Compounds A9 Research Articles

GPX4 allosteric activators inhibit ferroptosis and exert myocardial protection in doxorubicin-induced myocardial injury mouse model

Ferroptosis is a unique type of non-apoptotic form of cell death characterized by increased lipid hydroperoxide levels. It has relevance for a number of pathological conditions including multiple organ injuries and degenerative diseases. GPX4 plays an important role in ferroptosis by repairing lipid hydroperoxides. Based on the reported allosteric sites, we obtained the GPX4 allosteric activator hit compound A9 through virtual screening. A9 can bind to GPX4 and prevent RSL3-induced lipid peroxidation production in HT-1080 cells. In addition, A9 can specifically rescue erastin-induced cell death. Further chemical modification and structure-activity relationship studies afforded the optimized compound C3. C3 showed the activity of alleviating myocardial injury in the doxorubicin-induced myocardial injury mouse model. This study demonstrated that inhibiting ferroptosis by activating GPX4 is expected to be a potential solution to treat myocardial injury.

Designing Chromane Derivatives as α2A-Adrenoceptor Selective Agonists via Conformation Constraint.

Enhancing the selectivity of alpha2-adrenoceptor (α2A-AR) agonists remains an unresolved issue. Herein, we reported the design of an α2A-AR agonist using the conformation constraint method, beginning with medetomidine. The structure-activity relationship indicated that the 8-substituent of chromane derivatives exerted the most pronounced effect on α2A-AR agonistic activity. Compounds A9 and B9 were identified as the most promising, exhibiting EC50 values of 0.78 and 0.23 nM, respectively. Their selectivity indexes surpassed dexmedetomidine (DMED) by 10-80 fold. In vivo studies demonstrated that both A9 and B9 dose-dependently increased the loss of righting reflex in mice, with ED50 values of 1.54 and 0.138 mg/kg, respectively. Binding mode calculations and mutation studies suggested the indispensability of the hydrogen bond between ASP1283.32 and α2A-AR agonist. In particular, A9 and B9 showed no dual reverse pharmacological effect, a characteristic exhibited by DMED in α2A-AR activation.

Novel 2-pyridone Analogs with Anti-cancer Activity: Synthesis, In silico, and In vitro Evaluation

Background: 2-pyridone is frequently used to synthesize and develop new bioactive molecules approved for treating many diseases. The produced compounds play a significant role in inhibiting cancer growth. Objectives: Through a molecular docking investigation, we determined the binding affinity of 2-pyridone compounds with the Matrix Metalloproteinase receptor, which allowed us to develop, produce, and test the in vitro anticancer efficacy of those compounds. Method: 2-pyridones (A1-A12) were synthesized in a multistep process, followed by spectrum analysis to confirm the structure. In silico screening of the synthesized compounds was carried out with the assistance of AutoDock software. Flow cytometry was used on the HT-29 colon cancer cell line to measure A1-A12’s anticancer effect in a lab setting. Results: The enzyme matrix metalloproteinase receptor and A1-A12 interacted unexpectedly during a docking study (MMP3, MMP9 & MMP13). Research has shown a strong affinity for MMP3 receptors for A9, A10, A11, A12, and A4, respectively. Further flow cytometric testing revealed compound A9 (R1) to be highly cytotoxic, with an IC50 value of 20.77 M. The anticancer activity of A9 (R1) against HT-29 colon cancer cell lines was also confirmed by in vitro results. Conclusion: These findings suggested that 2-pyridone compounds have promising therapeutic potential for cancer treatment, and more research on these lead moieties would be advantageous to discovering an effective anticancer drug.

Discovery of novel amide derivatives as potent quorum sensing inhibitors of Pseudomonas aeruginosa

With the increasing reports of antibiotic resistance in this species, Pseudomonas aeruginosa is a common human pathogen with important implications for public health. Bacterial quorum sensing (QS) systems are potentially broad and versatile targets for developing new antimicrobial compounds. While previous reports have demonstrated that certain amide compounds can inhibit bacterial growth, there are few reports on the specific inhibitory effects of these compounds on bacterial quorum sensing systems. In this study, thirty-one amide derivatives were synthesized. The results of the biological activity assessment indicated that A9 and B6 could significantly inhibit the expression of lasB, rhlA, and pqsA, effectively reducing several virulence factors regulated by the QS systems of PAO1. Additionally, compound A9 attenuated the pathogenicity of PAO1 to Galleria mellonella larvae. Meanwhile, RT-qPCR, SPR, and molecular docking studies were conducted to explore the mechanism of these compounds, which suggests that compound A9 inhibited the QS systems by binding with LasR and PqsR, especially PqsR. In conclusion, amide derivatives A9 and B6 exhibit promising potential for further development as novel QS inhibitors in P. aeruginosa.

