Notoginsenoside ST-4 inhibits virus penetration of herpes simplex virus in vitro.

Further study on steam-treated notoginseng, the roots of Panax notoginseng (Burk.) F.H. Chen (Araliaceae), which is a famous traditional Chinese medicine that is used both in raw and treated forms for a long time, led to the isolation of a new dammarane-type saponin, namely notoginsenoside ST-4. Its structure was elucidated to be 3,12,20(S)-tri-hydroxydammar-24-ene-3-O--d-xylopyranosyl-(12)--d-glucopyranosyl-(12)--d-glu-copyranoside, based on the detailed analyses of the 1D and 2D NMR spectral data and acidic hydrolysis. Notoginsenoside ST-4 was investigated for its antiviral activity on herpes simplex type 1 (HSV-1) and type 2 (HSV-2) in vitro. The 50% effective concentration (EC50) values, determined by plaque reduction assay, were 16.47 +/- 0.67 and 19.44 +/- 1.16M for HSV-1 and HSV-2, respectively, whereas the 50% cytotoxic concentration (CC50) determined by the XTT test on Vero cells was 510.64 +/- 4.56M. As analyzed by attachment assay and penetration assay based on plaque reduction assay, the antiviral activity of notoginsenoside ST-4 was principally due to the penetration inhibition effects, which was confirmed by fluorescence microscopy observation that notoginsenoside ST-4 blocked the penetration of virus. Therefore, notoginsenoside ST-4 might be a promising agent for herpes simplex virus infection.