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.

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.

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.

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.

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.

Seedlings of Poncirus trifoliata exhibit tissue-specific detoxification in response to NH4 + toxicity

Ammonium nitrogen (NH4 +-N) is essential for fruit tree growth, but the impact of excess NH4 +-N from fertilizer on evergreen citrus trees is unclear. In a climate chamber, 8-month-old citrus plants were exposed to five different hydroponic NH4 +-N concentrations (0, 5, 10, 15 and 20 mm) for 1 month to study effects of NH4 +-N on growth characteristics, N uptake, metabolism, antioxidant enzymes and osmotic regulatory substances. Application of 10 mm NH4 +-N adversely affected root plasma membrane integrity, root physiological functions, and plant biomass. MDA, CAT, POD, APX and SOD content were significantly correlated with leaf N metabolic enzyme activity (GOGAT, GDH, GS and NR). GDH was the primary enzyme involved in NH4 +-N assimilation in leaves, while the primary pathway involved in roots was GS-GOGAT. Under comparatively high NH4 + addition, roots were the main organs involved in NH4 + utilization in citrus seedlings. Our results demonstrated that variations in NH4 + concentration and enzyme activity in various organs are associated with more effective N metabolism in roots than in leaves to prevent NH4 + toxicity in evergreen woody citrus plants. These results provide insight into the N forms used by citrus plants that are important for N fertilizer management.

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.

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.

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.

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.

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.

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.

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.

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.

Fibulin-1 Regulates Initiation of Successional Dental Lamina

In humans, teeth are replaced only once, and the successional dental lamina (SDL) of the permanent tooth is maintained in a quiescent state until adolescence. Recently, we showed that biomechanical stress generated by the rapid growth of the deciduous tooth inhibits SDL development via integrin β1-RUNX2 signaling at embryonic day 60 (E60) in miniature pigs. However, the mechanism by which RUNX2 regulates SDL initiation within the SDL stem cell niche remains unclear. In the current study, we transcriptionally profiled single cells from SDL and surrounding mesenchyme at E60 and identified the landscape of cellular heterogeneity. We then identified a specific fibroblast subtype in the dental follicle mesenchyme between the deciduous tooth and the SDL of the permanent tooth (DFDP), which constitutes the inner part of the niche (deciduous tooth side). Compared with traditional dental follicle cells, the specific expression profile of DFDP was identified and found to be related to biomechanical stress. Subsequently, we found that RUNX2 could bind to the enhancer regions of Fbln1 (gene of fibulin-1), one of the marker genes for DFDP. Through gain- and loss-of-function experiments, we proved that the biomechanical stress-mediated RUNX2-fibulin-1 axis inhibits the initiation of SDL by maintaining SDL niche homeostasis.

Contouring Analysis on Synthetic Contrast-Enhanced MR from GRMM-GAN and Implications on MR-Guide Radiation Therapy

PURPOSE/OBJECTIVE(S)

MR-guided linear accelerators have been commercialized making MR-only planning and adaptation an appealing alternative circumventing MR-CT registration. However, obtaining daily contrast-enhanced MR images can be prohibitive due to the increased risk of side effects from repeated contrast injections. In this work, we evaluate the quality of contrast-enhanced multi-modal MR image synthesis network GRMM-GAN (gradient regularized multi-modal multi-discrimination sparse-attention fusion generative adversarial network) for MR-guided radiation therapy.

MATERIALS/METHODS

With IRB approval, we trained the GRMM-GAN based on 165 abdominal MR studies from 65 patients. Each study included T2, T1 pre-contrast (T1pre), and T1 contrast enhanced (T1ce) images. The two pre-contrast MR modalities, T2 and T1pre images were adopted as inputs for GRMM-GAN, and the T1ce image at the portal venous phase was used as an output. Ten MR scans containing 21 liver tumors were selected for contouring analysis. A Turing test was first given to six radiation oncologists, in which 100 real T1ce and synthetic T1ce image slices are randomly given to the radiation oncologists to determine the authenticity of the synthesis. We then invited two radiation oncologists (RadOnc 1 and RadOnc2) to manually contour the 21 liver tumors independently on the real T1ce images. RadOnc2 then performed contouring on the respective synthetic T1ce MRs. DICE coefficient (defined as the intersection over the average of two volumes) and Hausdorff distance (HD, measuring how far two volumes are from each other) were used as analysis metrics. The DICE coefficients were calculated from the two radiation oncologists' contours on the real T1ce MR for each tumor. The DICE coefficients were also calculated from RadOnc 2's contours on real and synthetic MRs. Besides, tumor center shifts were extracted. The tumor center of mass coordinates was extracted from real and synthetic volumes. The difference in the coordinates indicated the shifts in the superior-inferior (SI), right-left (RL), and anterior-posterior (AP) directions between real and synthetic tumor volumes.