Green synthesis and anti-tumor efficacy via inducing pyroptosis of novel 1H-benzo[e]indole-2(3H)-one spirocyclic derivatives

Pyroptosis induction is anticipated to be a new approach to developing anti-tumor medications. A novel class of spirocyclic compounds was designed by hybridization of 1H-Benzo[e]indole-2(3H)-one with 1,4-dihydroquinoline and synthesized through a new green “one-pot” synthesis method using 10 wt% SDS/H2O as a solvent to screen novel tumor cell pyroptosis inducers. The anti-tumor activity of all compounds in vitro was determined by the MTT method, and a fraction of the compounds showed good cell growth inhibitory activity. The quantitative structure–activity relationship models of the compounds were established by artificial intelligence random forest algorithm (R2 = 0.9656 and 0.9747). The ideal compound A9 could, in a concentration-dependent manner, prevent ovarian cancer cells from forming colonies, migrating, and invading. Furthermore, A9 could significantly induce pyroptosis and upregulate the expression of pyroptosis-related proteins GSDME-N, in addition to inducing apoptosis and mediating the expression of apoptosis-related proteins in ovarian cancer cells. A9 (5 mg/kg) significantly reduced tumor volume and weight of ovarian cancer in vivo, decreased caspase-3 expression in tumor tissue, and induced the production of GSDME-N. This study provides a green and efficient atom-economic synthesis method for 1H-Benzo[e]indole-2(3H)-one spirocyclic derivatives and a promising pyroptosis inducer with anti-tumor activity.

Development of chalcone-like derivatives and their biological and mechanistic investigations as novel influenza nuclear export inhibitors

Concerning the emergence of resistance to current anti-influenza drugs, our previous phenotypic-based screening study identified the compound A9 as a promising lead compound. This chalcone analog, containing a 2,6-dimethoxyphenyl moiety, exhibited significant inhibitory activity against oseltamivir-resistant strains (H1N1 pdm09), with an EC50 value of 1.34 μM. However, it also displayed notable cytotoxicity, with a CC50 value of 41.46 μM. Therefore, compound A9 was selected as a prototype structure for further structural optimization in this study. Initially, it was confirmed that the substituting the α,β-unsaturated ketone with pent-1,4-diene-3-one as a linker group significantly reduced the cytotoxicity of the final compounds. Subsequently, the penta-1,4-dien-3-one group was utilized as a privileged fragment for further structural optimization. Following two subsequent rounds of optimizations, we identified compound IIB-2, which contains a 2,6-dimethoxyphenyl- and 1,4-pentadiene-3-one moieties. This compound exhibited inhibitory effects on oseltamivir-resistant strains comparable to its precursor (compound A9), while demonstrating reduced toxicity (CC50 > 100 μM). Furthermore, we investigated its mechanism of action against anti-influenza virus through immunofluorescence, Western blot, and surface plasmon resonance (SPR) experiments. The results revealed that compound IIB-2 can impede virus proliferation by blocking the export of influenza virus nucleoprotein. Thusly, our findings further emphasize influenza nuclear export as a viable target for designing novel chalcone-like derivatives with potential inhibitory properties that could be explored in future lead optimization studies.

Synthesis and Screening of Chemical Agents Targeting Viral Protein Genome-Linked Protein of Telosma Mosaic Virus.

The viral protein genome-linked protein (VPg) of telosma mosaic virus (TeMV) plays an important role in viral reproduction. In this study, the expression conditions of TeMV VPg were explored. A series of novel benzenesulfonamide derivatives were synthesized. The binding sites of the target compounds and TeMV VPg were studied by molecular docking, and the interaction was verified by microscale thermophoresis. The study revealed that the optimal expression conditions for TeMV VPg were in Escherichia coli Rosetta with IPTG concentration of 0.8 mM and induction temperature of 25 °C. Compounds A4, A6, A9, A16, and A17 exhibited excellent binding affinity to TeMV VPg, with Kd values of 0.23, 0.034, 0.19, 0.086, and 0.22 μM, respectively. LYS 121 is the key amino acid site. Compounds A9 inhibited the expression of TeMV VPg in Nicotiana benthamiana. The results suggested that TeMV VPg is a potential antiviral target to screen anti-TeMV compounds.

