Studies on the preparation, crystal structure and bioactivity of ginsenoside compound K

Abstract

Microbial transformation of Panax notoginseng saponins (PNS) using Aspergillus niger afforded, as the main metabolite, ginsenoside compound K (20-O-β-glucopyranosyl-20(S)-protopanaxadiol). Its structure was determined spectroscopically and by X-ray analysis, and this is the first time the crystal structure of ginsenoside has been reported. In comparison with ginsenoside Rb1, the pro-drug for this metabolite, compound K exhibits potent cytotoxic activity against tumor cell lines. The mean concentrations of compound K needed to inhibit the proliferation of cells by 50% (IC₅₀) were 12.7, 11.4, 8.5 and 9.7 μM for mouse high-metastatic melanoma (B16-BL6), human hepatoma (HepG2), human myeloid leukemia (K562) and human high-metastatic lung carcinoma (95-D) cell lines, respectively. The data show that ginsenoside compound K is a good antitumor drug candidate.

Keywords:

• Microbial transformation
• Ginsenoside compound K
• X-ray analysis
• Cytotoxic activity

Acknowledgements

This project was supported by the Shanghai SK Research and Development Foundation (No. 2003001-S). We sincerely thank Professor Jie Sun of the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS) for assistance with the X-ray crystallography. We are grateful to Professor Jian-Wen Liu of the State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology for the cell cultivation and bioactivity tests.