Yoshiaki Nakagawa - Academia.edu (original) (raw)
Papers by Yoshiaki Nakagawa
Pest Management Science, 2002
Fifteen 5-substituted 1-(6-chloro-3-pyridylmethyl)-2-nitromethylene-1,3-diazacyclohexanes and thr... more Fifteen 5-substituted 1-(6-chloro-3-pyridylmethyl)-2-nitromethylene-1,3-diazacyclohexanes and three other related compounds having a five- or seven-membered ring were synthesized and their biological activities were measured in vivo and in vitro. The insecticidal (in vivo) activity was evaluated against houseflies Musca domestica L under synergistic conditions with propargyl propyl phenyl phosphonate and piperonyl butoxide. The binding activity of each compound to nicotinic acetylcholine receptor in vitro was measured using [125I]α-bungarotoxin. The insecticidal activities of the unsubstituted diazacyclohexane analogues were slightly higher than those of the imidazolidine analogues, but the enlargement of ring size to diazacycloheptane lowered the activity. Substitution of 1,3-diazacyclohexane or imidazolidine rings was not generally favourable for the activity, but the unsubstituted 1,3-diazacyclohexane analogue showed the highest binding activity. Ring substitutions and ring enlargement decreased the activity 100–30 000-fold.© 2002 Society of Chemical Industry
![Research paper thumbnail of Inhibition of [ 3 H] ponasterone A binding by ecdysone agonists in the intact Kc cell line](https://attachments.academia-assets.com/49015072/thumbnails/1.jpg)
](Insect Biochemistry and Molecular Biology, 2002
PoA) by ecdysone agonists including diacylhydrazines such as RH-5849, tebufenozide (RH-5992) and ... more PoA) by ecdysone agonists including diacylhydrazines such as RH-5849, tebufenozide (RH-5992) and methoxyfenozide (RH-2485) was examined in intact Drosophila Kc cells. The reciprocal logarithm of the concentration at which there is 50% inhibition of [ 3 H]PoA binding, pIC 50 (M), was determined as the binding activity for all compounds from each concentration-response curve. The order of the activity was PoAϾ20-hydroxyecdysoneϾcyasteroneϾino-kosteroneՆmakisterone AϾmethoxyfenozideՆtebufenozideϾecdysoneϾRH-5849. The ranking of steroidal ecdysone analogs is consistent with that obtained against Spodoptera Sf-9 cells. Furthermore, in terms of pIC 50 , all binding activity for ecdysone analogs, except ecdysone, estimated in the Kc cell line system was significantly higher than that for the Sf-9 cell line system. However, the activity of ecdysone was comparable between Kc and Sf-9 cells. The activity of diacylhydrazine analogs against Kc cells was significantly low compared with that against Sf-9 cells. The potency of methoxyfenozide was 1/200 that of PoA, which showed the highest activity in the Kc cell line system among all compounds tested. The activity of tebufenozide analogs having an n-pentyl or n-hexyl group instead of a 4-ethylphenyl group was similar to that of RH-5849.
Pesticide Science, 1998
Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measur... more Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measured for a series of N-tert-butyl-dibenzoylhydrazines having various substituents on the benzoyl (A-ring) moiety nearer to the tert-butyl group, with the other benzoyl (B-ring) moiety being unsubstituted. The effects of these substituent on the larvicidal activity were analyzed using classical quantitative structure-activity relationship (QSAR) procedures. The effects of substituents on the A-ring moiety on larvicidal activity were entirely different from those against the lepidopteran rice stem borer Chilo suppressalis (Walker) previously reported. Position-speci®c steric and hydrophobic effects, as well as certain substitution patterns, were likely to participate in modifying the larvicidal activity. The activity of para-substituted compounds was generally lower than that of un-, ortho-and meta-substituted compounds. Most multi-substituted compounds showed an activity equivalent to or lower than that of the unsubstituted compound. Among 46 compounds tested, the 2-sec-butoxy analogue was most potent against L decemlineata, although this compound had previously been shown to be only weakly active against C suppressalis.
