5β,19-Epoxycucurbitane Triterpenoids from Momordica charantia and Their Anti-Inflammatory and Cytotoxic Activity

Five new 5β,19-epoxycucurbitane triterpenoids, taikugausins A-E (1-5), together with 5β,19-epoxy-25-methoxycucurbita-6,23-diene-3β,19-diol (6), have been isolated and characterized from the 70 % EtOH extract of the fresh fruits of Momordica charantia. The chemical structures of compounds 1-6 were elucidated on the basis of extensive spectroscopic analyses, especially 2D NMR (HMQC, HMBC, and NOESY) experiments and HRESIMS data. The relationship between NMR chemical shifts and the configuration of C-19 with an OMe group in 5β,19-epoxycucurbitane are described. Among them, compounds 3 and 4 exhibited remarkable anti-inflammatory activities by the inhibition of nitric oxide production at the concentration of 10 µg/mL. In addition, 3 and 4 also showed moderate cytotoxicity against WiDr, Hep G2, MCF-7, and HEp-2 human tumor cell lines.