Construction of oxime ester derivatives of osthole from Cnidium monnieri, and evaluation of their agricultural activities and control efficiency

Abstract

BACKGROUND: In order to discover natural-product-based pesticidal candidates, a series of coumarin-like derivatives containing oxime ester fragments at the C-8 position were prepared by structural modification of osthole, a natural plant product isolated from Cnidium monnieri. Their pesticidal activities were evaluated against two typically fruit trees/crop-threatening agricultural pests, Mythimna separata Walker and Tetranychus cinnabarinus Boisduval. RESULTS: Osthole was regioselectively oxidized by selenium dioxide to give the E-isomer, (2 0 E)-3 0-formaldehydylosthole (2). Four key steric structures of 2, (2'E, 4'E)-(o-chloropyrid-3-ylcarbonyl)oximinylosthole (4o), (2'E, 4'E)-(styrylcarbonyl)oximinylosthole (4t), and (2'E, 4'E)-(acetyl)oximinylosthole (4w) were undoubtedly confirmed by X-ray crystallography. Against T. cinnabarinus, it is noteworthy that (2 0 E, 4 0 E)-(p-chlorophenylcarbonyl)oximinylosthole (4c) exhibited over threefold more potent acaricidal activity of the precursor osthole, with especially good control efficiency observed in the glasshouse. Against M. separata, compounds 4c and (2 0 E, 4 0 E)-(p-nitrophenylcarbonyl)oximinylosthole (4f) showed the most pronounced growth inhibitory activity. The relationships between their structures and agricultural activities also were studied. CONCLUSION: These results demonstrate that compound 4c could be further structurally modified as pesticidal agents. It will lay the foundation for future application of osthole derivatives as pesticides.

Osthole: an overview of its sources, biological activities, and modification development

“…(Table 11). Additionally, Ren et al reported a series of osthole derivatives containing oxime ester fragments at the C-8 position and their pesticidal activities [131]. Aldehyde intermediate 34 was synthesized as above, which was reacted with hydroxylamine hydrochloride in the presence of sodium hydroxide to give the oxime intermediate 45.…”

Optimization of Osthole in the Lactone Ring: Structural Elucidation, Pesticidal Activities, and Control Efficiency of Osthole Ester Derivatives

“…Previously, we prepared a series of matrine esters , ( I and II , Figure ), andrographolide esters ( III , Figure ), and fraxinellone esters ( IV , Figure ) as pesticidal agents and found that some derivatives exhibited more potent pesticidal activities than their precursors and toosendanin (a botanical insecticide registered in China). More recently, we have prepared a series of osthole oxime esters ( V , Figure ) by structural modification of 3′-methy-l-2′-butylenyl at the C-8 position of osthole and found one derivative, (2′ E ,4′ E )-( p -chlorophenylcarbonyl)­oximinylosthole, that showed pronounced pesticidal activities against Tetranychus cinnabarinus Boisduval and Mythimna separata Walker . Based on the above results, to discover new high-value-added potential pesticidal agents from natural plant bioactive products, in this study, we want to investigate the importance of the lactone ring of osthole for pesticidal activities, and a series of novel target compounds (osthole-type ester derivatives, Figure ) were constructed by opening the lactone ring.…”

“…More recently, we have prepared a series of osthole oxime esters (V, Figure 1) by structural modification of 3′-methy-l-2′-butylenyl at the C-8 position of osthole and found one derivative, (2′E,4′E)-(pchlorophenylcarbonyl)oximinylosthole, that showed pronounced pesticidal activities against Tetranychus cinnabarinus Boisduval and Mythimna separata Walker. 11 Based on the above results, to discover new high-value-added potential pesticidal agents from natural plant bioactive products, in this study, we want to investigate the importance of the lactone ring of osthole for pesticidal activities, and a series of novel target compounds (osthole-type ester derivatives, Figure 1) were constructed by opening the lactone ring.…”

“…Osthole ( 1 , Figure ), a well-known coumarin compound, is the main component of the traditional Chinese medicine Cnidium monnieri. , It exhibited a broad scope of pharmacological activities, such as anticancer activity, − anti-inflammatory activity, − anti-Alzheimer’s disease, etc. On the other hand, osthole also possessed some agricultural properties including anti-tobacco mosaic virus (TMV) activity, antifungal activity, and pesticidal activity against larvae of mosquitoes. , Although osthole as a botanical insecticide was registered in China, its pesticidal activities are not in the same order of magnitude when compared with those of traditional agrochemicals.…”

Simple Osthole/Nanocarrier Pesticide Efficiently Controls Both Pests and Diseases Fulfilling the Need of Green Production of Strawberry

“…Osthole (7-methoxy-8-isopentenoxycoumarin, C 15 H 16 O 3 ) is a natural coumarin-like compound most frequently isolated from the traditional Chinese medicine Cnidium monnieri (L.), and has obvious significant medical activities such as anti-inflammation, antiosteoporosis, anti-Alzheimer, antitumor, and so forth. Meanwhile, as osthole is less risky for human health and environment, it has been applied as antifungal, larvicidal, and anthelminthic agents against plant pathogens and insect pests in China for a long time. − So far, osthole has been authorized to control powdery mildews, gray moulds, injurious mites, aphids, and thrips in China, and it seems to be a perfect botanical pesticide for controlling plant pests and diseases simultaneously. However, most botanical pesticides have limitations of slow action and short persistence for pest and disease management. , The pesticidal activities of osthole are far from being comparable to traditional agrochemicals, and its utilization efficiency should be further improved to meet the actual demands.…”