Pest Management Science, 2001
Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measur... more Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measured for a series of N-tert-butyl-dibenzoylhydrazines having various substituents on the benzoyl (A-ring) moiety nearer to the tert-butyl group, with the other benzoyl (B-ring) moiety being unsubstituted. The effects of these substituent on the larvicidal activity were analyzed using classical quantitative structure-activity relationship (QSAR) procedures. The effects of substituents on the A-ring moiety on larvicidal activity were entirely different from those against the lepidopteran rice stem borer Chilo suppressalis (Walker) previously reported. Position-specific steric and hydrophobic effects, as well as certain substitution patterns, were likely to participate in modifying the larvicidal activity. The activity of para-substituted compounds was generally lower than that of un-, ortho- and meta-substituted compounds. Most multi-substituted compounds showed an activity equivalent to or lower than that of the unsubstituted compound. Among 46 compounds tested, the 2-sec-butoxy analogue was most potent against L decemlineata, although this compound had previously been shown to be only weakly active against C suppressalis.© 2001 Society of Chemical Industry
Pest Management Science, 2003
The electrophysiological actions of various neonicotinoids, including substituted benzyl derivati... more The electrophysiological actions of various neonicotinoids, including substituted benzyl derivatives, against recombinant Drosophila SAD/chicken β2 hybrid nicotinic acetylcholine receptor (nAChR) were measured to analyze the relationships between the invivo (insecticidal) and in vitro (binding and agonist) activities. Most of the neonicotinoids tested were capable of inducing inward currents by activating the hybrid nAChRs expressed in Xenopuslaevis oocytes, whereas some compounds had no agonist activity and only blocked the acetylcholine-induced currents. Variations in the agonist activity were well correlated with those in the binding potency evaluated using [3H]imidacloprid as well as insecticidal activities. Copyright © 2003 Society of Chemical Industry
Steroids, 1995
Ecdysone analogs with various side chains at the 17-position of the steroid structure enhanced th... more Ecdysone analogs with various side chains at the 17-position of the steroid structure enhanced the incorporation of N-acetylglucosamine as 20-hydroxyecdysone into the cultured integument prepared from Chilo suppressalis. Their activity in terms of the concentration required to give 50% of the maximum response varied with the structure. Piperonyl butoxide, an inhibitor of oxidation metabolism, did not enhance the in vitro effect of the compounds. The order of potency was ponasterone A > 20-hydroxyecdysone > cyasterone > inokosterone > makisterone A >> ecdysone. (Steroids 60:401-405, 1995) hancing effect of 20E and analogs on the incorporation of GIuNAc in the absence and presence of PB. We discuss the structure-activity relationship of six ecdysone analogs.
Archives of Insect Biochemistry and Physiology, 1999
Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause ... more Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause precocious larval molt leading to death. Among them, tebufenozide (RH-5992) is used in practice as insecticide to control lepidopteran pests selectively. Recently, a new dibenzoylhydrazine, methoxyfenozide (RH-2485), with a higher activity for Lepidoptera, has been discovered. To obtain insight into the molecular mechanisms involved in the insecticidal selectivity of the dibenzoylhydrazine family, we measured the in vivo toxicity of these dibenzoylhydrazines against larval stages of the beet armyworm, Spodoptera exigua, and their action on in vitro cultured imaginal discs. We found that both nonsteroidal ecdysone agonists induced premature and lethal molting, and caused the same effect as 20-hydroxyecdysone in vitro. Furthermore, we measured the larvicidal activity against S. exigua of a series of dibenzoylhydrazines, in which ring-substituents were varied in a range of halogen, lower alkyl, OCH 3 , SCH 3 , Ph, CN, NO 2 , and CF 3 . The substituent effects on the larvicidal activity against S. exigua were very similar to that for another lepidopteran insect species Chilo suppressalis, suggesting that the molecular mechanism of action of these compounds is similar within both lepidopteran species. Arch. Insect Biochem. Physiol. 41:42-53, 1999.
Pesticide Science, 1999
Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measur... more Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measured for a series of N-tert-butyl-dibenzoylhydrazines having various substituents on the benzoyl (A-ring) moiety nearer to the tert-butyl group, with the other benzoyl (B-ring) moiety being unsubstituted. The effects of these substituent on the larvicidal activity were analyzed using classical quantitative structure-activity relationship (QSAR) procedures. The effects of substituents on the A-ring moiety on larvicidal activity were entirely different from those against the lepidopteran rice stem borer Chilo suppressalis (Walker) previously reported. Position-speci®c steric and hydrophobic effects, as well as certain substitution patterns, were likely to participate in modifying the larvicidal activity. The activity of para-substituted compounds was generally lower than that of un-, ortho-and meta-substituted compounds. Most multi-substituted compounds showed an activity equivalent to or lower than that of the unsubstituted compound. Among 46 compounds tested, the 2-sec-butoxy analogue was most potent against L decemlineata, although this compound had previously been shown to be only weakly active against C suppressalis.
