Discovery of phosphonate derivatives containing different substituted 1,2,3-triazole motif as promising tobacco mosaic virus (TMV) helicase inhibitors for controlling plant viral diseases

Discovery of new pesticide candidates from nature: design, synthesis and bioactivity research of rutaecarpine derivatives

BACKGROUND

The invasion of viruses and fungi can cause pathological changes in the normal growth of plants and is an important factor in causing plant infectious diseases. These pathogenic microorganisms can also secrete toxic metabolites, affecting crop quality and posing a threat to human health. In this work, we selected the natural product rutaecarpine as the lead compound to achieve the total synthesis and structural derivation. The antiphytoviral activities of these compounds were systematically studied using tobacco mosaic virus (TMV) as the tested strain, and the structure-activity relationships were summarized.

RESULT

The anti TMV activities of compounds 5a, 5n, 6b, and 7c are significantly higher than that of commercial antiviral agent ningnanmycin. We chose 5n for further antiviral mechanism research, and the results showed that it can directly act on viral particles. The molecular docking results further confirmed the interaction of compound 5n and coat protein (CP). These compounds also exhibited broad-spectrum fungicidal activities against eight plant pathogens. Especially compounds 5j and 5p have significant anti-fungal activities (EC50: 5j, 1.76 μg mL-1; 5p, 1.59 μg mL-1) and can be further studied as leads for plant-based anti-fungal agents.

CONCLUSION

The natural product rutaecarpine and its derivatives were synthesized, and evaluated for their anti-TMV and fungicidal activities. Compounds 5n and 5p with good activities emerged as new antiviral and anti-fungal candidates, respectively. This study provides important information for the research and development of the novel antiviral and fungicidal agents based on rutaecarpine derivatives. © 2024 Society of Chemical Industry.

Chemical and Biological Investigations of Antiviral Agents Against Plant Viruses Conducted in China in the 21st Century

Research into the biology of plant viruses, their mechanisms of pathogenicity, and the induction of host resistance has laid a solid foundation for the discovery of antiviral agents and their targets and the development of effective control technologies. Additionally, recent advancements in fields such as chemical biology, cheminformatics, bioinformatics, and synthetic biology have provided valuable methods and tools for the design of antiviral drugs, the synthesis of drug molecules, assessment of their activity, and investigation of their modes of action. Compared with drug development for human viral diseases, the control of plant viral diseases presents greater challenges, including the cost-benefit of agents, simplification of control technologies, and the effectiveness of treatments. Therefore, in the current context of complex outbreaks and severe damage caused by plant viral diseases, it is crucial to delve deeper into the research and development of antiviral agents. This review provides a detailed overview of the biological characteristics of current targets for antiviral agents, the mode of interaction between plant virus targets and antivirals, and insights for future drug development. We believe this review will not only facilitate the in-depth analysis of the development of antivirals for crops but also offer valuable perspectives for the development of antiviral agents for use in human and veterinary medicine.

Discovery of New 1,2,4-Triazole/1,3,4-Oxadiazole-Decorated Quinolinones as Agrochemical Alternatives for Controlling Viral Infection by Inhibiting the Viral Replication and Self-Assembly Process

Tobacco mosaic virus (TMV), a representative plant virus, is widely known and causes severe crop losses worldwide. In order to ensure the demand for crop and food security, the exploration of novel antiviral agents with outstanding activity and unique mechanisms of action is necessary. Herein, 40 new azole-quinolinone molecules were elaborately designed and systematically evaluated for their anti-TMV activity. Notably, compound A21 had significant therapeutic activity against TMV (EC50 value = 200 μg/mL), which was superior to commercial ningnanmycin (280 μg/mL). Studies on the anti-TMV mechanism showed that compound A21 could suppress the expression level of important TMV genes and affect the assembly of TMV viral particles by disrupting the self-assembly process of TMV coat protein (TMV-CP). In-depth antiviral behaviors were verified by molecular docking, fluorescence titration analysis, and TMV assembly assays, suggesting that compound A21 strongly interacted with TMV coat protein through various interactions. Overall, this promising work discloses a new paradigm for the exploitation of 2-quinolinone-based virucidal agents for hindering plant viral infection through triggering versatile antiviral behavior.

