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Tadamasa Terai - One of the best experts on this subject based on the ideXlab platform.
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Crystal and molecular structure of 10,20-epoxy-Grayanotoxin-II
Journal of Chemical Crystallography, 2004Co-Authors: Jun'ichi Katakawa, Masaaki Katai, Tadahiro Tetsumi, Ken-ichi Sakaguchi, Tadamasa TeraiAbstract:The photooxidation with HgO in benzene and the hydrolysis with 2%-KOH in methanol of the Grayanotoxin (GTX) derivative (4) gave a 10,20-epoxy-Grayanotoxin-II(5). The crystal structure of (5) has been determined by X-ray diffraction at room temperature. The crystal is monoclinic, space group P 2_1, with a = 14.248(10) Å, b = 6.670(10) Å, c = 9.990(10) Å, α = 105.507(8)°, V = 914.9(2) Å^3, Z = 2. The structure was solved by direct methods and refined by full-matrix least squares methods to a final R 1 = 0.046 ( wR 2 = 0.0833) for 1161 independent reflections. The molecule has a pentacyclic structure consisting of two five-membered, one six-membered, one seven-membered, and one three-membered rings. The three-membered ring is connected with the seven-membered ring by spiro-type bond.
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Preparation of 9-hydroxy Grayanotoxin derivatives and their acute toxicity in mice.
CHEMICAL & PHARMACEUTICAL BULLETIN, 2003Co-Authors: Tadamasa Terai, Kanehiro Osakabe, Masaaki Katai, Isao Narama, Tetsuro Matsuura, Jun'ichi Katakawa, Ken-ichi Sakaguchi, Tadahiro TetsumiAbstract:Novel 9alpha and 9beta-hydroxy Grayanotoxin II derivatives were prepared by photo-sensitized oxygenation of iso-Grayanotoxin II and oxidation of Grayanotoxin II tetraacetate with selenium dioxide respectively. The lethal dosage of 9alpha and 9beta-hydroxy Grayanotoxin II were lower than that of Grayanotoxin II. In addition, the lethal dosage of 9beta-hydroxy-dihydro Grayanotoxin II was higher than that of dihydro Grayanotoxin II.
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Crystal and molecular structure of iso-Grayanotoxin II
Journal of Chemical Crystallography, 2000Co-Authors: Jun'ichi Katakawa, Tadamasa Terai, Masaaki Katai, Tadahiro Tetsumi, Ken-ichi Sakaguchi, Mamoru SatoAbstract:The crystal and molecular structure of a Grayanotoxin derivative, iso-Grayanotoxin II, is presented. The crystal is orthorhombic, space group $$P2_1 2_1 2_1 ,{\text{ with }}a{\text{ = 12}}{\text{.357(1) }}{\AA}{\text{, }}b{\text{ = 23}}{\text{.354(1) }}{\AA}{\text{, }}c = 6.284(2){\text{ }}{\AA}{\text{, }}V = 1813.3(6)\,{\AA}^3 {\text{, }}Z = 4 $$ . The molecule is based on a tetracyclic structure consisting of two five-membered, one six-membered, and one seven-membered rings with various conformations.
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Isolation of Iso-Grayanotoxin II from Leaves of Leucothoe grayana MAX. Its X-Ray Crystallographic Analysis and Acute Toxicity in Mice
CHEMICAL & PHARMACEUTICAL BULLETIN, 2000Co-Authors: Tadamasa Terai, Daisuke Araho, Kanehiro Osakabe, Masaaki Katai, Isao Narama, Tetsuro Matsuura, Jun'ichi Katakawa, Tadahiro Tetsumi, Mamoru SatoAbstract:The structure of iso-trayanotoxin II, a new diterpenoid from Leucothoe grayana MAX., has been determined as 3β, 5β, 6β, 14β, 16α-pentahydroxygrayanotox-9(10)-ene by spectroscopic and X-ray crystallographic analysis. The lethal dosage level of iso-Grayanotoxin II in mice was lower than that of Grayanotoxin III.
