Design, Synthesis, and Bioactivities of Phthalide and Coumarin Derivatives Based on the Biosynthesis and Structure Simplification of Gossypol

Design, Synthesis, Antifungal Evaluation, and Action Mechanism of Novel l-Carvone-Based Derivatives as Potential Succinate Dehydrogenase Inhibitors

Natural products serve as a crucial source of compounds for developing novel agricultural antifungals. In this work, we utilized the natural product l-carvone as a molecular scaffold to design and synthesize three series of novel l-carvone-based derivatives. The in vitro bioassay results indicated that most target compounds exhibited remarkable antifungal activity. Notably, compound C3 demonstrated broad-spectrum antifungal activity against Rhizoctonia solani, Botrytis cinerea, Sclerotinia sclerotiorum, Gibberella zeae, and Valsa mali, with EC50 values of 0.274, 0.985, 4.17, 5.71, and 2.29 μg/mL, respectively. The in vivo preventative efficacies of compounds C3 and C11 against R. solani and of compound C13 against B. cinerea revealed that they had potential as novel agricultural antifungals. In the antifungal mechanism study, the cell membrane permeability experiment showed that compound C3 significantly increased the permeability of the cell membrane, and microscopic observations revealed that compound C3 could significantly destroy the structural integrity of cells and reduce the number of mitochondria, thus affecting the normal growth of mycelia. Furthermore, the mitochondrial membrane potential detection, succinate dehydrogenase (SDH) enzyme assay, molecular dynamics (MD) simulations, and docking experiments further demonstrated that the mechanism of action and binding mode of compound C3 with the SDH may be similar to those of thifluzamide. The abovementioned results provided a valuable reference for the discovery of novel SDH inhibitor fungicides.

Gossypol and Semisynthetic Derivatives: Chemistry, Bioactivities, and Mechanism of Actions

Gossypol, a polyphenolic compound predominantly derived from cotton plants, has garnered significant attention as a notable plant-derived bioactive compound with significant relevance in medicinal chemistry due to its diverse biological activities and potential therapeutic applications. Despite its inherent toxicity, gossypol exhibits insecticidal, antimicrobial, antiviral, antifertility, antiparasitic, anti-inflammatory, antioxidant, and anticancer properties. Furthermore, gossypol serves as a core molecule for synthesizing various derivatives, such as gossypol Schiff bases, gossypolone, and apogossypol, which are less toxic yet retain similar therapeutic benefits. The aim of this review is to provide a comprehensive overview of gossypol's diverse biological activities, with a particular focus on its anticancer potential, mechanisms of action, and recent advancements in its therapeutic applications. It highlights gossypol's wide-ranging biological activities, including its potent anticancer, antimicrobial, and antioxidant effects. Recent studies have shown promise in reducing gossypol's toxicity through the synthesis of derivatives, while advanced drug delivery methods, including nanocarriers, have been explored to enhance its therapeutic efficacy. Furthermore, gossypol has demonstrated significant synergistic potential when used in combination with conventional anticancer drugs, offering new avenues for cancer therapy.

Carbene-Catalyzed Phthalide Ether Functionalization for Discovering Chiral Phytovirucide that Specifically Targets Viral Nia Protein to Inhibit Proliferation

Plant diseases caused by vegetable viruses are an important threat to global food security, presenting a major challenge for the development of antiviral agrochemicals. Functional proteins of plant viruses play a crucial role in the viral life cycle, and targeted inhibition of these proteins has emerged as a promising strategy. However, the current discovery of antiviral small molecules is hampered by the limitations of synthetic approaches and the narrow range of targets. Herein, we report a practical application of organocatalysis for serving pesticide discovery that bears a unique molecular basis. An N-heterocyclic carbene-modulated reaction is first designed to asymmetrically functionalize diverse natural phenols with phthalides. Our designed method is capable of producing a series of new phthalidyl ethers under mild conditions with good yields, enantioselectivity, and functional group tolerance. Among these, compound (R)-3w exhibits excellent and enantioselectivity-preferred curative activity against potato virus Y (PVY). Mechanistically, it is proposed that (R)-3w interacts with the nuclear inclusion body A (Nia) protein of PVY at the His150 residue. This binding impairs Nia's function to cleavage polyprotein, thereby inhibiting formation of viral replication complex. The study provides insights into advancing synthetic protocol to facilitate agrochemical discovery, and our identified (R)-3w may serve as a potential lead for future research and development PVY-Nia inhibitors.

