Synthesis, Antifungal Evaluation, 3D-QSAR, and Preliminarily Mechanism Study of Novel Chiral Mandelic Acid Derivatives

Design and development of pyrazol-5-ylbenzamide derivatives containing chiral oxazoline moiety as fungicides based on molecular docking

BACKGROUND

Development of novel chiral antifungal agents for effective control of plant pathogens is urgently needed. In this study, a series of pyrazol-5-yl-benzamide derivatives containing chiral oxazoline moiety were rationally designed and developed based on molecular docking.

RESULTS

The in vitro antifungal assay results indicated that compounds (rac)-4h (R1 = Et), (S)-4 h (R1 = S-Et) and (R)-4 h (R1 = R-Et) exhibited remarkable antifungal activities against Valsa mali with median effective concentration (EC50) values of 0.24, 0.06 and 1.08 mg/L, respectively. Preliminary structure-activity relationships (SARs) revealed that the modification of the chiral substituent group at the oxazoline moiety significantly affected the antifungal activities of the target compounds. Furthermore, compounds (S)-4h (87.5%) and (R)-4h (84.3%) exhibited in vivo protective activities comparable to tebuconazole (87.5%) against V. mali. Subsequent molecular docking analysis, succinate dehydrogenase (SDH) enzyme inhibition assays and molecular dynamic (MD) simulations verified that the potential target enzyme of this class of derivatives could be SDH and helped to explain the large difference in antifungal activities of compounds (S)-4h and (R)-4h. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) observations confirmed that these two compounds severely disrupted the mycelial morphology of V. mali. Theoretical calculation studies provided some insight into the subsequent modification of such pyrazol-5-yl-benzamide derivatives. Resistance frequency studies showed that (S)-4h and (R)-4h treatments were less likely to produce resistant fungal strains than tebuconazole. Meanwhile, compounds (S)-4h and (R)-4h exhibited no apparent toxicity to the Apis mellifera L.

POPULATION

CONCLUSION

Therefore, these derivatives are potential candidates for the development of novel chiral fungicides for crop protection. © 2025 Society of Chemical Industry.

The Osteogenic Potential of Oligopeptides Derived from Black Bean: Insights into Structure-Activity Relationship

Food-derived oligopeptides have emerged as promising natural candidates for antiosteoporosis therapy due to their remarkable osteogenic activity. However, the structure-osteogenic activity relationship of these oligopeptides remains poorly defined. In this study, we investigated for the first time the correlation between the structural characteristics and osteogenic effects of black bean-derived oligopeptides. Among the 70 oligopeptides analyzed, 36, 29, and 30 oligopeptides were found to significantly enhance the proliferation (108.28%-136.78%), differentiation (115.02%-182.41%), and mineralization (110.91%-159.41%) of MC3T3-E1 cells, respectively. Notably, tetrapeptides demonstrated marked efficacy in inducing osteogenesis in vitro, with their mineralization activity significantly correlated with their isoelectric point (pI) values and net charge. Tetrapeptides containing lysine residues, such as KIGT and KGVG, were particularly effective in stimulating osteogenic mineralization. Furthermore, reliable three-dimensional quantitative structure-activity relationship (3D-QSAR) models were successfully established for all of the tetrapeptides. Importantly, the potent osteogenic tetrapeptides were characterized by bulky, electropositive, or hydrogen-bond acceptor groups at the R1 side chain of the N-terminal, along with electronegative or non-hydrogen bond acceptor groups at the R3 position and electronegative or hydrogen-bond acceptor groups at the R4 side chain of the C-terminal. Additionally, network pharmacology analysis highlighted the potential application of these osteogenic tetrapeptides in osteoporosis interventions. In conclusion, our findings demonstrated that the osteogenic activity of black bean-derived oligopeptides is attributed to their specific amino acid composition and structural features, providing novel insights for the efficient discovery and optimization of food-derived osteogenic oligopeptides.

Novel furazanoazepines derivatives as SDH inhibitors: Design, synthesis and their fungicidal activities

Plant pathogenic fungi are the damage causes of agriculture and food losses, and novel fungicides is an urgent need for dealing with the increasing resistance. Herein, 37 furazanoazepines derivatives were efficiently synthesized and their antifungal activities against four phytopathogenic fungi were investigated to obtain many effective compounds. Notably, compound 4h was found to exhibited excellent in vitro and in vivo activity against Alternaria alternata, which was obviously better than the positive control osthole. The scanning electron microscopy (SEM) study revealed that compound 4h could cause significant morphological damage of hyphae. Molecular docking indicated that compound 4h could interact with succinate dehydrogenase (SDH) by forming hydrogen bond with the Leu305 residue at the active site. Enzymatic activity assays proved that the compound 4h could inhibit SDH with the IC50 value of 3.59 μg/mL, which was better than that of commercial SDHI boscalid (IC50 value = 4.16 μg/mL). The structure-activity relationships of the compounds were studied by 3D-QSAR analysis to provide guidance for the further modification. It was concluded that furazanoazepines were promising for the further study to explore the potential agricultural fungicides.

