Neuraminidase Inhibitors from the Roots of Caragana sinica

Abstract Two new oligostilbenes, caragasinins D and E, along with four known compounds, kobophenol A, α‐viniferin, wistin, and 5‐hydroxy‐2‐[(4‐hydroxyphenyl)acetyl]‐3‐methoxybenzoic acid, were isolated from the roots of Caragana sinica . These compounds were spectroscopically analyzed for their structures and configurations and compared with existing data. The configurations of caragasinins D and E were elucidated by 1 H‐NMR spectroscopy, CD spectroscopy, and time‐dependent density‐functional theory simulated ECD spectral data. All six compounds were evaluated for their inhibitory activity against neuraminidase (NA) from Clostridium perfringens . Among the tested compounds, 5‐hydroxy‐2‐[(4‐hydroxyphenyl)acetyl]‐3‐methoxybenzoic acid demonstrated statistically significant NA inhibitory activity, which was comparable to the positive control, mangiferin.