![Research paper thumbnail of Inhibition of [ 3H]ponasterone A binding by ecdysone agonists in the intact Sf9 cell line](https://attachments.academia-assets.com/49014923/thumbnails/1.jpg)
](Steroids, 2000
Ecdysone agonists, including dibenzoylhydrazines, significantly inhibited the binding of [ 3 H]po... more Ecdysone agonists, including dibenzoylhydrazines, significantly inhibited the binding of [ 3 H]ponasterone A ([ 3 H]PoA) in intact Sf-9 cells (Spodoptera frugiperda). The amount of [ 3 H]PoA binding varied in a concentration-dependent manner. According to the IC 50 , concentration at which there is 50% inhibition, the order of potency of typical ecdysone agonists is tebufenozide
Journal of Pesticide Science, 2004
ABSTRACT
Febs Journal, 2005
cDNA cloning of ecdysone receptor (EcR) and ultraspiracle (USP) of the coleopteran Colorado potat... more cDNA cloning of ecdysone receptor (EcR) and ultraspiracle (USP) of the coleopteran Colorado potato beetle Leptinotarsa decemlineata (LdEcR and LdUSP) was conducted. Amino-acid sequences of the proteins deduced from cDNA sequences showed striking homology to those of other insects, especially the coleopteran yellow mealworm Tenebrio molitor. Northern hybridization analysis showed a 12.4-kb message for the LdEcR A-isoform, a 10.5-kb message for the LdEcR B1-isoform and a 5.7-kb message for the LdUSP, in fat body, gut, integument, testis and ovaries. In developmental profile studies, expression of both the LdEcR and LdUSP transcript in integument changed dramatically. In gel mobility shift assays, in vitro translated LdEcR alone bound weakly to the pal1 ecdysone response element, although LdUSP alone did not, and this binding was dramatically enhanced by the addition of LdUSP. LdEcR/LdUSP complex also showed significant binding to an ecdysone agonist, ponasterone A (KD = 2.8 nm), while LdEcR alone showed only weak binding (KD = 73.4 nm), and LdUSP alone did not show any binding. The receptor-binding affinity of various ecdysone agonists to LdEcR/LdUSP was not correlated to their larvicidal activity to L. decemlineata. From these results, it was suggested that multiple factors including the receptor binding affinity are related to the determination of the larvicidal activity of nonsteroidal ecdysone agonists in L. decemlineata.
Pesticide Science, 1998
... A., Nishiwaki, H., Cho, W.-J., Nakagawa, Y., Nishimura, K. and Ueno, T. (1998), Prediction of... more ... A., Nishiwaki, H., Cho, W.-J., Nakagawa, Y., Nishimura, K. and Ueno, T. (1998), Prediction of the binding mode of imidacloprid ... doi: 10.1002/(SICI)1096-9063(1998100)54:2<134::AID-PS786> 3.0.CO;2-G. ... Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan. 2 ...
Faseb Journal, 2003
Screening systems for ecdysteroid mimetic or antiecdysteroid substances in plant extracts or libr... more Screening systems for ecdysteroid mimetic or antiecdysteroid substances in plant extracts or libraries of synthetic compounds are commonly based on the observation of morphological and/or growth responses in insect cell lines. Because these responses are slow and require careful monitoring, existing screening systems are considered limited regarding their applicability to analysis in high-throughput (HT) formats. Here we describe the generation of transformed silkmoth (Bombyx mori) cell lines that respond to the addition of ecdysone-like substances through the expression of the green fluorescent protein (GFP) and the appearance of green fluorescence. Because tests consist of three simple steps, i.e., 1) distribution of transformed cells in microtiter plates; 2) addition of compounds/extracts at different concentrations; and 3) quantification of fluorescence intensity by a fluorescence plate reader, they can be performed quickly and be easily adapted to a HT format. The generated reporter cell lines are used for the screening of extracts from available plant collections for the presence of compounds with ecdysone mimetic or antagonistic activities as well as for monitoring subsequent activity during enrichment and purification steps. The same cell lines are also used here for the determination of structure-activity relationships among available synthetic dibenzoylhydrazine derivatives. Finally, for the identified agonists, we show that their activity as determined by the cell-based screening assays parallels their bioactivity in growth inhibition and toxicity assays carried out on live insects.
