Antiproliferative activity of new pentacyclic triterpene and a saponin fromGladiolus segetumKer-Gawl corms supported by molecular docking study

A new triterpenoidal saponin identified as 3-O-[beta-d-glucopyranosyl-(1 -> 2)-beta-d-glucopyranosyl-(1 -> 4)-beta-d-xylopyranosyl]-2 beta,3 beta,16 alpha-trihydroxyolean-12-en-23,28-dioic acid-28-O-alpha-l-rhamnopyranosyl-(1 -> 4)-alpha-l-rhamnopyranosyl-(1 -> 2)-beta-d-glucopyranosyl-(1 -> 2)-alpha-l-arabinopyranoside1together with a new oleanane triterpene identified as 2 beta,3 beta,13 alpha,22 alpha-tetrahydroxy olean-23,28-dioic acid2and 6 known compounds (3-8) have been isolated fromGladiolus segetumKer-Gawl corms. The structural elucidation of the isolated compounds was confirmed using different chemical and spectroscopic methods, including 1D and 2D NMR experiments as well as HR-ESI-MS. Moreover, thein vitrocytotoxic activity of the fractions and that of the isolated compounds1-8were investigated against five human cancer cell lines (PC-3, A-549, HePG-2, MCF-7 and HCT-116) using doxorubicin as a reference drug. The results showed that the saponin fraction exhibited potentin vitrocytotoxic activity against the five human cancer cell lines, whereas the maximum activity was exhibited against the PC-3 and A-549 cell lines with the IC(50)values of 1.13 and 1.98 mu g mL(-1), respectively. In addition, compound1exhibited potent activity against A-549 and PC-3 with the IC(50)values of 2.41 mu g mL(-1)and 3.45 mu g mL(-1), respectively. Interestingly, compound2showed the maximum activity against PC-3 with an IC(50)of 2.01 mu g mL(-1). These biological results were in harmony with that of the molecular modeling study, which showed that the cytotoxic activity of compound2might occur through the inhibition of the HER-2 enzyme.