RESULTS

An average of 52.3% test score was achieved from the six radiation oncologists, which is close to random guessing. RadOnc 1 and RadOnc 2, who had participated in the contouring analysis, achieved an average DICE of 0.91±0.02 from tumor volumes drawn on the real T1ce MRs. This result sets the inter-operator uncertainty baseline in the real clinical setting. RadOnc 2 achieved an average DICE (real vs. synth) of 0.90±0.04 and HD of 4.76±1.82 mm. Only sub-millimeter (SI: 0.67 mm, RL: 0.41 mm, AP: 0.39 mm) tumor center shifts were observed in all three directions.

CONCLUSION

The GRMM-GAN method has the potential for MR-guided liver radiation when contrast agents cannot be administered daily and provide synthetic contrast-enhanced MR for better tumor targeting. The network can produce synthetic MR images with satisfactory contour agreement and geometric integrity.

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.

3D-QSAR-Based Molecular Design to Discover Ultrahigh Active N-Phenylpyrazoles as Insecticide Candidates

Three-dimensional quantitative structure-activity relationship (3D-QSAR) is one of the most important and effective tools to direct molecular design in new pesticide development. Chlorantraniliprole is an anthranilic diamide ryanodine receptor (RyR) agonist with ultrahigh activity, high selectivity, and mammalian safety. To continue our studies on new insecticide development, here, we designed new insecticidal N-phenylpyrazoles by using 3D-QSAR of chlorantraniliprole analogues as a guide. Most of the target compounds synthesized exhibited medium to excellent activity against Mythimna separata, Plutella xylostella, and Spodoptera frugiperda. Compounds III b and III y showed similar activity against M. separata as chlorantraniliprole (LC₅₀ values: 0.21, 0.25, and 0.16 μg mL^-1 respectively). Compounds III b exhibited a 3-fold higher potency against P. xylostella than chlorantraniliprole. For S. frugiperda, the potency of III a and III b was 2.9 and 2.0 times higher than that of the positive control, respectively. The mode of action of the title compounds was validated by calcium imaging experiments and molecular docking using their target RyRs. III b can dock well with mutated P. xylostella RyRs, implying a potentially lower cross-resistance risk as compared with commercial RyR agonists. Density functional theory calculations suggested the feasibility of higher potency with the structural modifications. Compound III b was found to be an ultrahigh active insecticidal candidate with a broad spectrum for integrated pest management.

Exploration of Fungicidal Activity and Mode of Action of Ferimzone Analogs

Lead discovery and molecular target identification are important for developing novel pesticides. Scaffold hopping, an effective approach of modern medicinal and agrochemical chemistry for a rational design of target molecules, is aiming to design novel molecules with similar structures and similar/better biological performance. Herein, 24 new ferimzone derivatives were designed and synthesized by a scaffold-hopping strategy. In vitro bioassays indicated that compound 5o showed similar potency to ferimzone against Cercospora arachidicola and 2-fold higher potency than ferimzone against Alternaria solani. Compounds 5q, 6a, and 6d displayed fungicidal activity with EC₅₀ values ranging from 1.17 to 3.84 μg/mL against Rhizoctonia solani, and compounds 5q and 6a displayed 1.6-1.8-fold higher activity than ferimzone against Fusarium graminearum. The in vivo bioassays at 200 μg/mL indicated that compound 5q was more potent than ferimzone against Pyricularia oryzae (90% vs 70% efficacy, respectively). Density functional theory (DFT) calculations elucidated the structure-energy relationship. Although the mode of action of ferimzone is still unclear, studies suggested that compound 5q significantly inhibited the growth and reproduction of R. solani, and its energy metabolism pathways (e.g., starch, sucrose, lipids, and glutathione) were seriously downregulated after a 5q treatment.

A study on prenucleation and heterogeneous nucleation in liquid Pb on solid Al using molecular dynamics simulations

In this paper, we investigate prenucleation and heterogeneous nucleation in the liquid Pb/solid Al system as an example of systems with large lattice misfit using molecular dynamics simulation. Solid Pb and Al have a large positive lattice misfit (f) of 18.2% along the densely packed [110] direction. This study reveals that prenucleation occurs at 600 K (an undercooling of 15 K), and a 2-dimensional (2D) ordered structure forms at the interface with a coincidence site lattice (CSL) between the first Pb and first Al layers. The CSL accommodates the major part of the f, and only a small residual lattice misfit (f_r) of 1.9% remains. The formation of the CSL transforms the original substrate into a considerably potent nucleant, where the first Pb layer becomes the new surface layer of the substrate. At an undercooling of about 22 K, nucleation proceeds by merging 2D ordered structure through structural templating: the second Pb layer is epitaxial to the CSL Pb layer, the third Pb layer largely accommodates the f_r, and the fourth Pb layer is a nearly perfect crystalline plane. Further analysis indicates that the interface with the CSL has a lower interfacial energy than with a cube-to-cube orientation relationship. For the first time, we established that the CSL was an effective mechanism to accommodate the f for systems with a large positive misfits. Heterogeneous nucleation is governed not by a single mechanism (misfit dislocations in Turnbull's model), but instead by various mechanisms depending on f. This study sheds new light on the atomistic mechanism of heterogeneous nucleation.

