Triterpene glycosides, separation

A new HPLC method permitted the separation of 13 triterpene glycosides isolated from different Astragalus species within 40 min. A water/acetonitrile gradient was used as eluent, RP-18 was used as stationary phase, and evaporative light scattering detection was used. The method facilitated differentiation of different Astragalus species. 

Figure 6. Separation by GLC at 345° of a complex mixture of triterpene glycosides, the last peak with a retention time of 48 min.

There seems little point in subdividing the triterpenes into classes according to polarity, as done with the 10 -derivatives. With a view to preliminary separation of the substances during isolation, a division into neutral and acid triterpene derivatives is to be recommended. The hydrophilic triterpene glycosides can then profitably be separated from these ( bitter principles and saponins ). 

The various teams [19, 125, 128, 135, 191, 245, 256, 290, 319] have used mostly aqueous-alcoholic mobile phases hke, for example, chloro-form-methanol-water (65 + 35 -f 10) for separation of mixtures of neutral triterpene glycosides. The ethyl acetate-carbon tetrachloride mixtures which Linde [150] has employed for separation of Cimicifuga glycosides, are less polar (cf. also [35, 36]). 

Centrifugal liquid-liquid partition chromatography has been applied to separate efficiently flavonoid and triterpene glycosides that vary only in their sugar residues. ... 

Alcohol reflux extraction, ultrasound assisted extraction, Soxhlet extraction and supercritical fluid extraction (SPE) are the main teehniques used to isolate triterpenoids from Cornus spp. fimits [Zhao et al., 2005], Thin layer chromatography (TEC), HPLC and cyclodextrin-modified micellar eleetrokinetie ehromatography (CD-MEKC) have also been apphed for separation and determination of these three triterpenic acids in Iriiits [Zhang et al., 2005 Wang et al., 2008]. The isolated triterpenie compounds and their glycosides were identified by speetroscopie analysis NMR, IR and MS. 

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