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Sparks TC. ACS Agrochemical Division (AGRO): Fifty Years as a Catalyst for Innovation. J Agric Food Chem 2024. [PMID: 38592379 DOI: 10.1021/acs.jafc.4c00708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
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2
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Sparks TC. Insecticide mixtures-uses, benefits and considerations. Pest Manag Sci 2024. [PMID: 38356314 DOI: 10.1002/ps.7980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/04/2024] [Accepted: 01/17/2024] [Indexed: 02/16/2024]
Abstract
Insecticides remain an important tool for the control of many insect pests. There has long been an interest in insecticide mixtures (in-can and tank-mix) as a means to provide the needed efficacy and/or spectrum to control many insect public health, crop pests or crop pest complexes. This aspect has become more important since insecticides developed in the last 30 years tend to be narrower in spectrum with many primarily focused on either sap-feeding or chewing insect pests. Insecticide mixtures are also seen as an important approach to insect resistance management (IRM) with certain requirements for optimal implementation. Additionally, insecticide mixtures can also address certain agronomic, commercial and intellectual property needs and opportunities. This perspective will review some of the drivers and considerations for insecticide mixtures and their potential uses. © 2024 Society of Chemical Industry.
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Duke SO, Pan Z, Bajsa-Hirschel J, Tamang P, Hammerschmidt R, Lorsbach BA, Sparks TC. Molecular Targets of Herbicides and Fungicides─Are There Useful Overlaps for Fungicide Discovery? J Agric Food Chem 2023; 71:20532-20548. [PMID: 38100716 PMCID: PMC10755756 DOI: 10.1021/acs.jafc.3c07166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 12/17/2023]
Abstract
New fungicide modes of action are needed for fungicide resistance management strategies. Several commercial herbicide targets found in fungi that are not utilized by commercial fungicides are discussed as possible fungicide molecular targets. These are acetyl CoA carboxylase, acetolactate synthase, 5-enolpyruvylshikimate-3-phosphate synthase, glutamine synthase, phytoene desaturase, protoporphyrinogen oxidase, long-chain fatty acid synthase, dihydropteroate synthase, hydroxyphenyl pyruvate dioxygenase, and Ser/Thr protein phosphatase. Some of the inhibitors of these herbicide targets appear to be either good fungicides or good leads for new fungicides. For example, some acetolactate synthase and dihydropteroate inhibitors are excellent fungicides. There is evidence that some herbicides have indirect benefits to certain crops due to their effects on fungal crop pathogens. Using a pesticide with both herbicide and fungicide activities based on the same molecular target could reduce the total amount of pesticide used. The limitations of such a product are discussed.
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Affiliation(s)
- Stephen O. Duke
- National
Center for Natural Products Research, School of Pharmacy, University of Mississippi, University 38667, United States
| | - Zhiqiang Pan
- Natural
Products Utilization Research Unit, United
States Department of Agriculture, University 38667, United States
| | - Joanna Bajsa-Hirschel
- Natural
Products Utilization Research Unit, United
States Department of Agriculture, University 38667, United States
| | - Prabin Tamang
- Natural
Products Utilization Research Unit, United
States Department of Agriculture, University 38667, United States
| | - Raymond Hammerschmidt
- Department
of Plant, Soil and Microbial Sciences, Michigan
State University, East Lansing, Michigan 48824, United States
| | - Beth A. Lorsbach
- Nufarm, 4020 Aerial Center Parkway, Morrisville, North Carolina 27560, United States
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Sparks TC, Lorsbach BA. Insecticide discovery-"Chance favors the prepared mind". Pestic Biochem Physiol 2023; 192:105412. [PMID: 37105622 DOI: 10.1016/j.pestbp.2023.105412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/20/2023] [Accepted: 03/24/2023] [Indexed: 06/19/2023]
Abstract
New options for pest insect control, including new insecticides, are needed to ensure a plentiful food supply for an expanding global population. Any new insecticides must meet the increasingly stringent regulatory requirements for mammalian and environmental safety, and also address the need for new chemistries and modes of action to deal with resistance to available insecticides. As underscored by a paraphrase of a quote from Louis Pasteur "Chance favors the prepared mind", the agrochemical industry uses a variety of approaches that attempt to improve on "chance" for the discovery of new insecticides. Although there are a number of approaches to the discovery of new insecticidal active ingredients (AIs), historically most insecticides are based on a pre-existing molecule or product either from a competitor or from an internal company source. As such the first examples of a new insecticide representing a new type or class of AI (First-in-Class: FIC) are important as prototypes for other AIs stimulating further spectrum, efficacy, physicochemical, and environmental safety refinements. FIC insecticides also represent a measure of innovation. Understanding the origins of these FIC compounds and the approaches used in their discovery can provide insights into successful strategies for future new classes of insecticides. This perspective will focus on an analysis of the approaches that have been used for discovery of FIC insecticides highlighting those approaches that have been the most successful and providing a reference point for current and future directions.
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Affiliation(s)
| | - Beth A Lorsbach
- Nufarm, 4020 Aerial Center Parkway Morrisville, NC 27560, USA
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Duke SO, Pan Z, Chittiboyina AG, Swale DR, Sparks TC. Molecular targets of insecticides and herbicides - Are there useful overlaps? Pestic Biochem Physiol 2023; 191:105340. [PMID: 36963955 DOI: 10.1016/j.pestbp.2023.105340] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 01/07/2023] [Accepted: 01/10/2023] [Indexed: 06/18/2023]
Abstract
New insecticide modes of action are needed for insecticide resistance management strategies. The number of molecular targets of commercial herbicides and insecticides are fewer than 35 for both. Few commercial insecticide targets are found in plants, but ten targets of commercial herbicides are found in insects. For several of these commonly held targets, some compounds kill both plants and insects. For example, herbicidal inhibitors of p-hydroxyphenylpyruvate dioxygenase are effective insecticides on blood-fed insects. The glutamine synthetase-inhibiting herbicide glufosinate is insecticidal by the same mechanism of action, inhibition of glutamine synthetase. These and other examples of shared activities of commercial herbicides with insecticides through the same target site are discussed. Compounds with novel herbicide targets shared by insects that are not commercialized as pesticides (such as statins) are also discussed. Compounds that are both herbicidal and insecticidal can be used for insect pests not associated with crops or with crops made resistant to the compounds.
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Affiliation(s)
- Stephen O Duke
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38667, USA.
| | - Zhiqiang Pan
- Natural Products Utilization Research Unit, United States Department of Agriculture, University, MS 38667, USA
| | - Amar G Chittiboyina
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38667, USA
| | - Daniel R Swale
- Department of Entomology and Nematology, Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA
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Abstract
The continuing need to protect food and fiber production to address the demands of an expanding global population requires new pest management tools for crop protection. Natural products (NPs) have been and continue to be a key source of inspiration for new active ingredients (AIs) for crop protection, accounting for 17% of all crop protection AIs. However, potentially 50% of all crop protection compounds have or could have a NP origin if NP synthetic equivalents (NPSEs, synthetic compounds discovered by other approaches but for which a NP model also happens to exist) are also considered. The real and hypothetical NPs have their greatest impact as insight for new classes of crop protection compounds. Among the different product areas, NPs have their largest influence on the discovery of new insecticides, while herbicides have been the least affected by mining NPs for new AIs. While plants have historically been the largest (60% of the total) source of NPs of AIs for crop protection, in the last 30 years, bacterial NPs have become the largest source (42% of the total) of new classes (first in class) of NP-inspired crop protection AIs. Interest in NPs for crop protection continues, an aspect that is highlighted by the notable rise in the numbers of publications and patents on this topic, especially in the last 20 years. The present analysis further illustrates the continuing interest and value in NPs as sources of and inspiration for new classes of crop protection compounds.
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Affiliation(s)
| | - Janine M Sparks
- Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, United States
| | - Stephen O Duke
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, Oxford, Mississippi 38655, United States
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Mezei I, Valverde-Garcia P, Siebert MW, Gomez LE, Torne M, Watson GB, Raquel AM, Fereres A, Sparks TC. Impact of the nicotinic acetylcholine receptor mutation R81T on the response of European Myzus persicae populations to imidacloprid and sulfoxaflor in laboratory and in the field. Pestic Biochem Physiol 2022; 187:105187. [PMID: 36127049 DOI: 10.1016/j.pestbp.2022.105187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 07/22/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
Sulfoxaflor (Isoclast™ active) is a sulfoximine insecticide that is active on a broad range of sap-feeding insects, including species that exhibit reduced susceptibility to currently available insecticides. Colonies of Myzus persicae (green peach aphid) were established from aphids collected in the field from peach (Prunus persica) and nectarine (Prunus persica var. nucipersica) orchards in France, Italy and Spain. The presence of the nicotinic acetylcholine receptor (nAChR) point mutation R81T was determined for all the colonies. Eight of the 35 colonies collected were susceptible relative to R81T (i.e., R81T absent), three of the colonies were found to be homozygous for R81T while 24 colonies had R81T present in some proportion (heterozygous). Sulfoxaflor and imidacloprid were tested in the laboratory against these M. persicae field colonies, which exhibited a wide range of susceptibilities (sulfoxaflor RR = 0.6 to 61, imidacloprid RR = 0.7 to 986) (resistance ratios, RR) to both insecticides. Although sulfoxaflor was consistently more active than imidacloprid against these field collected M. persicae, there was a statistically significant correlation across all colonies between the RRs for imidacloprid and sulfoxaflor (Pearson's r = 0.939, p < 0.0001). However, when a larger group of the colonies from Spain possessing R81T were analyzed, there was no correlation observed for the RRs between imidacloprid and sulfoxaflor (r = 0.2901, p = 0.3604). Thus, consistent with prior studies, the presence of R81T by itself is not well correlated with altered susceptibility to sulfoxaflor. In field trials, sulfoxaflor (24 and 36 gai/ha) was highly effective (~avg. 88-96% control) against M. persicae, demonstrating similar levels of efficacy as flonicamid (60-70 gai/ha) and spirotetramat (100-180 gai/ha) at 13-15 days after application, in contrast to imidacloprid (110-190 gai/ha) and acetamiprid (50-75 gai/ha) with lower levels of efficacy (~avg. 62-67% control). Consequently, sulfoxaflor is an effective tool for use in insect pest management programs for M. persicae. However, it is recommended that sulfoxaflor be used in the context of an insecticide resistance management program as advocated by the Insecticide Resistance Action Committee involving rotation with insecticides possessing other modes of action (i.e., avoiding rotation with other Group 4 insecticides) to minimize the chances for resistance development and to extend its future utility.