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transformation of Grayanotoxin ii Grayanotoxin ii tetraacetate to 1 5 seco grayano toxin derivatives
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Tadamasa Terai, Yuuji Nishioku, Kunio GotoAbstract:Oxidation of Grayanotoxin (GTX) II with lead (IV) acetate in methanol gave a new derivative, the 1(R)-spiro-3,6(S),14,16-tetra-hydroxy-5-keto derivative. Treatment of GTX-II tetraacetate in acetic acid by using Pb(IV) acetate as an oxidizing agent gave a novel 1,5-seco-GTX derivative, Δ1(10)-1,5-seco-GTX-pentaacetate, together with the 1,5-seco-GTX-1(R) derivative. Oxidation of GTX-II-tetraacetate with Tl(III) acetate in acetic acid or benzene gave the 1,5-seco-GTX-1(S) derivative.
Abdulkadir Gunduz - One of the best experts on this subject based on the ideXlab platform.
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Grayanotoxin levels in blood, urine and honey and their association with clinical status in patients with mad honey intoxication
Elsevier, 2018Co-Authors: Ali Aygun, Suha Turkmen, Suleyman Turedi, Aynur Sahin, Yunus Karaca, Su Youn Ahn, Suncheun Kim, Abdulkadir GunduzAbstract:Objectives: The purpose of this study was to investigate whether there is an association between Grayanotoxin levels in urine and blood of patients with mad honey intoxication and in the honey consumed, and the resulting clinical picture. The pilot data acquired from this study was analysed in National Forensic Service, Daejeon Institute, South Korea and first results were published as a preliminary study. Patients and methods: This descriptive study was conducted at a university hospital emergency department in Turkey. 25 cases diagnosed with mad honey intoxication were obtained the study. Samples of mad honey consumed by patients were obtained. Blood and urine specimens were collected at presentation to the emergency department. GTX 1 and GTX 3 levels from patients' blood, urine and honey consumed were investigated simultaneously using the LC-MS/MS system. Results: Mean GTX 1 concentration in blood was 4.82 ng/mL and mean GTX 3 level 6.56 ng/mL. Mean GTX concentration in urine was 0.036 μg/mL and mean GTX 3 level 0.391 μg/mL. Mean GTX I concentration in honeys consumed was 8.73 μg/gr and mean GTX 3 level 27.60 μg/gr. Conclusion: This descriptive study is show Grayanotoxin levels in body fluids of patients with mad honey intoxication. No association was determined between Grayanotoxin levels in blood and clinical data. Keywords: Mad honey, Grayanotoxin, LC-MS/MS, Blood, Urine, Pulse, Blood pressur
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Grayanotoxin levels in blood, urine and honey and their association with clinical status in patients with mad honey intoxication.
Turkish Journal of Emergency Medicine, 2018Co-Authors: Ali Aygun, Suha Turkmen, Suleyman Turedi, Aynur Sahin, Yunus Karaca, Su Youn Ahn, Suncheun Kim, Abdulkadir GunduzAbstract:Abstract Objectives The purpose of this study was to investigate whether there is an association between Grayanotoxin levels in urine and blood of patients with mad honey intoxication and in the honey consumed, and the resulting clinical picture. The pilot data acquired from this study was analysed in National Forensic Service, Daejeon Institute, South Korea and first results were published as a preliminary study. Patients and methods This descriptive study was conducted at a university hospital emergency department in Turkey. 25 cases diagnosed with mad honey intoxication were obtained the study. Samples of mad honey consumed by patients were obtained. Blood and urine specimens were collected at presentation to the emergency department. GTX 1 and GTX 3 levels from patients' blood, urine and honey consumed were investigated simultaneously using the LC-MS/MS system. Results Mean GTX 1 concentration in blood was 4.82 ng/mL and mean GTX 3 level 6.56 ng/mL. Mean GTX concentration in urine was 0.036 μg/mL and mean GTX 3 level 0.391 μg/mL. Mean GTX I concentration in honeys consumed was 8.73 μg/gr and mean GTX 3 level 27.60 μg/gr. Conclusion This descriptive study is show Grayanotoxin levels in body fluids of patients with mad honey intoxication. No association was determined between Grayanotoxin levels in blood and clinical data.
