The influenza A virus (IAV), renowned for its high contagiousness and potential to catalyze global pandemics, poses significant challenges due to the emergence of drug-resistant strains. Given the critical role of RNA polymerase in IAV replication, it stands out as a promising target for anti-IAV therapies. In this study, we identified a novel C-3-substituted oleanolic acid benzyl amide derivative, A5, as a potent inhibitor of the PA_C-PB1_N polymerase subunit interaction, with an IC₅₀ value of 0.96 ± 0.21 μmol/L. A5 specifically targets the highly conserved PA_C domain and demonstrates remarkable efficacy against both laboratory-adapted and clinically isolated IAV strains, including multidrug-resistant strains, with EC₅₀ values ranging from 0.60 to 1.83 μmol/L. Notably, when combined with oseltamivir, A5 exhibits synergistic effects both in vitro and in vivo. In a murine model, dose-dependent administration of A5 leads to a significant reduction in IAV titers, resulting in a high survival rate among treated mice. Additionally, A5 treatment inhibits virus-induced Toll-like receptor 4 activation, attenuates cytokine responses, and protects against IAV-induced inflammatory responses in macrophages. In summary, A5 emerges as a novel inhibitor with high efficiency and broad-spectrum anti-influenza activity.

Objective To study the inhibitory activities of 3-O-β-chacotriosyl glycyrrhetinic acid derivatives against the entry of SARS-CoV-2 into host cells.Methods With pentacyclic triterpene saponin glycyrrhizic acid(a natural SARS-CoV-2 entry inhibitor)as the lead compound,a series of 3-O-β-chacotriosyl glycyrrhetinic acid derivatives were designed and synthesized based on hypridization principle,and their inhibitory activities against virus entry were tested in SARS-CoV-2 pseudovirus-infected cells.The antiviral targets of the lead compound 1b was identified by pseudotyped SARS-CoV-2 infection assay and surface plasmon resonance(SPR)assay,and the S protein-mediated cell-cell fusion assay was used to evaluate the effect of 1b on virus-cell membrane fusion.Molecular docking and single amino acid mutagenesis were carried out to analyze the effect of 1b on binding activitiy of S protein.Results The lead compound 1b showed significant inhibitory effect against Omicron pseudovirus with an EC50 value of 3.28μmol/L(P<0.05),and had broad-spectrum antiviral activity against other SARS-CoV-2 pseudovirus.Spike-dependent cell-cell fusion assay demonstrated an inhibitory effect of 1b against SARS-CoV-2 S protein-mediated cell-cell fusion.Molecular docking analysis predicted that the lead compound 1b could be well fitted into a cavity between the attachment(S1)and fusion(S2)subunits at the 3-fold axis,where it formed multiple hydrophobic interactions with Glu309,Ser305,Arg765 and Lys964 residues with a KD value of-8.6 kcal/mol.The compound 1b at 10,5,2.5 and 1.25 μmol/L showed a significantly reduced inhibitory activity against the pseudovirus with mutated Arg765,Lys964,Glu309 and Leu303(P<0.01).Conclusion 3-O-β-chacotriosyl glycyrrhetinic acid derivatives are capable of stabilizing spike protein in the pre-fusion step to interfere with the fusion of SARS-CoV-2 with host cell membrane,and can thus serve as potential novel small-molecule SARS-CoV-2 fusion inhibitors.

