Qingqianliusus A-N, 3,4-seco-dammarane triterpenoids from the leaves of Cyclocarya paliurus and their biological activities

Fourteen previously unreported 3,4-seco-dammarane triterpenoids named Qingqianliusus A-N (1–14), along with four known 3,4-seco-dammarane triterpenoid derivatives (15–18) were isolated from the 95 % ethanol extract of the Cyclocarya paliurus leaves. Compounds 1 and 2 possess a rare 3,11-heptacyclic lactone as natural product, and several pairs of the 3,4-seco-dammarane triterpenoid epimers with R/S configuration at C-24 were investigated and determined in detail for the first time. Compounds 8, 11, and 14 showed good α-glucosidase inhibitory effects with IC50 values of 4.97 ± 0.63, 7.08 ± 0.53, and 3.76 ± 0.77 μM, respectively. Meanwhile, compound 11 was also found potent inhibition rate of 35.83 % against COX-2, as compared with the positive control celecoxib (70.28 %). In addition, compounds 3, 7, 10, and 13 exhibited outstanding cytotoxicities against human gastric cancer cell lines (BGC-823) with IC50 values of 7.69 ± 0.21, 8.47 ± 0.41, 9.04 ± 0.61, and 8.86 ± 0.38 μM, respectively. Compounds 13 and 3 had modest activities on human colon cancer cell lines (HCT-116) with IC50 values of 8.80 ± 0.36 and 9.45 ± 0.93 μM, respectively.