Solid-state Characterization of Optically Pure (+)Dihydromyricetin Extracted from Ampelopsis Grossedentata Leaves

Dihydromyricetin (DMY) is a natural flavanol compound isolated from a traditional Chinese medicine, Ampelopsis grossedentata. Despite that optically pure (+)DMY is desired for treating chronic pharyngitis and alcohol use disorders, only DMY racemate is commercially available due to prolonged exposure time to high temperature and the presence of metal ions during industrial extraction, which cause racemization of the homochiral (+)DMY. We have developed an extraction method for successfully obtain optically pure (+)DMY. We have further assessed the physicochemical properties of the two phases using PXRD, DSC, TGA, FTIR, and moisture sorption. Among them, PXRD and FT-IR are suitable for quickly distinguishing homochiral (+)DMY from racemic (±)DMY. Lastly, with the aid of cocrystallization with theophylline, the absolute configuration of homochiral (+)DMY was identified to be (2R, 3R).