Objective To study the inhibitory activities of 3-O-β-chacotriosyl glycyrrhetinic acid derivatives against the entry of SARS-CoV-2 into host cells.Methods With pentacyclic triterpene saponin glycyrrhizic acid(a natural SARS-CoV-2 entry inhibitor)as the lead compound,a series of 3-O-β-chacotriosyl glycyrrhetinic acid derivatives were designed and synthesized based on hypridization principle,and their inhibitory activities against virus entry were tested in SARS-CoV-2 pseudovirus-infected cells.The antiviral targets of the lead compound 1b was identified by pseudotyped SARS-CoV-2 infection assay and surface plasmon resonance(SPR)assay,and the S protein-mediated cell-cell fusion assay was used to evaluate the effect of 1b on virus-cell membrane fusion.Molecular docking and single amino acid mutagenesis were carried out to analyze the effect of 1b on binding activitiy of S protein.Results The lead compound 1b showed significant inhibitory effect against Omicron pseudovirus with an EC50 value of 3.28μmol/L(P<0.05),and had broad-spectrum antiviral activity against other SARS-CoV-2 pseudovirus.Spike-dependent cell-cell fusion assay demonstrated an inhibitory effect of 1b against SARS-CoV-2 S protein-mediated cell-cell fusion.Molecular docking analysis predicted that the lead compound 1b could be well fitted into a cavity between the attachment(S1)and fusion(S2)subunits at the 3-fold axis,where it formed multiple hydrophobic interactions with Glu309,Ser305,Arg765 and Lys964 residues with a KD value of-8.6 kcal/mol.The compound 1b at 10,5,2.5 and 1.25 μmol/L showed a significantly reduced inhibitory activity against the pseudovirus with mutated Arg765,Lys964,Glu309 and Leu303(P<0.01).Conclusion 3-O-β-chacotriosyl glycyrrhetinic acid derivatives are capable of stabilizing spike protein in the pre-fusion step to interfere with the fusion of SARS-CoV-2 with host cell membrane,and can thus serve as potential novel small-molecule SARS-CoV-2 fusion inhibitors.

Objective To investigate the saponins from the Chinese materia medica Huluba (the seeds of Trigonella foenum-graecum L.). Methods To isolate and purify the single saponin by the column chromatography and dry column chromatography of silica gel H. The structural elucidation was carried on by spectroscopic evidence of (()~(13)C-NMR), FAB-MS, DEPT and the results of the fraction-hydrolysis of acquiring the secondary glucosides. Results The newly isolated saponin D was consisted by six molecules of sugar with diosgenin. The chemical structure of saponin D is: diosgenin-3-O-?-L-rhamnopyranosyl (1→3)-?-D-glucopyranosyl (1→4)-?-L-rhamnopyranosyl [(1→3)-?-L-rhamnopyranosyl] (1→4)-?-D-glucopyranosyl (1→4)-?-D-glucopyranoside. Conclusion Saponin D is a new one consisted of six molecules of su-(gar) with diosgenin.

Object To investigate the saponin from the seeds of Trigonella foenum graecum Linn (STFG) Methods The total saponin from STFG was extracted and purified by using the absorptive resin, the single saponin was isolated by using the column chromatography as well as dry column chromatography of silica gel H The chemical structure was elucidated by 13 CNMR , FAB MS, DEPT spectroscopic evidence and the results of fraction hydrolysis of acquiring their secondary glucosides Results A new saponin A from the total saponin has been obtained, the fraction hydrolysis carried out and the secondary glucoside Ⅰ and Ⅱ identified by determining the structure of saponin A The chemical structure of saponin A is: diosgenin 3 O ? L rhamnopyranosyl(1→4) ? D glucopyranosyl(1→4) ? D glucopyranoside The secondary glucoside Ⅰ is: diosgenin 3 O ? D glucopyranoside; Ⅱ is: diosgenin 3 O ? D glucopyranosyl(1→4) ? D glucopyranoside Conclusion Glucoside A is a new saponin with three molecules of sugar

Object To do detail investigation of the saponins from the Chinese materia medica Huluba (the seeds of Trigonella foenum graecum L ) Methods The pure saponins from the total saponins were isolated by employing the column chromatography and dry column chromatography of silica gel H Their chemical structures were elucidated by 13 C NMR , FAB MS, DEPT spectroscopic evidence and the results of the fraction hydrolysis of acquiring their secondary glucosides were obtained Results Two new saponins B and C were isolated and both were the glucosides consisted by four molecules of sugar with diosgenin The chemical structure of B is: diosgenin 3 O ? L rhamnopyranosyl (1→3) ? L rhamnopyranosyl (1→4) ? D glucopyranosyl (1→4) ? D glucopyranoside And saponin C is: diosgenin 3 O ? D glucopyranosyl (1→4) ? L rhamnopyranosyl (1→4) ? D glucopyranosyl (1→4) ? D glucopyranoside Conclusion Saponins B and C are two new ones with four molecules of sugar respectively