In vivo and in vitro studies to identify the hypoglycaemic constituents of Momordica charantia wild variant WB24

Wild bitter melon (the wild variant of Momordica charantia L.) native to the eastern region of Taiwan has been consumed by local residents as a folk medicine for the prevention or treatment of hyperglycaemia and related diseases, yet its hypoglycaemic activities and constituents have not been scientifically characterised. Thus, WB24, a strain of wild bitter melon originating from the eastern region of Taiwan, was investigated. By cell-based screening, the fruit of WB24 was revealed to be a rich source of hypoglycaemic molecules, and the in vivo hypoglycaemic activities of selected fractions were assessed. Five triterpenes were isolated from one of the most active fractions and their ability to activate AMP-activated protein kinase (AMPK) was observed. One triterpene of the five analysed exhibited the highest activation of AMPK in an insulin-independent manner, and the AMPK-activation activity of this triterpene was greater than that of troglitazone, a thiazolidinedione-type antidiabetic medicine.