Discovery of Novel Spiropiperidinyl-α-methylene-γ-butyrolactones as Antifungal and Antitoxin Agents Targeting Oxysterol Binding Protein.

Corn ear rot and fumonisin caused by Fusarium verticillioides pose a serious threat to food security. To find more highly active fungicidal and antitoxic candidates with structure diversity based on naturally occurring lead xanthatin, a series of novel spiropiperidinyl-α-methylene-γ-butyrolactones were rationally designed and synthesized. The in vitro bioassay results indicated that compound 7c showed broad-spectrum in vitro activity with EC50 values falling from 3.51 to 24.10 µg/mL against Rhizoctonia solani and Alternaria solani, which was more active than the positive controls xanthatin and oxathiapiprolin. In addition, compound 7c also showed good antitoxic efficacy against fumonisin with a 48% inhibition rate even at a concentration of 20 µg/mL. Fluorescence quenching and the molecular docking validated both 7c and oxathiapiprolin targeting at FvoshC. RNA sequencing analysis discovered that FUM gene cluster and protein processing in endoplasmic reticulum were downregulated. Our studies have discovered spiropiperidinyl-α-methylene-γ-butyrolactone as a novel FvoshC target-based scaffold for fungicide lead with antitoxin activity.

[Analysis of Field Inspection Issues and Some Suggestions for Software as Medical Device].

With the encouragement of policies and the rapid development of the biopharmaceutical industry, the number of software as medical device (SaMD) registration applications in Shanghai has continued to increase in recent years, and this paper summarizes the GMP nonconformities found in the field inspection of SaMD in Shanghai from 2020 to 2023, and the results show that nearly 70% of the problems were found in the software development process. Through in-depth analysis, this paper proposes the corresponding countermeasures for the problems found in the five most common stages such as software requirements, software design, software testing, software defect management and software configuration management, combined with the characteristics of software development. These suggested measures have certain reference significance for medical device software development and quality control personnel, and technical reviewer and inspectors.

Stem Cell-Derived Nanovesicles Embedded in Dual-Layered Hydrogel for Programmed ROS Regulation and Comprehensive Tissue Regeneration in Burn Wound Healing.

Burn wounds often bring high risks of delayed healing process and even death. Reactive oxygen species (ROS) play a crucial role in burn wound repair. However, the dynamic process in wound healing requires both the generation of ROS to inhibit bacteria and the subsequent reduction of ROS levels to initiate and promote tissue regeneration, which calls for a more intelligent ROS regulation dressing system. Hence, a dual-layered hydrogel (Dual-Gel) tailored to the process of burn wound repair is designed: the inner layer hydrogel (Gel 2) first responds to bacterial hyaluronidase (Hyal) to deliver aggregation-induced emission photosensitizer functionalized adipose-derived stem cell nanovesicles, which generate ROS upon light irradiation to eliminate bacteria; then the outer layer hydrogel (Gel 1) continuously starts a long-lasting consumption of excess ROS at the wound site to accelerate tissue regeneration. Simultaneously, the stem cell nanovesicles trapped in the burns wound also provide nutrients and mobilize neighboring tissues to thoroughly assist in inflammation regulation, cell proliferation, migration, and angiogenesis. In summary, this study develops an intelligent treatment approach on burn wounds by programmatically regulating ROS and facilitating comprehensive wound tissue repair.

Extracellular Vesicle-Inspired Therapeutic Strategies for the COVID-19.

Emerging infectious diseases like coronavirus pneumonia (COVID-19) present significant challenges to global health, extensively affecting both human society and the economy. Extracellular vesicles (EVs) have demonstrated remarkable potential as crucial biomedical tools for COVID-19 diagnosis and treatment. However, due to limitations in the performance and titer of natural vesicles, their clinical use remains limited. Nonetheless, EV-inspired strategies are gaining increasing attention. Notably, biomimetic vesicles, inspired by EVs, possess specific receptors that can act as "Trojan horses," preventing the virus from infecting host cells. Genetic engineering can enhance these vesicles by enabling them to carry more receptors, significantly increasing their specificity for absorbing the novel coronavirus. Additionally, biomimetic vesicles inherit numerous cytokine receptors from parent cells, allowing them to effectively mitigate the "cytokine storm" by adsorbing pro-inflammatory cytokines. Overall, this EV-inspired strategy offers new avenues for the treatment of emerging infectious diseases. Herein, this review systematically summarizes the current applications of EV-inspired strategies in the diagnosis and treatment of COVID-19. The current status and challenges associated with the clinical implementation of EV-inspired strategies are also discussed. The goal of this review is to provide new insights into the design of EV-inspired strategies and expand their application in combating emerging infectious diseases.

