Spirostanol saponins from Chinese onion (Allium chinense) exert pronounced anti-inflammatory and anti-proliferative activities

Chinese onion (Allium chinense) is widely cultivated as a vegetable, native to China and cultivated in many other countries. Its bulbs are commonly processed into pickles and spices. In this study, seven new spirostanol saponins (5, 7, 9-11, 13 and 15) together with ten known congeners (1-4, 6, 8, 12, 14, 16 and 17) were isolated from the bulbs of Chinese onion and their structures were elucidated by spectroscopic analysis and chemical degradation. The isolated components were evaluated for anti-inflammatory and anti-proliferative activities. As a result, compounds 4 and 8 showed potent inhibitory effects on the lipopolysaccharides (LPS) induced nitric oxide (NO) production in murine macrophage RAW264.7. Compound 13 displayed potential inhibitory activity against five human cancer cell lines with IC50 values of 1.43-6.81 µM. Compound 14 exhibited significant selective inhibition against these cancer cells (IC50 2.22-15.58 µM), in comparison with the normal cells MRC-5 (IC50 > 100 µM).