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Affiliation(s)
- Imre Mezei
- Corteva Agriscience, Neumann János u.1, 2040 Budaőrs, Hungary.
| | - Pablo Valverde-Garcia
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Melissa W Siebert
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Luis E Gomez
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Maria Torne
- Corteva Agriscience, Joaquín Turina 2, Oficina 6, 28224 Pozuelo de Alarcón, Spain
| | - Gerald B Watson
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Abad M Raquel
- Corteva Agriscience, Joaquín Turina 2, Oficina 6, 28224 Pozuelo de Alarcón, Spain
| | - Alberto Fereres
- Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Cient.ficas, ICA-CSIC, Calle Serrano 115 dpdo, 28006 Madrid, Spain
| | - Thomas C Sparks
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
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Sparks TC, Bryant RJ. Innovation in insecticide discovery: Approaches to the discovery of new classes of insecticides. Pest Manag Sci 2022; 78:3226-3247. [PMID: 35452182 DOI: 10.1002/ps.6942] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
The continuing demand for agrochemical insecticides that can meet increasing grower, environmental, consumer and regulatory requirements creates the need for the development of new solutions for managing crop pest insects. The development of resistance to the currently available insecticidal products adds another critical driver for new insecticidal active ingredients (AIs). One avenue to meeting these challenges is the creation of new classes of insecticidal molecules to act as starting points and prototypes stimulating further spectrum, efficacy and environmental impact refinements. A new class of insecticides is foreshadowed by the first molecule exemplifying that class (first-in-class, FIC) and offers one measure of innovation within the agrochemical industry. Most insecticides owe their discovery to competitor-inspired (i.e. competitor patents/products) or next-generation (follow-on to a company's pre-existing product) strategies. In contrast, FIC insecticides primarily emerge from a bioactive hypothesis approach, with the largest segment resulting from the exploration of new areas of chemistry/heterocycles and underexploited motifs. Natural products also play an important role in the discovery of FIC insecticides. Understanding the origins of these FIC compounds and the approaches used in their discovery can provide insights into successful strategies for future FIC insecticides. This review analyses information on historic and recently introduced FIC insecticides. Its main objective has been to identify the most successful discovery strategies for identifying new agrochemical solutions to meet the challenge of minimizing crop losses resulting from insects. © 2022 Society of Chemical Industry.
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Sparks TC, Bryant RJ. Impact of natural products on discovery of, and innovation in, crop protection compounds. Pest Manag Sci 2022; 78:399-408. [PMID: 34549518 DOI: 10.1002/ps.6653] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/10/2021] [Accepted: 09/21/2021] [Indexed: 05/26/2023]
Abstract
Natural products (NPs) have long been an important source of, and inspiration for, developing novel compounds to control weeds, pathogens and insect pests. In this review, we use a dataset of 800 historic, current and emerging crop protection compounds to explore the influence of NPs on the introduction of new crop protection compounds (fungicides, herbicides, insecticides) as a function of time. NPs, their semisynthetic derivatives (NPDs) and compounds inspired by NPs (NP mimics, NPMs) account for 17% of all crop protection compounds. NPs, NPDs, and NPMs have been a fairly constant source of new agrochemicals over the past 70 years. NP synthetic equivalents (NPSEs) is a fourth group of NP-related crop protection compounds composed of synthetic compounds which by chance also happen to have an NP model (but are not involved in the discovery). If NPSE compounds are also included, then 50% of all crop protection compounds hypothetically could have had a NP origin. Similar trends also hold true for the impact of NPs on the discovery of new modes of action (MoA) or innovation in crop protection compounds as measured by the number of first-in-class compounds. NPs have had the largest impact on the numbers and global sales (2018 USD) of insecticides compared to fungicides and herbicides. The present analysis highlights NPs as a long-standing and continuing source of new chemistry, new MoAs and innovation in crop protection compound discovery. © 2021 Society of Chemical Industry.
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Watson GB, Siebert MW, Wang NX, Loso MR, Sparks TC. Sulfoxaflor - A sulfoximine insecticide: Review and analysis of mode of action, resistance and cross-resistance. Pestic Biochem Physiol 2021; 178:104924. [PMID: 34446200 DOI: 10.1016/j.pestbp.2021.104924] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/08/2021] [Accepted: 07/11/2021] [Indexed: 06/13/2023]
Abstract
The sulfoximines, as exemplified by sulfoxaflor (Isoclast™active), are a relatively new class of nicotinic acetylcholine receptor (nAChR) competitive modulator (Insecticide Resistance Action Committee [IRAC] Group 4C) insecticides that provide control of a wide range of sap-feeding insect pests. The sulfoximine chemistry and sulfoxaflor exhibits distinct interactions with metabolic enzymes and nAChRs compared to other IRAC Group 4 insecticides such as the neonicotinoids (Group 4A). These distinctions translate to notable differences in the frequency and degree of cross-resistance between sulfoxaflor and other insecticides. Most insect strains exhibiting resistance to a variety of insecticides, including neonicotinoids, exhibited little to no cross-resistance to sulfoxaflor. To date, only two laboratory-based studies involving four strains (Koo et al. 2014, Chen et al. 2017) have observed substantial cross-resistance (>100 fold) to sulfoxaflor in neonicotinoid resistant insects. Where higher levels of cross-resistance to sulfoxaflor are observed the magnitude of that resistance is far less than that of the selecting neonicotinoid. Importantly, there is no correlation between presence of resistance to neonicotinoids (i.e., imidacloprid, acetamiprid) and cross-resistance to sulfoxaflor. This phenomenon is consistent with and can be attributed to the unique and differentiated chemical class represented by sulfoxalfor. Recent studies have demonstrated that high levels of resistance (resistance ratio = 124-366) to sulfoxaflor can be selected for in the laboratory which thus far appear to be associated with enhanced metabolism by specific cytochrome P450s, although other resistance mechanisms have not yet been excluded. One hypothesis is that sulfoxaflor selects for and is susceptible to a subset of P450s with different substrate specificity. A range of chemoinformatic, molecular modeling, metabolism and target-site studies have been published. These studies point to distinctions in the chemistry of sulfoxaflor, and its metabolism by enzymes associated with resistance to other insecticides, as well as its interaction with insect nicotinic acetylcholine receptors, further supporting the subgrouping of sulfoxaflor (Group 4C) separate from that of other Group 4 insecticides. Herein is an expansion of an earlier review (Sparks et al. 2013), providing an update that considers prior and current studies focused on the mode of action of sulfoxaflor, along with an analysis of the presently available resistance / cross-resistance studies, and implications and recommendations regarding resistance management.
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Affiliation(s)
- Gerald B Watson
- Corteva Agriscience LLC, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America.
| | - Melissa W Siebert
- Corteva Agriscience LLC, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Nick X Wang
- Corteva Agriscience LLC, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Michael R Loso
- Corteva Agriscience LLC, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Thomas C Sparks
- Corteva Agriscience LLC, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
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Sparks TC, Bryant RJ. East meets west: regional impact on agrochemical discovery and innovation. Pest Manag Sci 2021; 77:4211-4223. [PMID: 33821560 DOI: 10.1002/ps.6392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/30/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
The efficient production of the food needed to nourish an expanding global population continues to fuel the demand for new crop protection compounds. This task is made all the more difficult by the need to meet increasingly demanding grower, consumer and regulatory constraints. The discovery and development of new synthetic organic crop protection compounds has been largely the responsibility of the agrochemical industry in Europe, Japan and the USA, with government-funded academic research often playing a crucial role in the early stages of the invention and testing of novel activity. The way in which this process takes place has undergone a dramatic evolution over the past 75 years. Drastic consolidation and globalization among the research and development (R&D)-based companies in these regions have characterized these changes. This evolution in the agrochemical industry has, in turn, shaped the rate of introduction and geographic origin of new crop protection compounds. In spite of these changes, the rate of invention of new classes of crop protection compounds has remained relatively constant. During the past 30 years, the forefront of new compound introductions has moved towards Asia, and Japan in particular. Although there are now more agrochemical companies in Japan involved in the discovery and development of new crop protection compounds than in Europe and the USA combined, on a compound-per-company basis, US companies currently generate the highest output. However, it is expected that there will continue to be changes in the numbers and origins of new crop protection compounds, with contributions continuing from Europe, Japan and the USA, and increasingly from China. © 2021 Society of Chemical Industry.
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Abstract
Natural products (NPs) have a long history as sources of compounds for crop protection. Perhaps a more important role for NPs has been as models and inspiration for the discovery and development of synthetic crop protection compounds. NPs and their synthetic mimics account for 18% of all crop protection compounds, whereas another 38% of all crop protection compounds have a NP that could have served as a model. Because NPs are often complex molecules, have limited availability, or possess structural features that constrain their suitability for use in agricultural settings, a key element in NP-inspired compounds is the simplification of the NP structure to provide a synthetically accessible molecule that possesses the physicochemical properties needed for use in crop protection. Herein we review a series of examples of NP mimics that demonstrate the structural or synthetic simplification of NPs as a guide for the discovery of future NP-inspired agrochemicals focused on fungicides, herbicides, and insecticides.
