Triterpenoids of sour jujube show pronounced inhibitory effect on human tumor cells and antioxidant activity.

Sour jujube is a common fruit and traditional medicine in China. Bioactivity-guided fractionation of sour jujube was used to determine the chemical identity of potent antiproliferative and antioxidant constituents. Four novel ursane-type triterpenoids, together with 8 known were isolated and identified. The new triterpenoids were elucidated to be 2α,3β,13β,23-tetrahydroxy-urs-11-en-28-oic acid (3), 2α,3β-dihydroxy-urs-20(30)-en-28-oic acid (9), 2α,3β,28-trihydroxy-urs-20(30)-ene (10), and 3β,12β,13β-trihydroxy-ursan-28-oic acid (11). Among the triterpenoids isolated, 2α,3β,19α-trihydroxy-urs-12-en-28-oic acid (7), 9 and 10 showed high potent inhibitory activity toward the proliferation of HepG2 cells, which the IC50 values were lower than 5 μM. Compounds 9 and 10 also exhibited pronounced activity against MCF-7 cells, with IC50 value of 0.8 ± 0.03 and 1.5 ± 0.1 μM, respectively. Compound 10 showed high antioxidant activity with an EC50 of 0.8 ± 0.02 μM, which was 18.9 times higher than ascorbic acid in antioxidant capacity.