Charantin is a typical cucurbitane-type triterpenoid in M. charantia and is a potential substance with antidiabetic properties[35],[36]. Pitiphanpong et al. demonstrated that charantin could be used to treat diabetes and can potentially replace treatment[37]. It is a mixture of two compounds, namely, sitosteryl glucoside and stigmasteryl glucoside[37]. Chen et al. isolated 14 cucurbitane triterpenoids, kuguacins, including two pentanorcucurbitacins, one octanorcucurbitacin, and two trinorcucurbitacins, along with six known analogues from the vines and leaves of M. charantia[38]. The charantin from bitter melon fruit was extracted and estimated by high performance thin layer chromatographic method[39].
Studies have reported that the compound is more effective than the oral hypoglycemic agent tolbutamide[12]. In a study, two aglycones of charantin were isolated and identified as sitosterol and stigmastadienol glycosides, however, when tested separately for their hypoglycemic effects in vivo, these two constituents did not produce any notable changes in blood glucose levels[40]. This is an indication that charantin may contain other specific components, yet to be identified, that are responsible for the hypoglycemic activity observed in diabetics.