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Affiliation(s)
| | - Stephen O Duke
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi 38677, United States
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Sparks TC, Bryant RJ. Crop protection compounds - trends and perspective. Pest Manag Sci 2021; 77:3608-3616. [PMID: 33486823 DOI: 10.1002/ps.6293] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/19/2021] [Accepted: 01/23/2021] [Indexed: 06/12/2023]
Abstract
The Industry responsible for the discovery and development of crop protection compounds has undergone dramatic changes and increasing consolidation since the initial innovations in synthetic organic fungicides, herbicides and insecticides in the late 1940s and early 1950s. Likewise, there have been striking changes in the rate of introduction of new crop protection compounds over the past 70 years. While numerous studies over the past five decades have signaled the ongoing decline in the numbers of new active ingredients (AIs), a detailed analysis of the trends in the rate of introduction of crop protection compounds shows a more complex pattern in the overall output of new AIs. The recent (post-2000) decline in the numbers of new herbicides is the primary source of the perceived decline in overall numbers. When herbicides are excluded, the output of new fungicides and insecticides has been relatively constant, especially for the past 20 years. A notable observation is that innovation, as measured by the number of compounds representing a new chemical class (First-in-Class) has been relatively constant for the past 70 years, and most recently has been driven by the appearance of new fungicides and insecticides. Thus, the discovery and development of new AIs for crop protection and public health continues, in spite of the many challenges and changes to the Industry. © 2021 Society of Chemical Industry.
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Sparks TC, Crouse GD, Benko Z, Demeter D, Giampietro NC, Lambert W, Brown AV. The spinosyns, spinosad, spinetoram, and synthetic spinosyn mimics - discovery, exploration, and evolution of a natural product chemistry and the impact of computational tools. Pest Manag Sci 2021; 77:3637-3649. [PMID: 32893433 DOI: 10.1002/ps.6073] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/16/2020] [Accepted: 09/07/2020] [Indexed: 05/28/2023]
Abstract
Natural products (NPs) have long been a source of insecticidal crop protection products. Like many macrolide NPs, the spinosyns originated from a soil inhibiting microorganism (Saccharopolyspora spinosa). More than 20 years after initial registration, the spinosyns remain a unique class of NP-based insect control products that presently encompass two insecticidal active ingredients, spinosad, a naturally occurring mixture of spinosyns, and spinetoram, a semi-synthetic spinosyn product. The exploration and exploitation of the spinosyns has, unusually, been tied to an array of computational tools including artificial intelligence (AI)-based quantitative structure activity relationship (QSAR) and most recently computer-aided modeling and design (CAMD). The AI-based QSAR directly lead to the discovery of spinetoram, while the CAMD studies have recently resulted in the discovery and building of a series of synthetic spinosyn mimics. The most recent of these synthetic spinosyn mimics show promise as insecticides targeting lepidopteran insect pests as demonstrated by field studies wherein the efficacy has been shown to be comparable to spinosad and spinetoram. These and a range of other aspects related to the exploration of the spinosyns over the past 30 years are reviewed herein. © 2020 Society of Chemical Industry.
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Affiliation(s)
| | - Gary D Crouse
- Corteva Agriscience, Discovery Research, Indianapolis, IN, USA
| | - Zoltan Benko
- Corteva Agriscience, Discovery Research, Indianapolis, IN, USA
| | - David Demeter
- Corteva Agriscience, Discovery Research, Indianapolis, IN, USA
| | | | - William Lambert
- Corteva Agriscience, Discovery Research, Indianapolis, IN, USA
| | - Annette V Brown
- Corteva Agriscience, Discovery Research, Indianapolis, IN, USA
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Sparks TC, Storer N, Porter A, Slater R, Nauen R. Insecticide resistance management and industry: the origins and evolution of the Insecticide Resistance Action Committee (IRAC) and the mode of action classification scheme. Pest Manag Sci 2021; 77:2609-2619. [PMID: 33421293 PMCID: PMC8248193 DOI: 10.1002/ps.6254] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 01/09/2021] [Indexed: 05/26/2023]
Abstract
Insecticide resistance is a long-standing problem affecting the efficacy and utility of crop protection compounds. Insecticide resistance also impacts the ability and willingness of companies around the world to invest in new crop protection compounds and traits. The Insecticide Resistance Action Committee (IRAC) was formed in 1984 to provide a coordinated response by the crop protection industry to the problem of insecticide resistance. Since its inception, participation in IRAC has grown from a few agrochemical companies in Europe and the US to a much larger group of companies with global representation and an active presence (IRAC Country Groups) involving an even wider array of companies in more than 20 countries. The focus of IRAC has also evolved from that of defining and documenting cases of insecticide resistance to a pro-active role in addressing insecticide resistance management (IRM) providing an array of informational and educational tools (videos, posters, pamphlets) on insect pests, bioassay methods, insecticide mode of action and resistance management, all publicly available through its website (https://irac-online.org/). A key tool developed by IRAC is the Insecticide Mode of Action (MoA) Classification Scheme, which has evolved from a relatively simple acaricide classification started in 1998 to the far broader scheme that now includes biologics as well as insecticides and acaricides. A separate MoA Classification Scheme has also been recently developed for nematicides. The IRAC MoA Classification Scheme coupled with expanding use of MoA labeling on insecticide and acaricide product labels provides a straightforward means to implement IRM. An overview of the history of IRAC along with some of its notable accomplishments and future directions are reviewed. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Thomas C Sparks
- Corteva AgriscienceIndianapolisINUSA
- Agrilucent LLCGreenfieldINUSA
| | | | | | | | - Ralf Nauen
- Bayer AG, Crop Science Division, R&DMonheim am RheinGermany
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16
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Perry T, Chen W, Ghazali R, Yang YT, Christesen D, Martelli F, Lumb C, Bao Luong HN, Mitchell J, Holien JK, Parker MW, Sparks TC, Batterham P. Role of nicotinic acetylcholine receptor subunits in the mode of action of neonicotinoid, sulfoximine and spinosyn insecticides in Drosophila melanogaster. Insect Biochem Mol Biol 2021; 131:103547. [PMID: 33548485 DOI: 10.1016/j.ibmb.2021.103547] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 01/28/2021] [Accepted: 01/29/2021] [Indexed: 06/12/2023]
Abstract
Insecticides remain valuable tools for the control of insect pests that significantly impact human health and agriculture. A deeper understanding of insecticide targets is important in maintaining this control over pests. Our study systematically investigates the nicotinic acetylcholine receptor (nAChR) gene family, in order to identify the receptor subunits critical to the insect response to insecticides from three distinct chemical classes (neonicotinoids, spinosyns and sulfoximines). Applying the CRISPR/Cas9 gene editing technology in D. melanogaster, we were able to generate and maintain homozygous mutants for eight nAChR subunit genes. A ninth gene (Dβ1) was investigated using somatic CRISPR in neural cells to overcome the low viability of the homozygous germline knockout mutant. These findings highlight the specificity of the spinosyn class insecticide, spinosad, to receptors containing the Dα6 subunit. By way of contrast, neonicotinoids are likely to target multiple receptor subtypes, beyond those receptor subunit combinations previously identified. Significant differences in the impacts of specific nAChR subunit deletions on the resistance level of flies to neonicotinoids imidacloprid and nitenpyram indicate that the receptor subtypes they target do not completely overlap. While an R81T mutation in β1 subunits has revealed residues co-ordinating binding of sulfoximines and neonicotinoids differ, the resistance profiles of a deletion of Dβ1 examined here provide new insights into the mode of action of sulfoxaflor (sulfoximine) and identify Dβ1 as a key component of nAChRs targeted by both these insecticide classes. A comparison of resistance phenotypes found in this study to resistance reported in insect pests reveals a strong conservation of subunit targets across many different insect species and that mutations have been identified in most of the receptor subunits that our findings would predict to have the potential to confer resistance.
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Affiliation(s)
- Trent Perry
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia.
| | - Wei Chen
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Razi Ghazali
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Ying Ting Yang
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Danielle Christesen
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Felipe Martelli
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Chris Lumb
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia; Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, 3052, Australia
| | - Hang Ngoc Bao Luong
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Judith Mitchell
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Jessica K Holien
- St. Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, Victoria, 3065, Australia
| | - Michael W Parker
- St. Vincent's Institute of Medical Research, 9 Princes St, Fitzroy, Victoria, 3065, Australia; Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Thomas C Sparks
- Corteva Agriscience, 9330 Zionville Road, Indianapolis, IN, 46268, USA
| | - Philip Batterham
- School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
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Sparks TC, Crossthwaite AJ, Nauen R, Banba S, Cordova D, Earley F, Ebbinghaus-Kintscher U, Fujioka S, Hirao A, Karmon D, Kennedy R, Nakao T, Popham HJR, Salgado V, Watson GB, Wedel BJ, Wessels FJ. Insecticides, biologics and nematicides: Updates to IRAC's mode of action classification - a tool for resistance management. Pestic Biochem Physiol 2020; 167:104587. [PMID: 32527435 DOI: 10.1016/j.pestbp.2020.104587] [Citation(s) in RCA: 160] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/19/2020] [Accepted: 04/17/2020] [Indexed: 05/21/2023]
Abstract
Insecticide resistance has been and continues to be a significant problem for invertebrate pest control. As such, effective insecticide resistance management (IRM) is critical to maintain the efficacy of current and future insecticides. A technical group within CropLife International, the Insecticide Resistance Action Committee (IRAC) was established 35 years ago (1984) as an international association of crop protection companies that today spans the globe. IRAC's focus is on preserving the long-term utility of insect, mite, and most recently nematode control products through effective resistance management to promote sustainable agriculture and improved public health. A central task of IRAC has been the continual development and documentation of the Mode of Action (MoA) Classification scheme, which serves as an important tool for implementing IRM strategies focused on compound rotation / alternations. Updates to the IRAC MoA Classification scheme provide the latest information on the MoA of current and new insecticides and acaricides, and now includes information on biologics and nematicides. Details for these new changes and additions are reviewed herein.