Archives of Insect Biochemistry and Physiology, 1999
Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause ... more Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause precocious larval molt leading to death. Among them, tebufenozide (RH-5992) is used in practice as insecticide to control lepidopteran pests selectively. Recently, a new dibenzoylhydrazine, methoxyfenozide (RH-2485), with a higher activity for Lepidoptera, has been discovered. To obtain insight into the molecular mechanisms involved in the insecticidal selectivity of the dibenzoylhydrazine family, we measured the in vivo toxicity of these dibenzoylhydrazines against larval stages of the beet armyworm, Spodoptera exigua, and their action on in vitro cultured imaginal discs. We found that both nonsteroidal ecdysone agonists induced premature and lethal molting, and caused the same effect as 20-hydroxyecdysone in vitro. Furthermore, we measured the larvicidal activity against S. exigua of a series of dibenzoylhydrazines, in which ring-substituents were varied in a range of halogen, lower alkyl, OCH 3 , SCH 3 , Ph, CN, NO 2 , and CF 3 . The substituent effects on the larvicidal activity against S. exigua were very similar to that for another lepidopteran insect species Chilo suppressalis, suggesting that the molecular mechanism of action of these compounds is similar within both lepidopteran species. Arch. Insect Biochem. Physiol. 41:42-53, 1999.
Pest Management Science, 2000
ABSTRACT
Pesticide Science, 1995
The ability to stimulate N-acetylglucosamine (GluNAc) incorporation in-vitro of a number of N-ter... more The ability to stimulate N-acetylglucosamine (GluNAc) incorporation in-vitro of a number of N-tert-butyl-N,N′-dibenzoylhydrazines having various substituents on both phenyl rings was measured in cultured integument excised from the rice stem borer (Chilo suppressalis Walker). The relationship between in-vitro and larvicidal potency was approximately linear. The substituent effects on variations in the potency were similar between in-vitro and larvicidal activities. An inhibitor of oxidative detoxication, piperonyl butoxide, had no synergistic effects on the in-vitro potency. The ability of some dibenzoylhydrazines to inhibit GluNAc incorporation at exposure periods longer than the optimum for stimulation was also measured in a similar cultured integument system. The relationship between the inhibitory and stimulatory potency indices was linear, indicating that the larvicidal activity of dibenzoylhydrazines is closely related to its ability to stimulate as well as to inhibit GluNAc incorporation into the larval cuticle.
Environmental Toxicology and Chemistry, 1992
The partition coefficient P i n the 1-octanol/water system was analyzed for a great number of mul... more The partition coefficient P i n the 1-octanol/water system was analyzed for a great number of multisubstituted benzenes of ecotoxicological importance consisting of acetanilides, benzamides, nitrobenzenes, and anisoles having various substitution patterns in terms of the A log P(1og Plog P [unsubstituted benzene]) quantitatively with free energy-related physicochemical substituent parameters. The analyses showed that the stereoelectronic effects of ortho, meta, and para substituents on the relative solvation of individual polar groups capable of hydrogen bonding with the partitioning solvents are very important in determining the variations in the log P value. The effects were additive in the set of complicated multisubstituted benzenes, leading to a correlation equation represented by a linear combination of terms of hydrophobic, electronic, and steric parameters summed up over substituents. It was suggested that the procedure be extended to analyze and predict the log P value of any multiply substituted benzenes.
Pesticide Science, 1994
The larvicidal activity of a number of 1-(substituted benzoyl)-2-benzoyl–1 -ten-butylhydrazines a... more The larvicidal activity of a number of 1-(substituted benzoyl)-2-benzoyl–1 -ten-butylhydrazines against the rice stem borer (Chilo suppressalis Walk.) was measured. Variations in the activity were examined quantitatively using physico-chemical substituent and molecular parameters and regression analysis. The results indicated that the molecular hydrophobicity and the electron-withdrawing inductive/ field effect of ontho substituents are favourable to larvicidal activity. The bulkiness of substituents at the meta and para positions was unfavourable to activity, substitution at the para position being more unfavourable than that at the meta position in terms of van der Waals' volume. The 2,3–, 2,5- and 2,6-disubstitution patterns were also unfavourable to activity. Reductions in larvicidal activity caused by the 2,6-,- 2,3,5- and 2,3,4,5-substitutions were greater than those induced by the 2,3- and 2,5-disubstitutions. When the sum of contributions from favourable effects is greater than that from unfavourable effects, the larvicidal activity is expected to be superior to that of the unsubstituted compound.