Recent Advances of Coumarin-Type Compounds in Discovery of Pesticides

Coumarin, a naturally occurring active ingredient with various biological activities in pesticides, is commonly found in plants belonging to the Rutaceae and Apiaceae families. Thanks to its unique structural properties and natural benefits, coumarin and its derivatives exhibit a wide range of physiological activities, including insecticidal, antifungal, antibacterial, herbicidal, and antiviral properties. These compounds have attracted considerable interest in the field of pesticide development, although there is a lack of comprehensive reviews on their use in pesticides. This Review aims to provide a detailed overview of the applications of coumarin and its derivatives in pesticides, covering biological activities, structure-activity relationship analyses, and mechanisms of action. It is hoped that this Review will offer new insights into the discovery and mechanisms of these compounds in pesticide development.

Discovery of Pyrazole-5-yl-amide Derivatives Containing Cinnamamide Structural Fragments as Potential Succinate Dehydrogenase Inhibitors

To promote the development of novel agricultural succinate dehydrogenase inhibitor (SDHI) fungicides, we introduced cinnamamide and nicotinamide structural fragments into the structure of pyrazol-5-yl-amide by carbon chain extension and scaffold hopping, respectively, and synthesized a series of derivatives. The results of the biological activity assays indicated that most of the target compounds exhibited varying degrees of inhibitory activity against the tested fungi. Notably, compounds G22, G28, G34, G38, and G39 exhibited excellent in vitro antifungal activities against Valsa mali with EC50 values of 0.48, 0.86, 0.57, 0.73, and 0.87 mg/L, respectively, and this result was significantly more potent than boscalid (EC50 = 2.80 mg/L) and closer to the specialty control drug tebuconazole (EC50 = 0.30 mg/L). Compounds G22 and G34 also exhibited excellent in vivo protective and curative effects against V. mali at 40 mg/L. The SEM and TEM observations indicated that compounds G22 and G34 may affect normal V. mali mycelial morphology as well as the cellular ultrastructure. Molecular docking analysis results indicated that G22 and boscalid possessed a similar binding mode to that of SDH, and detailed SDH inhibition assays validated the feasibility of the designed compounds as potential SDH inhibitors. Compounds G22 and G3 were selected for theoretical calculations, and the terminal carboxylic acid group of this series of compounds may be a key region influencing the antifungal activity. Furthermore, toxicity tests on Apis mellifera l. revealed that compounds G22 and G34 exhibited low toxicity to A. mellifera l. populations. The above results demonstrated that these series of pyrazole-5-yl-amide derivatives are promising for development as potential low-risk drug-resistance agricultural SDHI fungicides.

Furofuran Lignans for Plant Protection: Discovery of Sesamolin and Its Derivatives as Novel Anti-Tobacco Mosaic Virus and Antibacterial Agents

Natural products have been a valuable source of efficient and low-risk pesticides. In this work, a series of novel sesamolin derivatives A0-A31 and B0-B4 were designed and synthesized via structural simplification of furofuran lignan phrymarolin II, and their antiviral and antibacterial activities were systematically evaluated. The bioassay results showed that compound A24 displayed remarkable inactivation activity against tobacco mosaic virus (TMV) with an EC₅₀ value of 130.4 μg/mL, which was superior to that of commercial ningnanmycin (EC₅₀ = 202.0 μg/mL). The antiviral mode of action assays suggested that compound A24 may obstruct self-assembly by binding to TMV coat protein (CP), thus resisting the TMV infection. In addition, compound A25 possessed prominent antibacterial activities, especially against Ralstonia solanacearum with an EC₅₀ value of 43.8 μg/mL, which is better than those of commercial bismerthiazol and thiodiazole copper. This research lays a solid foundation for the utilization of furofuran lignans in crop protection.

