The Triterpenoids from Munronia pinnata and Their Anti-Proliferative Effects.

Six new tirucallane-type triterpenoids, named munropenes A-F (-), were extracted from the whole plants of using a water extraction method. Their chemical structures were determined based on detailed spectroscopic data. The relative configurations of the acyclic structures at C-17 of munropenes A-F (-) were established using carbon-proton spin-coupling constants () and inter-proton spin-coupling constants (). Furthermore, the absolute configurations of munropenes A-F (-) were determined through high-performance liquid chromatography (HPLC), single-crystal X-ray diffraction, and electronic circular dichroism (ECD) analyses. The antiproliferative effects of munropenes A-F were evaluated in five tumor cell lines: HCT116, A549, HepG2, MCF7, and MDAMB. Munropenes A, B, D, and F (, , , and ) inhibited proliferation in the HCT116 cell line with IC values of 40.90, 19.13, 17.66, and 32.62 µM, respectively.