Profiling of isoflavonoids in Iris germanica rhizome extracts by microprobe NMR and HPLC-PDA-MS analysis

Lipophilic and polar extracts of iris rhizomes (Iris germanica) were submitted to a phytochemical profiling by a combination of HPLC-PDA-MS and semi-preparative HPLC/off-line microprobe NMR measurements. A total of 20 compounds were purified in sub-milligram to milligram amounts via two successive chromatographic steps. They were identified as isoflavones, isoflavone glycosides and acetovanillone by analysis of on-line MS and PDA, and off-line NMR data. A new isoflavone glycoside, iriflogenin-4'-O-gentiobioside, was subsequently isolated at preparative scale for full chemical characterization. This study demonstrates the applicability of the HPLC/off-line microprobe NMR approach as a robust means for rapid phytochemical profiling of plant extracts.