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doi:10.3906/sag-1209-11 The
2016Co-Authors: Suha Turkmen, Abdulkadir Gunduz, Metehan Akça, Ülkü Karagöz, Süleyman Türedi̇, Mehmet YildirimAbstract:dose-dependent effect of Grayanotoxin on the cardiovascular syste
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Is Grayanotoxin directly responsible for mad honey poisoning-associated seizures
Turkish Journal of Medical Sciences, 2012Co-Authors: Abdulkadir Gunduz, Murat Aydin, Metehan Akça, Suha Turkmen, Suleyman Turedi, Umut Eryiğit, Ali Cansu, Mehmet YildirimAbstract:The aim of this study was to investigate the effects of Grayanotoxin on epileptiform activity in rats. Materials and methods: Forty-two male Sprague Dawley rats were equally divided into 1 of 7 groups. Thirty minutes after induction of epileptiform activity induced by penicillin injection, 0.5, 1, 2, 4, or 8 µg of Grayanotoxin-III was intracerebroventricularly administered. Epileptiform activity spike frequency and amplitude were converted into numerical data using software following the experiment. Results: Our results show that Grayanotoxin reduces epileptiform spike frequency and amplitude in a dose-dependent manner. Five minutes postinjection, Grayanotoxin significantly reduced epileptiform activity, especially at higher doses. This acute effect subsequently declined, but a dose-dependent decrease was observed through the end of the experiment. This suggests that the first observed effect of Grayanotoxin on spikes probably consists of blocking voltage-gated sodium channel inactivation. Conclusion: Grayanotoxin's suppression of epileptiform activity in this experimental study indicates that Grayanotoxin is not directly responsible for mad honey poisoning-associated seizures observed in a clinical context.
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Clinical review of Grayanotoxin/mad honey poisoning past and present
Clinical Toxicology, 2008Co-Authors: Abdulkadir Gunduz, Suleyman Turedi, Robert M Russell, Faik Ahmet AyazAbstract:Grayanotoxin is a naturally occurring sodium channel toxin which enters the human food supply by honey made from the pollen and nectar of the plant family Ericaceae in which rhododendron is a genus. Grayanotoxin/mad honey poisoning is a little known, but well studied, cholinergic toxidrome resulting in incapacitating and, sometimes, life-threatening bradycardia, hypotension, and altered mental status. Complete heart blocks occur in a significant fraction of patients. Asystole has been reported. Treatment with saline infusion and atropine alone is almost always successful. A pooled analysis of the dysrhythmias occurring in 69 patients from 11 different studies and reports is presented. The pathophysiology, signs, symptoms, clinical course, and treatment of Grayanotoxin/mad honey poisoning are discussed. In the nineteenth century Grayanotoxin/mad honey poisoning was reported in Europe and North America. Currently, documented poisoning from locally produced honey in Europe or North America would be reportable. Possible reasons for this epidemiologic change are discussed.
Dong-cheul Moon - One of the best experts on this subject based on the ideXlab platform.
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Development of a liquid chromatography-tandem mass spectrometry method for the determination of Grayanotoxins in rat blood and its application to toxicokinetic study.