Discovery of novel 3-(piperazin-1-yl)propan-2-ol decorated carbazole derivatives as new membrane-targeting antibacterial agents

The increasing resistance problems of pathogens have drastically reduced the efficiency of existing drugs and agricultural chemicals, increasing the difficulty of preventing and controlling bacterial diseases. To create effective bactericide alternatives, a series of novel 3-(piperazin-1-yl)propan-2-ol decorated carbazole derivatives was fabricated, and their bioactivities and drug-likeness properties were evaluated. The in vitro bioassays showed that target molecules had outstanding antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and Pseudomonas syringae pv. actinidiae (Psa), with optimal EC50 values of 6.80 μg/mL (A9), 6.37 μg/mL (A9), and 10.75 μg/mL (A10), respectively. Furthermore, a series of biochemical assays indicated that title molecules could negatively impact the function of bacteria by irreversibly damaging their cell membranes, resulting in cytoplasmic components leakage (nucleic acids and proteins). In addition, phytotoxicity test and in silico toxicity predictions suggested that compound A9 had low phytotoxicity, and possessed acceptable drug-like properties. Our results showed that carbazole derivatives containing an 3-(piperazin-1-yl)propan-2-ol moiety were promising skeletons to develop novel bactericides with low toxicity for controlling refractory microbial diseases by targeting cell membranes.

One pot synthesis of 1,3,4-oxadiazoles by Lewis acid catalyst and their study of 2D-QSAR, antimicrobial and anti-tubercular activities

In the present work, Lewis acid catalyzed reactions have been carried out between mefenamic acid, substituted aldehyde and semicarbazide in the presence of ZnCl2 to give the final compounds (E)-N-(2-(5-((substitutedene)amino)-1,3,4-oxadiazol-2-yl)phenyl)-2,3-dimethylaniline, A. The synthesized compounds have been characterized by IR, 1H NMR, 13C NMR, mass spectral studies and biologically screened for the antimicrobial, antitubercular and antimalarial activities. Among the screened molecules, the molecules A1, A3, A4, A6, A8, A9, A10 show activity against different antibacterial species. The compounds, active against different antifugal species are A3, A7, A8, A9 against C. albicans, compound A3 is active against A. niger. Whereas, compound A9 shows good antimycobacterial activity. Compound A6 having 4-hydroxybenzenesubstituent exhibits promising activity against P. falciparum antimalerial parasite.

Design and synthesis of mogrol derivatives modified on a ring with anti-inflammatory and anti-proliferative activities

A class of novel mogrol derivatives modified on A ring were synthesized. The screening result showed that indole-fused derivatives exhibited lower toxicity and better anti-inflammatory activity in LPS-induced RAW 264.7 cells model than mogrol and other compounds. Derivative B8 exerted superior inhibitory result of NO production (IC50 = 5.05 μM) and inhibitory ability of TNF-α and IL-6 secretion to mogrol through iNOS/NF-κB pathway. Besides, the CCK8 assay was performed to evaluate their anti-proliferative activity against non-small cell lung cancer including A549, NCI-H460, H1299 and H1975 cells. Compared with mogrol, compound B8 showed moderate anti-proliferative activities against A549 and H1975 cells, while derivatives bearing α, β-unsaturated ketone scaffold displayed broad-spectrum growth inhibition against four cell lines. Among them, compound A9 showed 12-fold higher activity than mogrol against H1299 and H1975 cells. The suppressive effect on expression level of p-p65 might account for the compound A9-induced growth inhibition and cell cycle arrest at G1 phase.

In-silico DESIGN, SYNTHESIS, AND ANTIBACTERIAL EVALUATION OF NOVEL TRIPHENYL-SUBSTITUTED IMIDAZOLES

In an effort towards the discovery of new chemical entities to combat antimicrobial resistance, a series of novel 2,4,5- triphenyl imidazole derivatives were designed to target lanosterol 14α demethylase to screen the molecules for their antimicrobial potential. The designed molecules were synthesized and characterized by MS, FTIR, and NMR. The compounds were screened for their antimicrobial properties at a concentration of 100 µg/ml against Escherichia coli, Bacillus subtilis, and Aspergillus Niger. Compounds A9, B9, C9, and D9 were found to be active against Escherichia coli at the tested concentration. Computational studies including XP docking, induced fit docking, and MMGBSA were performed to assess their ability to bind at the active site.

