Acaricidal potential of active components derived from Alpinia galanga rhizome oils and their derivatives against Haemaphysalis longicornis (Acari: Ixodidae).

Acaricidal activities and acetylcholinesterase (AChE) inhibitory activities were evaluated of active constituents of the essential oil extracted from Alpinia galanga rhizomes cultivated from India and their derivatives against Haemaphysalis longicornis nymphs. In addition, the effect was investigated of active components of A. galanga oil on egg laying of adult females of H. longicornis and egg hatchability. Of the volatile components identified in A. galanga oil, ethyl cinnamate, ethyl methoxycinnamate, and methyl cinnamate at 0.32 mg/cm2 resulted in 100% mortality, respectively, indicating that the acaricidal activity of the A. galanga oil against H. longicornis nymphs could be attributed to these compounds. To evaluate the structure-activity relationship between cinnamate derivatives and their acaricidal activities, allyl cinnamate, benzyl cinnamate, isopropyl cinnamate, isobutyl cinnamate, and isoamyl cinnamate were selected. Among cinnamate derivatives tested, allyl cinnamate exhibited the most potent toxicity (LC50 = 0.055 mg/cm2) against H. longicornis nymphs. The allyl cinnamate was also tested for AChE activity in vivo in H. longicornis nymphs and was found to affect the AChE activity. Allyl cinnamate at 10-50 mg/mL inhibited egg laying of adult females of H. longicornis by 10-43%. Egg hatching was suppressed completely by treatment with allyl cinnamate at 50 mg/mL, whereas allyl cinnamate was minimally toxic against non-target earthworms, Eisenia fetida. These results suggest that allyl cinnamate can be used as an active ingredient for the development of eco-friendly tick acaricides against H. longicornis, a vector for Sever fever with thrombocytopenia syndrome (SFTS) virus.

Larvicidal activity of naturally occurring naphthalenedione and its structurally related analogs against three mosquito species.

The objective of this study was to determine the larvicidal activity of an active compound isolated from Cercis chinensis heartwood and its structurally related analogs against 4th-stage Aedes aegypti, Culex pipiens pallens, and Ae. togoi. The larvicidal compound of C. chinensis was isolated with the use of various chromatographic techniques and identified as analogs of 1,4-naphthalenedione. Based on the median lethal concentration (LC(50)) values of commercially procured analogs against Ae. aegypti larvae, the most toxic analog was 2-bromo-1,4-naphthalenedione (1.19 µg/ml); followed by 5-hydroxy-1,4-naphthalenedione (1.72 µg/ml); 2-methyl-1,4-naphthalenedione (9.12 µg/ml); 2-hydroxy-1,4-naphthalenedione (10.76 µg/ml); and 2-methoxy-1,4-naphthalenedione (12.50 µg/ml). Similar results were observed against Cx. p. pallens and Ae. togoi larvae with 1,4-naphthalenedione analogs. These results also showed that 1,4-naphthalenedione analogs were less toxic than the organophosphate pirimiphos-methyl. Nonetheless, naturally occurring C. chinensis-derived materials and 1,4-naphthalenedione analogs have potential for development as mosquito larvicidal agents.

Antimicrobial activities of active component isolated from Lawsonia inermis leaves and structure-activity relationships of its analogues against food-borne bacteria.

The antimicrobial activities of Lawsonia inermis leaf extract and 2-hydroxy-1,4-naphthoquinone analogues against food-borne bacteria. The antimicrobial activities of five fractions derived from the methanol extract of Lawsonia inermis leaves were evaluated against 7 food-borne bacteria. 2-Hydroxy-1,4-naphthoquinone was isolated by chromatographic analyses. 2-Hydroxy-1,4-naphthoquinone showed the strong activities against Bacillus cereus, Listeria monocytogenes, Salmonella enterica, Shigella sonnei, Staphylococcus epidermidis, and S. intermedius, but exerted no growth-inhibitory activities against S. typhimurium. The antimicrobial activities of the 2-hydroxy-1,4-naphthoquinone analogues were tested against 7 food-borne bacteria to establish structure-activity relationships. Hydroxyl (2-hydroxy-1,4-naphthoquinone and 5-hydroxy-1,4-naphthoquinone), methoxy (2-methoxy-1,4-naphthoquinone), and methyl (2-methyl-1,4-naphthoquinone, and 5-hydroxy-2-methyl-1,4-naphthoquinone) functional groups on the 1,4-naphthoquinone skeleton possessed potent activities, whereas bromo (2-bromo-1,4-naphthoquinone and 2,3-dibromo-1,4-naphthoquione) and chloro (2,3-dichloro-1,4-naphthoquinone) exhibited no activity against 7 food-borne bacteria. The L. inermis leaf extract and 2-hydroxy-1,4-naphthoquinone analogues should be useful as natural antimicrobial agents against food-borne bacteria.

