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Asahi M, Yamato K, Ozoe F, Ozoe Y. External amino acid residues of insect GABA receptor channels dictate the action of the isoxazoline ectoparasiticide fluralaner. PEST MANAGEMENT SCIENCE 2023; 79:4078-4082. [PMID: 37288963 DOI: 10.1002/ps.7606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/05/2023] [Accepted: 06/08/2023] [Indexed: 06/09/2023]
Abstract
BACKGROUND Fluralaner is the first isoxazoline ectoparasiticide developed to protect companion animals from fleas and ticks. Fluralaner primarily inhibits arthropod γ-aminobutyric acid receptors (GABARs), which are ligand-gated ion channels comprising five subunits arranged around the channel pore. We previously reported that the action site of fluralaner resides at the M1-M3 transmembrane interface between adjacent GABAR subunits. To investigate whether fluralaner interacts with the second transmembrane segment (M2) located deep in the interface, we generated four housefly RDL GABAR mutants with non-conservative amino acid substitutions in the M2 region. RESULTS Electrophysiological analysis of GABARs expressed in Xenopus oocytes indicated that S313A and S314A mutants exhibited fluralaner sensitivities similar to that of the wild type. M312S mutant exhibited approximately seven-fold lower sensitivity than that of the wild type. Notably, the N316L mutant was almost insensitive to fluralaner. CONCLUSION The findings of this study indicate that the conserved external amino acid residues of insect GABAR channels play a critical role in the antagonistic effect of fluralaner. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Miho Asahi
- Biological Research Laboratories, Nissan Chemical Corporation, Shiraoka, Saitama, Japan
| | - Kohei Yamato
- Faculty of Life and Environmental Sciences, Shimane University, Matsue, Shimane, Japan
| | - Fumiyo Ozoe
- Faculty of Life and Environmental Sciences, Shimane University, Matsue, Shimane, Japan
- Interdisciplinary Institute for Science Research, Organization for Research and Academic Information, Shimane University, Matsue, Shimane, Japan
| | - Yoshihisa Ozoe
- Faculty of Life and Environmental Sciences, Shimane University, Matsue, Shimane, Japan
- Interdisciplinary Institute for Science Research, Organization for Research and Academic Information, Shimane University, Matsue, Shimane, Japan
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Huang C, Wu Y, Zhai N, Ju X, Zhao C, Luo X, Ozoe Y, Liu G. 5-(4-Pyridinyl)-3-isothiazolols as Competitive Antagonists of Insect GABA Receptors: Design, Synthesis, and a New Mechanism Leading to Insecticidal Effects. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:5765-5772. [PMID: 35535594 DOI: 10.1021/acs.jafc.1c08030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ionotropic γ-aminobutyric acid (GABA) receptors (iGABARs) are validated targets of drugs and insecticides. Our previous studies showed that the competitive antagonists of insect iGABARs exhibit insecticidal activities and that the 3-isothiazolol scaffold is used as a lead for developing novel iGABAR antagonists. Here, we designed a novel series of 4-aryl-5-(4-pyridinyl)-3-isothiazolol (4-API) analogs that have various aromatic substituents at the 4-position. Two-electrode voltage clamp experiments showed that all synthesized 4-APIs exhibited antagonistic activity against Musca domestica and Spodoptera litura iGABARs (RDL) expressed in oocytes of Xenopus laevis at 100 μM. Of the 4-APIs, the 4-(1,1'-biphenylyl) analog was the most potent antagonist with IC50s of 7.1 and 9.9 μM against M. domestica and S. litura RDL receptors, respectively. This analog also showed a certain insecticidal activity against S. litura larvae, with >75% mortality at 100 μg/g diet. Molecular docking studies with a M. domestica iGABAR model indicated that the π-π stacking interactions formed between the pyridinyl ring and Y252 and between the 4-substituted aromatic group and Y107 might be important for antagonism by the 4-(1,1'-biphenylyl) analog. Our studies provide important information for designing novel iGABAR antagonists and suggest that the 4-APIs acting on iGABARs are promising insecticide leads for further studies.