Mid-infrared frequency combs and staggered spectral patterns in χ(2) microresonators

The potential of frequency comb spectroscopy has aroused great interest in generating mid-infrared frequency combs in the integrated photonic setting. However, despite remarkable progress in microresonators and quantum cascade lasers, the availability of suitable mid-IR comb sources remains scarce. Here, we generate mid-IR microcombs relying on cascaded three-wave-mixing for the first time. By pumping a CdSiP₂ microresonator at 1.55 µm wavelength with a low power continuous wave laser, we generate χ⁽²⁾ frequency combs at 3.1 µm wavelength, with a span of about 30 nm. We observe ordinary combs states with a line spacing of the free spectral range of the resonator, and combs where the sideband numbers around the pump and half-harmonic alternate, forming staggered patterns of spectral lines. Our scheme for mid-IR microcomb generation is compatible with integrated telecom lasers. Therefore, it has the potential to be used as a simple and fully integrated mid-IR comb source, relying on only one single material.

Plant-specific features of respiratory supercomplex I + III2 from Vigna radiata

The last steps of cellular respiration-an essential metabolic process in plants-are carried out by mitochondrial oxidative phosphorylation. This process involves a chain of multi-subunit membrane protein complexes (complexes I-V) that form higher-order assemblies called supercomplexes. Although supercomplexes are the most physiologically relevant form of the oxidative phosphorylation complexes, their functions and structures remain mostly unknown. Here we present the cryogenic electron microscopy structure of the supercomplex I + III₂ from Vigna radiata (mung bean). The structure contains the full subunit complement of complex I, including a newly assigned, plant-specific subunit. It also shows differences in the mitochondrial processing peptidase domain of complex III₂ relative to a previously determined supercomplex with complex IV. The supercomplex interface, while reminiscent of that in other organisms, is plant specific, with a major interface involving complex III₂'s mitochondrial processing peptidase domain and no participation of complex I's bridge domain. The complex I structure suggests that the bridge domain sets the angle between the enzyme's two arms, limiting large-scale conformational changes. Moreover, complex I's catalytic loops and its response in active-to-deactive assays suggest that, in V. radiata, the resting complex adopts a non-canonical state and can sample deactive- or open-like conformations even in the presence of substrate. This study widens our understanding of the possible conformations and behaviour of complex I and supercomplex I + III₂. Further studies of complex I and its supercomplexes in diverse organisms are needed to determine the universal and clade-specific mechanisms of respiration.

3D-QSAR Directed Discovery of Novel Halogenated Phenyl 3-Trifluoroethoxypyrazole Containing Ultrahigh Active Insecticidal Anthranilic Diamides

Pests are one of the major factors causing crop damage and food security problems worldwide. Based on our previous studies on the discovery of insecticidal leads targeting the ryanodine receptors (RyRs), a three-dimensional quantitative structure-activity relationship (3D-QSAR) model was established to design and synthesize a series of anthranilic diamides containing a halogenated phenyl 3-trifluoroethoxypyrazole moiety. The preliminary bioassays disclosed that IIb, IIIb, and IIIf against Mythimna separata showed comparable activity to chloranthraniliprole (LC₅₀: 0.16, 0.16, 0.14, and 0.13 mg·L^-1, respectively). More than half of the target compounds displayed good activity against Plutella xylostella, where IIIf was the most active compound, 25 times more active than chloranthraniliprole (LC₅₀: 6.0 × 10^-6 versus 1.5 × 10^-4 mg·L^-1). For Spodoptera frugiperda, IIIf displayed slightly inferior potency to chlorantraniliprole (LC₅₀: 0.47 versus 0.31 mg·L^-1). For RyR mutants of S. frugiperda (G4891E, I4734M), compound IIIf could show higher affinity than chlorantraniliprole according to the binding mode and energy in molecular docking experiments. Calcium imaging technique, molecular docking, density functional theory calculations, and electrostatic potential studies validated that the RyR was the target of the most active candidate IIIf, which deserves further development.

Tumor-Homing and Immune-Reprogramming Cellular Nanovesicles for Photoacoustic Imaging-Guided Phototriggered Precise Chemoimmunotherapy

Many studies have focused on developing effective therapeutic strategies to selectively destroy primary tumors, eliminate metastatic lesions, and prevent tumor recurrence with minimal side effects on normal tissues. In this work, we synthesized engineered cellular nanovesicles (ECNVs) with tumor-homing and immune-reprogramming functions for photoacoustic (PA) imaging-guided precision chemoimmunotherapy. M1-macrophage-derived cellular nanovesicles (CNVs) were loaded with gold nanorods (GNRs), gemcitabine (GEM), CpG ODN, and PD-L1 aptamer. The good histocompatibility and tumor-homing effect of CNVs improved drug retention in the bloodstream and led to their enrichment in tumor tissues. Furthermore, the photothermal ability of GNRs enabled PA imaging-guided drug release. GEM induced tumor immunogenic cell death (ICD), and CpG ODN promoted an immune response to the antigens released by ICD, leading to long-term specific antitumor immunity. In addition, the PD-L1 aptamer relieved the inhibitory effect of the PD1/PD-L1 checkpoint on CD8⁺ T-cells and augmented the immunotherapeutic effect. The synergistic innate and adaptive immune responses enhanced the antitumor effect of ECNVs. In summary, this nanoplatform integrates local targeted photothermal therapy with extensive progressive chemotherapy and uses ICD to reshape the immune microenvironment for tumor ablation.