Acaricidal activities against house dust mites of spearmint oil and its constituents.

The aim of this study was to evaluate the acaricidal activities of spearmint oil and carvone derivatives against house dust mites using contact and fumigant toxicity bioassays to replace benzyl benzoate as a synthetic acaricide. Based on the LD50 values, the contact toxicity bioassay revealed that dihydrocarvone (0.95 and 0.88 µg/cm2) was 7.7 and 6.8 times more toxic than benzyl benzoate (7.33 and 6.01 µg/cm2) against Dermatophagoides farinae and Dermatophagoides pteronyssinus, respectively, followed by carvone (3.78 and 3.23 µg/cm2), spearmint oil (5.16 and 4.64 µg/cm2), carveol (6.00 and 5.80 µg/cm2), and dihydrocarveol (8.23 and 7.10 µg/cm2). Results of the fumigant toxicity bioassay showed that dihydrocarvone (2.73 and 2.16 µg/cm2) was approximately 4.0 and 4.8 times more effective than benzyl benzoate (11.00 and 10.27 µg/cm2), followed by carvone (6.63 and 5.78 µg/cm2), carveol (7.58 and 7.24 µg/cm2), spearmint oil (9.55 and 8.10 µg/cm2), and dihydrocarveol (9.79 and 8.14 µg/cm2). Taken together, spearmint oil and carvone derivatives are a likely viable alternative to synthetic acaricides for managing house dust mites.

Acaricidal activities of bicyclic monoterpene ketones from Artemisia iwayomogi against Dermatophagoides spp.

The acaricidal properties of 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one isolated from Artemisia iwayomogi and its structural analogues were evaluated against Dermatophagoides farinae and D. pteronyssinus, and their effects were compared with that of the commercial acaricide benzyl benzoate. Based on the 50 % lethal dose (LD50) values against D. farinae, 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (0.82 µg/cm(2)) was 9.71 times more effective than benzyl benzoate (7.96 µg/cm(2)), followed by (1R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (1.03 µg/cm(2)), (1S)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (1.58 µg/cm(2)), and (1R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one oxime (3.05 µg/cm(2)) in a filter paper bioassay. The acaricidal activities of 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one and its structural analogues against D. pteronyssinus were similar to those against D. farinae. These results demonstrate that naturally occurring A. iwayomogi-isolated 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one and its structural analogues are suitable for the production of natural acaricides against house dust mites.

Antimicrobial potentials of active component isolated from Citrullus colocynthis fruits and structure-activity relationships of its analogues against foodborne bacteria.

BACKGROUND: Synthetic preservatives have been consistently used to maintain the quality of food products. However, the degree of danger to human health cannot be ignored. In this study, the antimicrobial activities of Citrullus colocynthis fruits and 4-methylquinoline analogues were investigated to develop natural preservatives against foodborne bacteria. RESULTS: Antimicrobial activities of the methanol extract and five fractions derived from C. colocynthis fruits were evaluated against five foodborne bacteria. The chloroform fraction possessed strong activities against five foodborne bacteria. 4-Methylquinoline was isolated by chromatographic analyses. To establish the structure-activity relationships, the antimicrobial activities of 4-methylquinoline analogues (2-hydroxyquinoline, 4-hydroxyquinoline, 6-hydroxyquinoline, 2-methylquinoline, 6-methyquinoline, 8-methylquinoline and 2-methyl-8-hydroxyquinoline) were tested against food-borne bacteria. When employing the agar diffusion method, 2-methyl-8-hydroxyquinoline was found to have potent activities against the five foodborne bacteria. In terms of minimum bactericidal concentration or minimum inhibitory concentration, 2-methyl-8-hydroxyquinoline had significantly higher antimicrobial activity against the five foodborne bacteria. CONCLUSION: Citrullus colocynthis fruits and 4-methylquinoline analogues could be useful for the development of eco-friendly food supplemental agents and pharmaceuticals.