Synthesis of Novel Antiviral Ferulic Acid-Eugenol and Isoeugenol Hybrids Using Various Link Reactions.

To develop novel antiviral agents, some novel conjugates between ferulic acid and eugenol or isoeugenol were designed and synthesized by the link reaction. The antiviral activities of compounds were evaluated using the half leaf dead spot method. Bioassay results showed acceptable antiviral activities of some conjugates against the tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV). Compounds A9, A10, E1, and E4 showed remarkable curative, protective, and inactivating effects on TMV and CMV at 500 μg mL-1. Notably, these compounds exhibited excellent protective effects on TMV and CMV. The EC50 values of compounds A9, A10, E1, and E4 against TMV were 180.5, 169.5, 211.4, and 135.5 μg mL-1, respectively, and those against CMV were 210.5, 239.1, 218.4, and 178.6 μg mL-1, respectively, which were superior to those of ferulic acid (471.5 and 489.2 μg mL-1), eugenol (456.3 and 463.2 μg mL-1), isoeugenol (478.4 and 487.5 μg mL-1), and ningnanmycin (246.5 and 286.6 μg mL-1). Then, the antiviral mechanisms of compound E4 were investigated by determining defensive enzyme activities and multi-omics analysis. The results indicated that compound E4 resisted the virus infection by enhancing defensive responses via inducing the accumulation of secondary metabolites from the phenylpropanoid biosynthesis pathway in tobacco.

Discovery of Novel Small-Molecule Inhibitors of PD-1/PD-L1 Interaction via Structural Simplification Strategy.

Blockade of the programmed cell death 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) interaction is currently the focus in the field of cancer immunotherapy, and so far, several monoclonal antibodies (mAbs) have achieved encouraging outcomes in cancer treatment. Despite this achievement, mAbs-based therapies are struggling with limitations including poor tissue and tumor penetration, long half-life time, poor oral bioavailability, and expensive production costs, which prompted a shift towards the development of the small-molecule inhibitors of PD-1/PD-L1 pathways. Even though many small-molecule inhibitors targeting PD-1/PD-L1 interaction have been reported, their development lags behind the corresponding mAb, partly due to the challenges of developing drug-like small molecules. Herein, we report the discovery of a series of novel inhibitors targeting PD-1/PD-L1 interaction via structural simplification strategy by using BMS-1058 as a starting point. Among them, compound A9 stands out as the most promising candidate with excellent PD-L1 inhibitory activity (IC50 = 0.93 nM, LE = 0.43) and high binding affinity to hPD-L1 (KD = 3.64 nM, LE = 0.40). Furthermore, A9 can significantly promote the production of IFN-γ in a dose-dependent manner by rescuing PD-L1 mediated T-cell inhibition in Hep3B/OS-8/hPD-L1 and CD3-positive T cells co-culture assay. Taken together, these results suggest that A9 is a promising inhibitor of PD-1/PD-L1 interaction and is worthy for further study.

The design, synthesis and anti-tumor mechanism study of new androgen receptor degrader

Targeted protein degradation using small molecules is a novel strategy for drug development. In order to solve the problem of drug resistance in the treatment of prostate cancer, proteolysis-targeting chimeras (PROTAC) was introduced into the design of anti-prostate cancer derivatives. In this work, we synthesized two series of selective androgen receptor degraders (SARDs) containing the hydrophobic degrons with different linker, and then investigated the structure-activity relationships of these hybrid compounds. Most of the synthesized compounds exhibited moderate to good activity against all the cancer cell lines selected. Among them, compound A9 displayed potent inhibitory activity against LNCaP prostate cancer cell line with IC50 values of 1.75 μM, as well as excellent AR degradation activity. Primary mechanism studies elucidated compound A9 arrested cell cycle at G0/G1 phase and induced a mild apoptotic response in LNCaP cells. Further study indicated that the degradation of AR was mediated through proteasome-mediated process. For all these reasons, compound A9 held promising potential as anti-proliferative agent for the development of highly efficient SARDs for drug-resistance prostate cancer therapies.