Biochemical synthesis of taxanes from mevalonate.

Taxanes are kinds of diterpenoids with important bioactivities, such as paclitaxel (taxol®) is an excellent natural broad-spectrum anticancer drug. Attempts to biosynthesize taxanes have made with limited success, mainly due to the bottleneck of the low efficiency catalytic elements. In this study, we developed an artificial synthetic system to produce taxanes from mevalonate (MVA) by coupling biological and chemical methods, which comprises in vitro multi-enzyme catalytic module, chemical catalytic module and yeast cell catalytic module. Through optimizing in vitro multienzyme catalytic system, the yield of taxadiene was increased to 946.7 mg/L from MVA within 8 h and the productivity was 14.2-fold higher than microbial fermentation. By incorporating palladium catalysis, the conversion rate of Taxa-4(20),11(12)-dien-5α-yl acetate (T5α-AC) reached 48 %, effectively addressing the product promiscuity and the low yield rate of T5αOH. Finally, we optimized the expression of T10ßOH in yeast resulting in the biosynthesis of Taxa-4(20),11(12)-dien-5α-acetoxy-10ß-ol(T5α-AC-10ß-ol) at a production of 15.8 mg/L, which displayed more than 2000-fold higher than that produced by co-culture fermentation strategy. These technologies offered a promising new approach for efficient synthesis of taxanes.

Fungicidal Activity of New Pyrrolo[2,3-d]thiazoles and Their Potential Action on the Tryptophan Metabolic Pathway and Wax Biosynthesis.

The main challenge in the development of agrochemicals is the lack of new leads and/or targets. It is critical to discover new molecular targets and their corresponding ligands. YZK-C22, which contains a 1,2,3-thiadiazol-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole skeleton, is a fungicide lead compound with broad-spectrum fungicidal activity. Previous studies suggested that the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole scaffold exhibited good antifungal activity. Inspired by this, a series of pyrrolo[2,3-d]thiazole derivatives were designed and synthesized through a bioisosteric strategy. Compounds C1, C9, and C20 were found to be more active against Rhizoctonia solani than the positive control YZK-C22. More than half of the target compounds provided favorable activity against Botrytis cinerea, where the EC50 values of compounds C4, C6, C8, C10, and C20 varied from 1.17 to 1.77 µg/mL. Surface plasmon resonance and molecular docking suggested that in vitro potent compounds C9 and C20 have a new mode of action instead of acting as pyruvate kinase inhibitors. Transcriptome analysis revealed that compound C20 can impact the tryptophan metabolic pathway, cutin, suberin, and wax biosynthesis of B. cinerea. Overall, pyrrolo[2,3-d]thiazole is discovered as a new fungicidal lead structure with a potential new mode of action for further exploration.

Design, synthesis and systemic acquired resistance of 2-benzothiadiazolylquinoline-4-carboxamides by COI1 based virtual screening.

Coronatine-insensitive 1 (COI1) has been identified as a target receptor of plant elicitor coronatine (COR). To discover novel plant elicitor leads, most of the potential molecules among 129 compounds discovered from the ZINC database by docking based virtual screening targeting COI1 were quinoline amides. On this lead basis, 2-benzothiadiazolylquinoline-4-carboxamides were rationally designed and synthesized for bioassay. All target compounds did not show significantly in vitro antifungal activity, compounds 4d, 4e and 4o displayed good in vivo systemic acquired resistance activity for Arabidopsis thaliana against Hyaloperonospora arabidopsidis isolate Noco2 with over 80% of inhibitory rate at the concentration of 50 µM. These results indicate that 2-benzothiadiazolylquinoline-4-carboxamides are promising plant elicitor leads for further study.

Light-Triggered Nanozymes Remodel the Tumor Hypoxic and Immunosuppressive Microenvironment for Ferroptosis-Enhanced Antitumor Immunity.

