Saponins from the traditional medicinal plant Momordica charantia stimulate insulin secretion in vitro.

Abstract The antidiabetic activity of Momordica charantia (L.), Cucurbitaceae, a widely-used treatment for diabetes in a number of traditional medicine systems, was investigated in vitro . Antidiabetic activity has been reported for certain saponins isolated from M. charantia . In this study insulin secretion was measured in MIN6 β-cells incubated with an ethanol extract, saponin-rich fraction, and five purified saponins and cucurbitane triterpenoids from M. charantia , 3 β ,7 β ,25-trihydroxycucurbita-5,23( E )-dien-19-al (1), momordicine I (2), momordicine II (3), 3-hydroxycucurbita-5,24-dien-19-al-7,23-di- O - β -glucopyranoside (4), and kuguaglycoside G (5). Treatments were compared to incubation with high glucose (27 mM) and the insulin secretagogue, glipizide (50 μM). At 125 μg/ml, an LC–ToF-MS characterized saponin-rich fraction stimulated insulin secretion significantly more than the DMSO vehicle, p  = 0.02. At concentrations 10 and 25 μg/ml, compounds 3 and 5 also significantly stimulated insulin secretion as compared to the vehicle, p  ≤ 0.007, and p  = 0.002, respectively. This is the first report of a saponin-rich fraction, and isolated compounds from M. charantia , stimulating insulin secretion in an in vitro , static incubation assay.