HPLC-NMR chemical profiling of the Australian carnivorous plant, Drosera erythrohiza subspecies magna

On-line HPLC-NMR chemical profiling of crude extracts derived from the bulbs of the Australian carnivorous plant Drosera erythrohiza subspecies magna was undertaken. A combination of on-flow and stop-flow HPLC-NMR methodologies enabled partial identification of two structurally related naphthoquinones as well as a mixture of their corresponding glycosides. Subsequent semi-preparative HPLC off-line isolation followed by NMR spectroscopic and mass spectrometric analysis of crude extracts of the bulbs of the plant permitted the unequivocal identification of droserone, hydroxydroserone, droserone-5-O-β-glycoside and hydroxydroserone-5-O-β-glycoside. In addition off-line separation methodologies of the aerial parts of the plant led to the identification of the bioactive compound plumbagin. This study represents only the second application of HPLC-NMR to chemically profile crude extracts of an Australian plant.