Cancer immunotherapy holds significant promise for addressing diverse malignancies. Nevertheless, its efficacy remains constrained by the intricate tumor immunosuppressive microenvironment. Herein, a light-triggered nanozyme Fe-TCPP-R848-PEG (Fe-MOF-RP) was designed for remodeling the immunosuppressive microenvironment. The Fe-TCPP-MOFs were utilized not only as a core catalysis component against tumor destruction but also as a biocompatible delivery vector of an immunologic agonist, improving its long circulation and tumor enrichment. Concurrently, it catalyzes the decomposition of H2O2 within the tumor, yielding oxygen to augment photodynamic therapy. The induced ferroptosis, in synergy with photodynamic therapy, prompts the liberation of tumor-associated antigens from tumor cells inducing immunogenic cell death. Phototriggered on-demand release of R848 agonists stimulated the maturation of dendritic cells and reverted the tumor-promoting M2 phenotypes into adoptive M1 macrophages, which further reshaped the tumor immunosuppressive microenvironment. Notably, the nanozyme effectively restrains well-established tumors, such as B16F10 melanoma. Moreover, it demonstrates a distal tumor-inhibiting effect upon in situ light treatment. What is more, in a lung metastasis model, it elicits robust immune memory, conferring enduring protection against tumor rechallenge. Our study presents a straightforward and broadly applicable strategy for crafting nanozymes with the potential to effectively thwart cancer recurrence and metastasis.

Discovery of Trisubstituted N-Phenylpyrazole Containing Diamides with Improved Insecticidal Activity.

To increase the structural diversity of insecticides and meet the needs of effective integrated insect management, the structure of chlorantraniliprole was modified based on a previously established three-dimensional quantitative structure-activity relationship (3D-QSAR) model. The pyridinyl moiety in the structure of chlorantraniliprole was replaced with a 4-fluorophenyl group. Further modifications of this 4-fluorophenyl group by introducing a halogen atom at position 2 and an electron-withdrawing group (e.g., iodine, cyano, and trifluoromethyl) at position 5 led to 34 compounds with good insecticidal efficacy against Mythimna separata, Plutella xylostella, and Spodoptera frugiperda. Among them, compound IV f against M. separata showed potency comparable to that of chlorantraniliprole. IV p against P. xylostella displayed a 4.5 times higher potency than chlorantraniliprole. In addition, IV d and chlorantraniliprole exhibited comparable potencies against S. frugiperda. Transcriptome analysis showed that the molecular target of compound IV f is the ryanodine receptor. Molecular docking was further performed to verify the mode of action and insecticidal activity against resistant P. xylostella.

Key role of the ryanodine receptor I4790K mutation in mediating diamide resistance in Plutella xylostella.

The diamondback moth Plutella xylostella, a global insect pest of cruciferous vegetables, has evolved resistance to many classes of insecticides including diamides. Three point mutations (I4790M, I4790K, and G4946E) in the ryanodine receptor of P. xylostella (PxRyR) have been identified to associate with varying levels of resistance. In this study, we generated a knockin strain (I4790K-KI) of P. xylostella, using CRISPR/Cas9 to introduce the I4790K mutation into PxRyR of the susceptible IPP-S strain. Compared to IPP-S, the edited I4790K-KI strain exhibited high levels of resistance to both anthranilic diamides (chlorantraniliprole 1857-fold, cyantraniliprole 1433-fold) and the phthalic acid diamide flubendiamide (>2272-fold). Resistance to chlorantraniliprole in the I4790K-KI strain was inherited in an autosomal and recessive mode, and genetically linked with the I4790K knockin mutation. Computational modeling suggests the I4790K mutation reduces the binding of diamides to PxRyR by disrupting key hydrogen bonding interactions within the binding cavity. The approximate frequencies of the 4790M, 4790K, and 4946E alleles were assessed in ten geographical field populations of P. xylostella collected in China in 2021. The levels of chlorantraniliprole resistance (2.3- to 1444-fold) in these populations were significantly correlated with the frequencies (0.017-0.917) of the 4790K allele, but not with either 4790M (0-0.183) or 4946E (0.017-0.450) alleles. This demonstrates that the PxRyR I4790K mutation is currently the major contributing factor to chlorantraniliprole resistance in P. xylostella field populations within China. Our findings provide in vivo functional evidence for the causality of the I4790K mutation in PxRyR with high levels of diamide resistance in P. xylostella, and suggest that tracking the frequency of the I4790K allele is crucial for optimizing the monitoring and management of diamide resistance in this crop pest.

Engineered macrophage-derived cellular vesicles for NIR-II fluorescence imaging-guided precise cancer photo-immunotherapy.

