Triterpenoid saponins from Camellia sinensis roots with cytotoxic and immunomodulatory effects.

Camellia sinensis L. (Theaceae) leaves have been used as a beverage in both Eastern and Western cultures for a long time, while its root has not been intensively studied. In this study, seven undescribed triterpenoid saponins (1-7) and twelve known saponins (8-19) with different combinations of substituents, such as oxygenated isoprenyl substituents and sugar moieties, and lengths of sugar chains, were isolated from the C. sinensis roots. Their structures were unequivocally determined using one- and two-dimensional nuclear magnetic resonance data and acid hydrolysis analysis. Investigation of the biological activities of isolated compounds revealed that only those without functional acetyl groups exhibited cytotoxic activities against mouse and human cancer cells (B16F10) and human cervical cancer cell line (HeLa) at 50 μM. Compounds with an aldehyde group at C-23 of aglycone showed immunomodulatory activity against Th1 and Th17 cells at 10 μM. Ten compounds with biological activities from C. sinensis roots extracts, including three previously undescribed ones (3, 6, and 7), were identified.