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Affiliation(s)
- Thomas C Sparks
- Corteva Agriscience, Discovery Research, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Andrew J Crossthwaite
- Syngenta Crop Protection, Jealott's Hill International Research Centre, Bracknell Berkshire RG42 6EY, UK.
| | - Ralf Nauen
- Bayer AG, Crop Science Division, R&D, Alfred-Nobel Str. 50, 40789 Monheim am Rhein, Germany
| | - Shinichi Banba
- Mitsui Chemicals Agro Inc., Agrochemical Research Center, Mobara, Chiba 297-0017, Japan
| | - Daniel Cordova
- FMC Agricultural Solutions, Stine Research Center, 1090 Elkton Rd., Newark, DE 19711, USA
| | - Fergus Earley
- Syngenta Crop Protection, Jealott's Hill International Research Centre, Bracknell Berkshire RG42 6EY, UK
| | | | - Shinsuke Fujioka
- Nihon Nohyaku Co. Ltd., Research Center, Research Division, 345 Oyamada-cho, Kawachinagano, Osaka 586-0094, Japan
| | - Ayako Hirao
- Sumitomo Chemical Company, Ltd., AgroSolutions Division-International, Tokyo Sumitomo Twin Bldg., East 27-1 Shinkawa 2- Chome, Tokyo, Japan
| | - Danny Karmon
- Adama Agricultural Solutions, Airport City, Golan Street, 7015103, Israel
| | - Robert Kennedy
- Vestaron, 4717 Campus Dr, Suite 1200, Kalamazoo, MI 49008, USA
| | - Toshifumi Nakao
- Mitsui Chemicals Agro Inc., Agrochemical Research Center, Mobara, Chiba 297-0017, Japan
| | | | - Vincent Salgado
- BASF Corporation, Agricultural Solutions, 26 Davis Drive, Research Triangle Park, Raleigh, NC, 27709, USA
| | - Gerald B Watson
- Corteva Agriscience, Discovery Research, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Barbara J Wedel
- BASF Corporation, Agricultural Solutions, 26 Davis Drive, Research Triangle Park, Raleigh, NC, 27709, USA
| | - Frank J Wessels
- Corteva Agriscience, Discovery Research, 9330 Zionsville Road, Indianapolis, IN 46268, USA
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Mezei I, Bielza P, Siebert MW, Torne M, Gomez LE, Valverde-Garcia P, Belando A, Moreno I, Grávalos C, Cifuentes D, Sparks TC. Sulfoxaflor efficacy in the laboratory against imidacloprid-resistant and susceptible populations of the green peach aphid, Myzus persicae: Impact of the R81T mutation in the nicotinic acetylcholine receptor. Pestic Biochem Physiol 2020; 166:104582. [PMID: 32448428 DOI: 10.1016/j.pestbp.2020.104582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 06/11/2023]
Abstract
A key to effective insect pest management and insecticide resistance management is to provide growers with a range of new tools as potential alternatives to existing compounds or approaches. Sulfoxaflor (Isoclast™ active) is a new sulfoximine insecticide which is active on a broad range of sap-feeding insects, including species that have reduced susceptibility to currently used insecticides, such as imidacloprid from the neonicotinoid class. Sulfoxaflor (SFX) and imidacloprid (IMI) were tested in laboratory bioassays to compare the susceptibility of field populations of green peach aphid, Myzus persicae (Sulzer), exhibiting varying degrees of resistance involving an alteration (R81T) to the insect nicotinic acetylcholine receptor. The LC50 values for M. persicae exposed to SFX ranged from 0.09 to 1.31 (mg litre-1), whereas when the same populations were exposed to IMI the LC50 values ranged from 0.6 to 76.2 (mg litre-1). M. persicae were significantly more sensitive to SFX as compared to IMI for nine of the 13 populations tested. For M. persicae populations confirmed to be homozygous susceptible (ss) or heterozygous rs) for the R81T point mutation, there was no significant differences in the observed LC50 values for either SFX or IMI relative to the susceptible reference population (15LP1). However, in all M persicae populations that were homozygous (rr) for the R81T point mutation, susceptibility was significantly less to IMI as compared to the reference population with resistance ratios ranging from 22.1 to 63.5-fold. In contrast, only one homozygous resistant population (15MP9) exhibited a statistically significant change in susceptibility (RR = 10-fold) to SFX as compared to the reference population, which was far less than the 56-fold observed for imidacloprid in that same population. Thus, this study indicates there is no specific correlation between the laboratory efficacy of SFX and IMI in field collected populations in Spain displaying varying degrees of resistance to IMI. Furthermore, the presence of target site resistance in M. persicae to IMI, in the form of the R81T mutation, does not a priori translate to a reduction in sensitivity to sulfoxaflor. Consequently, SFX can be an effective tool for use in insect pest management programs for green peach aphid. These data also serve as a baseline reference for green peach aphid sensitivity to SFX prior to commercial uses in Spain.
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Affiliation(s)
- Imre Mezei
- Corteva Agriscience, Neumann János u.1, 2040 Budaőrs, Hungary.
| | - Pablo Bielza
- Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain
| | - Melissa W Siebert
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Maria Torne
- Corteva Agriscience, Joaquín Turina 2, Oficina 6, 28224 Pozuelo de Alarcón, Spain
| | - Luis E Gomez
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Pablo Valverde-Garcia
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
| | - Ana Belando
- Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain
| | - Inmaculada Moreno
- Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain
| | - Carolina Grávalos
- Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain
| | - Dina Cifuentes
- Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain
| | - Thomas C Sparks
- Corteva Agriscience, 9330 Zionsville Road, Indianapolis, IN 46268, United States of America
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Hamm RL, Gregg A, Sparks TC. Intellectual property in entomology: Analysis and perspective on recent trends in global patent publications. Pest Manag Sci 2020; 76:1603-1611. [PMID: 32034856 DOI: 10.1002/ps.5780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/02/2020] [Accepted: 02/07/2020] [Indexed: 06/10/2023]
Abstract
Intellectual property (IP) is an important consideration for entomological research and provides a means to capture value from new discoveries. Herein, we describe an analysis of more than 26 000 patent publications from 2007-2017 related to the field of entomology. These patents were divided among 8000 patent assignees; however, only 5% of the assignees had ≥10 patents. Corporations accounted for the largest share of patents (59%), with individuals (20%), academic institutions (17%) and government organizations (4%) making up the remaining segments. From 2007-2017 the number of entomological patents increased by 400%, with the largest number being from China. However, unlike patents from Europe, Japan or the US, which target a range of countries, the Chinese patents almost exclusively focus on China. Among the array of subjects covered are transgenic insects and plants, repellents, recombinant insect cells, with the highest proportion of patents focused on insecticides (39%), followed by insecticide mixtures (27%) and formulations (21%). The top 30 patent assignees included companies/institutions from China (18), Europe (3), Japan (6) and the US (3). Among the top 12 entities, IP from the US assignees was distributed across insecticides, mixtures and insecticidal traits while those from China were more focused on mixtures. However, given expanding IP numbers from China it is expected that in the future there will be a greater impact on new insecticides and related technologies. © 2020 Society of Chemical Industry.
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Affiliation(s)
| | | | - Thomas C Sparks
- Corteva Agriscience, Indianapolis, IN, USA
- Retired, present address, Agrilucent LLC, Greenfield, Indiana, USA
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20
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Sparks TC, Wessels FJ, Lorsbach BA, Nugent BM, Watson GB. The new age of insecticide discovery-the crop protection industry and the impact of natural products. Pestic Biochem Physiol 2019; 161:12-22. [PMID: 31685191 DOI: 10.1016/j.pestbp.2019.09.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 09/03/2019] [Accepted: 09/09/2019] [Indexed: 06/10/2023]
Abstract
Improvements in food production and disease vector control, to feed and protect an expanding global population, require new options and approaches for insect control. A changing and an increasingly stringent regulatory landscape, shifts in pest spectrum due to changes in agronomic practices, and insect resistance to existing insecticides, all contribute to the challenges of, and need for, developing new insect control agents. The nature of insecticides emanating from discovery R&D-based companies in the European Union, Japan, and the United States have evolved from a concentration on a few classes of insecticides and modes of action (MoA), to a far more diversified collection of insecticidal molecules that embody many new, or under-utilized MoAs. Since 1990 there has arguably been a new age of insecticide discovery, with more new classes of insecticides introduced, with greater economic impact, than the prior 50 years combined. Although there has been an on-going evolution and consolidation in the size and shape of the crop protection industry, for the past two decades the output of new insecticides has remained relatively constant. The diversity of approaches employed in the insecticide discovery process (competitor inspired, bioactive hypothesis and natural products) has contributed to the discovery of these new classes of insecticides. Insecticide discovery is today a global enterprise, that armed with new tools and capabilities, will continue to build and provide the future insect control products to meet global grower and consumer demands.