Poly-γ-glutamic acid enhances the quality of recombant erythropoietin produced by CHO cells.

The effect of poly-γ-glutamic acid (γPGA), which is produced by Bacillus sp., on the production of recombinant erythropoietin (rEPO) by Chinese hamster ovary (CHO) cells in suspension culture was evaluated. The growth, viability, and productivity of recombinant CHO cells were investigated in a chemically defined medium with 50 and 500 kD γPGAs at 0.075% or with Pluronic F68. Cell growth with the two γPGAs was lower than that with Pluronic F68 but significantly higher than that without any additive (control). The effect of additives on rEPO productivity was 50 kDa γPGA > 500 kDa γPGA > Pluronic F68 > control. Using EPO-dependent F-36E cells, we found that the effect of additives on rEPO quality was 500 kDa γPGA > 50 kDa γPGA > control > Pluronic F68. γPGA has an enhancement effect on the quality of rEPO produced by CHO cells.

Acaricidal toxicities of 1-hydroxynaphthalene from Scutellaria barbata and its derivatives against house dust and storage mites.

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.

T cell epitopes of SARS-CoV-2 spike protein and conserved surface protein of Plasmodium malariae share sequence homology.

Since its emergence in late 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading remarkably fast worldwide. Effective countermeasures require the rapid development of data and tools to monitor its spread and better understand immunogenic profile. However, limited information is available about the tools and target of the immune responses to SARS-CoV-2. In this study, we excogitated a new approach for analyzing phylogenetic relationships by using the whole prototype proteome sequences. Phylogenetic analysis on the whole prototype proteome sequences showed that SARS-CoV-2 was a direct descendant of Bat-CoV and was closely related to Pangolin-CoV, Bat-SL-CoV, and SARS-CoV. The pairwise comparison of SARS-CoV-2 with Bat-CoV showed an unusual replacement of the motif consisting of seven amino acids (NNLDSKV) within the spike protein of SARS-CoV-2. The replaced motif in the spike protein of SARS-CoV-2 was found in 12 other species, including a conserved surface protein of a malaria-causing pathogen, Plasmodium malariae. We further identified the T and B cell epitope sequence homology of SARS-CoV-2 spike protein with conserved surface protein of P. malariae using the Immune Epitope Database and Analysis Resource (IEDB). The shared immunodominant epitopes may provide immunity against SARS-CoV-2 infection to those previously infected with P. malariae.

Acaricidal activities of major constituents of essential oil of Juniperus chinensis leaves against house dust and stored food mites.

The acaricidal activities of major constituents from the oil of Juniperus chinensis (var. globosa) leaves were compared with those of DEET (N,N-diethyl-m-toluamide) by using impregnated fabric disk bioassay against Dermatophagoides spp. and Tyrophagus putrescentiae. Toxicity varied with doses as well as chemical composition. The 50% lethal doses (LD50) of J. chinensis oil against Dermatophagoides farinae, Dermatophagoides pteronyssinus, and T. putrescentiae were 21.60, 19.89, and 38.10 microg/cm2, respectively. The active constituent was purified using silica gel chromatography and high-performance liquid chromatography. The acaricidal component was identified as bomyl acetate through gas chromatography-mass spectrometry, 1H nuclear magnetic resonance (NMR), 13C-NMR, 1H-13C shift correlation spectrum-NMR, and distortionless enhancement by polarization transfer-NMR. The LD50 of bornyl acetate (2.94 microg/cm2) against D. farinae was significantly lower than those of DEET (37.13 microg/cm2) and alpha-eudesmol (29.72 microg/cm2). Similar results were observed when bomyl acetate and alpha-eudesmol were tested against D. pteronyssinus and T. putrescentiae. The lower LD50 of bornyl acetate indicates that it may be responsible for the major acaricidal activity against house dust and stored food mites, even though it constitutes only 19.5% of J. chinensis oil. Overall, these findings indicated that bornyl acetate and c-eudesmol have potential for use as control agents against house dust and stored food mites.

Acaricidal activity of triketone analogues derived from Leptospermum scoparium oil against house-dust and stored-food mites.