Pest Management Science, 2002
Fifteen 5-substituted 1-(6-chloro-3-pyridylmethyl)-2-nitromethylene-1,3-diazacyclohexanes and thr... more Fifteen 5-substituted 1-(6-chloro-3-pyridylmethyl)-2-nitromethylene-1,3-diazacyclohexanes and three other related compounds having a five- or seven-membered ring were synthesized and their biological activities were measured in vivo and in vitro. The insecticidal (in vivo) activity was evaluated against houseflies Musca domestica L under synergistic conditions with propargyl propyl phenyl phosphonate and piperonyl butoxide. The binding activity of each compound to nicotinic acetylcholine receptor in vitro was measured using [125I]α-bungarotoxin. The insecticidal activities of the unsubstituted diazacyclohexane analogues were slightly higher than those of the imidazolidine analogues, but the enlargement of ring size to diazacycloheptane lowered the activity. Substitution of 1,3-diazacyclohexane or imidazolidine rings was not generally favourable for the activity, but the unsubstituted 1,3-diazacyclohexane analogue showed the highest binding activity. Ring substitutions and ring enlargement decreased the activity 100–30 000-fold.© 2002 Society of Chemical Industry
Insect Biochemistry and Molecular Biology, 2002
PoA) by ecdysone agonists including diacylhydrazines such as RH-5849, tebufenozide (RH-5992) and ... more PoA) by ecdysone agonists including diacylhydrazines such as RH-5849, tebufenozide (RH-5992) and methoxyfenozide (RH-2485) was examined in intact Drosophila Kc cells. The reciprocal logarithm of the concentration at which there is 50% inhibition of [ 3 H]PoA binding, pIC 50 (M), was determined as the binding activity for all compounds from each concentration-response curve. The order of the activity was PoAϾ20-hydroxyecdysoneϾcyasteroneϾino-kosteroneՆmakisterone AϾmethoxyfenozideՆtebufenozideϾecdysoneϾRH-5849. The ranking of steroidal ecdysone analogs is consistent with that obtained against Spodoptera Sf-9 cells. Furthermore, in terms of pIC 50 , all binding activity for ecdysone analogs, except ecdysone, estimated in the Kc cell line system was significantly higher than that for the Sf-9 cell line system. However, the activity of ecdysone was comparable between Kc and Sf-9 cells. The activity of diacylhydrazine analogs against Kc cells was significantly low compared with that against Sf-9 cells. The potency of methoxyfenozide was 1/200 that of PoA, which showed the highest activity in the Kc cell line system among all compounds tested. The activity of tebufenozide analogs having an n-pentyl or n-hexyl group instead of a 4-ethylphenyl group was similar to that of RH-5849.
Pesticide Science, 1998
Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measur... more Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measured for a series of N-tert-butyl-dibenzoylhydrazines having various substituents on the benzoyl (A-ring) moiety nearer to the tert-butyl group, with the other benzoyl (B-ring) moiety being unsubstituted. The effects of these substituent on the larvicidal activity were analyzed using classical quantitative structure-activity relationship (QSAR) procedures. The effects of substituents on the A-ring moiety on larvicidal activity were entirely different from those against the lepidopteran rice stem borer Chilo suppressalis (Walker) previously reported. Position-speci®c steric and hydrophobic effects, as well as certain substitution patterns, were likely to participate in modifying the larvicidal activity. The activity of para-substituted compounds was generally lower than that of un-, ortho-and meta-substituted compounds. Most multi-substituted compounds showed an activity equivalent to or lower than that of the unsubstituted compound. Among 46 compounds tested, the 2-sec-butoxy analogue was most potent against L decemlineata, although this compound had previously been shown to be only weakly active against C suppressalis.