Overall survival in the OlympiA phase III trial of adjuvant olaparib in patients with germline pathogenic variants in BRCA1/2 and high risk, early breast cancer

BACKGROUND

The randomized, double-blind OlympiA trial compared 1 year of the oral poly(adenosine diphosphate-ribose) polymerase inhibitor, olaparib, to matching placebo as adjuvant therapy for patients with pathogenic or likely pathogenic variants in germline BRCA1 or BRCA2 (gBRCA1/2pv) and high-risk, human epidermal growth factor receptor 2-negative, early breast cancer (EBC). The first pre-specified interim analysis (IA) previously demonstrated statistically significant improvement in invasive disease-free survival (IDFS) and distant disease-free survival (DDFS). The olaparib group had fewer deaths than the placebo group, but the difference did not reach statistical significance for overall survival (OS). We now report the pre-specified second IA of OS with updates of IDFS, DDFS, and safety.

PATIENTS AND METHODS

One thousand eight hundred and thirty-six patients were randomly assigned to olaparib or placebo following (neo)adjuvant chemotherapy, surgery, and radiation therapy if indicated. Endocrine therapy was given concurrently with study medication for hormone receptor-positive cancers. Statistical significance for OS at this IA required P < 0.015.

RESULTS

With a median follow-up of 3.5 years, the second IA of OS demonstrated significant improvement in the olaparib group relative to the placebo group [hazard ratio 0.68; 98.5% confidence interval (CI) 0.47-0.97; P = 0.009]. Four-year OS was 89.8% in the olaparib group and 86.4% in the placebo group (Δ 3.4%, 95% CI -0.1% to 6.8%). Four-year IDFS for the olaparib group versus placebo group was 82.7% versus 75.4% (Δ 7.3%, 95% CI 3.0% to 11.5%) and 4-year DDFS was 86.5% versus 79.1% (Δ 7.4%, 95% CI 3.6% to 11.3%), respectively. Subset analyses for OS, IDFS, and DDFS demonstrated benefit across major subgroups. No new safety signals were identified including no new cases of acute myeloid leukemia or myelodysplastic syndrome.

CONCLUSION

With 3.5 years of median follow-up, OlympiA demonstrates statistically significant improvement in OS with adjuvant olaparib compared with placebo for gBRCA1/2pv-associated EBC and maintained improvements in the previously reported, statistically significant endpoints of IDFS and DDFS with no new safety signals.

Tandem Synthesis of 1,2,3-Thiadiazoles with 3,4-Dichloroisothiazoles and Hydrazines under External Oxidant- and Sulfur-Free Conditions

1,2,3-Thiadiazoles are among the most important heterocyclic motifs, with wide applications in natural products and medicinal chemistry. Herein, we disclose a tandem reaction for the synthesis of structurally diverse 1,2,3-thiadiazoles from 3,4-dichloroisothiazol-5-ketones and hydrazines. This method is characterized by mild external oxidant- and sulter-free reaction conditions, a broad substrate scope, and easy purification.

Novel Fluorinated Aniline Anthranilic Diamides Improved Insecticidal Activity Targeting the Ryanodine Receptor

The diamide insecticides show exceptional activity against Lepidoptera insects via activation of ryanodine receptors (RyRs). In the present study, a series of anthranilic diamides containing a fluoroaniline moiety were designed, synthesized, and evaluated for insecticidal potency. Most titled compounds exerted moderate to remarkably high activity against Mythimna separata, Plutella xylostella, and Spodoptera frugiperda. The insecticidal activity of compound II l and II ac against M. separata was 26.7 and 26.7% at 0.1 mg L^-1, respectively, equivalent to that of chlorantraniliprole (0.1 mg L^-1, 30.0%). Compounds II l, II y, and II z exhibited 8.0-, 1.8-, and 4.7-fold higher potency than chlorantraniliprole against P. xylostella, respectively, as compared with their LC₅₀s. Compounds II k and II aa showed good insecticidal activity against S. frugiperda with LC₅₀ of 0.56 and 0.46 mg L^-1, respectively, comparable to that of the commercial insecticide chlorantraniliprole with LC₅₀ of 0.31 mg L^-1. Calcium imaging experiments indicated RyRs as the action target. Molecular docking suggested a higher binding energy of 8.647 kcal/mol between II l and the M. separata RyR than the 7.820 kcal/mol between chlorantraniliprole and the M. separata RyR. Meanwhile, the docking results of II l with mutated P. xylostella RyR at site G4946E showed that II l could have a good inhibition effect on the resistant P. xylostella. The density functional theory calculations suggested the importance of the fluoroaniline moiety in potency. Those novel anthranilic diamides containing a fluorinated aniline moiety are good insecticidal candidates.