Synergistic Enhancing of Biological Activity and Natural Light Self-Degradation of Organic-Inorganic Hybrid Nano-organometallic Pesticide-Fused Phenylpyrazole Amine Derivatives with Hollow Box TiO2 by One-pot Microwave Synthesis

Nano-TiO2 as an antimicrobial inorganic material, can stimulate cells to produce reactive oxygen species and exhibit effective biochemical properties; however, phenylpyrazole derivatives, as organic pesticides, are widely used in agriculture and food. To find novel pesticides with environmental friendliness, combined with three-dimensional quantitative structure-activity relationship (3D-QSAR) prediction analysis, three types of alkaloidal phenylpyrazole amine derivatives (PA) were synthesized by a one-pot microwave method. Based on the dye sensitization strategy, four nano-organometallic pesticides (PT) were prepared by organic-inorganic hybridization. PA and PT showed 2.5 and 5.2 times higher insecticidal activity against P. xylostella than fipronil, and PT had 3.9 times greater antibacterial activity against A. tumefaciens. The synergistic effect realizes the balance of amphiphilicity, enhances the biological activity of PT, improves the phloem fluidity, and promotes the absorption and transportation of substances. In addition, this synergistic effect reduces the band gap width, improves the light absorption capacity, induces cells to produce active reactive oxygen species and free radicals (ROS: ·O2-, ·OH), and destroys the cytomembrane so that PT can better enter the cell, resulting in cell death. PT has excellent natural light self-degradation performance and converts to the phenylpyrazole parent moiety, which enhances biological activity and greatly reduces the environmental residues, implying that nano-organometallic pesticide (PT) provides a new idea for its natural degradation and fluorescence detection of pesticide residues.

Rational design and discovery of novel hydrazide derivatives as potent succinate dehydrogenase inhibitors inspired by natural d/l-camphor

BACKGROUND

Succinate dehydrogenase inhibitors (SDHIs) have rapidly become one of the fastest-growing categories of fungicides used against plant pathogenic fungi. Recent research advancements have emphasized that structural modifications of SDHIs using naturally sourced scaffolds represent an innovative strategy for developing new, highly effective, broad-spectrum fungicides. A novel series of d/l-camphorhydrazide derivatives potentially targeting fungal succinate dehydrogenase (SDH) were designed, synthesized and evaluated for their antifungal effects against Rhizoctonia solani, Fusarium graminearum, Valsa mali and Botrytis cinerea.

RESULTS

Amongst them, compounds A1-7 (d-camphor) and A2-7 (l-camphor) displayed excellent in vitro activity against R. solani with median effective concentration (EC50) values of 0.38 and 0.48 μg mL-1, which were obviously superior to that of boscalid (0.87 μg mL-1). A2-5 (l-camphor, EC50 = 3.27 μg mL-1) exhibited good activity against V. mali. A2-7 (2.13 μg mL-1), A2-21 (5.2 μg mL-1) and A1-5 (5.15 μg mL-1) showed good antifungal activity against F. graminearum with EC50 values below that of boscalid (5.85 μg mL-1). Preliminary mechanistic studies, using scanning and transmission electron microscopy, indicated that compound A1-7 induced disordered entanglement of hyphae, shrinkage of hyphal surfaces, and vacuole swelling and rupture, which disrupted normal hyphal growth. Additionally, compound A1-7 induced the production and accumulation of reactive oxygen species, disrupted mitochondrial membrane potential, and effectively inhibited the germination and formation of sclerotia in R. solani. Moreover, the molecular docking results and SDH enzyme assays yielded promising outcomes.

CONCLUSION

In this study, the designed and optimized compounds A1-7 and A2-7 emerged as promising candidates for SDH-targeting fungicides, demonstrating strong antifungal activity. These compounds hold potential as new antifungal agents for further research. © 2024 Society of Chemical Industry.