BACKGROUND: Various attempts to control the populations of house-dust and stored-food mites have been implemented using synthetic chemicals. Although effective, the repeated use of these chemicals has led to resistance owing to the mite's high reproductive potential and short life cycle. Therefore, this study aimed to develop natural acaricides using oils derived from Leptospermum scoparium JR & G Forst., which may affect the overall biological activity of a mite without adverse effects. Results were compared with those from using benzyl benzoate and N,N-diethyl-3-methylbenzamide (DEET). RESULTS: The LD(50) values of L. scoparium oil were 0.54, 0.67 and 1.12 microg cm(-2) against Dermatophagoides farinae (Hughes), D. pteronyssinus (Troussart) and Tyrophagus putrescentiae (Schrank) respectively. The active constituent isolated from L. scoparium was identified as leptospermone (6-isovaleryl-2,2,4,4-tetramethyl-1,3,5-cyclohexanetrione) by spectroscopic analysis. Based on the LD(50) values of leptospermone and its derivatives, the most toxic compound against D. farinae was leptospermone (0.07 microg cm(-2)), followed by 2,2,4,4,6,6-hexamethyl-1,3,5-cyclohexanetrione (1.21 microg cm(-2)), benzyl benzoate (10.03 microg cm(-2)) and DEET (37.12 microg cm(-2)). Furthermore, similar results were observed when the leptospermone and its derivatives were tested against D. pteronyssinus and T. putrescentiae. CONCLUSIONS: These results indicate that L. scoparium oil-derived materials, particularly leptospermone and 2,2,4,4,6,6-hexamethyl-1,3,5-cyclohexanetrione, have potential for development as new agents for the control of three species of mite.

The ABA effect on the accumulation of an invertase inhibitor transcript that is driven by the CAMV35S promoter in ARABIDOPSIS.

Invertase (beta-D-fructofuranosidase; EC 3.2.1.26) catalyzes the conversion of sucrose into glucose and fructose and is involved in an array of important processes, including phloem unloading, carbon partitioning, the response to pathogens, and the control of cell differentiation and development. Its importance may have caused the invertases to evolve into a multigene family whose members are regulated by a variety of different mechanisms, such as pH, sucrose levels, and inhibitor proteins. Although putative invertase inhibitors in the Arabidopsis genome are easy to locate, few studies have been conducted to elucidate their individual functions in vivo in plant growth and development because of their high redundancy. In this study we assessed the functional role of the putative invertase inhibitors in Arabidopsis by generating transgenic plants harboring a putative invertase inhibitor gene under the control of the CaMV35S promoter. A transgenic plant that expressed high levels of the putative invertase inhibitor transcript when grown under normal conditions was chosen for the current study. To our surprise, the stability of the invertase inhibitor transcripts was shown to be down-regulated by the phytohormone ABA (abscisic acid). It is well established that ABA enhances invertase activity in vivo but the underlying mechanisms are still poorly understood. Our results thus suggest that one way ABA regulates invertase activity is by down-regulating its inhibitor.

Acaricidal activity and function of mite indicator using plumbagin and its derivatives isolated from Diospyros kaki Thunb. roots (Ebenaceae).

Acaricidal effects of materials derived from Diospyros kaki roots against Dermatophagoides farinae and D. pteronyssinus were assessed using impregnated fabric disk bioassay and compared with that of the commercial benzyl benzoate. The observed responses varied according to dosage and mite species. The LD50 values of the chloroform extract of Diospyros kaki roots were 1.66 and 0.96 microg/cm2 against D. farinae and D. pteronyssinus. The chloroform extract of Diospyros kaki roots was approximately 15.2 more toxic than benzyl benzoate against D. farinae, and 7.6 times more toxic against D. pteronyssinus. Purification of the biologically active constituent from D. kaki roots was done by using silica gel chromatography and high-performance liquid chromatography. The structure of the acaricidal component was analyzed by GCMS, 1H-NMR, 13C-NMR, 1H-13C COSY-NMR, and DEPTNMR spectra, and identified as plumbagin. The acaricidal activity of plumbagin and its derivatives (naphthazarin, dichlon, 2,3-dibromo-1,4-naphthoquinone, and 2-bromo-1,4- naphthoquinone) was examined. On the basis of LD50 values, the most toxic compound against D. farinae was naphthazarin (0.011 microg/cm2) followed by plumbagin (0.019 microg/cm2), 2- bromo-1,4-naphthoquinone (0.079 microg/cm2), dichlon (0.422 microg/ cm2), and benzyl benzoate (9.14 microg/cm2). Additionally, the skin color of the dust mites was changed from colorless-transparent to dark brown-black by the treatment of plumbagin. Similar results have been exhibited in its derivatives (naphthazarin, dichlon, and 2-bromo-1,4-naphthoquinone). In contrast, little or no discoloration was observed for benzyl benzoate. From this point of view, plumbagin and its derivatives can be very useful for the potential control agents, lead compounds, and indicator of house dust mites.