Significant progress has been made in cancer immunotherapy; however, challenges such as interpatient variability, limited treatment response, and severe side effects persist. Although nanoimmunotherapy has emerged as a promising approach, the construction of precise and efficient nanosystems remain formidable challenges. Herein, a multifunctional nanoplatform was developed using macrophage-derived cellular vesicles (MCVs) for NIR-II imaging-guided precise cancer photo-immunotherapy. MCVs exhibited excellent tumor targeting and TAMs re-education effects, serving as both delivery carriers and therapeutic agents. Through amide bond, indocyanine green (ICG) was conjugated to the surface of MCVs, enabling in vivo tracking of MCVs distribution. Notably, ICG exhibited dual functionality as a NIR-II fluorescent agent and possessed photodynamic and photothermal effects, enabling the conversion of light energy into chemical or heat energy to eliminate tumor cells. This precision phototherapy triggered immunogenic cell death (ICD) of tumor, thereby activating the anti-tumor immune response. Additionally, MCVs loaded with R848, a toll-like receptor agonist, augmented the ICD-induced anti-tumor immunity. Animal experiments confirmed that MCVs-mediated photoimmunotherapy promoted T cell infiltration, inhibited tumor growth, and improved survival rates. In conclusion, we have developed a promising precision immunotherapy strategy capable of enhancing the immune response while mitigating off-target effects. These findings offer encouraging prospects for clinical translation.

In vivo visualization of tumor-associated macrophages re-education by photoacoustic/fluorescence dual-modal imaging with a metal-organic frames-based caspase-1 nanoreporter.

Tumor-associated macrophages (TAMs) are vital in the tumor microenvironment, contributing to immunosuppression and therapy tolerance. Despite their importance, the precise re-education of TAMs in vivo continues to present a formidable challenge. Moreover, the lack of real-time and efficient methods to comprehend the spatiotemporal kinetics of TAMs repolarization remains a significant hurdle, severely hampering the accurate assessment of treatment efficacy and prognosis. Herein, we designed a metal-organic frameworks (MOFs) based Caspase-1 nanoreporter (MCNR) that can deliver a TLR7/8 agonist to the TAMs and track time-sensitive Caspase-1 activity as a direct method to monitor the initiation of immune reprogramming. This nanosystem exhibits excellent TAMs targeting ability, enhanced tumor accumulation, and stimuli-responsive behavior. By inducing the reprogramming of TAMs, they were able to enhance T-cell infiltration in tumor tissue, resulting in inhibited tumor growth and improved survival in mice model. Moreover, MCNR also serves as an activatable photoacoustic and fluorescent dual-mode imaging agent through Caspase-1-mediated specific enzyme digestion. This feature enables non-invasive and real-time antitumor immune activation monitoring. Overall, our findings indicate that MCNR has the potential to be a valuable tool for tumor immune microenvironment remodeling and noninvasive quantitative detection and real-time monitoring of TAMs repolarization to immunotherapy in the early stage.

Computation-Directed Molecular Design, Synthesis, and Fungicidal Activity of Succinate Dehydrogenase Inhibitors.

Succinate dehydrogenase inhibitors (SDHIs) are a class of fungicides targeting the pathogenic fungi mitochondrial SDH. Here, molecular docking, three-dimensional quantitative structure-activity relationship (3D-QSAR), and molecular dynamics (MD) simulations were used to guide SDHI innovation. Molecular docking was performed to explore the binding modes of SDH and its inhibitors. 3D-QSAR models were carried out on 33 compounds with activity against Rhizoctonia cerealis (R. cerealis); their structure-activity relationships were analyzed using comparative molecular field analysis and comparative molecular similarity indices analysis. MD simulations were used to assess the stability of the complexes under physiological conditions, and the results were consistent with molecular docking. Binding free energy was calculated through the molecular mechanics generalized born surface area method, and the binding free energy was decomposed. The results are consistent with the activity of bioassay and indicate that van der Waals and lipophilic interactions contribute the most in the molecular binding process. Afterward, we designed and synthesized 12 compounds under the guidance of the above-mentioned analyses, bioassay found that F9 was active against R. cerealis with the EC50 value of 9.43 µg/mL, and F4, F5, and F9 were active against Botrytis cinerea with an EC50 values of 5.80, 3.17, and 1.63 µg/mL, respectively. They all showed good activity between positive controls of pydiflumetofen and thifluzamide. Our study provides new considerations for effective SDHIs discovery.

Synthesis of fungicidal morpholines and isochromenopyridinones via acid-catalyzed intramolecular reactions of isoindolinones.

