Isolation of Cucurbitane-Type Triterpenoids from Momordica charantia (Bitter Melon)

Abstract

Momordica charantia L. (Cucurbitaceae), commonly known as bitter melon, grows in many tropical and subtropical areas of the world and has been used extensively in folk medicines as a remedy for diabetes. In the U.S., many dietary supplements containing bitter melon can be purchased over-the-counter and from internet suppliers. However, no LC-MS analytical method has been developed for monitoring the concentration of bitter melon compounds in dietary supplements. In this study, the powdered whole plant material, including leaves, stems, and roots, was extracted with methanol and defatted with hexane. The defatted methanol extract was subjected to fractionation to isolate the major marker compounds. Several cucurbitane-type triterpenoids, including triterpenoid glycosides, were isolated over normal (silica gel column, chloroform-methanol solvent system) and reversed-phase (C18 column, water-methanol solvent system) stationary phases. Their structures were elucidated by mass and NMR spectrometry. These compounds will be used as standards in the development of an LC-MS analytical method for monitoring the identification and concentrations of these compounds in dietary supplements and will also be tested in in vitro systems.