Cytotoxic activity of Pulsatilla chinensis saponins and their structure–activity relationship

Abstract

The cytotoxic activity of 36 saponins isolated from roots of Pulsatilla chinensis (Bunge) Regel against the human cancer cell lines (A549, SGC-7901) and the human hepatic cell line (HL-7702) was tested by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay. Saponins 1–14 showed considerable cytotoxic activity, whereas saponins 15–36 showed no significant activity, which suggested that a free carboxylic group located at C-28 of aglycon is essential for their cytotoxic activity. Moreover, the analysis of structure–activity relationships also suggested that the oleanane-type saponins showed better cytotoxic activity than lupane-type saponins, and the length and linkage of glycolic chain attached to C-3 of aglycon displayed an important effect to the potent cytotoxicity. In conclusion, oleanolic acid 3-O-α-l-rhamnopyranosyl-(1 → 2)-[β-d-glucopyranosyl-(1 → 4)]-α-l-arabinopyranoside (5) exhibited the most significant cytotoxic activity.

Keywords:

• Pulsatilla chinensis
• saponins
• cytotoxic activity
• structure–activity relationship

Acknowledgements

This study was funded by National Sciences Foundation of China (No. 81172954), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the Natural Science Foundation of Jiangsu Province (No. BK2012620), and the grant of National Scientific and Technological Major Special Project for Significant New Drug Creation (No. 2011ZX09102-001-19). We also want to express our thanks to Mrs Li-Ping Shi in Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences for the determination of NMR spectral data.

Notes

^1. K. Xu and Z. Shu contributed equally to this work.

^1. K. Xu and Z. Shu contributed equally to this work.

Additional information

Notes on contributors

Kun Xu

1 1. K. Xu and Z. Shu contributed equally to this work.

Zhan Shu

1 1. K. Xu and Z. Shu contributed equally to this work.