Four New Cucurbitacins from the Fruit of Momordica charantia

Four new 5 beta,19-epoxycucurbitacins, kuguacins T-W (1-4, resp.), along with nine known cucurbitane derivatives, 5-13, were obtained from the fresh fruit of Momordica chrantia. Structures of the new metabolites were elucidated as 5 beta,19-epoxy-25-hydroxycucurbitane-3,7,23-trione (1), 5 beta,19-epoxy-3,7-dioxo-23,24,25,26,27-pentanorcucurbitan-22-oic acid (2), 5 beta,19-epoxy-3 beta-hydroxycucurbit-24-ene-7,23-dione (3), and 5 beta, 19-epoxy-25-hydroxycucurbit-23-ene-3,7-dione (4), by extensive spectroscopic investigations, which were confirmed by a single-crystal X-ray diffraction analyses in the case of compound 4.