Synthesis, structural modification, and biological activity of a novel bisindole alkaloid iheyamine A

Diseases caused by plant viruses and pathogens pose a serious threat to crop yield and quality. Traditional pesticides have gradually developed drug resistance and brought certain environmental safety issues during long-term overuse. There is an urgent need to discover new candidate compounds to address these issues. In this study, we achieved the efficient synthesis of iheyamine A and its derivatives, and discovered their excellent antiviral activities against tobacco mosaic virus (TMV). Most compounds displayed higher antiviral activities against TMV than commercial ribavirin at 500 μg/mL, with compounds 3a (Inactive effect IC50: 162 µg/mL), 3d (Inactive effect IC50: 249 µg/mL), 6p (Inactive effect IC50: 254 µg/mL), and 7a (Inactive effect IC50: 234 µg/mL) exhibiting better antiviral activities than ningnanmycin at 500 μg/mL (Inactive effect IC50: 269 µg/mL). Meanwhile, the structure-activity relationships of this type of compounds were systematically studied. We chose 3a for further antiviral mechanism research and found that it can directly act on viral coat protein (CP). The interaction of 3a and CP was further verified via molecular docking. These compounds also showed broad-spectrum fungicidal activities against 8 plant pathogenic fungi, especially for P. piricola. This study provides a reference for the role of iheyamine alkaloids in combating plant pathogenic diseases.

Application of Asymmetric Catalysis in Chiral Pesticide Active Molecule Synthesis

The different configurations of chiral pesticides generally have significant influence on their biological activities. Chiral agrochemicals with high optical purities have become a prominent topic in the research field of new pesticides due to their advantages including lower toxicity, higher efficiency, and reduced residue levels. However, most commercially available pesticides that possess chiral elements are still used in their racemic forms. To date, asymmetric catalysis has emerged as a versatile tool for the enantioselective synthesis of various chiral agrochemicals and novel chiral pesticide active molecules. This perspective provides a comprehensive overview of the applications of diverse asymmetric catalytic approaches in the facile preparation of numerous novel pesticide active molecules, and our own outlook on the future development of this highly active research direction is also presented at the end of this review.

Identification of natural Rutaecarpine as a potent tobacco mosaic virus (TMV) helicase candidate for managing intractable plant viral diseases

BACKGROUND

Naturally occurring alkaloids are particularly suitable for use as pesticide precursors and further modifications due to their cost-effectiveness, unique mechanism of action, tolerable degradation, and environmental friendliness. The famous tobacco mosaic virus (TMV) is a persistent plant pathogenic virus that can parasitize many plants and severely reduce crop production. To treat TMV disease, TMV helicase acts as a crucial target by hydrolyzing adenosine triphosphate (ATP) to provide energy for double-stranded RNA unwinding.

RESULTS

To seek novel framework alkaloid leads targeting TMV helicase, this work successfully established an efficient screening platform for TMV helicase inhibitors based on natural alkaloids. In vivo activity screening, enzyme activity detection, and binding assays showed that Rutaecarpine from Evodia rutaecarpa (Juss.) Benth exhibited excellent TMV helicase inhibitory properties [dissociation constant (Kd ) = 1.1 μm, half maximal inhibitory concentration (IC50 ) = 227.24 μm] and excellent anti-TMV ability. Molecular docking and dynamic simulations depicted that Rutaecarpine could stably bind in active pockets of helicase with low binding energy (ΔGbind  = -17.8 kcal/mol) driven by hydrogen bonding and hydrophobic interactions.

CONCLUSION

Given Rutaecarpine's laudable bioactivity and structural modifiability, it can serve as a privileged building block for further pesticide discovery.

Antiviral Activity of Ailanthone from Ailanthus altissima on the Rice Stripe Virus

Rice stripe disease caused by the rice stripe virus (RSV), which infects many Poaceae species in nature, is one of the most devastating plant viruses in rice that causes enormous losses in production. Ailanthone is one of the typical C20 quassinoids synthesized by the secondary metabolism of Ailanthus altissima, which has been proven to be a biologically active natural product with promising prospects and great potential for use as a lead structure for pesticide development. Based on the achievement of the systemic infection and replication of RSV in Nicotiana benthamiana plants and rice protoplasts, the antiviral properties of Ailanthone were investigated by determining its effects on viral-coding RNA gene expression using reverse transcription polymerase chain reaction, and Western blot analysis. Ailanthone exhibited a dose-dependent inhibitory effect on RSV NSvc3 expression in the assay in both virus-infected tobacco plants and rice protoplasts. Further efforts revealed a potent inhibitory effect of Ailanthone on the expression of seven RSV protein-encoding genes, among which NS3, NSvc3, NS4, and NSvc4 are the most affected genes. These facts promoted an extended and greater depth of understanding of the antiviral nature of Ailanthone against plant viruses, in addition to the limited knowledge of its anti-tobacco mosaic virus properties. Moreover, the leaf disc method introduced and developed in the study for the detection of the antiviral activity of Ailanthone facilitates an available and convenient screening method for anti-RSV natural products or synthetic chemicals.