Mite-control activities of active constituents isolated from Pelargonium graveolens against house dust mites.

The mite-control activities of materials obtained from Pelargonium graveolens oil against Dermatophagoides farinae and D. pteronyssinus were examined using an impregnated fabric disk bioassay and were compared with those shown by commercial benzyl benzoate and N,N-diethylm- toluamide (DEET). Purification of the biologically active constituents from P. graveolens oil was done by silica gel chromatography and high performance liquid chromatography. The structures of the active components were analyzed by EI/MS, (1)H-NMR, (13)C-NMR, (1)H-(13)C COSYNMR, and DEPT-NMR spectra, and were identified as geraniol (C(10)H(18)O, MW 154.25, trans-3,7-dimethyl-2,6- octadien-1-ol) and beta-citronellol (C(10)H(20)O, MW 156.27, 3,7-dimethyl-6-octen-1-ol). Based on the LD50 values, the most toxic compound was geraniol (0.26 microg/cm(2)), followed by beta-citronellol (0.28 microg/cm(2)), benzyl benzoate (10.03 microg/ cm(2)), and DEET (37.12 microg/cm(2)) against D. farinae. In the case of D. pteronyssinus, geraniol (0.28 microg/cm(2)) was the most toxic, followed by beta-citronellol (0.29 microg/cm(2)), benzyl benzoate (9.58 microg/cm(2)), and DEET (18.23 microg/cm(2)). These results suggest that D. farinae and D. pteronyssinus may be controlled more effectively by the application of geraniol and beta-citronellol than benzyl benzoate and DEET. Furthermore, geraniol and beta-citronellol isolated from P. graveolens could be useful for managing populations of D. farinae and D. pteronyssinus.

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.

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.

Antimicrobial activities of leptospermone isolated from Leptospermum scoparium seeds and structure-activity relationships of its derivatives against foodborne bacteria.

This study was carried out to determine the antimicrobial activities of leptospermone isolated from Leptospermum scoparium and its derivatives against six foodborne bacteria (Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, Shigella sonnei, Staphylococcus intermedius and Staphylococcus aureus), with a view to developing safer antimicrobial agents. The essential oil of L. scoparium seeds possessed potent antimicrobial activity against six bacterial strains. The antimicrobial compound of L. scoparium was isolated by chromatographic analyses and identified as leptospermone. To investigate the structure-activity relationships, the antimicrobial activities of leptospermone and its derivatives (2-acetyl-1,3-cyclohexanedione, 1,3-cyclohexanedione, 1,2,3-cyclohexanetrione-1,3-dioxime, 5,5-dimethyl-1,3-cyclohexanedione and 2,2,4,4,6,6-hexamethyl-1,3,5-cyclohexanetrione) were examined against six foodborne bacteria. Based on the MIC values, leptospermone (MIC 23.6-69.7 µg/mL), 1,2,3-cyclohexanetrione-1,3-dioxime (MIC 43.9-88.5 µg/mL) and 2,2,4,4,6,6-hexamethyl-1,3,5-cyclohexanetrione (MIC 43.9-88.5 µg/mL) exhibited antimicrobial activities against the six foodborne bacteria. These results indicated that leptospermone and its derivatives could potentially be developed as natural food preservatives, rather than using hazardous synthetic preservatives.

Acaricidal toxicities and synergistic activities of Salvia lavandulifolia oil constituents against synanthropic mites.

