Gypsophila saponins enhance the cytotoxicity of etoposide in HD-MY-Z lymphoma cells.

Glucuronide Oleanane-type Triterpenoid Carboxylic Acid 3,28-Bidesmosides (GOTCAB) are accumulated in Gypsophila L. roots. In the study we aimed at investigating the possible synergistic effects of Gypsophila trichotoma GOTCABs and cytostatic etoposide towards the Hodgkin lymphoma cell line HD-MY-Z. The combination effects with etoposide were evaluated using the symbolic mathematical software MAPLE. Liquid chromatography-mass spectrometry allowed the identification or tentative assignment of 28 core GOTCAB structures together with 6 monodesmosides in the root extract. Tested gypsogenin-based saponins possessed C-28 ester-bonded chain substituted with acetyl, cis/trans methoxycinnamoyl and both acetyl and sulfate groups. No cytotoxic effect was observed up to 20 μg/mL on normal mice fibroblasts (CCL-1 cell line) and lymphoma cells. Etoposide alone exerted IC₅₀ 93 μg/mL. In the presence of acetylated saponins (20 μg/mL), a strong synergism (Fa = 0.8, CI = 0.1) was observed with IC₅₀ 11 μg/mL. The combination induced apoptosis witnessed by caspase activation, elevated levels of cytosolic mono- and oligonucleosomes, and nuclear fragmentation together with discernible increase in ROS generation. The results emphasize the arabinose in the C-3 chain and acetylation pattern of the C-28 chain of the saponins as important structural features for cytotoxicity enhancing activity. Triterpenoid saponins are a valuable tool to improve the efficacy of cytostatics.