,5-dichloro-, and 2,5-dimethyl-) were evaluated at 0.5 mg/disc against seven food-borne bacteria. 2,6-Dimethoxy-1,4-benzoquinone showed antimicrobial activity against Staphylococcus intermedius (22.0 mm), Staphlococcus epidermidis (19.5 mm), Shigella sonnei (16.0 mm), and Listeria monocytogenes (15.0 mm). Furthermore, these structural analogues exhibited antimicrobial activity against all tested food-borne bacteria except 2,6-dichloro-1,4-benzoquinone. In conclusion, 2,6-dimethoxy-1,4-benzoquinone and its structural analogues are useful as a source of food supplemental agents.

Acaricidal activity of constituents derived from peppermint oil against Tyrophagus putrescentiae.

The acaricidal activities of peppermint oil and menthol isomers against mites in stored food were evaluated using fumigant and contact bioassays and were compared with the activity of benzyl benzoate as a synthetic acaricide. Based on the 50% lethal dose (LD50) values against Tyrophagus putrescentiae in the fumigant bioassay, menthol (0.96 μg/cm(2)) was approximately 12.18 times more effective than benzyl benzoate (11.70 μg/cm(2)), followed by (+)-neomenthol (1.33 μg/cm(2)), (-)-menthol (1.60 μg/cm(2)), and (+)-menthol (1.90 μg/cm(2)). In the filter paper bioassay, menthol (0.55 μg/cm(2)) was about 15.18 times more active than benzyl benzoate (8.35 μg/cm(2)), followed by (-)-menthol (0.84 μg/cm(2)), (+)-menthol (0.92 μg/cm(2)), and (+)-neomenthol (1.72 μg/cm(2)). However, (+)-isomenthol did not exhibit any acaricidal activity against T. putrescentiae in the fumigant and filter paper bioassays. These results indicate that peppermint oil and menthol isomers could be effective natural acaricides for managing mites in stored food.

Acaricidal target and mite indicator as color alteration using 3,7-dimethyl-2,6-octadienal and its derivatives derived from Melissa officinalis leaves

Toxicities and color deformation were evaluated of essential oils of Melissa officinalis cultivated in France, Ireland, and Serbia and their constituents, along with the control efficacy of spray formulations (0.25, 0.5, and 1%) containing M. officinalis oils cultivated in France and its main compound against Dermatophagoides farinae and D. pteronyssinus adults. In a contact + fumigant bioassay, M. officinalis oil (France) was more active against D. farinae and D. pteronyssinus, compared to M. officinalis oils (Ireland and Serbia). Interestingly, color alteration of D. farinae and D. pteronyssinus was exhibited, changing from colorless to golden brown through the treatment with M. officinalis oils. The acaricidal and color alteration principle of three M. officinalis oils was determined to be 3,7-dimethyl-2,6-octadienal. M. officinalis oil (France) and 3,7-dimethyl-2,6-octadienal were significantly more effective in closed containers than in open containers, indicating that their acaricidal route of action was largely a result of vapor action. Sprays (0.5 and 1%) containing 3,7-dimethyl-2,6-octadienal and 1% spray containing M. officinalis oil (France) resulted in 100% mortality and color alteration against D. farinae and D. pteronyssinus. These results indicated that M. officinalis oil and 3,7-dimethyl-2,6-octadienal could be developed as a suitable acaricidal and mite indicator ingredient for the control of dust mites.

Toxicities of Eucalyptus dives Oil, 3-Carvomenthenone, and Its Analogues against Stored-Product Insects

The insecticidal toxicities of essential oils and other active components extracted from Eucalyptus dives leaves (as well as structural analogues) were studied against stored-product insects, Plodia interpunctella and Tribolium castaneum. 3-Carvomenthenone was purified from E. dives oil, and the structures were elucidated by electron ionization mass spectra, 1H-nuclear magnetic resonance (NMR), 13C-NMR, heteronuclear multiple quantum coherence, 1H-1H correlation spectroscopy, and distortionless enhancement by polarization transfer NMR. Using the fumigant method against P. interpunctella larvae and adults, cyclohexenone exhibited the strongest toxicity (50% lethal dose [LD50] against larvae and adults, 2.45 and 3.63 μg/cm3), followed by methylcyclohexenone (2.95 and 4.24 μg/cm3), seudenone (3.02 and 4.44 μg/cm3), and 3-carvomenthenone (52.4 and 68.7 μg/cm3). Using the contact method, cyclohexenone (LD50 against larvae and adults, 17.25 and 19.35 μg/cm2) exhibited the most potent toxicities against T. castaneum larvae and adults, followed by methylcyclohexenone, seudenone, and 3-carvomenthenone. No functional radical on the backbone (2-cyclohexen-1-one) was more toxic than other chemicals. Structure-activity relationships between 3-carvomenthenone analogues and toxicities indicated that the toxicity of 3-carvomenthenone, cyclohexenone, methylcyclohexenone, and seudenone might be conferred through the dermal organs of T. castaneum and P. interpunctella. This study indicates that E. dives oil, 3-carvomenthenone, cyclohexenone, methylcyclohexenone, and seudenone have potential as natural agents to control stored-product insects.

Food Protective Effects of 3-Methylbenzaldehyde Derived from Myosotis arvensis and Its Analogues against Tyrophagus putrescentiae

The potential abilities of 3-methylbenzaldehyde derived from Myosotis arvensis oil and its structural analogues to act as new acaricide and mite kit (mite color deformation) against Tyrophagus putrescentiae (Schrank) were evaluated in the present study. Based on the LD50 values, 2,4,5-trimethylbenzaldehyde (0.78 μg/cm3) had highest vapor action against T. putrescentiae, followed by 2,4-methylbenzaldehyde (1.14 μg/cm3), 2,5-dimethylbenzaldehyde (1.29 μg/cm3), 2-methylbenzaldehyde (1.32 μg/cm3), 2,3-dimethylbenzaldehyde (1.55 μg/cm3), 3-methylbenzaldehyde (1.97 μg/cm3), and 4-methylbenzaldehyde (2.34 μg/cm3). The color deformation of seven methylbenzaldehyde analogues mixed with 2,3-dihydroxybenzaldehyde against T. putrescentiae showed mite color deformation, from coloress to reddish brown, and valuable to distinguish with the naked eye. In addition, there was no antagonistic interactions between 2,3-dihydroxybenzaldehyde and the methylbenzaldehyde analogues. These finding suggests that the methylbenzaldehyde analogues could be developed as dual functional agent to protect from fall in the commercial value of stored food products.

An object-based information retrieval model: toward the structural construction of thesauri

We propose an information retrieval model, where the object-oriented paradigm is applied to the construction of thesauri and the interpretation of user queries. This model provides a mechanism to assist domain experts in constructing thesauri; it determines a considerable part of the relationship degrees between term objects by inheritance, and supplies domain experts with information available from a thesaurus being constructed. It enables domain experts to incrementally construct a thesaurus as well, since the automatically determined degree of relationships can be refined whenever a more sophisticated thesaurus is needed. It may minimize the domain experts burden caused from exhaustive specification of individual relationships. All the relationships between term objects of our thesaurus (called object-based thesaurus) are represented in terms of two levels: concept level and instance level. The former defines the relationships between concepts, whereas the latter specifies the relationships between instances. We also propose a new query evaluation mechanism to exploit the thesaurus when interpreting the intent of user queries.