Biomedical Chromatography, 2014Co-Authors: Seung-hyeok Park, Kyung-hwa Hwang, Dong-cheul MoonAbstract:A sensitive and specific high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed for the determination of Grayanotoxin I (GTX I) and Grayanotoxin III (GTX III) in rat whole blood. Grayanotoxins (GTXs) and clindamycin as internal standard (IS) were extracted from rat blood via solid-phase extraction using PEP solid-phase extraction cartridges. Chromatographic separation of the analytes was achieved on a Kinetex C18 (100 × 2.1 mm, 2.6 µm) reversed-phase column using a gradient elution with the mobile phase of 1% acetic acid in water and methanol at a flow rate of 0.2 mL/min. Electrospray ionization mass spectrometry was operated in the positive ion mode with multiple reaction monitoring. The calibration curves obtained were linear over the concentration range of 1–100 ng/mL with a lower limit of quantification of 1 ng/mL for GTXs. The relative standard deviation of intra-day and inter-day precision was below 6.8% and accuracy ranged from 94.8 to 106.6%. The analytes were stable in the stability studies. The validated method was successfully applied to the quantification and toxicokinetic study of GTXs in rats for the first time after oral administration of 11.52 mg/kg mad honey and 0.35 mg/kg GTX III, respectively. Copyright © 2014 John Wiley & Sons, Ltd.
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Development of a liquid chromatography-tandem mass spectrometry method for the determination of Grayanotoxins in rat blood and its application to toxicokinetic study.
Biomedical Chromatography, 2014Co-Authors: Seung-hyeok Park, Kyung-hwa Hwang, Dong-cheul MoonAbstract:A sensitive and specific high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed for the determination of Grayanotoxin I (GTX I) and Grayanotoxin III (GTX III) in rat whole blood. Grayanotoxins (GTXs) and clindamycin as internal standard (IS) were extracted from rat blood via solid-phase extraction using PEP solid-phase extraction cartridges. Chromatographic separation of the analytes was achieved on a Kinetex C18 (100 × 2.1 mm, 2.6 µm) reversed-phase column using a gradient elution with the mobile phase of 1% acetic acid in water and methanol at a flow rate of 0.2 mL/min. Electrospray ionization mass spectrometry was operated in the positive ion mode with multiple reaction monitoring. The calibration curves obtained were linear over the concentration range of 1–100 ng/mL with a lower limit of quantification of 1 ng/mL for GTXs. The relative standard deviation of intra-day and inter-day precision was below 6.8% and accuracy ranged from 94.8 to 106.6%. The analytes were stable in the stability studies. The validated method was successfully applied to the quantification and toxicokinetic study of GTXs in rats for the first time after oral administration of 11.52 mg/kg mad honey and 0.35 mg/kg GTX III, respectively. Copyright © 2014 John Wiley & Sons, Ltd.
Tadahiro Tetsumi - One of the best experts on this subject based on the ideXlab platform.
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Crystal and molecular structure of 10,20-epoxy-Grayanotoxin-II
Journal of Chemical Crystallography, 2004Co-Authors: Jun'ichi Katakawa, Masaaki Katai, Tadahiro Tetsumi, Ken-ichi Sakaguchi, Tadamasa TeraiAbstract:The photooxidation with HgO in benzene and the hydrolysis with 2%-KOH in methanol of the Grayanotoxin (GTX) derivative (4) gave a 10,20-epoxy-Grayanotoxin-II(5). The crystal structure of (5) has been determined by X-ray diffraction at room temperature. The crystal is monoclinic, space group P 2_1, with a = 14.248(10) Å, b = 6.670(10) Å, c = 9.990(10) Å, α = 105.507(8)°, V = 914.9(2) Å^3, Z = 2. The structure was solved by direct methods and refined by full-matrix least squares methods to a final R 1 = 0.046 ( wR 2 = 0.0833) for 1161 independent reflections. The molecule has a pentacyclic structure consisting of two five-membered, one six-membered, one seven-membered, and one three-membered rings. The three-membered ring is connected with the seven-membered ring by spiro-type bond.
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Preparation of 9-hydroxy Grayanotoxin derivatives and their acute toxicity in mice.