Acid-catalyzed intramolecular cyclization or rearrangement of isoindolinone derivatives is described. 3-Hydroxy/ethoxy-3,4-dihydro-6H-[1,4]-oxazino-[3,4-a]-isoindol-6-ones are obtained in moderate to good yields. Further acid-catalyzed intramolecular rearrangement reactions give 6H-isochromeno-[4,3-b]-pyridin-6-ones. The mild reaction conditions with convenient starting materials show broad substrate scope and provide the target compounds as novel pesticide leads with good fungicidal or systemical acquired resistance activities.

Biomimetic nanovaccine-mediated multivalent IL-15 self-transpresentation (MIST) for potent and safe cancer immunotherapy.

Cytokine therapy, involving interleukin-15 (IL-15), is a promising strategy for cancer immunotherapy. However, clinical application has been limited due to severe toxicity and the relatively low immune response rate, caused by wide distribution of cytokine receptors, systemic immune activation and short half-life of IL-15. Here we show that a biomimetic nanovaccine, developed to co-deliver IL-15 and an antigen/major histocompatibility complex (MHC) selectively targets IL-15 to antigen-specific cytotoxic T lymphocytes (CTL), thereby reducing off-target toxicity. The biomimetic nanovaccine is composed of cytomembrane vesicles, derived from genetically engineered dendritic cells (DC), onto which IL-15/IL-15 receptor α (IL-15Rα), tumor-associated antigenic (TAA) peptide/MHC-I, and relevant costimulatory molecules are simultaneously anchored. We demonstrate that, in contrast to conventional IL-15 therapy, the biomimetic nanovaccine with multivalent IL-15 self-transpresentation (biNV-IL-15) prolonged blood circulation of the cytokine with an 8.2-fold longer half-life than free IL-15 and improved the therapeutic window. This dual targeting strategy allows for spatiotemporal manipulation of therapeutic T cells, elicits broad spectrum antigen-specific T cell responses, and promotes cures in multiple syngeneic tumor models with minimal systemic side effects.

Design and Synthesis of Pyrimidine Amine Containing Isothiazole Coumarins for Fungal Control.

Developing new fungicides is always crucial to protecting crops. A series of 4-(3,4-dichloroisothiazol-5-yl)-7-(2-((5-(5-pyrimidin-4-yl)amino)ethoxy)-8-methyl) coumarin derivatives were designed and synthesized by Williamson ether condensation and substitution reactions. Structure determinations were clarified by 1H NMR, 13C NMR, and HRMS, and compound 4h crystallized by the fusion method for further structural confirmation. The in vitro bioassay results showed that the target compounds displayed good fungicidal activity against Alternaria solani, Botrytis cinerea, Cercospora arachidicola, Fusarium graminearum, Physalospora piricola, Rhizoctonia solani, and Sclerotinia sclerotiorum. Among them, compounds 4b and 4d showed higher inhibitory activity against R. solani, with EC50 values of 11.3 and 13.7 µg/mL, respectively, and they were more active than the positive control diflumetorim with an EC50 value of 19.8 µg/mL. Molecular docking suggested that compound 4b and diflumetorim may have similar interactions with complex I NADH oxidoreductase. Density functional theory calculation and pesticide-likeness analysis studies gave a rational explanation of their fungicidal activity. These results indicated that compounds 4b and 4d deserved further optimization according to the principle of pesticide-likeness.

Tumor Microenvironment Activated Photoacoustic-Fluorescence Bimodal Nanoprobe for Precise Chemo-immunotherapy and Immune Response Tracing of Glioblastoma.

Synergistic therapy strategy and prognostic monitoring of glioblastoma's immune response to treatment are crucial to optimize patient care and advance clinical outcomes. However, current systemic temozolomide (TMZ) chemotherapy and imaging methods for in vivo tracing of immune responses are inadequate. Herein, we report an all-in-one theranostic nanoprobe (PEG/αCD25-Cy7/TMZ) for precise chemotherapy and real-time immune response tracing of glioblastoma by photoacoustic-fluorescence imaging. The nanoprobe was loaded with TMZ and targeted regulatory T lymphocyte optical dye αCD25-Cy7 encapsulated by glutathione-responsive DSPE-SS-PEG2000. The results showed that the targeted efficiency of the nanoprobe to regulatory T lymphocytes is up to 92.3%. The activation of PEG/αCD25-Cy7/TMZ by glutathione enhanced the precise delivery of TMZ to the tumor microenvironment for local chemotherapy and monitored glioblastoma's boundary by photoacoustic-fluorescence imaging. Immunotherapy with indoleamine 2,3-dioxygenase inhibitors after chemotherapy could promote immunological responses and reduce regulatory T lymphocyte infiltration, which could improve the survival rate. Photoacoustic imaging has in real-time and noninvasively depicted the dynamic process of immune response on a micrometer scale, showing that the infiltration of regulatory T lymphocytes after chemotherapy was up-regulated and would down-regulate after IDO inhibitor treatment. This all-in-one theranostic strategy is a promising method for precisely delivering TMZ and long-term dynamically tracing regulatory T lymphocytes to evaluate the immune response in situ for accurate tumor chemo-immunotherapy.