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Affiliation(s)
| | - Frank J Wessels
- Corteva Agriscience, Indianapolis, IN 46268, United States of America
| | - Beth A Lorsbach
- Corteva Agriscience, Indianapolis, IN 46268, United States of America
| | - Benjamin M Nugent
- Corteva Agriscience, Indianapolis, IN 46268, United States of America
| | - Gerald B Watson
- Corteva Agriscience, Indianapolis, IN 46268, United States of America
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Lorsbach BA, Sparks TC, Cicchillo RM, Garizi NV, Hahn DR, Meyer KG. Natural products: a strategic lead generation approach in crop protection discovery. Pest Manag Sci 2019; 75:2301-2309. [PMID: 30672097 DOI: 10.1002/ps.5350] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/16/2019] [Accepted: 01/19/2019] [Indexed: 05/14/2023]
Abstract
With the anticipated population growth in the coming decades, the changing regulatory environment, and the continued emergence of resistance to commercial pesticides, there is a constant need to discover new lead chemistries with novel modes of action. We have established a portfolio of approaches to accelerate lead generation. One of these approaches capitalizes on the rich bioactivity of natural products (NPs), highlighted by the numerous examples of NP-based crop protection compounds. Within Corteva Agriscience and the affiliated preceding companies, NPs have been a fruitful approach, for nearly three decades, to identifying and bringing to the market crop protection products inspired by or originating from NPs, . Included in these NP-based crop protection products are the spinosyns family of insecticides, and those from more recent areas of NP-based fungicidal chemistry, as highlighted in this perspective. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Beth A Lorsbach
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Thomas C Sparks
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Robert M Cicchillo
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Negar V Garizi
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Donald R Hahn
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Kevin G Meyer
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
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Sparks TC, Crouse GD, Demeter DA, Samaritoni G, McLeod CL. Discovery of highly insecticidal synthetic spinosyn mimics - CAMD enabled de novo design simplifying a complex natural product. Pest Manag Sci 2019; 75:309-313. [PMID: 30242953 DOI: 10.1002/ps.5217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/06/2018] [Accepted: 09/14/2018] [Indexed: 06/08/2023]
Abstract
Simplifying complex natural products: Computer modeling-based design leads to highly insecticidal, chemically simpler synthetic mimics of the spinosyn natural products that are active in the field. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Thomas C Sparks
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
| | - Gary D Crouse
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
| | - David A Demeter
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
| | - Geno Samaritoni
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
| | - Casandra L McLeod
- Corteva Agriscience™, Agriculture Division of DowDuPont™, Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
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Abstract
Current crop protection chemicals span an array of chemistry classes and modes of action. Typically, within each chemistry class, there are multiple chemically distinct active ingredients competing with each other for market position. In this competition, the first product to market in a new class or mode of action may or may not have an advantage depending upon a number of parameters, including relative efficacy against the target pests, pest resistance, regulatory pressures, synthetic complexity, and marketing effectiveness. The number of companies involved in the discovery of new crop protection compounds has been declining, and patenting strategies have become more sophisticated, making it more challenging to break into an existing area of chemistry. One result is new classes of chemistry tend to be smaller, making first to market more beneficial than in the past. Additionally, the first into a market with a new class of chemistry has the opportunity to set positioning and expectations.
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Affiliation(s)
- Thomas C Sparks
- Corteva Agrisciences, Agriculture Division of DowDuPont, Discovery Research , Dow AgroSciences , 9330 Zionsville Road , Indianapolis , Indiana 46268 , United States
| | - James E Hunter
- Corteva Agrisciences, Agriculture Division of DowDuPont, Discovery Research , Dow AgroSciences , 9330 Zionsville Road , Indianapolis , Indiana 46268 , United States
| | - Beth A Lorsbach
- Corteva Agrisciences, Agriculture Division of DowDuPont, Discovery Research , Dow AgroSciences , 9330 Zionsville Road , Indianapolis , Indiana 46268 , United States
| | - Greg Hanger
- Corteva Agrisciences, Agriculture Division of DowDuPont, Discovery Research , Dow AgroSciences , 9330 Zionsville Road , Indianapolis , Indiana 46268 , United States
| | - Roger E Gast
- Corteva Agrisciences, Agriculture Division of DowDuPont, Discovery Research , Dow AgroSciences , 9330 Zionsville Road , Indianapolis , Indiana 46268 , United States
| | - Greg Kemmitt
- Corteva Agrisciences, Agriculture Division of DowDuPont, Discovery Research , Dow AgroSciences , 9330 Zionsville Road , Indianapolis , Indiana 46268 , United States
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Zhang Y, Lorsbach BA, Castetter S, Lambert WT, Kister J, Wang NX, Klittich CJR, Roth J, Sparks TC, Loso MR. Physicochemical property guidelines for modern agrochemicals. Pest Manag Sci 2018; 74:1979-1991. [PMID: 29667318 DOI: 10.1002/ps.5037] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/04/2018] [Accepted: 04/09/2018] [Indexed: 05/08/2023]
Abstract
The relentless need for the discovery and development of new agrochemicals continues as a result of driving forces such as loss of existing products through the development of resistance, the necessity for products with more favorable environmental and toxicological profiles, shifting pest spectra, and the changing agricultural needs and practices of the farming community. These new challenges underscore the demand for novel, high-quality starting points to accelerate the discovery of new agrochemicals that address market challenges. This article discusses the efforts to identify the optimum ranges of physicochemical properties of agrochemicals through analysis of modern commercial products. Specifically, we reviewed literature studies examining physicochemical property effects and analyzed the properties typical of successful fungicides, herbicides, and insecticides (chewing and sap-feeding pests). From the analysis, a new set of physicochemical property guidelines for each discipline, as well as building block class, are proposed. These new guidelines should significantly aid in the discovery of next-generation agrochemicals. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Yu Zhang
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Beth A Lorsbach
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Scott Castetter
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | | | - Jeremy Kister
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Nick X Wang
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | | | - Joshua Roth
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Thomas C Sparks
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
| | - Mike R Loso
- Crop Protection Discovery, Dow AgroSciences, Indianapolis, IN, USA
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Crouse GD, Demeter DA, Samaritoni G, McLeod CL, Sparks TC. De Novo Design of Potent, Insecticidal Synthetic Mimics of the Spinosyn Macrolide Natural Products. Sci Rep 2018; 8:4861. [PMID: 29559660 PMCID: PMC5861068 DOI: 10.1038/s41598-018-22894-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/01/2018] [Indexed: 11/22/2022] Open
Abstract
New insect pest control agents are needed to meet the demands to feed an expanding global population, to address the desire for more environmentally-friendly insecticide tools, and to fill the loss of control options in some crop-pest complexes due to development of insecticide resistance. The spinosyns are a highly effective class of naturally occurring, fermentation derived insecticides, possessing a very favorable environmental profile. Chemically, the spinosyns are composed of a large complex macrolide tetracycle coupled to two sugars. As a means to further exploit this novel class of natural product-based insecticides, molecular modeling studies coupled with bioactivity-directed chemical modifications were used to define a less complex, synthetically accessible replacement for the spinosyn tetracycle. These studies lead to the discovery of highly insecticidal analogs, possessing a simple tri-aryl ring system as a replacement for the complex macrolide tetracycle.
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Affiliation(s)
- Gary D Crouse
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, IN, 46268, USA.,5069 E 146th St Noblesville IN 46062, Indianapolis, IN, USA
| | - David A Demeter
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Geno Samaritoni
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, IN, 46268, USA.,Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN, 46202, USA
| | - Casandra L McLeod
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, IN, 46268, USA.,6034 Haverford Ave, Indianapolis, IN, 46220, USA
| | - Thomas C Sparks
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, IN, 46268, USA.
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Watson GB, Olson MB, Beavers KW, Loso MR, Sparks TC. Characterization of a nicotinic acetylcholine receptor binding site for sulfoxaflor, a new sulfoximine insecticide for the control of sap-feeding insect pests. Pestic Biochem Physiol 2017; 143:90-94. [PMID: 29183616 DOI: 10.1016/j.pestbp.2017.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 08/30/2017] [Accepted: 09/02/2017] [Indexed: 06/07/2023]
Abstract
Sulfoxaflor (SFX, Isoclast™ Active) is a recently developed sulfoximine insecticide that is highly effective against sap-feeding insect pests. SFX has been shown to act through an interaction with insect nicotinic acetylcholine receptors (nAChRs). SFX was previously found to interact weakly with the binding site for the neonicotinoid imidacloprid. However, radioligand displacement studies characterizing the binding site of the insecticide SFX itself have not been conducted. In this study, we report the characterization of a high affinity [3H]SFX Myzus persicae (green peach aphid, GPA) binding site with relatively low abundance. Through the evaluation of a set of SFX analogs, we have demonstrated that displacement of [3H]SFX shows an excellent correlation with GPA toxicity, and thus is toxicologically relevant. Comparison with the previously described methyl-SFX binding site information reveals differences with the SFX binding site that are discussed herein. [3H]SFX therefore represents a new tool for the characterization of insect nAChRs.