Novel [1,2,4]-Triazolo[3,4-b]-[1,3,4]thiadizoles as Potent Pyruvate Kinase Inhibitors for Fungal Control

To discover novel target-based fungicidal candidates, a molecular design model was established with a three-dimensional (3D) structure of Rhizoctonia solani pyruvate kinase (RsPK) simulated with the AlphaFold 2 and YZK-C22 as a fungicidal lead. A series of novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives were rationally designed, synthesized, evaluated for their fungicidal performance, and validated for their mode of action. The in vitro bioassays with R. solani indicated that compounds 5g, 5o, and 5z with an EC₅₀ value ranging from 1.01 to 1.54 μg/mL displayed higher fungicidal activity than the positive control YZK-C22 with its EC₅₀ of 3.14 μg/mL. Especially, 5o exhibited high potency and a broad spectrum against Alternaria solani, Botrytis cinerea, Cercospora arachidicola, Physalospora piricola, R. solani, and Sclerotinia sclerotiorum with its EC₅₀ value falling between 1.54 and 13.10 μg/mL. Like all positive controls, 5g, 5o, and 5z showed excellent in vivo growth inhibition against Pseudoperonospora cubensis at 200 μg/mL. Even though the PK enzymatic inhibition assay showed that 5o was approximately 2.6 times less active than YZK-C22 (IC₅₀: 29.14 vs 11.15 μg/mL, respectively), the similar fluorescence quenching patterns of RsPK by 5o and YZK-C22, and the docking results of interactions between RsPK and 5o or YZK-C22 implied that they might share the similar binding site in the RsPK active pocket. Our studies suggested that 5o could be used as a potent fungicidal lead for further optimization. The results of comparative molecular field analysis (CoMFA) provided a direction for further molecular design.

Improving Insecticidal Activity of Chlorantraniliprole by Replacing the Chloropyridinyl Moiety with a Substituted Cyanophenyl Group

Insect ryanodine receptors (RyRs) are molecular targets of the anthranilic diamide insecticides. In the present study, a new series of anthranilic diamides containing a cyanophenyl pyrazole moiety were rationally designed by active-fragment assembly and computer-aided design using the 3D structure of Plutella xylostella RyRs as a receptor and chlorantraniliprole as a ligand. Most of the titled compounds showed good toxicity against Mythimna separate, P. xylostella, and Spodoptera frugiperda. Compounds CN06, CN11, and CN16 with corresponding LC₅₀ values of 0.15, 0.29, and 0.52 mg·L^-1, respectively, against M. separate showed comparable activity to that of chlorantraniliprole (0.13 mg·L^-1). Surprisingly, CN06, CN11, and CN16 with corresponding LC₅₀ values of 1.6 × 10^-5, 3.0 × 10^-5, and 2.8 × 10^-5 mg·L^-1, respectively, against P. xylostella were at least 5-fold more active than chlorantraniliprole (1.5 × 10^-4 mg·L^-1). In the case of S. frugiperda, CN06, CN11, and CN16 had good potency but lower than chlorantraniliprole in terms of LC₅₀ values (0.58, 0.54, and 0.56 mg·L^-1 versus 0.31 mg·L^-1). Molecular docking of CN06 and chlorantraniliprole to P. xylostella RyRs validated the molecular design, and the calcium imaging technique further proved the potential target of CN06 as RyRs. Compounds CN06, CN11, and CN16 could be more effective than chlorantraniliprole in targeting the resistant RyR mutants of S. frugiperda (G4891E, I4734M) through the binding mode and energy obtained by molecular docking. Density functional theory calculations (DFT) and electrostatic potential (ESP) studies gave the structure-activity relationship. Compounds CN06, CN11, and CN16 could be used as potent insecticide leads for further optimization.

Engineered extracellular vesicles and their mimetics for cancer immunotherapy

Extracellular vesicles (EVs) are heterogeneous membranous vesicles secreted by living cells that are involved in many physiological and pathological processes as intermediaries for intercellular communication and molecular transfer. Recent studies have shown that EVs can regulate the occurrence and development of tumors by transferring proteins, lipids and nucleic acids to immune cells as signaling molecules. As a new diagnostic biomarker and drug delivery system, EVs have broad application prospects in immunotherapy. In addition, the breakthrough of nanotechnology has promoted the development and exploration of engineered EVs for immune-targeted therapy. Herein, we review the uniqueness of EVs in immune regulation and the engineering strategies used for immunotherapy and highlight the logic of their design through typical examples. The present situation and challenges of clinical transformation are discussed, and the development prospects of EVs in immunotherapy are proposed. The goal of this review is to provide new insights into the design of immune-regulatory EVs and expand their application in cancer immunotherapy.

Extracellular vesicles in pancreatic cancer immune escape: Emerging roles and mechanisms

Pancreatic cancer (PC) is the most lethal malignancy worldwide due to its delayed diagnosis and limited treatment options. Despite great progress in clinical trials of immunotherapies for various cancers, their effectiveness in PC is very low, indicating that immune evasion is still a major obstacle to immunotherapy in PC. However, the mechanism of immune escape in PC is not fully understood, which substantially restricts the development of immunotherapy. As an important component of intercellular communication networks, extracellular vesicles (EVs) have attracted increasing attention in relation to immune escape. This review aims to provide a better understanding of the roles of EVs in tumor immune escape and the potential to expand their application in cancer immunotherapy. The relationship between PC and the tumor immune microenvironment is briefly introduced. Then, the mechanism by which EVs are involved in immune regulation is summarized, and the latest progress in determining the role of EVs in regulating PC immune escape is highlighted.