Synthesis and Biological Evaluation of HDAC Inhibitors With a Novel Zinc Binding Group

Vorinostat (SAHA) with great therapeutic potential has been approved by the FDA for the treatment of cutaneous T-cell lymphoma as the first HDACs inhibitor, but the drawbacks associated with hydroxamic acid group (poor stability, easy metabolism, weak binding ability to class IIa isozymes, and poor selectivity) have been exposed during the continuous clinical application. Based on the pharmacophore of HDAC inhibitors, two series of compounds with novel zinc binding group (ZBG) were designed and synthesized, and the antitumor bioactivities were evaluated in four human cancer cell lines (A549, Hela, HepG2, and MCF-7). Among the synthesized compounds, compounds a6, a9, a10, b8, and b9 exhibited promising inhibitory activities against the selected tumor cell lines, especially compounds a9 and b8 on Hela's cytostatic activity (a9: IC50 = 11.15 ± 3.24 μM; b8: IC50 = 13.68 ± 1.31 μM). The enzyme inhibition assay against Hela extracts and HDAC1&6 subtypes showed that compound a9 had a certain broad-spectrum inhibitory activity, while compound b8 had selective inhibitory activity against HDAC6, which was consistent with Western blot results. In addition, the inhibitory mechanism of compounds a9 and b8 in HDAC1&6 were both compared through computational approaches, and the binding interactions between the compounds and the enzymes target were analyzed from the perspective of energy profile and conformation. In summary, the compounds with novel ZBG exhibited certain antitumor activities, providing valuable hints for the discovery of novel HDAC inhibitors.

Development of selective mono or dual PROTAC degrader probe of CDK isoforms

Cyclin-dependent kinase (CDK) family members are promising molecular targets in discovering potent inhibitors in disease settings, they function differentially. CDK2, CDK4 and CDK6, directly regulate the cell cycle, while CDK9 primarily modulates the transcription regulation. In discovering inhibitors of these CDKs, toxicity associated with off-target effect on other CDK homologs often posts as a clinical issue and hinders their further therapeutic development. To improve efficacy and reduce toxicity, here, using the Proteolysis Targeted Chimeras (PROTACs) approach, we design and further optimize small molecule degraders targeting multiple CDKs. We showed that heterobifunctional compound A9 selectively degraded CDK2. We also identified a dual-degrader, compound F3, which potently induced degradation of both CDK2 (DC50: 62 nM) and CDK9 (DC50: 33 nM). In human prostate cancer PC-3 cells, compound F3 potently inhibits cell proliferation by effectively blocking the cell cycle in S and G2/M phases. Our preliminary data suggests that PROTAC-oriented CDK2/9 degradation is potentially an effective therapeutic approach.

Discovery of Substituted N-(6-Chloro-3-cyano-4-phenyl-4H-chromen-2-yl)- 2-(4-chloro-phenoxy)-acetamide for Biphasic Anticancer and Anticonvulsant Activities.

Privileged 4H-chromenes possess potent anticancer and anticonvulsant activities. By the inspiring potency of 4H-chromenes and demands of the present era of scaffolds, an effective molecule was discovered for the treatment of cancer and related diseases. This study designed and synthesized a novel series of 4H-chromene derivatives from one-port synthesis for the treatment of cancer and other such diseases. A side amide chain was substituted in multiple steps on the amine group of chromene. Later, the anticancer activity of synthesized compounds was investigated against the human colon adenocarcinoma cell line (HT-29) using sulforhodamine B (SRB) assay. Moreover, anticonvulsant activity was also detected using maximal electroshock seizure (MES) model and subcutaneous Metrazol Seizure Threshold Test (scMET) in albino Wistar rats. Neurotoxicity was evaluated by using the rotarod test. Before the synthesis, docking studies were performed using various molecular targets. Subsequently, the computational study of the titled compounds was performed to predict the pharmacokinetic profile. Among the fifteen tested compounds, A4 and A9 were found to be active against HT-29 cells (growth inhibitory dose 50% (GI50) <11μM). Moreover, compounds A4 showed the protection at 300mg/kg in scMET (h) for albino Wistar rats and compounds A9, A11, and A15 exhibited the anticonvulsant effect at the doses 100, 300 and 300 mg/kg, respectively in MES screen (h). Due to these encouraging results, we concluded that both A4 and A9 may be effective for treatement against colon cancer, while compound A9 may be used as a considerable effective molecule for the treatment of epilepsy.