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Affiliation(s)
- Gerald B Watson
- Dow AgroSciences, LLC, 9330 Zionsville Rd., Indianapolis, IN 46268, United States.
| | - Monica B Olson
- Dow AgroSciences, LLC, 9330 Zionsville Rd., Indianapolis, IN 46268, United States
| | - Kenneth W Beavers
- Dow AgroSciences, LLC, 9330 Zionsville Rd., Indianapolis, IN 46268, United States
| | - Michael R Loso
- Dow AgroSciences, LLC, 9330 Zionsville Rd., Indianapolis, IN 46268, United States
| | - Thomas C Sparks
- Dow AgroSciences, LLC, 9330 Zionsville Rd., Indianapolis, IN 46268, United States
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Loso MR, Garizi N, Hegde VB, Hunter JE, Sparks TC. Lead generation in crop protection research: a portfolio approach to agrochemical discovery. Pest Manag Sci 2017; 73:678-685. [PMID: 27301075 DOI: 10.1002/ps.4336] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
The need for increased food and feed supply to support future global demand with the added challenges of resistance pressure and an evolving regulatory environment necessitates the discovery of new crop protection agents for growers of today and tomorrow. Lead generation is the critical 'engine' for maintaining a robust pipeline of new high-value products. A wide variety of approaches exist for the generation of new leads, many of which have demonstrated success. Each approach features some degree of merit or benefit while also having some inherent drawback or level of risk. While risk for any single approach can be mitigated in a variety of different ways depending on the approach, long-term viability of a successful lead generation program merits utilization of a portfolio of different approaches and methodologies for the generation of new leads. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Michael R Loso
- Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
| | - Negar Garizi
- Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
| | | | - James E Hunter
- Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
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Lambert WT, Goldsmith ME, Sparks TC. Insecticidal activity of novel thioureas and isothioureas. Pest Manag Sci 2017; 73:743-751. [PMID: 27391046 DOI: 10.1002/ps.4353] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 06/24/2016] [Accepted: 07/01/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND We hypothesized that the exploration of chemical space around compounds with reported insecticidal activity could be a viable strategy for discovering novel, insecticidally active areas of chemistry. RESULTS A series of thioureas and isothioureas were prepared as part of a scaffold-hopping effort around known insecticidal compounds. Many of these compounds showed excellent activity against key sap-feeding insect pests in insecticidal bioassays. While analogs bearing monocyclic thiophene head groups showed activity against Myzus persicae (green peach aphid), analogs with diarylethane head groups were active against both M. persicae and Bemisia tabaci (sweetpotato whitefly). Despite compelling activity in these laboratory tests, these compounds showed diminished activity when applied to host plants via tracksprayer. CONCLUSIONS The initial hypothesis that structural modification of molecules reported to have insecticidal activity would yield novel compounds that also exhibit insecticidal activity was validated. Despite excellent activity in laboratory bioassays, these new compounds failed to show compelling activity in more demanding tracksprayer tests. © 2016 Society of Chemical Industry.
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Sparks TC, Hahn DR, Garizi NV. Natural products, their derivatives, mimics and synthetic equivalents: role in agrochemical discovery. Pest Manag Sci 2017; 73:700-715. [PMID: 27739147 DOI: 10.1002/ps.4458] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/10/2016] [Accepted: 10/11/2016] [Indexed: 06/06/2023]
Abstract
Natural products (NPs) have a long history as a source of, and inspiration for, novel agrochemicals. Many of the existing herbicides, fungicides, and insecticides have their origins in a wide range of NPs from a variety of sources. Owing to the changing needs of agriculture, shifts in pest spectrum, development of resistance, and evolving regulatory requirements, the need for new agrochemical tools remains as critical as ever. As such, NPs continue to be an important source of models and templates for the development of new agrochemicals, demonstrated by the fact that NP models exist for many of the pest control agents that were discovered by other means. Interestingly, there appear to be distinct differences in the success of different NP sources for different pesticide uses. Although a few microbial NPs have been important starting points in recent discoveries of some insecticidal agrochemicals, historically plant sources have contributed the most to the discovery of new insecticides. In contrast, fungi have been the most important NP sources for new fungicides. Like insecticides, plant-sourced NPs have made the largest contribution to herbicide discovery. Available data on 2014 global sales and numbers of compounds in each class of pesticides indicate that the overall impact of NPs to the discovery of herbicides has been relatively modest compared to the impact observed for fungicides and insecticides. However, as new sourcing and approaches to NP discovery evolve, the impact of NPs in all agrochemical arenas will continue to expand. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Thomas C Sparks
- Dow AgroSciences, Discovery Research, Indianapolis, IN, 46268, USA
| | - Donald R Hahn
- Dow AgroSciences, Discovery Research, Indianapolis, IN, 46268, USA
| | - Negar V Garizi
- Dow AgroSciences, Discovery Research, Indianapolis, IN, 46268, USA
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Sparks TC, Lorsbach BA. Perspectives on the agrochemical industry and agrochemical discovery. Pest Manag Sci 2017; 73:672-677. [PMID: 27753242 DOI: 10.1002/ps.4457] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 10/10/2016] [Accepted: 10/11/2016] [Indexed: 06/06/2023]
Abstract
Agrochemicals have been critical to the production of food and fiber, as well as the control of vectors of disease. The need for the discovery and development of new agrochemicals continues unabated due to the loss of existing products through the development of resistance, the desire for products with more favorable environmental and toxicological profiles, shifting pest spectra, and changing agricultural needs and practices. As presented in the associated analysis of the agrochemical industry, the rising costs and complexities of agrochemical discovery have, in part, led to increasing consolidation, especially in the USA and Europe. However, as demonstrated by the present analysis, the discovery of new agrochemicals continues in spite of the challenges. © 2016 Society of Chemical Industry.
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Dent WH, Pobanz MA, Geng C, Sparks TC, Watson GB, Letherer TJ, Beavers KW, Young CD, Adelfinskaya YA, Ross RR, Whiteker G, Renga J. Discovery of the aryl heterocyclic amine insecticides: synthesis, insecticidal activity, field results, mode of action and bioavailability of a leading field candidate. Pest Manag Sci 2017; 73:774-781. [PMID: 27607882 DOI: 10.1002/ps.4431] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 08/25/2016] [Accepted: 08/31/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND γ-Amino butyric acid (GABA) antagonists are proven targets for control of lepidopteran and other pests. New heterocyclic compounds with high insecticidal activity were discovered using a competitive-intelligence-inspired scaffold-hopping approach to generate analogs of fipronil, a known GABA antagonist. These novel aryl heterocyclic amines (AHAs) displayed broad-spectrum activity on a number of chewing insect pests. RESULTS Through >370 modifications of the core AHA structure, a 7-pyrazolopyridine lead molecule was found to exhibit much improved activity on a number of insect pests. In field trial studies, its performance was 2-4 times lower than commercial standards and also appeared to be species dependent, with good activity seen for larvae of Spodoptera exigua, but inactivity on larvae of Trichoplusia ni. CONCLUSION An extensive investigational biology effort demonstrated that these AHA analogs appear to have multiple modes of action, including GABA receptor antagonism and mitopotential or uncoupler activity. The limited capability in larvae of T. ni to convert the lead molecule to its associated open form correlates with the low toxicity of the lead molecule in this species. This work has provided information that could aid investigations of novel GABA antagonists. © 2016 Society of Chemical Industry.
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Lorsbach BA, Sparks TC. Innovations in Agrochemical Discovery and the Role of Metabolism, Bioavailability and Formulations. Pest Manag Sci 2017; 73:655-657. [PMID: 28247502 DOI: 10.1002/ps.4533] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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Wang NX, Watson GB, Loso MR, Sparks TC. Molecular modeling of sulfoxaflor and neonicotinoid binding in insect nicotinic acetylcholine receptors: impact of the Myzus β1 R81T mutation. Pest Manag Sci 2016; 72:1467-1474. [PMID: 26732903 DOI: 10.1002/ps.4220] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/16/2015] [Accepted: 12/20/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND Sulfoxaflor (Isoclast™ active), a new sulfoximine-class insecticide, targets sap-feeding insect pests, including those resistant to neonicotinoids. Sulfoxaflor acts on the insect nicotinic acetylcholine receptor (nAChR) in a distinct manner relative to neonicotinoids. Unlike any of the neonicotinoids, sulfoxaflor has four stereoisomers. A homology model of Myzus persicae (green peach aphid) based on the ACh binding protein from Aplysia californica, overlaid with M. persicae nAChR sequence (α2 and β1 subunits) was used to investigate the interactions of the sulfoxaflor stereoisomers with WT and R81T versions of the nAChR. RESULTS Whole-molecule van der Waals interactions are highly correlated with the binding affinity for the neonicotinoids and correctly predict the rank order of binding affinity for neonicotinoids and sulfoxaflor. The R81T mutation in M. persicae nAChR is predicted to have much less effect on binding of sulfoxaflor's stereoisomers than that of the neonicotinoids. CONCLUSION All four stereoisomers predictably contribute to the activity of sulfoxaflor. The WT and R81T nAChR homology models suggest that changes in a whole-molecule electrostatic energy component can potentially explain the effects of this target-site mutation on the pattern of reduced efficacy for the modeled neonicotinoids, and provide a basis for the reduced effect of this mutation on sulfoxaflor. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Nick X Wang
- Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
| | | | - Michael R Loso
- Dow AgroSciences, Discovery Research, Indianapolis, IN, USA
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Loso MR, Benko Z, Buysse A, Johnson TC, Nugent BM, Rogers RB, Sparks TC, Wang NX, Watson GB, Zhu Y. SAR studies directed toward the pyridine moiety of the sap-feeding insecticide sulfoxaflor (Isoclast™ active). Bioorg Med Chem 2016; 24:378-82. [DOI: 10.1016/j.bmc.2015.11.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 11/13/2015] [Accepted: 11/20/2015] [Indexed: 10/22/2022]
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35
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Oliver MP, Crouse GD, Demeter DA, Sparks TC. Synthesis and Insecticidal Activity of Spinosyns with C9-O-Benzyl Bioisosteres in Place of the 2',3',4'-Tri-O-methyl Rhamnose. J Agric Food Chem 2015; 63:5571-5577. [PMID: 25993441 DOI: 10.1021/acs.jafc.5b01987] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The spinosyns are fermentation-derived natural products active against a wide range of insect pests. They are structurally complex, consisting of two sugars (forosamine and rhamnose) coupled to a macrocyclic tetracycle. Removal of the rhamnose sugar results in a >100-fold reduction in insecticidal activity. C9-O-benzyl analogues of spinosyn D were synthesized to determine if the 2',3',4'-tri-O-methyl rhamnose moiety could be replaced with a simpler, synthetic bioisostere. Insecticidal activity was evaluated against larvae of Spodoptera exigua (beet armyworm) and Helicoverpa zea (corn earworm). Whereas most analogues were far less active than spinosyn D, a few of the C9-O-benzyl analogues, such as 4-CN, 4-Cl, 2-isopropyl, and 3,5-diOMe, were within 3-15 times the activity of spinosyn D for larvae of S. exigua and H. zea. Thus, although not yet quite as effective, synthetic bioisosteres can substitute for the naturally occurring 2',3',4'-tri-O-methyl rhamnose moiety.