BACKGROUND: The acaricidal activity of Salvia lavandulifolia oil and its major components was evaluated using contact and vapor bioassays. Synergistic interactions among components contained in S. lavandulifolia oil were studied. RESULTS: The 50% lethal dose (LD50 ) of S. lavandulifolia oil was 3.66, 3.37, and 5.04 µg cm-3 , respectively, in the vapor bioassay against Dermatophagoides farinae, Dermatophagoides pteronyssinus and Tyrophagus putrescentiae. The major components of S. lavandulifolia oil were (-)-camphor, camphene, 1,8-cineole, (±)-limonene, and α-pinene (79.11% combined). Several combinations of these components exhibited synergistic effects against D. farinae, D. pteronyssinus, and T. putrescentiae, particularly (-)-camphor, camphene, and α-pinene. (-)-Camphor usually had synergistic interactive effects in the mixtures. For the vapor action, the mixture of (-)-camphor, camphene and α-pinene was the most potent combination against D. farinae (R = 2.34), D. pteronyssinus (R = 2.75), and T. putrescentiae (R = 2.30) when used at their naturally occurring ratio. CONCLUSION: This study is the first report on the acaricidal activity of S. lavandulifolia oil and the synergistic interactive effects of its components against D. farinae, D. pteronyssinus and T. putrescentiae. The oil may be an alternative tool for the control of synanthropic mites. © 2018 Society of Chemical Industry.

Combined toxicity of endosulfan and phenanthrene mixtures and induced molecular changes in adult Zebrafish (Danio rerio).

Individual and combined toxicities of endosulfan (ENDO) with phenanthrene (PHE) were evaluated using zebrafish (Danio rerio) adults. The 96-h LC50 values for ENDO and PHE were 4.6 µg L-1 and 920 µg L-1, respectively. To evaluate the mixture toxicity, LC10 and LC50 concentrations were grouped into four combinations as ENDO-LC10 + PHE-LC10, ENDO-LC10 + PHE-LC50, ENDO-LC50 + PHE-LC10, and ENDO-LC50 + PHE-LC50, and their acute toxicities were determined. The combination of LC50-ENDO and LC10-PHE exhibited a synergistic effect. In addition, acetylcholinesterase activity decreased in zebrafish bodies exposed to ENDO with or without PHE. Combined treatments induced higher glutathione S-transferase activity compared to individual treatments. Carboxylesterase activity increased in both heads and bodies of ENDO-treated fishes compared with PHE-treated fishes. Using RT-qPCR technique, CYP1A gene expression significantly up-regulated in all combinations, whereas CYP3A was unchanged, suggesting that enzymes involved in defense may play different roles in the detoxification. CYP7A1 gene responsible for bile acid biosynthesis is dramatically down-regulated after exposure to the synergistic combination exposure, referring that the synergistic effect may be resulted from the reduction of bile production in zebrafishes. Among gender-related genes, CYP11A1 and CYP17A1 genes in female zebrafish decreased after treatment with ENDO alone and combination of LC50-ENDO and LC10-PHE. This might be related to a reduction in cortisol production. The overall results indicated that ENDO and PHE were toxic to zebrafish adults both individually and in combination, and that their co-presence induced changes in the expression of genes responsible for metabolic processes and defense mechanisms.

Acaricidal effects of quinone and its congeners and color alteration of Dermatophagoides spp. with quinone.

Acaricidal activity of the active constituent derived from Pyrus ussuriensis fruits against Dermatophagoides farinae and D. pteronyssinus was examined and compared with that of the commercial benzyl benzoate. The LD50 value of the ethyl acetate fraction obtained from the aqueous extract of P ussuriensis fruits was 9.51 and 8.59 microg/cm3 against D. farinae and D. pteronyssinus, respectively. The active constituent was identified as quinone by spectroscopic analyses. On the basis of LD50 values with quinone and its congeners, the compound most toxic against D. farinae was quinone (1.19 microg/cm3), followed by quinaldine (1.46), benzyl benzoate (9.32), 4-quinolinol (86.55), quinine (89.16), and 2-quinolinol (91.13). Against D. pteronyssinus, these were quinone (1.02 microg/ cm3), followed by quinaldine (1.29), benzyl benzoate (8.54), 4-quinolinol (78.63), quinine (82.33), and 2-quinolinol (86.24). These results indicate that the acaricidal activity of the aqueous extracts can be mostly attributed to quinone. Quinone was about 7.8 and 8.4 times more toxic than benzyl benzoate against D. farinae and D. pteronyssinus. Additionally, quinaldine was about 6.4 and 6.6 times more toxic than benzyl benzoate against D. farinae and D. pteronyssinus, respectively. Furthermore, the skin color of the dust mites was changed from colorless-transparent to dark brown-black by the treatment of quinone. These results indicate that quinone can be very useful as potential control agents, lead compounds, or the indicator of house dust mites.