CHEMICAL & PHARMACEUTICAL BULLETIN, 2003Co-Authors: Tadamasa Terai, Kanehiro Osakabe, Masaaki Katai, Isao Narama, Tetsuro Matsuura, Jun'ichi Katakawa, Ken-ichi Sakaguchi, Tadahiro TetsumiAbstract:Novel 9alpha and 9beta-hydroxy Grayanotoxin II derivatives were prepared by photo-sensitized oxygenation of iso-Grayanotoxin II and oxidation of Grayanotoxin II tetraacetate with selenium dioxide respectively. The lethal dosage of 9alpha and 9beta-hydroxy Grayanotoxin II were lower than that of Grayanotoxin II. In addition, the lethal dosage of 9beta-hydroxy-dihydro Grayanotoxin II was higher than that of dihydro Grayanotoxin II.
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Crystal and molecular structure of iso-Grayanotoxin II
Journal of Chemical Crystallography, 2000Co-Authors: Jun'ichi Katakawa, Tadamasa Terai, Masaaki Katai, Tadahiro Tetsumi, Ken-ichi Sakaguchi, Mamoru SatoAbstract:The crystal and molecular structure of a Grayanotoxin derivative, iso-Grayanotoxin II, is presented. The crystal is orthorhombic, space group $$P2_1 2_1 2_1 ,{\text{ with }}a{\text{ = 12}}{\text{.357(1) }}{\AA}{\text{, }}b{\text{ = 23}}{\text{.354(1) }}{\AA}{\text{, }}c = 6.284(2){\text{ }}{\AA}{\text{, }}V = 1813.3(6)\,{\AA}^3 {\text{, }}Z = 4 $$ . The molecule is based on a tetracyclic structure consisting of two five-membered, one six-membered, and one seven-membered rings with various conformations.
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Isolation of Iso-Grayanotoxin II from Leaves of Leucothoe grayana MAX. Its X-Ray Crystallographic Analysis and Acute Toxicity in Mice
CHEMICAL & PHARMACEUTICAL BULLETIN, 2000Co-Authors: Tadamasa Terai, Daisuke Araho, Kanehiro Osakabe, Masaaki Katai, Isao Narama, Tetsuro Matsuura, Jun'ichi Katakawa, Tadahiro Tetsumi, Mamoru SatoAbstract:The structure of iso-trayanotoxin II, a new diterpenoid from Leucothoe grayana MAX., has been determined as 3β, 5β, 6β, 14β, 16α-pentahydroxygrayanotox-9(10)-ene by spectroscopic and X-ray crystallographic analysis. The lethal dosage level of iso-Grayanotoxin II in mice was lower than that of Grayanotoxin III.
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Crystal and Molecular Structure of (1R,6S)-3,6,14,16-Tetrahydroxyspiro[1,5]Grayanotoxin-5-one
Bulletin of the Chemical Society of Japan, 1993Co-Authors: Mamoru Sato, Tadamasa Terai, Jun'ichi Katakawa, Yukiteru Katsube, Tadahiro TetsumiAbstract:The three-dimensional structure of a Grayanotoxin II derivative, (1R,6S)-3,6,14,16-tetrahydroxyspiro[1,5]Grayanotoxin-5-one, has been determined by X-ray diffraction at room temperature. The structure was solved by direct methods and refined by the full matrix least-squares method to a final R = 0.043 for 1436 independent reflections with Fo ≥ 3σ(Fo). The molecule is based on a tetracyclic structure and consists of two six-membered and two five-membered rings. The absolute configuration at C(1) atom (spiro atom) was determined as R on the basis of internal comparison with the absolute structure of Grayanotoxin II.
Philip C. Stevenson - One of the best experts on this subject based on the ideXlab platform.
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Leaf trichomes and foliar chemistry mediate defence against glasshouse thrips; Heliothrips haemorrhoidalis (Bouché) in Rhododendron simsii.
