The antigluconeogenic activity of cucurbitacins from Momordica charantia

Five new cucurbitacins, kuguacins II-VI (1-5), along with five known analogues (6-10), were obtained from the fruit of Momordica charantia. Structures of the new compounds were elucidated as 5β,19-epoxycucurbit-23-en-7-on-3β,25-diol (1), 5β,19-epoxycucurbit-7,23-dion-3β,25-diol (2), 5β,19-epoxycucurbit-6-en-19,23-dion-3β,25-diol (3), 5β,19-epoxy-23,24,25,26,27-pentanorcucurbit-6-en-7,19-dion-3β,22-diol (4), and cucurbit-5-en-7,23-dion-3β,19,25-triol (5) by extensive spectroscopic and single-crystal X-ray diffraction analyses. Some cucurbitane compounds from this species were screened for their potential antidiabetic properties in terms of antigluconeogenic activity. As a result, compounds 1, 10, 11, and 12 (at 25-100 µM) showed concentration-dependent inhibition on glucose production from liver cells. In addition, compounds 11 and 12 (at 100 µM) showed around 20-30 % inhibition on PEPCK activity.