Design and Green Synthesis of Piperlongumine Analogs and Their Antioxidant Activity against Cerebral Ischemia-Reperfusion Injury.

The supplementation of exogenous antioxidants to scavenge excessive reactive oxygen species (ROS) is an effective treatment for cerebral ischemia-reperfusion injury (CIRI) in stroke. Piperlongumine (PL), a natural alkaloid, has a great potential as a neuroprotective agent, but it also has obvious toxicity. Moreover, its neuroprotective effects remain to be improved. In this study, we designed a series of novel PL analogs by hybridizing the screened low-toxicity diketene skeleton with antioxidant effect and the 3,4,5-trimethoxyphenyl group, which may increase the antioxidant activity of PL. The intermediate was synthesized by a novel green synthesis method, and 34 compounds were obtained. The compounds without obvious cytotoxicity have remarkable antioxidant effects, especially compared with diketene skeletons and PL. The cytoprotection of the active compound decreased significantly by reduction of the carbon-carbon double bonds of the Michael acceptor in the diketene skeleton. More importantly, further study revealed that compound A9, which has the best activity, can confer protection for cells against oxidative stress and attenuate brain injury in vivo. Overall, this study provided a promising drug candidate for the treatment of CIRI and guided the further development of drug research in oxidative stress-mediated diseases.

SYNTHESIS, ANTIBACTERIAL, ANTIFUNGAL ANTITUBERCULAR ACTIVITIES AND MOLECULAR DOCKING STUDIES OF NITROPHENYL DERIVATIVES

Infectious diseases are one of the common problems encountered globally. Even though there are a number of drugs available in the market for the treatment of infectious diseases, still many new molecules are required due to the problems with the existing drugs. Hence we prepared a series of chalcones (A1-A10) containing nitrophenyl moieties by Claisen-Schmidt condensation reaction. All the ten compounds were characterized by IR, NMR, Mass spectroscopy and elemental analysis. The compounds were further screened for antitubercular activity employing MABA assay and antibacterial and antifungal activities by cup plate method against selected tubercular, bacterial and fungal organisms. The compound A9 displayed potent antitubercular activity with MIC 11.02±0.030, whereas the compound A3 showed superior antibacterial and antifungal activities. Further, molecular docking studies were performed on Thymidine Kinase (TMP) of Mycobacterium tuberculosis by employing AU autodocker. The docking scores were in association with the in vitro MABA results and also identified the potent nature of A9 with the docking score -6.7. This study helped to identify novel nitrophenyl derivatives against thymidylate kinase.

Structural analyses reveal the mechanism of inhibition of influenza virus NS1 by two antiviral compounds

The influenza virus is a significant public health concern causing 250,000-500,000 deaths worldwide each year. Its ability to change quickly results in the potential for rapid generation of pandemic strains for which most individuals would have no antibody protection. This pandemic potential highlights the need for the continuous development of new drugs against influenza virus. As an essential component and well established virulence determinant, NS1 (nonstructural protein 1) of influenza virus is a highly prioritized target for the development of anti-influenza compounds. Here, we used NMR to determine that the NS1 effector domain (NS1ED) derived from the A/Brevig Mission/1/1918 (H1N1) strain of influenza (1918H1N1) binds to two previously described anti-influenza compounds A9 (JJ3297) and A22. We then used X-ray crystallography to determine the three-dimensional structure of the 1918H1N1 NS1ED Furthermore, we mapped the A9/A22-binding site onto our 1918H1N1 NS1ED structure and determined that A9 and A22 interact with the NS1ED in the hydrophobic pocket known to facilitate binding to the 30-kDa subunit of the cleavage and polyadenylation specificity factor (CPSF30), suggesting that the two compounds likely attenuate influenza replication by inhibiting the NS1ED-CPSF30 interaction. Finally, our structure revealed that NS1ED could dimerize via an interface that we termed the α3-α3 dimer. Taken together, the findings presented here provide strong evidence for the mechanism of action of two anti-influenza compounds that target NS1 and contribute significant structural insights into NS1 that we hope will promote and inform the development and optimization of influenza therapies based on A9/A22.