Pest Management Science, 2001
Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measur... more Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measured for a series of N-tert-butyl-dibenzoylhydrazines having various substituents on the benzoyl (A-ring) moiety nearer to the tert-butyl group, with the other benzoyl (B-ring) moiety being unsubstituted. The effects of these substituent on the larvicidal activity were analyzed using classical quantitative structure-activity relationship (QSAR) procedures. The effects of substituents on the A-ring moiety on larvicidal activity were entirely different from those against the lepidopteran rice stem borer Chilo suppressalis (Walker) previously reported. Position-specific steric and hydrophobic effects, as well as certain substitution patterns, were likely to participate in modifying the larvicidal activity. The activity of para-substituted compounds was generally lower than that of un-, ortho- and meta-substituted compounds. Most multi-substituted compounds showed an activity equivalent to or lower than that of the unsubstituted compound. Among 46 compounds tested, the 2-sec-butoxy analogue was most potent against L decemlineata, although this compound had previously been shown to be only weakly active against C suppressalis.© 2001 Society of Chemical Industry
Pest Management Science, 2003
The electrophysiological actions of various neonicotinoids, including substituted benzyl derivati... more The electrophysiological actions of various neonicotinoids, including substituted benzyl derivatives, against recombinant Drosophila SAD/chicken β2 hybrid nicotinic acetylcholine receptor (nAChR) were measured to analyze the relationships between the invivo (insecticidal) and in vitro (binding and agonist) activities. Most of the neonicotinoids tested were capable of inducing inward currents by activating the hybrid nAChRs expressed in Xenopuslaevis oocytes, whereas some compounds had no agonist activity and only blocked the acetylcholine-induced currents. Variations in the agonist activity were well correlated with those in the binding potency evaluated using [3H]imidacloprid as well as insecticidal activities. Copyright © 2003 Society of Chemical Industry
Steroids, 1995
Ecdysone analogs with various side chains at the 17-position of the steroid structure enhanced th... more Ecdysone analogs with various side chains at the 17-position of the steroid structure enhanced the incorporation of N-acetylglucosamine as 20-hydroxyecdysone into the cultured integument prepared from Chilo suppressalis. Their activity in terms of the concentration required to give 50% of the maximum response varied with the structure. Piperonyl butoxide, an inhibitor of oxidation metabolism, did not enhance the in vitro effect of the compounds. The order of potency was ponasterone A > 20-hydroxyecdysone > cyasterone > inokosterone > makisterone A >> ecdysone. (Steroids 60:401-405, 1995) hancing effect of 20E and analogs on the incorporation of GIuNAc in the absence and presence of PB. We discuss the structure-activity relationship of six ecdysone analogs.
Archives of Insect Biochemistry and Physiology, 1999
Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause ... more Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause precocious larval molt leading to death. Among them, tebufenozide (RH-5992) is used in practice as insecticide to control lepidopteran pests selectively. Recently, a new dibenzoylhydrazine, methoxyfenozide (RH-2485), with a higher activity for Lepidoptera, has been discovered. To obtain insight into the molecular mechanisms involved in the insecticidal selectivity of the dibenzoylhydrazine family, we measured the in vivo toxicity of these dibenzoylhydrazines against larval stages of the beet armyworm, Spodoptera exigua, and their action on in vitro cultured imaginal discs. We found that both nonsteroidal ecdysone agonists induced premature and lethal molting, and caused the same effect as 20-hydroxyecdysone in vitro. Furthermore, we measured the larvicidal activity against S. exigua of a series of dibenzoylhydrazines, in which ring-substituents were varied in a range of halogen, lower alkyl, OCH 3 , SCH 3 , Ph, CN, NO 2 , and CF 3 . The substituent effects on the larvicidal activity against S. exigua were very similar to that for another lepidopteran insect species Chilo suppressalis, suggesting that the molecular mechanism of action of these compounds is similar within both lepidopteran species. Arch. Insect Biochem. Physiol. 41:42-53, 1999.
Pesticide Science, 1999
Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measur... more Larvicidal activity against the Colorado potato beetle Leptinotarsa decemlineata (Say) was measured for a series of N-tert-butyl-dibenzoylhydrazines having various substituents on the benzoyl (A-ring) moiety nearer to the tert-butyl group, with the other benzoyl (B-ring) moiety being unsubstituted. The effects of these substituent on the larvicidal activity were analyzed using classical quantitative structure-activity relationship (QSAR) procedures. The effects of substituents on the A-ring moiety on larvicidal activity were entirely different from those against the lepidopteran rice stem borer Chilo suppressalis (Walker) previously reported. Position-speci®c steric and hydrophobic effects, as well as certain substitution patterns, were likely to participate in modifying the larvicidal activity. The activity of para-substituted compounds was generally lower than that of un-, ortho-and meta-substituted compounds. Most multi-substituted compounds showed an activity equivalent to or lower than that of the unsubstituted compound. Among 46 compounds tested, the 2-sec-butoxy analogue was most potent against L decemlineata, although this compound had previously been shown to be only weakly active against C suppressalis.
