Structure Modification of Ginsenoside Rh(2) and Cytostatic Activity on Cancer Cells

[Image: see text] Ginsenoside Rh(2) (Rh(2)) is one of the most effective anticancer components extracted from red ginseng, but the poor solubility limits its clinical application. In this paper, ginsenoside Rh(2) was modified with maleimidocaproic acid or maleimidoundecanoic acid with functional groups at both ends. The structures of derivatives were determined by analysis of 1D and 2D nuclear magnetic resonance, Fourier transform infrared, and high-resolution mass spectrometry. Antiproliferative cell experiments showed that Rh(2) modified with maleimidocaproic acid (C–Rh(2)) displayed higher cytostatic activity against different tumor cells compared with Rh(2), while Rh(2) modified with maleimidoundecanoic acid (U–Rh(2)) did not exhibit obvious cytotoxicity. The results suggest that the length of the spacer arm may play an important role in the cytostatic activity of the Rh(2) derivatives.