Functional Plant Biology, 2016Co-Authors: Alison S. Scott-brown, Iain W. Farrell, Tom Gregory, Philip C. StevensonAbstract:Herbivore defence mechanisms are a costly diversion of resources away from growth and reproduction. Thus time-limited and tissue specific expression in critical plant parts is more efficient as defined by optimal defence theory. Surprisingly little is known about Rhododendron herbivore defence but it may be mediated by combined chemical and physical mechanisms. Rhododendron simsii Planch. survives cyclic infestations of a leaf-feeding thrips, Heliothrips haemorrhoidalis (Bouche), which severely damage mature leaves but avoid terminal young leaves suggesting specific, localised defence expression. We examined correlations between the distribution of thrips and feeding damage with density of trichomes and the concentration of the diterpenoid, Grayanotoxin I, a compound implicated in but not previously reported to mediate invertebrate defence in Rhododendron. Our data show that as leaves matured the number of thrips and area of feeding damage increased as trichome density and Grayanotoxin I concentration decreased, this inverse correlation suggesting trichomes and Grayanotoxin I mediate defence in younger leaf tissue. Grayanotoxin I was tested against H. haemorrhoidalis and was toxic to immature life stages and repellent to the adult thrips, reducing numbers of first instars emerging on leaves when applied at ecologically relevant concentrations. This work demonstrates that the pattern of defensive traits in foliage of a species of Rhododendron is key to its ability to tolerate cyclic infestations of a generalist herbivore, effectively conserving vital tissues required for growth and reproduction.
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Nectar chemistry modulates the impact of an invasive plant on native pollinators
Functional Ecology, 2015Co-Authors: Erin Jo Tiedeken, Iain W. Farrell, Philip C. Stevenson, Paul A. Egan, Geraldine A. Wright, Mark J. F. Brown, Eileen F. Power, Sharon M. Matthews, Jane C. StoutAbstract:1. Invasive species are considered a main driver of pollinator declines, yet the direct effects of invasive alien plants on pollinators are poorly understood. 2. Abundant, invasive plant species can provide a copious nectar resource for native pollinators. However, the nectar of some plants contains secondary compounds, usually associated with defence against herbivores. The impacts of these compounds on pollinators are often unknown. 3. We compared how consumption of Grayanotoxin I and III, natural secondary compounds in the nectar of invasive Rhododendron ponticum L., affected three native bee species: a honeybee, (Apis mellifera L.), a solitary mining bee (Andrena carantonica, Perez) and a bumblebee, (Bombus terrestris, L.). 4. Survival of the solitary bee and the bumblebee species was not affected by either Grayanotoxin, but honeybees were ∼20× more likely to die when fed solutions containing Grayanotoxin I. Furthermore, solitary bees were deterred from feeding and exhibited malaise behaviours indicative of sublethal toxicity in response to consumption of Grayanotoxin I. In contrast, Grayanotoxins did not affect bumblebee survival or behaviour, even when bees were subjected to multiple stressors (parasite infection or food stress). 5. Our experiments suggest that while R. ponticum provides abundant floral nectar, it is only available as a food resource to pollinators that tolerate Grayanotoxins. Pollinators whose health is negatively affected by Grayanotoxins may experience negative impacts from R. ponticum invasion directly (if they consume R. ponticum nectar) or indirectly (if native floral resources are replaced by R. ponticum). 6. Our study makes a novel comparison of the effects of a natural nectar secondary compound on three pollinator species and clearly demonstrates drastic variation in the responses of different key pollinator taxa to a nectar toxin. Our findings are thus in congruence with literature demonstrating the varying effects of invasive plant chemistry on native foliar herbivores, and our work demonstrates that nectar chemistry should be taken into account when determining the impacts of plant invasion for native pollinators.
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Chemical structures of compounds used in this study.
2015Co-Authors: Caitlin J. Oliver, Philip C. Stevenson, Samantha Softley, Sally M. Williamson, Geraldine A. WrightAbstract:(A) Grayanotoxin I [38]; (B) aconitine [39]; (C) pyrethrin [40]; (D) allethrin [41]; (E) cyfluthrin [21]; (F) permethrin [22]; (G) tau-fluvalinate [23].