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Affiliation(s)
- Cheng Huang
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
| | - Yun Wu
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
| | - Na Zhai
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
| | - Xiulian Ju
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
| | - Chunqing Zhao
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P. R. China
| | - Xiaogang Luo
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
- School of Materials Science and Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou City 450001, Henan Province, P. R. China
| | - Yoshihisa Ozoe
- Faculty of Life and Environmental Sciences, Shimane University, Matsue 690-8504, Shimane, Japan
| | - Genyan Liu
- Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, P. R. China
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Kono M, Ozoe F, Asahi M, Ozoe Y. State-dependent inhibition of GABA receptor channels by the ectoparasiticide fluralaner. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 181:105008. [PMID: 35082031 DOI: 10.1016/j.pestbp.2021.105008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/15/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
γ-Aminobutyric acid (GABA) receptors (GABARs) are ligand-gated Cl- channels, which cause an influx of Cl- that inhibits excitation in postsynaptic cells upon activation. GABARs are important targets for drugs and pest control chemicals. We previously reported that the isoxazoline ectoparasiticide fluralaner inhibits GABA-induced currents in housefly (Musca domestica) GABARs by binding to the putative binding site in the transmembrane subunit interface. In the present study, we investigated whether fluralaner inhibits the GABA response in the GABAR activated state, the resting state, or both, using two-electrode voltage clamp electrophysiology protocols. We found that inhibition progresses over time to steady-state levels by repeated short applications of GABA during fluralaner perfusion. The GABA response was not impaired by fluralaner treatment in the GABAR resting state. However, once inhibited, the GABA response was not restored by repeated applications of GABA. These findings suggest that fluralaner might reach the binding site of the activated conformation of GABARs in a stepwise fashion and tightly bind to it.
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Affiliation(s)
- Miku Kono
- Faculty of Life and Environmental Sciences, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Fumiyo Ozoe
- Interdisciplinary Institute for Science Research, Organization for Research and Academic Information, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Miho Asahi
- Biological Research Laboratories, Nissan Chemical Corporation, Shiraoka, Saitama 349-0294, Japan
| | - Yoshihisa Ozoe
- Faculty of Life and Environmental Sciences, Shimane University, Matsue, Shimane 690-8504, Japan; Interdisciplinary Institute for Science Research, Organization for Research and Academic Information, Shimane University, Matsue, Shimane 690-8504, Japan.
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4
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Bhagat K, Singh JV, Pagare PP, Kumar N, Sharma A, Kaur G, Kinarivala N, Gandu S, Singh H, Sharma S, Bedi PMS. Rational approaches for the design of various GABA modulators and their clinical progression. Mol Divers 2021; 25:551-601. [PMID: 32170466 PMCID: PMC8422677 DOI: 10.1007/s11030-020-10068-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/28/2020] [Indexed: 12/20/2022]
Abstract
GABA (γ-amino butyric acid) is an important inhibitory neurotransmitter in the central nervous system. Attenuation of GABAergic neurotransmission plays an important role in the etiology of several neurological disorders including epilepsy, Alzheimer's disease, Huntington's chorea, migraine, Parkinson's disease, neuropathic pain, and depression. Increase in the GABAergic activity may be achieved through direct agonism at the GABAA receptors, inhibition of enzymatic breakdown of GABA, or by inhibition of the GABA transport proteins (GATs). These functionalities make GABA receptor modulators and GATs attractive drug targets in brain disorders associated with decreased GABA activity. There have been several reports of development of GABA modulators (GABA receptors, GABA transporters, and GABAergic enzyme inhibitors) in the past decade. Therefore, the focus of the present review is to provide an overview on various design strategies and synthetic approaches toward developing GABA modulators. Furthermore, mechanistic insights, structure-activity relationships, and molecular modeling inputs for the biologically active derivatives have also been discussed. Summary of the advances made over the past few years in the clinical translation and development of GABA receptor modulators is also provided. This compilation will be of great interest to the researchers working in the field of neuroscience. From the light of detailed literature, it can be concluded that numerous molecules have displayed significant results and their promising potential, clearly placing them ahead as potential future drug candidates.
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Affiliation(s)
- Kavita Bhagat
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Jatinder V Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Piyusha P Pagare
- Department of Medicinal Chemistry, School of Pharmacy and Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond, VA, 23219, USA
| | - Nitish Kumar
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Anchal Sharma
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Gurinder Kaur
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India
| | - Nihar Kinarivala
- Program in Chemical Biology, Sloan Kettering Institute, New York, NY, 10065, USA
| | - Srinivasa Gandu
- Department of Cell Biology and Neuroscience, Cell and Development Biology Graduate Program, The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Harbinder Singh
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India.
| | - Sahil Sharma
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India.
- Program in Chemical Biology, Sloan Kettering Institute, New York, NY, 10065, USA.
| | - Preet Mohinder S Bedi
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, PB, 143005, India.
