Chemical Constituents of Primulina eburnea (Gesneriaceae) and their Cytotoxic Activities

Two new ursane-type triterpenes, eburnealactone A and B (1 and 2), one new flavonoid, eburneatin A (6), and one new phenylethanoid glycoside, chiritoside D (7), along with 9 known compounds (3-5, 8-13) were isolated from the whole plant of Primulina eburnea. Their structures were elucidated by comprehensive spectroscopic data analysis (IR, UV, NMR, and HR-ESI-MS). All the compounds were evaluated for their cytotoxic activities. Among which, compound 1 showed significant cytotoxic activities against MKN-45 cell line and 5637 cell line with the IC50 values of 9.57 μM and 8.30 μM, respectively. compound 1 exhibited moderate cytotoxic activities against A549 and PATU8988T cell lines with the IC50 values of 30.70 μM and 38.22 μM respectively, compound 6 exhibited moderate cytotoxic activities against MKN-45, HCT116, PATU8988T, 5637 and A-673 cell lines with the IC50 values of 19.69 μM, 16.44 μM, 18.07 μM, 11.51 μM and 18.15 μM respectively, compound 5 showed moderate cytotoxic activities against A549 cell line with the IC50 values of 24.06 μM.