Synthesis, Anti-Tomato Spotted Wilt Virus Activities, and Interaction Mechanisms of Novel Dithioacetal Derivatives Containing a 4(3H)-Quinazolinone Pyrimidine Ring

Quinolizidine Alkaloids and Isoflavones from the Herb of Thermopsis lupinoides and Their Antiviral, Antifungal, and Insecticidal Activities

As part of our ongoing investigation of natural bioactive substances from the genus Thermopsis of the tribe Fabaceae for agricultural protection, the chemical constituents of the herb Thermopsis lupinoides were systematically investigated, which led to the isolation of 39 quinolizidine alkaloids (QAs) (1-39), including 14 new QAs (1-14) and 14 isoflavones (40-53). Their structures were elucidated through comprehensive spectroscopic data analysis (IR, UV, NMR, HRESIMS), ECD calculations, and X-ray crystallography. The antitomato spotted wilt virus (TSWV) and antifungal (against Botrytis cinerea, Gibberella zeae, Phytophythora capsica, and Alternaria alternata) and insecticidal (against Aphis fabae and Tetranychus urticae) activities of the isolated compounds were screened using the lesion counting method, mycelial inhibition assay, and spray method, respectively. The bioassay results showed that 34 exhibited excellent protective activity against TSWV, with an EC50 value of 36.04 μg/mL, which was better than that of the positive control, ningnanmycin (86.03 μg/mL). The preliminary mechanistic exploration illustrated that 34 induced systemic acquired resistance in the host plant by acting on the salicylic acid signaling pathway. Moreover, 1 showed significant antifungal activity against B. cinerea (EC50 value of 20.83 μg/mL), while 2 exhibited good insecticidal activity against A. fabae (LC50 value of 24.97 μg/mL). This research is promising for the invention of novel pesticides from QAs with high efficiency and satisfactory ecological compatibility.

Synthesis, Antifungal, and Antibacterial Activities of Novel Benzoylurea Derivatives Containing a Pyrimidine Moiety

To explore more efficient and less toxic antibacterial and antifungal pesticides, we utilized 2,6-difluorobenzamide as a starting material and ultimately synthesized 23 novel benzoylurea derivatives containing a pyrimidine moiety. Their structures were characterized and confirmed by 1H NMR, 13C NMR, 19F NMR, and HRMS. The bioassay results demonstrated that some of the title compounds exhibited moderate to good in vitro antifungal activities against Botrytis cinerea in cucumber, Botrytis cinerea in tobacco, Botrytis cinerea in blueberry, Phomopsis sp., and Rhizoctonia solani. Notably, compounds 4j and 4l displayed EC50 values of 6.72 and 5.21 μg/mL against Rhizoctonia solani, respectively, which were comparable to that of hymexazol (6.11 μg/mL). Meanwhile, at 200 and 100 concentrations, the target compounds 4a-4w exhibited lower in vitro antibacterial activities against Xanthomonas oryzae pv. oryzicola and Xanthomonas citri subsp. citri, respectively, compared to those of thiodiazole copper. Furthermore, the molecular docking simulation demonstrated that compound 4l formed hydrogen bonds with SER-17 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 antifungal and antibacterial activities of novel benzoylurea derivatives containing a pyrimidine moiety.

Design, synthesis, computational study and cytotoxic evaluation of some new quinazoline derivatives containing pyrimidine moiety

Quinazoline derivatives, as an important category of heterocyclic compounds, have received much attention for the design and development of new drugs due to their various pharmacological properties. Besides, there is a great deal of evidence showing pyrimidine analogs as anticancer agents. Thus, in the present study, for the design of new target compounds with cytotoxic activity, we focused on various quinazolinone and pyrimidine hybrids. A new series of quinazoline-pyrimidine hybrid derivatives (6a-6n) have been designed and synthesized as novel antiproliferative agents. All the synthesized compounds characterized based on their IR, NMR and Mass spectroscopic data. Antiproliferative activities of the new compounds were evaluated against three human cancer cell lines (MCF-7, A549, SW-480). The compounds were found to have appropriate potential with IC50 values ranging from 2.3 ± 5.91 to 176.5 ± 0.7 μM against the tested cell lines. Compound 6n exerted the highest antiproliferative activity with IC50 values of 5.9 ± 1.69 μM, 2.3 ± 5.91 μM and 5.65 ± 2.33 μM against A549, SW-480 and MCF-7 respectively. The results indicated that 6n could induce apoptosis in A549 cell line in a dose dependent manner and arrest in the S phase of cell cycle. Docking studies were also done to investigate the detailed binding pattern of the synthesized compounds against EGFR. Furthermore, molecular dynamic simulation and binding free energy calculation have been done to rescore initial docking pose of the synthesized compounds using ensemble-based MMGB/PBSA free energy method. According to the results, free energy calculation confirmed biological activity of compounds and also, Arg 817 and Lys 721 residues had the pivotal role in the high potency of 6n. Finally, the drug likeness and in silico ADME study were also predicted.