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Jiang X, Yang S, Yan Y, Lin F, Zhang L, Zhao W, Zhao C, Xu H. Design, Synthesis, and Insecticidal Activity of 5,5-Disubstituted 4,5-Dihydropyrazolo[1,5- a]quinazolines as Novel Antagonists of GABA Receptors. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:15005-15014. [PMID: 33269911 DOI: 10.1021/acs.jafc.0c02462] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
To control the development of resistance to conventional insecticides acting as γ-aminobutyric acid (GABA) receptor antagonists (e.g., fipronil), new GABAergic 5,5-disubstituted 4,5-dihydropyrazolo[1,5-a]quinazolines were designed via a scaffold-hopping strategy and synthesized with a facile method. Among the 50 target compounds obtained, compounds 5a, 5b, 7a, and 7g showed excellent insecticidal activities against a susceptible strain of Plutella xylostella (LC50 values ranging from 1.03 to 1.44 μg/mL), which were superior to that of fipronil (LC50 = 3.02 μg/mL). Remarkably, the insecticidal activity of compound 5a was 64-fold better than that of fipronil against the field population of fipronil-resistant P. xylostella. Electrophysiological studies against the housefly GABA receptor heterologously expressed in Xenopus oocytes indicated that compound 5a could act as a potent GABA receptor antagonist, and IC50 was calculated to be 32.5 nM. Molecular docking showed that the binding poses of compound 5a with the housefly GABA receptor can be different compared to fipronil, which explains the effectiveness of compound 5a against fipronil-resistant insects. These findings have suggested compound 5a as a lead compound for a novel GABA receptor antagonist controlling field-resistant insects and provided a basis for further design, structural modification, and development of 4,5-dihydropyrazolo[1,5-a]quinazoline motifs as new insecticidal GABA receptor antagonists.
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Affiliation(s)
- Xunyuan Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China
| | - Shuai Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China
| | - Ying Yan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China
| | - Fei Lin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China
| | - Ling Zhang
- College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Weijing Zhao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China
| | - Chen Zhao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China
| | - Hanhong Xu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources and Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou 510642, China
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6
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Liu G, Wu Y, Gao Y, Ju X, Ozoe Y. Potential of Competitive Antagonists of Insect Ionotropic γ-Aminobutyric Acid Receptors as Insecticides. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:4760-4768. [PMID: 32243147 DOI: 10.1021/acs.jafc.9b08189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ionotropic γ-aminobutyric acid (GABA) receptors (GABARs) represent an important insecticide target. Currently used GABAR-targeting insecticides are non-competitive antagonists (NCAs) of these receptors. Recent studies have demonstrated that competitive antagonists (CAs) of GABARs have functions of inhibiting insect GABARs similar to NCAs and that they also exhibit insecticidal activity. CAs have different binding sites and different mechanisms of action compared to those of NCAs. Therefore, GABAR CAs should have the potential to be developed into novel insecticides, which could be used to overcome the developed resistance of insect pests to conventional NCA insecticides. Although research on insect GABAR CAs has lagged behind that on mammalian GABAR CAs, research on the CAs of insect ionotropic GABARs has made great progress in recent years, and several series of heterocyclic compounds, such as 3-isoxazolols and 6-iminopyridazines, have been identified as insect GABAR CAs. In this review, we briefly summarize the design strategies, structures, and biological activities of the novel GABAR CAs that have been found in the past decade. Updated information about GABAR CAs may benefit the design and development of novel GABAR-targeting insecticides.