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Affiliation(s)
- M Paige Oliver
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - Gary D Crouse
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - David A Demeter
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
| | - Thomas C Sparks
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
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Sparks TC, Nauen R. IRAC: Mode of action classification and insecticide resistance management. Pestic Biochem Physiol 2015; 121:122-8. [PMID: 26047120 DOI: 10.1016/j.pestbp.2014.11.014] [Citation(s) in RCA: 542] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 05/05/2023]
Abstract
Insecticide resistance is a long standing and expanding problem for pest arthropod control. Effective insecticide resistance management (IRM) is essential if the utility of current and future insecticides is to be preserved. Established in 1984, the Insecticide Resistance Action Committee (IRAC) is an international association of crop protection companies. IRAC serves as the Specialist Technical Group within CropLife International focused on ensuring the long term efficacy of insect, mite and tick control products through effective resistance management for sustainable agriculture and improved public health. A key function of IRAC is the continued development of the Mode of Action (MoA) classification scheme, which provides up-to-date information on the modes of action of new and established insecticides and acaricides and which serves as the basis for developing appropriate IRM strategies for crop protection and vector control. The IRAC MoA classification scheme covers more than 25 different modes of action and at least 55 different chemical classes. Diversity is the spice of resistance management by chemical means and thus it provides an approach to IRM providing a straightforward means to identify potential rotation/alternation options.
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Affiliation(s)
- Thomas C Sparks
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
| | - Ralf Nauen
- Bayer CropScience AG, R&D Pest Control Biology, Alfred-NobelStr. 50, 40789 Monheim, Germany
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Gerwick BC, Sparks TC. Natural products for pest control: an analysis of their role, value and future. Pest Manag Sci 2014; 70:1169-85. [PMID: 24478254 DOI: 10.1002/ps.3744] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/22/2014] [Accepted: 01/29/2014] [Indexed: 05/14/2023]
Abstract
Natural products (NPs) have long been used as pesticides and have broadly served as a source of inspiration for a great many commercial synthetic organic fungicides, herbicides and insecticides that are in the market today. In light of the continuing need for new tools to address an ever-changing array of fungal, weed and insect pests, NPs continue to be a source of models and templates for the development of new pest control agents. Interestingly, an examination of the literature suggests that NP models exist for many of the pest control agents that were discovered by other means, suggesting that, had circumstances been different, these NPs could have served as inspiration for the discovery of a great many more of today's pest control agents. Here, an attempt is made to answer questions regarding the existence of an NP model for existing classes of pesticides and what is needed for the discovery of new NPs and NP models for pest control agents.
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Abstract
There is an on-going need for the discovery and development of new insecticides due to the loss of existing products through the development of resistance, the desire for products with more favorable environmental and toxicological profiles, shifting pest spectrums, and changing agricultural practices. Since 1960, the number of research-based companies in the US and Europe involved in the discovery of new insecticidal chemistries has been declining. In part this is a reflection of the increasing costs of the discovery and development of new pesticides. Likewise, the number of compounds that need to be screened for every product developed has, until recently, been climbing. In the past two decades the agrochemical industry has been able to develop a range of new products that have more favorable mammalian vs. insect selectivity. This review provides an analysis of the time required for the discovery, or more correctly the building process, for a wide range of insecticides developed during the last 60 years. An examination of the data around the time requirements for the discovery of products based on external patents, prior internal products, or entirely new chemistry provides some unexpected observations. In light of the increasing costs of discovery and development, coupled with fewer companies willing or able to make the investment, insecticide resistance management takes on greater importance as a means to preserve existing and new insecticides.
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Affiliation(s)
- Thomas C Sparks
- Dow AgroSciences, Discovery Research, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
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Sparks TC, Watson GB, Loso MR, Geng C, Babcock JM, Thomas JD. Sulfoxaflor and the sulfoximine insecticides: chemistry, mode of action and basis for efficacy on resistant insects. Pestic Biochem Physiol 2013; 107:1-7. [PMID: 25149228 DOI: 10.1016/j.pestbp.2013.05.014] [Citation(s) in RCA: 215] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 05/30/2013] [Accepted: 05/31/2013] [Indexed: 06/03/2023]
Abstract
The sulfoximines, as exemplified by sulfoxaflor ([N-[methyloxido[1-[6-(trifluoromethyl)-3-pyridinyl]ethyl]-λ(4)-sulfanylidene] cyanamide] represent a new class of insecticides. Sulfoxaflor exhibits a high degree of efficacy against a wide range of sap-feeding insects, including those resistant to neonicotinoids and other insecticides. Sulfoxaflor is an agonist at insect nicotinic acetylcholine receptors (nAChRs) and functions in a manner distinct from other insecticides acting at nAChRs. The sulfoximines also exhibit structure activity relationships (SAR) that are different from other nAChR agonists such as the neonicotinoids. This review summarizes the sulfoximine SAR, mode of action and the biochemistry underlying the observed efficacy on resistant insect pests, with a particular focus on sulfoxaflor.
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Affiliation(s)
- Thomas C Sparks
- Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, United States.
| | - Gerald B Watson
- Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, United States
| | - Michael R Loso
- Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, United States
| | - Chaoxian Geng
- Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, United States
| | - Jon M Babcock
- Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, United States
| | - James D Thomas
- Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, United States
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Watson GB, Loso MR, Babcock JM, Hasler JM, Letherer TJ, Young CD, Zhu Y, Casida JE, Sparks TC. Novel nicotinic action of the sulfoximine insecticide sulfoxaflor. Insect Biochem Mol Biol 2011; 41:432-9. [PMID: 21296156 DOI: 10.1016/j.ibmb.2011.01.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/19/2011] [Accepted: 01/27/2011] [Indexed: 05/25/2023]
Abstract
The novel sulfoximine insecticide sulfoxaflor is as potent or more effective than the neonicotinoids for toxicity to green peach aphids (GPA, Myzus persicae). The action of sulfoxaflor was characterized at insect nicotinic acetylcholine receptors (nAChRs) using electrophysiological and radioligand binding techniques. When tested for agonist properties on Drosophila melanogaster Dα2 nAChR subunit co-expressed in Xenopus laevis oocytes with the chicken β2 subunit, sulfoxaflor elicited very high amplitude (efficacy) currents. Sulfoximine analogs of sulfoxaflor were also agonists on Dα2/β2 nAChRs, but none produced maximal currents equivalent to sulfoxaflor nor were any as toxic to GPAs. Additionally, except for clothianidin, none of the neonicotinoids produced maximal currents as large as those produced by sulfoxaflor. These data suggest that the potent insecticidal activity of sulfoxaflor may be due to its very high efficacy at nAChRs. In contrast, sulfoxaflor displaced [(3)H]imidacloprid (IMI) from GPA nAChR membrane preparations with weak affinity compared to most of the neonicotinoids examined. The nature of the interaction of sulfoxaflor with nAChRs apparently differs from that of IMI and other neonicotinoids, and when coupled with other known characteristics (novel chemical structure, lack of cross-resistance, and metabolic stability), indicate that sulfoxaflor represents a significant new insecticide option for the control of sap-feeding insects.
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Affiliation(s)
- Gerald B Watson
- Dow AgroSciences, LLC, 9330 Zionsville Rd., Indianapolis, IN 46268, USA.
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Zhu Y, Loso MR, Watson GB, Sparks TC, Rogers RB, Huang JX, Gerwick BC, Babcock JM, Kelley D, Hegde VB, Nugent BM, Renga JM, Denholm I, Gorman K, DeBoer GJ, Hasler J, Meade T, Thomas JD. Discovery and characterization of sulfoxaflor, a novel insecticide targeting sap-feeding pests. J Agric Food Chem 2011; 59:2950-7. [PMID: 21105655 DOI: 10.1021/jf102765x] [Citation(s) in RCA: 248] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The discovery of sulfoxaflor [N-[methyloxido[1-[6-(trifluoromethyl)-3-pyridinyl]ethyl]-λ(4)-sulfanylidene] cyanamide] resulted from an investigation of the sulfoximine functional group as a novel bioactive scaffold for insecticidal activity and a subsequent extensive structure-activity relationship study. Sulfoxaflor, the first product from this new class (the sulfoximines) of insect control agents, exhibits broad-spectrum efficacy against many sap-feeding insect pests, including aphids, whiteflies, hoppers, and Lygus, with levels of activity that are comparable to those of other classes of insecticides targeting sap-feeding insects, including the neonicotinoids. However, no cross-resistance has been observed between sulfoxaflor and neonicotinoids such as imidacloprid, apparently the result of differences in susceptibility to oxidative metabolism. Available data are consistent with sulfoxaflor acting via the insect nicotinic receptor in a complex manner. These observations reflect the unique structure of the sulfoximines compared with neonicotinoids.