Steroids, 2000
Ecdysone agonists, including dibenzoylhydrazines, significantly inhibited the binding of [ 3 H]po... more Ecdysone agonists, including dibenzoylhydrazines, significantly inhibited the binding of [ 3 H]ponasterone A ([ 3 H]PoA) in intact Sf-9 cells (Spodoptera frugiperda). The amount of [ 3 H]PoA binding varied in a concentration-dependent manner. According to the IC 50 , concentration at which there is 50% inhibition, the order of potency of typical ecdysone agonists is tebufenozide
Journal of Pesticide Science, 2004
ABSTRACT
Febs Journal, 2005
cDNA cloning of ecdysone receptor (EcR) and ultraspiracle (USP) of the coleopteran Colorado potat... more cDNA cloning of ecdysone receptor (EcR) and ultraspiracle (USP) of the coleopteran Colorado potato beetle Leptinotarsa decemlineata (LdEcR and LdUSP) was conducted. Amino-acid sequences of the proteins deduced from cDNA sequences showed striking homology to those of other insects, especially the coleopteran yellow mealworm Tenebrio molitor. Northern hybridization analysis showed a 12.4-kb message for the LdEcR A-isoform, a 10.5-kb message for the LdEcR B1-isoform and a 5.7-kb message for the LdUSP, in fat body, gut, integument, testis and ovaries. In developmental profile studies, expression of both the LdEcR and LdUSP transcript in integument changed dramatically. In gel mobility shift assays, in vitro translated LdEcR alone bound weakly to the pal1 ecdysone response element, although LdUSP alone did not, and this binding was dramatically enhanced by the addition of LdUSP. LdEcR/LdUSP complex also showed significant binding to an ecdysone agonist, ponasterone A (KD = 2.8 nm), while LdEcR alone showed only weak binding (KD = 73.4 nm), and LdUSP alone did not show any binding. The receptor-binding affinity of various ecdysone agonists to LdEcR/LdUSP was not correlated to their larvicidal activity to L. decemlineata. From these results, it was suggested that multiple factors including the receptor binding affinity are related to the determination of the larvicidal activity of nonsteroidal ecdysone agonists in L. decemlineata.
Pesticide Science, 1998
... A., Nishiwaki, H., Cho, W.-J., Nakagawa, Y., Nishimura, K. and Ueno, T. (1998), Prediction of... more ... A., Nishiwaki, H., Cho, W.-J., Nakagawa, Y., Nishimura, K. and Ueno, T. (1998), Prediction of the binding mode of imidacloprid ... doi: 10.1002/(SICI)1096-9063(1998100)54:2<134::AID-PS786> 3.0.CO;2-G. ... Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan. 2 ...
Faseb Journal, 2003
Screening systems for ecdysteroid mimetic or antiecdysteroid substances in plant extracts or libr... more Screening systems for ecdysteroid mimetic or antiecdysteroid substances in plant extracts or libraries of synthetic compounds are commonly based on the observation of morphological and/or growth responses in insect cell lines. Because these responses are slow and require careful monitoring, existing screening systems are considered limited regarding their applicability to analysis in high-throughput (HT) formats. Here we describe the generation of transformed silkmoth (Bombyx mori) cell lines that respond to the addition of ecdysone-like substances through the expression of the green fluorescent protein (GFP) and the appearance of green fluorescence. Because tests consist of three simple steps, i.e., 1) distribution of transformed cells in microtiter plates; 2) addition of compounds/extracts at different concentrations; and 3) quantification of fluorescence intensity by a fluorescence plate reader, they can be performed quickly and be easily adapted to a HT format. The generated reporter cell lines are used for the screening of extracts from available plant collections for the presence of compounds with ecdysone mimetic or antagonistic activities as well as for monitoring subsequent activity during enrichment and purification steps. The same cell lines are also used here for the determination of structure-activity relationships among available synthetic dibenzoylhydrazine derivatives. Finally, for the identified agonists, we show that their activity as determined by the cell-based screening assays parallels their bioactivity in growth inhibition and toxicity assays carried out on live insects.