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Affiliation(s)
- Genyan Liu
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Yun Wu
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Ya Gao
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Xiulian Ju
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan, Hubei 430205, People's Republic of China
| | - Yoshihisa Ozoe
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
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Liu G, Li H, Shi J, Wang W, Furuta K, Liu D, Zhao C, Ozoe F, Ju X, Ozoe Y. 4-Aryl-5-carbamoyl-3-isoxazolols as competitive antagonists of insect GABA receptors: Synthesis, biological activity, and molecular docking studies. Bioorg Med Chem 2018; 27:416-424. [PMID: 30579800 DOI: 10.1016/j.bmc.2018.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 12/09/2018] [Accepted: 12/11/2018] [Indexed: 12/01/2022]
Abstract
Competitive antagonists (CAs) of ionotropic GABA receptors (GABARs) reportedly exhibit insecticidal activity and have potential for development as novel insecticides for overcoming emerging resistance to traditional GABAR-targeting insecticides. Our previous studies demonstrated that 4,5-disubstituted 3-isoxazolols or 3-isothiazolols are an important class of insect GABAR CAs. In the present study, we synthesized a series of 4-aryl-5-carbamoyl-3-isoxazolols and examined their antagonism of insect GABARs expressed in Xenopus oocytes. Several of these 3-isoxazolols exhibited potent antagonistic activities against housefly and common cutworm GABARs, with IC50 values in the low-micromolar range in both receptors. 4-(3-Amino-4-methylphenyl)-5-carbamoyl-3-isoxazolol (3u) displayed the highest antagonism, with IC50 values of 2.0 and 0.9 μM in housefly and common cutworm GABARs, respectively. Most of the synthesized 3-isoxazolols showed moderate larvicidal activities against common cutworms, with more than 50% mortality at 100 μg/g. These results indicate that 4-monocyclic aryl-5-carbamoyl-3-isoxazolol is a promising scaffold for insect GABAR CA discovery and provide important information for the design and development of GABAR-targeting insecticides with a novel mode of action.
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Affiliation(s)
- Genyan Liu
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, PR China.
| | - Huaguang Li
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, PR China
| | - Jiaying Shi
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, PR China
| | - Wenjie Wang
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, PR China
| | - Kenjiro Furuta
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Di Liu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Chunqing Zhao
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, PR China.
| | - Fumiyo Ozoe
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Xiulian Ju
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, PR China
| | - Yoshihisa Ozoe
- Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan.
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RNA-Seq Analysis Reveals Candidate Targets for Curcumin against Tetranychus cinnabarinus. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2796260. [PMID: 27672652 PMCID: PMC5031819 DOI: 10.1155/2016/2796260] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 07/21/2016] [Accepted: 07/27/2016] [Indexed: 01/11/2023]
Abstract
Tetranychus cinnabarinus is an important agricultural pest with a broad host range. We previously identified curcumin as a promising acaricidal compound against T. cinnabarinus. However, the acaricidal mechanism of curcumin remains unknown. In this study, RNA-seq was employed to analyze the transcriptome changes in T. cinnabarinus treated with curcumin or the solvent. A total of 105,706,297 clean sequence reads were generated by sequencing, with more than 90% of the reads successfully mapped to the reference sequence. The RNA-seq identified 111 and 96 differentially expressed genes between curcumin- and solvent-treated mites at 24 and 48 h after treatment, respectively. GO enrichment analysis of differentially expressed genes showed that the cellular process was the dominant group at both time points. Finally, we screened 23 differentially expressed genes that were functionally identical or similar to the targets of common insecticide/acaricides or genes that were associated with mite detoxification and metabolism. Calmodulin, phospholipase A2, and phospholipase C were activated upon curcumin treatment suggesting that the calcium channel related genes might play important roles in mite's response to curcumin. Overall our results revealed the global transcriptional changes in T. cinnabarinus after curcumin treatment to enable further identification of the targets of curcumin in mites.
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Liu G, Frølund B, Ozoe F, Ozoe Y. Differential interactions of 5-(4-piperidyl)-3-isoxazolol analogues with insect γ-aminobutyric acid receptors leading to functional selectivity. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 66:64-71. [PMID: 26453818 DOI: 10.1016/j.ibmb.2015.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/15/2015] [Accepted: 10/02/2015] [Indexed: 06/05/2023]
Abstract
γ-Aminobutyric acid (GABA) receptors (GABARs) mediate fast inhibitory synaptic transmission and are also targets for drugs and insecticides. To better understand the molecular interactions of ligands with the orthosteric sites of GABARs, we examined 4-aryl/arylalkyl-5-(4-piperidyl)-3-isoxazolol, 4-aryl-5-(4-piperidyl)-3-isothiazolol, and 5-aryl-4-(4-piperidyl)-1-hydroxypyrazole for their antagonism with regard to three insect GABARs. The 3-isoxazolol was preferable to the 3-isothiazolol and 1-hydroxypyrazole in antagonism to common cutworm and housefly GABARs. Of the tested analogues, 4-(3-biphenylyl)-5-(4-piperidyl)-3-isoxazolol (2a) displayed the greatest antagonism for common cutworm and housefly GABARs, with IC50 values of 3.4 and 10.2 μM, respectively. In contrast to the antagonism of the two GABARs, 2a showed partial agonism for the case of small brown planthopper GABARs, with an EC50 value of 31.3 μM. Homology models and docking simulations revealed that a cation-π interaction between an analogue and an Arg residue in loop C or E of the orthosteric site is a key component of antagonism. This specific phenomenon was lacking in the interactions between 2a and the orthosteric site of small brown planthopper GABARs. These findings provide important insights into designing and developing novel drugs and insecticides.