3D-QSAR Combination with Molecular Dynamics Simulations to Effectively Design the Active Ryanodine Receptor Agonists against Spodoptera frugiperda.

Computer-aided molecular modeling was applied to design a series of Spodoptera frugiperda RyR agonists. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were used to generate 3D-QSAR models. MD simulations in the complex with S. frugiperda native, mutant RyR, and mammalian RyR1 under physiological conditions were used to validate the detailed binding mechanism. Binding free energy calculation by molecular mechanics generalized surface area (MM-GBSA) explained the role of key amino acid residues in ligand-receptor binding. Therefore, 14 new compounds were effectively designed and synthesized, and a bioassay indicated that compounds A-2 and A-3 showed comparable activity to that of chloranthraniliprole with LC50 values of 0.27, 0.18, and 0.20 mg L-1, respectively, against S. frugiperda. Most target compounds also displayed good activity against Mythinma separata at 0.1 mg L-1. Molecular docking and MM-GBSA calculations demonstrated that A-3 had a better binding capacity with native and mutant S. frugiperda RyRs.

CoMFA Directed Molecular Design for Significantly Improving Fungicidal Activity of Novel [1,2,4]-Triazolo-[3,4-b][1,3,4]-thiadizoles.

Target based molecular design via the aid of computation is one of the most efficient methods in the discovery of novel pesticides. Here, a combination of the comparative molecular field analysis (CoMFA) and molecular docking was applied for discovery of potent fungicidal [1,2,4]-triazolo-[3,4-b][1,3,4]-thiadiazoles. Bioassay results indicated that the synthesized target compounds 3a, 3b, and 3c exhibited good activity against Alternaria solani, Botrytis cinerea, Cercospora arachidicola, Fusarium graminearum, Physalospora piricola, Rhizoctonia solani, and Sclerotinia sclerotiorum with an EC50 value falling between 0.64 and 16.10 µg/mL. Specially, 3c displayed excellent fungicidal activity against C. arachidicola and R. solani, which was 5 times more potent than the lead YZK-C22. The enzymatic inhibition assay and fluorescence quenching analysis with R. solani pyruvate kinase (RsPK) showed a weaker binding affinity between RsPK and 3a, 3b, or 3c. Transcriptomic analyses showed that 3c exerted its fungicidal activity by disrupting steroid biosynthesis and ribosome biogenesis in eukaryotes. These findings support that 3c is a promising fungicide candidate, and a fine modification from a lead may lead to a totally different mode of action.

Design, Synthesis and Fungicidal Activity of Ester Derivatives of 4-(3,4-Dichloroisothiazole) 7-Hydroxy Coumarin.

The development of new fungicides is vital for safeguarding crops and ensuring sustainable agriculture. Building on our previous finding that 4-(3,4-dichloroisothiazole)-7-hydroxy coumarins can be used as fungicidal leads, 44 novel coumarin ester derivatives were designed and synthesized to evaluate whether esterification could enhance their fungicidal activity. In vitro fungicidal bioassays indicated that compound 2ai displayed good activity against Alternaria solani, Botrytis cinereal, Cercospora arachidicola, Physalospora piricola and Sclerotinia sclerotiorum, with an EC50 value ranging from 2.90 to 5.56 µg/mL, comparable to the lead compound 1a, with its EC50 value ranging from 1.92 to 9.37 µg/mL. In vivo bioassays demonstrated that compounds 1a, 2ar and 2bg showed comparable, excellent efficacy against Pseudoperonospora cubensis at a dose of 25 µg/mL. Our research shows that the esterification of 4-(3,4-dichloroisothiazole) 7-hydroxycoumarins results in a fungicidal activity equivalent to that of its lead compounds. Furthermore, our density functional theory (DFT) calculations and 3D-QSAR modeling provide a rational explanation of the structure-activity relationship and offer valuable insights to guide further molecular design.