Trinorcucurbitane and cucurbitane triterpenoids from the roots of Momordica charantia

Cucurbitacins, kuguacins A–E ( 1– 5), were isolated from the roots of Momordica charantia together with three known analogues. Compounds ( 3– 5) possess an unprecedented 25,26,27-trinorcucurbitane backbone. Kuguacin C ( 3) showed moderate anti-HIV-1 activity with a selectivity index more than 23.68. Five cucurbitacins, kuguacins A–E ( 1– 5), together with three known analogues, 3β,7β,25-trihydroxycucurbita-5,(23 E)-diene-19-al ( 6), 3β,25-dihydroxy-5β,19-epoxycucurbita-6,(23 E)-diene ( 7), and momordicine I ( 8), were isolated from roots of Momordica charantia. Structures of 1– 5 were elucidated by NMR and MS spectroscopic analysis. Among them, compounds 3– 5 possess an unprecedented 25,26,27-trinorcucurbitane backbone. Compounds 3 and 5 showed moderate anti-HIV-1 activity with EC 50 values of 8.45 and 25.62 μg/ml, and exerted minimal cytotoxicity against C8166 cells (IC 50 > 200 μg/ml), with a selectivity index more than 23.68 and 7.81, respectively.