Piperazine Derivatives Containing the α-Ketoamide Moiety Discovered as Potential Anti-Tomato Spotted Wilt Virus Agents

A total of 35 piperazine derivatives were designed and synthesized, and their activities against tomato spotted wilt virus (TSWV) were evaluated systematically. Compounds 34 and 35 with significant anti-TSWV activity were obtained. Their EC₅₀ values were 62.4 and 59.9 μg/mL, prominently better than the control agents ningnanmycin (113.7 μg/mL) and ribavirin (591.1 μg/mL). To explore the mechanism of the interaction between these compounds and the virus, we demonstrated by agrobacterium-mediated, molecular docking, and microscale thermophoresis (MST) experimental methods that compounds 34 and 35 could inhibit the infection of TSWV by binding with the N protein to prevent the assembly of the virus core structure ribonucleoprotein (RNP), and it also meant that the arginine at 94 of the N protein was the key site of interaction between the compounds and the TSWV N target. Therefore, this study demonstrated the potential for forming antiviral agents from piperazine derivatives containing α-ketoamide moieties.

Matrine-Type Alkaloids with Anti-Tomato Spotted Wilt Virus Activity from the Root of Sophora tonkinensis Gagnep

As a continuation of our research on the development of pesticide active quinolizidine alkaloids (QAs) from the family Fabaceae, the chemical constituents of the root of Sophora tonkinensis Gagnep. were systematically investigated. Seventeen new matrine-type alkaloids (1-17), including one new naturally occurring compound (17), along with 20 known ones were isolated from the EtOH extract of S. tonkinensis. Notably, compound 5 possessed an unprecedented 6/6/5/4/6/6 hexacyclic system. Their structures were confirmed via comprehensive spectroscopic data analysis (IR, UV, NMR, HRESIMS), ECD calculation, and X-ray crystallography. Biological tests indicated that compounds 1, 4, 10, 12, 13, and 30 displayed significant anti-tomato spotted wilt virus (TSWV) activities compared with the positive control ningnanmycin. Moreover, compound 12 strongly inhibited the expression of the TSWV N, NSs, and NSm genes and TSWV NSs protein in plant host. Furthermore, compounds 4, 10, 12, 20, and 22 exhibited moderate insecticidal activities against TSWV thrip vector (Frankliniella occidentalis).

Recent Achievements in Antiviral Agent Development for Plant Protection

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

Design, synthesis, antiviral activity, and mechanisms of novel ferulic acid derivatives containing amide moiety

To explore the novel compounds with high antiviral activity, three series ferulic acid derivatives containing amide moiety were gradually designed and synthesized based on antiviral activity tracking. The bioassay results exhibited that some target compounds had notable antiviral activities against tomato spotted wilt virus (TSWV) and cucumber mosaic virus (CMV). Compounds Y1, Y2, Y8, Z1 and Z2 presented splendid curative, protective, and inactivating activities to TSWV and CMV at 500 μg/mL. Especially, these compounds displayed outstanding inactivating effects on TSWV with the EC₅₀ values of 225.9, 126.1, 224.6, 216.1, and 147.3 μg/mL, which were superior to ningnanmycin (249.1 μg/mL) and ribavirin (315.7 μg/mL). Furthermore, the antiviral mechanisms of compound Y2 were investigated by conducting microscale thermophoresis experiment and molecular docking experiment. The results suggested that compound Y2 performed excellent binding affinity to TSWV coat protein (TSWV CP) with the binding constant of 2.14 μM, which due to two strong hydrogen bonds of compound Y2 to the key amino acids ARG94 of TSWV CP. Therefore, compound Y2 can be regarded as a leading structure for development of the potential antiviral agent.

Synthesis, Anti-Potato Virus Y Activities, and Interaction Mechanisms of Novel Quinoxaline Derivatives Bearing Dithioacetal Moiety

Quinoxaline and its derivatives are important functional molecules with a broad range of applications. Disclosed here is a design and synthesis of a series of novel quinoxaline derivatives containing dithioacetal moieties as well as their antiviral activities against potato virus Y (PVY). The compound D30 was developed on the basis of the three-dimensional quantitative structure-activity relationship. The anti-PVY activity test showed that the half maximal effective concentration of the anti-PVY protective activity of compound D30 is 197 μg/mL, which was better than the control agents ningnanmycin (423 μg/mL) and xiangcaoliusuobingmi (281 μg/mL). Significantly, compound D30 can increase defense enzyme activity and chlorophyll content, promote photosynthesis by accelerating carbon fixation in tobacco, and further improve plant disease resistance. All of these results suggest that compound D30 could be employed as a lead compound for novel PVY inhibitor discovery.

Design, Synthesis, Anti-Tomato Spotted Wilt Virus Activity, and Mechanism of Action of Thienopyrimidine-Containing Dithioacetal Derivatives

Currently, there is insufficient viricide to effectively control tomato spotted wilt virus (TSWV). To address this pending issue, a series of thienopyrimidine-containing dithioacetal derivatives were prepared and tested for their anti-TSWV activities. A subsequent three-dimensional quantitative structure-activity relationship was constructed to indicate the development of optimal compound 35. The obtained compound 35 had excellent anti-TSWV curative, protective, and inactivating activities (63.0, 56.6, and 74.1%, respectively), and the EC₅₀ values of protective and inactivating activities of compound 35 were 252.8 and 113.5 mg/L, respectively, better than those of ningnanmycin (284.8 and 144.7 mg/L) and xiangcaoliusuobingmi (624.9 and 300.0 mg/L). In addition, the anti-TSWV activity of compound 35 was associated with defense-related enzyme activities, enhanced photosynthesis, and reduced stress response, thereby enhancing disease resistance.