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Affiliation(s)
- Genyan Liu
- Division of Bioscience and Biotechnology, Course of Bioresources Science, The United Graduate School of Agricultural Sciences, Tottori University, Tottori 680-8553, Japan
| | - Bente Frølund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 162, 2100 Copenhagen Φ, Denmark
| | - Fumiyo Ozoe
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Yoshihisa Ozoe
- Division of Bioscience and Biotechnology, Course of Bioresources Science, The United Graduate School of Agricultural Sciences, Tottori University, Tottori 680-8553, Japan; Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan.
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10
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Liu G, Ozoe F, Furuta K, Ozoe Y. 4,5-Substituted 3-Isoxazolols with Insecticidal Activity Act as Competitive Antagonists of Housefly GABA Receptors. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:6304-6312. [PMID: 26120732 DOI: 10.1021/acs.jafc.5b01843] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The insect GABA receptor (GABAR), which is composed of five RDL subunits, represents an important target for insecticides. A series of 4,5-disubstituted 3-isoxazolols, including muscimol analogues, were synthesized and examined for their activities against four splice variants (ac, ad, bc, and bd) of housefly GABARs expressed in Xenopus oocytes. Muscimol was a more potent agonist than GABA in all four splice variants, whereas synthesized analogues did not exhibit agonism but rather antagonism in housefly GABARs. The introduction of bicyclic aromatic groups at the 4-position of muscimol and the simultaneous replacement of the aminomethyl group with a carbamoyl group at the 5-position to afford six 4-aryl-5-carbamoyl-3-isoxazolols resulted in compounds that exhibited significantly enhanced antagonism with IC50 values in the low micromolar range in the ac variant. The inhibition of GABA-induced currents by 100 μM analogues was approximately 1.5-4-fold greater in the ac and bc variants than in the ad and bd variants. 4-(3-Biphenylyl)-5-carbamoyl-3-isoxazolol displayed competitive antagonism, with IC50 values of 30, 34, 107, and 96 μM in the ac, bc, ad, and bd variants, respectively, and exhibited moderate insecticidal activity against houseflies, with an LD50 value of 5.6 nmol/fly. These findings suggest that these 3-isoxazolol analogues are novel lead compounds for the design and development of insecticides that target the orthosteric site of housefly GABARs.
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Affiliation(s)
- Genyan Liu
- †Division of Bioscience and Biotechnology, The United Graduate School of Agricultural Sciences, Tottori University, Tottori 680-8553, Japan
| | - Fumiyo Ozoe
- §Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Kenjiro Furuta
- †Division of Bioscience and Biotechnology, The United Graduate School of Agricultural Sciences, Tottori University, Tottori 680-8553, Japan
- §Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
| | - Yoshihisa Ozoe
- †Division of Bioscience and Biotechnology, The United Graduate School of Agricultural Sciences, Tottori University, Tottori 680-8553, Japan
- §Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan
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Xu Y, Furutani S, Ihara M, Ling Y, Yang X, Kai K, Hayashi H, Matsuda K. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels. PLoS One 2015; 10:e0122629. [PMID: 25902139 PMCID: PMC4406737 DOI: 10.1371/journal.pone.0122629] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 02/23/2015] [Indexed: 12/17/2022] Open
Abstract
Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori) larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA)-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR) RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs.
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Affiliation(s)
- Yan Xu
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P.R. China
| | - Shogo Furutani
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kinki University, 3327–204 Nakamachi, Nara 631–8505, Japan
| | - Makoto Ihara
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kinki University, 3327–204 Nakamachi, Nara 631–8505, Japan
| | - Yun Ling
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P.R. China
| | - Xinling Yang
- Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, P.R. China
| | - Kenji Kai
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1–1 Gakuen-cho, Naka-ku, Sakai, Osaka 599–8531, Japan
| | - Hideo Hayashi
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1–1 Gakuen-cho, Naka-ku, Sakai, Osaka 599–8531, Japan
| | - Kazuhiko Matsuda
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kinki University, 3327–204 Nakamachi, Nara 631–8505, Japan
- * E-mail:
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