Efficient strategies for preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa.

Efficient strategies for preparative separation of iridoid glycosides and flavonoid glycosides from Hedyotis diffusa using preparative HPLC combining with appropriate pretreatment technologies were developed. Four fractions (Fr.1-1, Fr.1-2, Fr.1-3 and Fr.2-1) were firstly isolated from the crude extract of Hedyotis diffusa by column chromatography with C18, resin and silica gel materials, respectively. Then, corresponding separation strategies were developed according to the polarity and chemical constituents. High-polar compounds of Fr.1-1 were purified by hydrophilic reversed phase liquid chromatography and HILIC mode. The combination of C18 and phenyl columns realized the complementary separation of iridoid glycosides in Fr.1-2. Meanwhile, the improved selectivity caused by change of organic solvent in the mobile phase was utilized to realize the purification of flavonoid glycosides in Fr.1-3 and Fr. 2-1. Finally, 27 compounds (purity >95%) mainly involving 9 iridoid glycosides and 5 flavonoid glycosides were obtained. A complete strategy was established for the separation of complex sample with wide polarity range, to jointly solve the problems of enrichment of target components and separation of structural analogues. This article is protected by copyright. All rights reserved.