Engineered extracellular vesicles as intelligent nanosystems for next-generation nanomedicine

Extracellular vesicles (EVs), as natural carriers of bioactive cargo, have a unique micro/nanostructure, bioactive composition, and characteristic morphology, as well as fascinating physical, chemical and biochemical features, which have shown promising application in the treatment of a wide range of diseases. However, native EVs have limitations such as lack of or inefficient cell targeting, on-demand delivery, and therapeutic feedback. Recently, EVs have been engineered to contain an intelligent core, enabling them to (i) actively target sites of disease, (ii) respond to endogenous and/or exogenous signals, and (iii) provide treatment feedback for optimal function in the host. These advances pave the way for next-generation nanomedicine and offer promise for a revolution in drug delivery. Here, we summarise recent research on intelligent EVs and discuss the use of "intelligent core" based EV systems for the treatment of disease. We provide a critique about the construction and properties of intelligent EVs, and challenges in their commercialization. We compare the therapeutic potential of intelligent EVs to traditional nanomedicine and highlight key advantages for their clinical application. Collectively, this review aims to provide a new insight into the design of next-generation EV-based theranostic platforms for disease treatment.

Design, synthesis and fungicidal evaluation of novel psoralen derivatives containing sulfonohydrazide or acylthiourea moiety

To search a novel lead structure for antiphytopathogenic fungus agent, a series of novel psoralen derivatives possessing sulfonohydrazide or acylthiourea structure were designed and synthesized, and their fungicidal activity against seven phytopathogens was evaluated. Their structures were confirmed by melting points, ¹H NMR, ¹³C NMR and HRMS, and the typical crystal structure was determined by X-ray diffraction for validation. Preliminary fungicidal activity showed that some of the title compounds exhibited certain-to-high fungicidal activity. Compound I-13 exhibited good fungicidal activity against Botrytis cinerea, Cercospora arachidicola and Physalospora piricola with EC₅₀ values of 12.49, 13.22 and 12.12 μg/mL, respectively. Compounds II-9 and II-15 showed over 90% inhibition against B. cinerea at 50 μg/mL in vitro. In particular, II-9 exhibited significant higher fungicidal activity with a lower EC₅₀ value of 9.09 μg/mL than the positive control YZK-C22 (13.41 μg/mL). Our studies found that sulfonohydrazide or acylthiourea-containing psoralen derivatives were promising fungicide leads deserve for further study.

Plant Defense Responses to a Novel Plant Elicitor Candidate LY5-24-2

Plant elicitors enhance plant defense against pathogen attacks by inducing systemic acquired resistance (SAR) with no or low direct fungicidal activity. Here we report the synthesis of a novel plant elicitor candidate LY5-24-2 [3,4-dichloro-N-(3-chloro-5-(trifluoromethyl)pyridin-2-yl)isothiazole-5-carboxamide] and evaluation of its SAR inducing activity. Bioassays indicated that LY5-24-2 did not show significant anti-fungal activity but provided long-lasting resistance in Arabidopsis thaliana (A. thaliana) through promoting the accumulation of lignin, cellulose and pectin by 60.1%, 82.4% and 305.6%, respectively, at a concentration of 100 µM. LY5-24-2 also facilitated the closure of leaf stomata and increased the intracellular free Ca2+ by 47.8%, induced reactive oxygen species (ROS) accumulation, and inhibited the activity of ascorbate peroxidase (APX, EC 1.11.1.11) and catalase (CAT, EC 1.11.1.6) by 38.9% and 34.0%, respectively, as compared with the control at a concentration of 100 µM. LY5-24-2 induced SAR in plants and was dependent on the NPR1-mediated SA pathway by up-regulating expression of 2273 genes in A. thaliana. Meanwhile, LY5-24-2 also improved cucumber (Cucumis sativus L.) defense against Pseudoperonospora cubensis (P. cubensis) through promoting ROS accumulation and inhibiting activity of APX and CAT by 30.7% and 23.1%, respectively. Its expression of SA signaling genes CsNPR1, CsPR4 and CsPR5 was enhanced by 10.8, 5.8 and 6.6 times, respectively. These results demonstrated that LY5-24-2 is a novel elicitor candidate for plant protection via inducing SAR.