Archives of Insect Biochemistry and Physiology, 1999
Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause ... more Ring-substituted dibenzoylhydrazines are well known as nonsteroidal ecdysone agonists that cause precocious larval molt leading to death. Among them, tebufenozide (RH-5992) is used in practice as insecticide to control lepidopteran pests selectively. Recently, a new dibenzoylhydrazine, methoxyfenozide (RH-2485), with a higher activity for Lepidoptera, has been discovered. To obtain insight into the molecular mechanisms involved in the insecticidal selectivity of the dibenzoylhydrazine family, we measured the in vivo toxicity of these dibenzoylhydrazines against larval stages of the beet armyworm, Spodoptera exigua, and their action on in vitro cultured imaginal discs. We found that both nonsteroidal ecdysone agonists induced premature and lethal molting, and caused the same effect as 20-hydroxyecdysone in vitro. Furthermore, we measured the larvicidal activity against S. exigua of a series of dibenzoylhydrazines, in which ring-substituents were varied in a range of halogen, lower alkyl, OCH 3 , SCH 3 , Ph, CN, NO 2 , and CF 3 . The substituent effects on the larvicidal activity against S. exigua were very similar to that for another lepidopteran insect species Chilo suppressalis, suggesting that the molecular mechanism of action of these compounds is similar within both lepidopteran species. Arch. Insect Biochem. Physiol. 41:42-53, 1999.
Pest Management Science, 2000
ABSTRACT
Pesticide Science, 1995
The ability to stimulate N-acetylglucosamine (GluNAc) incorporation in-vitro of a number of N-ter... more The ability to stimulate N-acetylglucosamine (GluNAc) incorporation in-vitro of a number of N-tert-butyl-N,N′-dibenzoylhydrazines having various substituents on both phenyl rings was measured in cultured integument excised from the rice stem borer (Chilo suppressalis Walker). The relationship between in-vitro and larvicidal potency was approximately linear. The substituent effects on variations in the potency were similar between in-vitro and larvicidal activities. An inhibitor of oxidative detoxication, piperonyl butoxide, had no synergistic effects on the in-vitro potency. The ability of some dibenzoylhydrazines to inhibit GluNAc incorporation at exposure periods longer than the optimum for stimulation was also measured in a similar cultured integument system. The relationship between the inhibitory and stimulatory potency indices was linear, indicating that the larvicidal activity of dibenzoylhydrazines is closely related to its ability to stimulate as well as to inhibit GluNAc incorporation into the larval cuticle.
Environmental Toxicology and Chemistry, 1992
The partition coefficient P i n the 1-octanol/water system was analyzed for a great number of mul... more The partition coefficient P i n the 1-octanol/water system was analyzed for a great number of multisubstituted benzenes of ecotoxicological importance consisting of acetanilides, benzamides, nitrobenzenes, and anisoles having various substitution patterns in terms of the A log P(1og Plog P [unsubstituted benzene]) quantitatively with free energy-related physicochemical substituent parameters. The analyses showed that the stereoelectronic effects of ortho, meta, and para substituents on the relative solvation of individual polar groups capable of hydrogen bonding with the partitioning solvents are very important in determining the variations in the log P value. The effects were additive in the set of complicated multisubstituted benzenes, leading to a correlation equation represented by a linear combination of terms of hydrophobic, electronic, and steric parameters summed up over substituents. It was suggested that the procedure be extended to analyze and predict the log P value of any multiply substituted benzenes.
Pesticide Science, 1994
The larvicidal activity of a number of 1-(substituted benzoyl)-2-benzoyl–1 -ten-butylhydrazines a... more The larvicidal activity of a number of 1-(substituted benzoyl)-2-benzoyl–1 -ten-butylhydrazines against the rice stem borer (Chilo suppressalis Walk.) was measured. Variations in the activity were examined quantitatively using physico-chemical substituent and molecular parameters and regression analysis. The results indicated that the molecular hydrophobicity and the electron-withdrawing inductive/ field effect of ontho substituents are favourable to larvicidal activity. The bulkiness of substituents at the meta and para positions was unfavourable to activity, substitution at the para position being more unfavourable than that at the meta position in terms of van der Waals' volume. The 2,3–, 2,5- and 2,6-disubstitution patterns were also unfavourable to activity. Reductions in larvicidal activity caused by the 2,6-,- 2,3,5- and 2,3,4,5-substitutions were greater than those induced by the 2,3- and 2,5-disubstitutions. When the sum of contributions from favourable effects is greater than that from unfavourable effects, the larvicidal activity is expected to be superior to that of the unsubstituted compound.