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Affiliation(s)
- Yuanming Zhu
- Dow AgroSciences, R&D, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States
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Babcock JM, Gerwick CB, Huang JX, Loso MR, Nakamura G, Nolting SP, Rogers RB, Sparks TC, Thomas J, Watson GB, Zhu Y. Biological characterization of sulfoxaflor, a novel insecticide. Pest Manag Sci 2011; 67:328-334. [PMID: 21308958 DOI: 10.1002/ps.2069] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 09/06/2010] [Accepted: 09/27/2010] [Indexed: 05/30/2023]
Abstract
BACKGROUND The commercialization of new insecticides is important for ensuring that multiple effective product choices are available. In particular, new insecticides that exhibit high potency and lack insecticidal cross-resistance are particularly useful in insecticide resistance management (IRM) programs. Sulfoxaflor possesses these characteristics and is the first compound under development from the novel sulfoxamine class of insecticides. RESULTS In the laboratory, sulfoxaflor demonstrated high levels of insecticidal potency against a broad range of sap-feeding insect species. The potency of sulfoxaflor was comparable with that of commercial products, including neonicotinoids, for the control of a wide range of aphids, whiteflies (Homoptera) and true bugs (Heteroptera). Sulfoxaflor performed equally well in the laboratory against both insecticide-susceptible and insecticide-resistant populations of sweetpotato whitefly, Bemisia tabaci Gennadius, and brown planthopper, Nilaparvata lugens (Stål), including populations resistant to the neonicotinoid insecticide imidacloprid. These laboratory efficacy trends were confirmed in field trials from multiple geographies and crops, and in populations of insects with histories of repeated exposure to insecticides. In particular, a sulfoxaflor use rate of 25 g ha(-1) against cotton aphid (Aphis gossypii Glover) outperformed acetamiprid (25 g ha(-1) ) and dicrotophos (560 g ha(-1) ). Sulfoxaflor (50 g ha(-1) ) provided a control of sweetpotato whitefly equivalent to that of acetamiprid (75 g ha(-1) ) and imidacloprid (50 g ha(-1) ) and better than that of thiamethoxam (50 g ha(-1) ). CONCLUSION The novel chemistry of sulfoxaflor, its unique biological spectrum of activity and its lack of cross-resistance highlight the potential of sulfoxaflor as an important new tool for the control of sap-feeding insect pests.
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Watson GB, Chouinard SW, Cook KR, Geng C, Gifford JM, Gustafson GD, Hasler JM, Larrinua IM, Letherer TJ, Mitchell JC, Pak WL, Salgado VL, Sparks TC, Stilwell GE. A spinosyn-sensitive Drosophila melanogaster nicotinic acetylcholine receptor identified through chemically induced target site resistance, resistance gene identification, and heterologous expression. Insect Biochem Mol Biol 2010; 40:376-384. [PMID: 19944756 DOI: 10.1016/j.ibmb.2009.11.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 11/19/2009] [Accepted: 11/22/2009] [Indexed: 05/28/2023]
Abstract
Strains of Drosophila melanogaster with resistance to the insecticides spinosyn A, spinosad, and spinetoram were produced by chemical mutagenesis. These spinosyn-resistant strains were not cross-resistant to other insecticides. The two strains that were initially characterized were subsequently found to have mutations in the gene encoding the nicotinic acetylcholine receptor (nAChR) subunit Dalpha6. Subsequently, additional spinosyn-resistant alleles were generated by chemical mutagenesis and were also found to have mutations in the gene encoding Dalpha6, providing convincing evidence that Dalpha6 is a target site for the spinosyns in D. melanogaster. Although a spinosyn-sensitive receptor could not be generated in Xenopus laevis oocytes simply by expressing Dalpha6 alone, co-expression of Dalpha6 with an additional nAChR subunit, Dalpha5, and the chaperone protein ric-3 resulted in an acetylcholine- and spinosyn-sensitive receptor with the pharmacological properties anticipated for a native nAChR.
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Affiliation(s)
- Gerald B Watson
- Dow AgroSciences LLC, Discovery Research, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
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Meng L, Lorsbach BA, Sparks TC, Fettinger JC, Kurth MJ. Parallel Synthesis of Bis-heterocyclic Isoxazolylmethyl- and Isoxazolinylmethylpyrazoles. ACTA ACUST UNITED AC 2009; 12:129-36. [DOI: 10.1021/cc900133k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Liping Meng
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, and Dow AgroSciences, Discovery R&D, 9330 Zionsville Road, Indianapolis, Indiana 46268
| | - Beth A. Lorsbach
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, and Dow AgroSciences, Discovery R&D, 9330 Zionsville Road, Indianapolis, Indiana 46268
| | - Thomas C. Sparks
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, and Dow AgroSciences, Discovery R&D, 9330 Zionsville Road, Indianapolis, Indiana 46268
| | - James C. Fettinger
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, and Dow AgroSciences, Discovery R&D, 9330 Zionsville Road, Indianapolis, Indiana 46268
| | - Mark J. Kurth
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, and Dow AgroSciences, Discovery R&D, 9330 Zionsville Road, Indianapolis, Indiana 46268
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Milinkevich KA, Yoo CL, Sparks TC, Lorsbach BA, Kurth MJ. Synthesis and biological activity of 2-(4,5-dihydroisoxazol-5-yl)-1,3,4-oxadiazoles. Bioorg Med Chem Lett 2009; 19:5796-8. [DOI: 10.1016/j.bmcl.2009.07.139] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 07/24/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
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Yu GJ, Iwamoto S, Robins LI, Fettinger JC, Sparks TC, Lorsbach BA, Kurth MJ. 3-(Arylthiomethyl)isoxazole-4,5-dicarboxamides: chemoselective nucleophilic chemistry and insecticidal activity. J Agric Food Chem 2009; 57:7422-7426. [PMID: 19624156 PMCID: PMC2847632 DOI: 10.1021/jf901512t] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A collection of 91 3-(arylthiomethyl)isoxazole-4,5-dicarboxamides was prepared starting from dimethyl 3-(chloromethyl)isoxazole-4,5-dicarboxylate. The thioether moieties in these compounds were subsequently oxidized to give the corresponding 3-(arylsulfonylmethyl)isoxazole-4,5-dicarboxamides. By carefully controlling stoichiometry and reaction conditions, the C4 and C5 carbomethoxy groups could be differentially derivatized to carboxamides. A total of 182 trisubstituted isoxazoles are reported and deposited in the National Institutes of Health Molecular Repository; an 80 compound subset was evaluated for insecticidal activity.
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Affiliation(s)
- Gui J. Yu
- Department of Chemistry, University of California, One Shields Ave. Davis, CA, 95616
| | - Satori Iwamoto
- Department of Chemistry, University of California, One Shields Ave. Davis, CA, 95616
| | - Lori I. Robins
- Department of Chemistry, University of California, One Shields Ave. Davis, CA, 95616
| | - James C. Fettinger
- Department of Chemistry, University of California, One Shields Ave. Davis, CA, 95616
| | - Thomas C. Sparks
- Dow AgroSciences LLC, Discovery R&D, 9330 Zionsville Rd, Indianapolis, IN 46268
| | - Beth A. Lorsbach
- Dow AgroSciences LLC, Discovery R&D, 9330 Zionsville Rd, Indianapolis, IN 46268
| | - Mark J. Kurth
- Department of Chemistry, University of California, One Shields Ave. Davis, CA, 95616
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Lewer P, Hahn DR, Karr LL, Duebelbeis DO, Gilbert JR, Crouse GD, Worden T, Sparks TC, Edwards PMR, Graupner PR. Discovery of the butenyl-spinosyn insecticides: Novel macrolides from the new bacterial strain Saccharopolyspora pogona. Bioorg Med Chem 2009; 17:4185-96. [DOI: 10.1016/j.bmc.2009.02.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 02/11/2009] [Accepted: 02/18/2009] [Indexed: 11/24/2022]
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Gaisser S, Carletti I, Schell U, Graupner PR, Sparks TC, Martin CJ, Wilkinson B. Glycosylation engineering of spinosyn analogues containing an L-olivose moiety. Org Biomol Chem 2009; 7:1705-8. [PMID: 19343260 DOI: 10.1039/b900233b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Biosynthetic genes encoding proteins involved in the first steps of deoxyhexose biosynthesis from D-glucose-1-phosphate were expressed in Saccharopolyspora erythraea. The resulting mutant was able to accumulate and utilise TDP-L-olivose. Co-expression of the spinosyn glycosyl transferase SpnP in the resulting mutant endowed upon it the ability to biotransform exogenously added spinosyn aglycones to yield novel spinosyn analogues.
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Affiliation(s)
- Sabine Gaisser
- Biotica Technology Ltd, Chesterford Research Park, Cambridge, UK CB10 1XL
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Sheehan LS, Lill RE, Wilkinson B, Sheridan RM, Vousden WA, Kaja AL, Crouse GD, Gifford J, Graupner PR, Karr L, Lewer P, Sparks TC, Leadlay PF, Waldron C, Martin CJ. Engineering of the spinosyn PKS: directing starter unit incorporation. J Nat Prod 2006; 69:1702-10. [PMID: 17190446 DOI: 10.1021/np0602517] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The spinosyns are a family of potent and highly selective insect control agents that display a favorable environmental profile. As some regions of the spinosyn molecule are recalcitrant to chemical modification, a targeted genetic approach was carried out to generate new analogues. The polyketide synthase (PKS) loading modules from the avermectin PKS of Streptomyces avermitilis and the erythromcyin PKS of Saccharopolyspora erythraea were each used to replace the spinosyn PKS loading module. Both of the resulting strains containing hybrid PKS pathways produced the anticipated spinosyn analogues. Supplementation of the culture media with a range of exogenous carboxylic acids led to the successful incorporation of these novel elements to yield further novel spinosyn molecules, some of which demonstrated potent and new insecticidal activities. Furthermore, it has been demonstrated that semisynthesis of such novel metabolites can then be used to generate active analogues, demonstrating the effectiveness of utilizing these complementary methods to search the chemical space around this template.
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Affiliation(s)
- Lesley S Sheehan
- Biotica Technology Limited, Chesterford Research Park, Essex, CB10 1XL, U.K
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