Bioactivity-Guided Synthesis Accelerates the Discovery of Evodiamine Derivatives as Potent Insecticide Candidates

Pests threaten worldwide food security by decreasing crop yields and damaging their quality. Natural product-based molecular design and structural optimization have been one of the most effective ways to innovate pesticides for integrated insect management. To continue our previous studies on the discovery of insecticidal lead, a series of evodiamine derivatives were designed, synthesized, and evaluated for their insecticidal activities. The bioassay results demonstrated that compounds Ian and Iao exhibited 90 and 80% insecticidal activities against Mythimna separata at 2.5 mg/L, respectively, which were superior to evodiamine (10% at 10 mg/L), matrine (45% at 600 mg/L), and rotenone (30% at 200 mg/L). Compounds Ian-Iap showed 90% insecticidal activities against Plutella xylostella at 1.0 mg/L, far more potent than those of evodiamine, matrine, and rotenone. Compound Ian displayed 60% insecticidal activity against Helicoverpa armigera at 5.0 mg/L, while evodiamine, matrine, and rotenone showed very poor activities. The study on the insecticidal mechanism of action by a calcium imaging experiment indicated that the insect ryanodine receptors (RyRs) could be the potential target of Ian. Furthermore, the molecular docking indicated that Ian anchored in the binding site of the RyR of P. xylostella. The above results manifested the potential of evodiamine derivatives as potent insecticide candidates.

Synthesis of potent antifungal 3,4-dichloroisothiazole-based strobilurins with both direct fungicidal activity and systemic acquired resistance

To continue our efforts to discover novel fungicide lead structures, a series of 3,4-dichloroisothiazole-based-strobilurin derivatives were synthesized and characterized. In vitro bioassay screening with 9 different plant pathogens suggested that the linker between 3,4-dichloroisothiazole and the pharmacophore played a critical role in fungicidal potency and scope. Among these, compound 2a with a cis-methoxy oxime ether as a linker was a better active compound. Further modification of 2a, 4a and 6a by replacement of carboxylic ester with a carboxamide led to the best active compound 7a in this study. In vivo bioassay screening and verification indicated that compounds 1c and 7a displayed the best efficacy against wheat white powder (Erysiphe graminis) and corn rust (Puccinia sorghi Schw). In addition, compound 7a was validated by upregulating salicylic acid (SA) signaling and reactive oxygen species (ROS)-related gene expression. A potent lead compound with a broad spectrum of fungicidal and systemic acquired resistance activity has been discovered by bridging 3,4-dichloroisothiazole and the strobilurin pharmacophore with various linkers.

Designer Functional Nanomedicine for Myocardial Repair by Regulating the Inflammatory Microenvironment

Acute myocardial infarction is a major global health problem, and the repair of damaged myocardium is still a major challenge. Myocardial injury triggers an inflammatory response: immune cells infiltrate into the myocardium while activating myofibroblasts and vascular endothelial cells, promoting tissue repair and scar formation. Fragments released by cardiomyocytes become endogenous “danger signals”, which are recognized by cardiac pattern recognition receptors, activate resident cardiac immune cells, release thrombin factors and inflammatory mediators, and trigger severe inflammatory responses. Inflammatory signaling plays an important role in the dilation and fibrosis remodeling of the infarcted heart, and is a key event driving the pathogenesis of post-infarct heart failure. At present, there is no effective way to reverse the inflammatory microenvironment in injured myocardium, so it is urgent to find new therapeutic and diagnostic strategies. Nanomedicine, the application of nanoparticles for the prevention, treatment, and imaging of disease, has produced a number of promising applications. This review discusses the treatment and challenges of myocardial injury and describes the advantages of functional nanoparticles in regulating the myocardial inflammatory microenvironment and overcoming side effects. In addition, the role of inflammatory signals in regulating the repair and remodeling of infarcted hearts is discussed, and specific therapeutic targets are identified to provide new therapeutic ideas for the treatment of myocardial injury.

Design, Synthesis, and Biological Evaluation of Novel Psoralen-Based 1,3,4-Oxadiazoles as Potent Fungicide Candidates Targeting Pyruvate Kinase

Pyruvate kinase (PK) has been considered as a promising fungicide target discovered in our previous studies. Natural compounds are important sources for discovery and development of new pesticides. To continue our ongoing studies on the discovery of novel PK-targeted fungicides, a series of novel psoralen derivatives including a 1,3,4-oxadiazole moiety were designed by a computer-aided pesticide molecular design method, synthesized, and evaluated for their fungicidal activity. The bioassay results indicated that compounds 11d, 11e, 11g, 11i, and 12a showed excellent in vitro fungicidal activity against Botrytis cinerea with EC₅₀ values of 4.8, 3.3, 6.3, 5.4, and 3.9 μg/mL, respectively. They were more active than the corresponding positive control YZK-C22 [3-(4-methyl-1,2,3-thiadiazol-5-yl)-6-(trichloromethyl)-[1,2,4]-triazolo-[3,4-b][1,3,4]-thiadiazole] (with an EC₅₀ value of 13.4 μg/mL). Compounds 11g and 11i displayed promising in vivo fungicidal activity against B. cinerea with 80 and 70% inhibition at a concentration of 200 μg/mL, respectively. They possessed much higher fungicidal activity than the positive control psoralen and comparable activity with the positive control pyrisoxazole. Enzymatic assays indicated that 11i showed good BcPK inhibition with an IC₅₀ value of 39.6 μmol/L, comparable to the positive control YZK-C22 (32.4 μmol/L). Molecular docking provided a possible binding mode of 11i in the BcPK active site. Our studies suggested that the psoralen-based 1,3,4-oxadiazole 11i could be used as a new fungicidal lead targeting PK for further structural optimization.

