Four New Cucurbitacins from the Fruit of Momordica charantia

Four new 5 β ,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 β ,19‐epoxy‐25‐hydroxycucurbitane‐3,7,23‐trione ( 1 ), 5 β ,19‐epoxy‐3,7‐dioxo‐23,24,25,26,27‐pentanorcucurbitan‐22‐oic acid ( 2 ), 5 β ,19‐epoxy‐3 β ‐hydroxycucurbit‐24‐ene‐7,23‐dione ( 3 ), and 5 β ,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 .