Novel mandelic acid derivatives containing piperazinyls as potential candidate fungicides against Monilinia fructicola: Design, synthesis and mechanism study

Brown rot of stone fruit, a disease caused by the ascomycete fungus Monilinia fructicola, has caused significant losses to the agricultural industry. In order to explore and discover potential fungicides against M. fructicola, thirty-one novel mandelic acid derivatives containing piperazine moieties were designed and synthesized based on the amide skeleton. Among them, target compound Z31 exhibited obvious in vitro antifungal activity with the EC50 value of 11.8 mg/L, and significant effects for the postharvest pears (79.4 % protective activity and 70.5 % curative activity) at a concentration of 200 mg/L. Antifungal activity for the target compounds was found to be significantly improved by the large steric hindrance of the R1 groups and the electronegative of the piperazines in the molecular structure, according to a three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis. Further mechanism studies have demonstrated that the compound Z31 can disrupt cell membrane integrity, resulting in increased membrane permeability, release of intracellular electrolytes, and affect the normal growth of hyphae. Additional, morphological study also indicated that Z31 may disrupt the integrity of the membrane by inducing generate excess endogenous reactive oxygen species (ROS) and resulting in the peroxidation of cellular lipids, which was further verified by the detection of malondialdehyde (MDA) content. These studies have provided the basis for the creation of novel fungicides to prevent brown rot in stone fruits.

Design, Synthesis and Antifungal Activity of Nootkatone Derivatives Containing Acylhydrazone and Oxime Ester

In an attempt to search for new natural products-based antifungal agents, fifty-three nootkatone derivatives were designed, synthesized, and evaluated for their antifungal activity against Phytophthora parasitica var nicotianae, Fusarium oxysporum, Fusarium graminearum and Phomopsis sp. by the mycelium growth rate method. Nootkatone derivatives N17 exhibited good inhibitory activity against Phomopsis. sp. with EC50 values of 2.02 μM. The control effect of N17 against Phomopsis. sp. on kiwifruit showed that N17 exhibited a good curative effect in reducing kiwifruit rot at the concentration of 202 μM(100×EC50 ), with the curative effect of 41.11 %, which was better than commercial control of pyrimethanil at the concentration of 13437 μM(100×EC50 ) with the curative effect of 38.65 %. Phomopsis. sp. mycelium treated with N17 showed irregular surface collapse and shrinkage, and the cell membrane crinkled irregularly, vacuoles expanded significantly, mitochondria contracted, and organelles partially swollen by the SEM and TEM detected. Preliminary pharmacological experiments show that N17 exerted antifungal effects by altering release of cellular contents, and altering cell membrane permeability and integrity. The cytotoxicity test demonstrated that N17 showed almost no toxicity to K562 cells. The presented results implied that N17 may be as a potential antifungal agents for developing more efficient fungicides to control Phomopsis sp.

Discovery of Novel Compounds for Combating Rising Severity of Plant Diseases Caused by Fungi and Viruses

In recent years, the severity of plant diseases caused by plant pathogenic fungi and viruses has been on the rise. However, there is a limited availability of pesticide chemicals in the market for effectively controlling both fungal and viral infections. To solve this problem, a series of novel pyrimidine derivatives containing a 1,3,4-oxadiazole thioether fragment were synthesized. Among them, compound 6s exhibited remarkable in vivo protection activity against tobacco mosaic virus, demonstrating the superior 50% effective concentration (EC50) value of 0.42 μM, outperforming ningnanmycin (0.60 μM). Meanwhile, compound 6s exhibited remarkable antifungal activity against Botrytis cinerea Pers. in postharvest blueberry in vitro, with an EC50 value of 0.011 μM, surpassing the inhibition rate of Pyrimethanil (0.262 μM). Additionally, compound 6s also demonstrated remarkable curative and protection activities against blueberry fruit gray mold in vivo, with control efficiencies of 54.2 and 60.4% at 200 μg/mL concentration, respectively, which were comparable to those of Pyrimethanil (49.3 and 63.9%, respectively). Scanning electron microscopy showed that the compound 6s-treated hyphae of B. cinerea Pers. in postharvest blueberry became abnormally collapsed and shriveled. Furthermore, the molecular docking simulation demonstrated that compound 6s formed hydrogen bonds with SER-17, ARG-43, and SER-39 of succinate dehydrogenase (SDH), providing a possible explanation for the mechanism of action between the target compounds and SDH. This study represents the first report on the antiviral and antifungal activities of novel pyrimidine derivatives containing a 1,3,4-oxadiazole thioether fragment.

Effects of 2-Phenylethanol on Controlling the Development of Fusarium graminearum in Wheat

Applying plant-derived fungicides is a safe and sustainable way to control wheat scab. In this study, volatile organic compounds (VOCs) of wheat cultivars with and without the resistance gene Fhb1 were analyzed by GC-MS, and 2-phenylethanol was screened out. The biocontrol function of 2-phenylethanol on Fusarium graminearum was evaluated in vitro and in vivo. Metabolomics analysis indicated that 2-phenylethanol altered the amino acid pathways of F. graminearum, affecting its normal life activities. Under SEM and TEM observation, the mycelial morphology changed, and the integrity of the cell membrane was destroyed. Furthermore, 2-phenylethanol could inhibit the production of mycotoxins (DON, 3-ADON, 15-ADON) by F. graminearum and reduce grain contamination. This research provides new ideas for green prevention and control of wheat FHB in the field.