Triterpenoids and Steroids from the Fruits of Melia toosendan and Their Cytotoxic Effects on Two Human Cancer Cell Lines

Ten new triterpenoids, named meliasenins I−R (1−10), one new steroid (11), and 11 related known compounds (12−22) were isolated from fruits of Melia toosendan. The structures of the new compounds were established on the basis of spectroscopic methods, including 2D NMR techniques and mass spectrometry. The relative configuration of 1, (20R*,23E)-25-hydroperoxyeupha-7,23-diene-3β,16β-diol (meliasenin I), was confirmed by single-crystal X-ray diffraction analysis. All isolated triterpenoids (1−10, 12−15) and two steroids (11, 20) were tested for their cytotoxicity against U20S human osteosarcoma and MCF-7 human breast cancer cells using the MTT assay, and some of them were significantly cytotoxic (IC50 <10 μg/mL). The insecticidal properties of compounds 1−15 and 20 were also briefly evaluated.