Methoxyacrylate Fungicide Candidate CL-15C Also Functions as a Plant Elicitor in Arabidopsis thaliana and Oryza sativa L

Unlike traditional fungicides targeting fungi, plant elicitors usually lack direct fungicidal activity but improve the plant immune system to resist fungi infection, which has gained increasing attention for better fungi resistance management and environment protection. (E)-methyl-2-(2-((((Z)-(amino-(3,4-dichloroisothiazol-5-yl)methylene)amino)oxy)methyl)phenyl)-2-(methoxyimino)acetate (CL-15C) was found to be a fungicide candidate with a broad spectrum. Here, we studied its immune-inducing ability and mechanism to strengthen the resistance of Arabidopsis thaliana against Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and Oryza sativa L. against Magnaporthe oryzae. CL-15C promoted a 2.20- and 1.47-fold increase in phenylalanine ammonia-lyase (PAL) activity in A. thaliana and O. sativa, respectively. It also facilitated a 1.89- and 1.32-fold increase in accumulation of salicylic acid (SA) in A. thaliana and O. sativa, respectively. Differential genes were clustered in the SA signaling pathway at 24 h after a CL-15C treatment in A. thaliana. Because PAL is a rate-limiting enzyme in the phenylalanine metabolic pathway, after a CL-15C treatment, a pal1(PAL 1) mutant was more susceptible to Pst DC3000 when compared with the wild type. Bacterial counts in leaves after a CL-15C treatment showed a 1.11-fold reduction in the pal1 mutant and a 1.54-fold reduction in the wild type. The effect of CL-15C on the PAL enzyme activity and SA content was attenuated in the pal1 mutant. Present experimental data implied that the immune-inducing activity of CL-15C was dependent on PAL gene-mediated synthesis of SA.

Synthesis of novel N-(2-phenyl-3-pyridyl) thiadiazole/isothiazole carboxamide analogs as potent plant elicitors

BACKGROUND

Plant elicitors are a class of plant protection agents that can stimulate plant immunity against phytopathogen without a potential resistance problem. In searching for novel plant elicitor candidates, a series of novel N-(2-phenyl-3-pyridyl) thiadiazole/isothiazole carboxamide analogs were designed and synthesized.

RESULTS

In vitro bioassay showed that all new compounds exhibited weak direct fungicidal activity. However, compounds 3b, 3g, 3n and 3o showed broad spectrum of in vivo activity against four plant fungi tested. In particularly, 3g showed 80% activity against Rhizoctonia solani in a glasshouse at a concentration of 1 μg mL-1 . For induction activity of tobacco against tobacco mosaic virus (TMV), compounds 3c and 3v showed 67% and 68% inhibitory activity, respectively, which were superior to the positive controls ribavirin and ningnanmycin. Compound 3g showed moderate induction activity (41%). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis found that, 3g could up-regulate expression of genes that are related to reactive oxygen species (ROS), pathogenesis-related protein (PRP) and salicylic acid (SA) signalling.

CONCLUSION

These results indicated that 3g as an elicitor candidate might act on the SA signalling pathway. According to our findings, N-(2-phenyl-3-pyridyl) thiadiazole/isothiazole carboxamide analogs might be promising lead scaffolds as a novel plant elicitor for further investigation.

Discovery of Novel Triazolothiadiazines as Fungicidal Leads Targeting Pyruvate Kinase

Pyruvate kinase (PK) was discovered as a potent new target for novel fungicide development. A series of novel triazolothiadiazine derivatives were rationally designed and synthesized by a ring expansion strategy and computer-aided pesticide design using the 3D structure of Rhizoctonia solani PK (RsPK) obtained by homology modeling as a receptor and our previously discovered lead YZK-C22 as a ligand. The in vitro bioassay results indicated that compounds 4g, 6h, 6m, 6n, 6o, and 6p exhibited good activity against R. solani with the EC₅₀ values falling between 10.99 and 72.76 μM. Especially, 6m showed similar potency to YZK-C22 (10.99 vs 11.97 μM of the EC₅₀ value, respectively). The in vivo bioassay results suggested that 6m against R. solani at a concentration of 200 μg/mL displayed a numerically higher inhibition than YZK-C22 (70 vs 60%, respectively). A field experiment validated that 6m at an application rate of 120 g ai/ha showed comparable efficacy against R. solani to thifluzamide at an application rate of 80 g ai/ha (77.80 vs 84.5%, respectively). Enzymatic inhibition suggested that the potency of 6m was about twofold lower than that of YZK-C22 (67.30 vs 32.64 μM of IC₅₀, respectively). Fluorescence quenching studies validated that RsPK was quenched by both 6m and YZK-C22, implying that they both might act at the same target site of PK. A possible binding conformation of 6m in the RsPK active site was depicted by molecular docking. Our studies suggest that 6m could be a fungicidal lead targeting PK.