The resilient cotton plant: uncovering the effects of stresses on secondary metabolomics and its underlying molecular mechanisms

Cotton is an important fiber crop cultivated around the world under diverse climate conditions and generates billions of dollars in annual revenue globally. Biotic and abiotic stresses have caused reduction in yield and productivity of cotton crops. In this review, we comprehensively analyzed and summarized the effect of biotic and abiotic stress on secondary metabolite production in cotton. The development of cotton varieties with improved tolerance against abiotic and biotic stress can play an important role in sustainable cotton production. Under stress conditions, plants develop a variety of defense mechanisms such as initiating signaling functions to upregulate defense responsive genes and accumulation of secondary metabolites. Understanding the impact of stress on secondary metabolite production in cotton is crucial for developing strategies to alleviate the negative effects of stress on crop yield and quality. Further, the potential industrial applications of these secondary metabolites in cotton, such as gossypol, could provide new opportunities for sustainable cotton production and the development of value-added products. Additionally, transgenic and genome-edited cotton cultivars can be developed to provide tolerance to both abiotic and biotic stress in cotton production.

Recent Achievements in Antiviral Agent Development for Plant Protection

Plant virus disease is the second most prevalent plant diseases and can cause extensive loss in global agricultural economy. Extensive work has been carried out on the development of novel antiplant virus agents for preventing and treating plant virus diseases. In this review, we summarize the achievements of the research and development of new antiviral agents in the recent five years and provide our own perspective on the future development in this highly active research field.

Design, Synthesis, Calculation and Biological Activity Studies Based on Privileged Coumarin Derivatives as Multifunctional Anti-AD Lead Compound

Coumarins and their derivatives possessed a variety of biological activities and some of coumarin-based drugs have been approved by the US Food and Drug Administration. Alzheimer's disease (AD) has caused great losses to human society. However, due to its complex pathogenesis, the ideal therapeutic approach has not been found yet. Free radical scavenging activity which is one of the main activities of coumarin core structure is closely related to other anti-AD activities. Therefore, in this work coumarins were chosen as privileged lead compounds for the development of anti-AD drugs based on strategy of multi-target directed ligands (MTDLs). Derivatives 1-3 which could modulate multiple targets simultaneously, including ROS, cholinesterase, βamyloid (Aβ) aggregation, and metal dyshomeostasis were designed and for the first time synthesized. Their anti-AD activities were studied both in vitro and in silico. Results showed that 1-3 possessed potent antioxidant activities and 7-OH group did change the electron distribution of the molecule and enhance the antioxidant activities. They also have good inhibition activities on acetylcholinesterase (AChE) and Aβ aggregation and compound 1 had the strongest AChE inhibitory effect among the three compounds (AChE IC₅₀ =11.15 μM). Compound 1-3 could also selectively chelate with Cu²⁺ and Al³⁺ to regulate the metal homeostasis. In silico simulations, including molecular docking and prediction of ADMET performance, indicated that 1-3 could interact with target proteins and cross the blood brain barrier. In conclusion, 1-3 could be promising MTDLs applied as anti-AD candidate drugs.

Discovery of Novel α-Methylene-γ-Butyrolactone Derivatives Containing Vanillin Moieties as Antiviral and Antifungal Agents

On the basis of the structure of nicotlactone A (L1), a series of novel α-methylene-γ-butyrolactone derivatives B1-B43 were designed and synthesized by structure simplification and active fragment replacement strategies, and their antiviral and antifungal activities were evaluated. The bioassay studies indicated that many target compounds possessed good to excellent antiviral activity against tobacco mosaic virus (TMV) and some of these compounds exhibited specific antifungal activities against Valsa mali and Fusarium graminearum. Compound B32 exhibited the best anti-TMV activity (inactivation effect, 88.9%; protection effect, 65.8%; curative effect, 52.8%) in vivo at 500 mg/L, which is significantly higher than that of commercial virucides ribavirin and ningnanmycin. The inhibition effect of compound B32 was also visualized by the inoculation test using green fluorescent protein (GFP)-labeled TMV. The preliminary antiviral mechanism of compound B32 was investigated. Transmission electron microscopy (TEM) showed that compound B32 could destroy the integrity of virus particles. Then, molecular docking and isothermal titration calorimetry (ITC) analysis further demonstrated that compound B32 exhibited a strong binding affinity to the TMV coat protein with a dissociation constant (K_d) of 3.06 μM, superior to ribavirin. Thus, we deduced that compound B32 may interfere with the self-assembly of TMV particles by binding TMV coat protein (CP). In addition, compound B28 showed good in vitro activity against F. graminearum with an inhibition rate of 90.9% at 50 mg/L, which was greater than that of fluxapyroxad (59.1%) but lower than that of the commercial fungicide carbendazim (96.8%). The present study provides support for the application of these α-methylene-γ-butyrolactone derivatives as novel antiviral and antifungal agents in crop protection.