Rapid Separation of Three Proanthocyanidin Dimers from Iris lactea Pall. var. Chinensis (Fisch.) Koidz by High-Speed Counter-Current Chromatography With Continuous Sample Load and Double-Pump Balancing Mode.

BACKGROUND

The dried seeds of Iris lactea have been used in traditional Chinese medicine. Previous studies have been focused on irisquinones while other chemical components are rarely reported.

OBJECTIVE

To establish an efficient high-speed counter-current chromatography (HSCCC) separation method with continuous sample load (CSL) and double-pump balancing (DPB) mode to isolate proanthocyanidins from I. lactea.

METHODS

Firstly, an ethyl acetate extract of I. lactea was pre-fractionated by silica column chromatography for the enrichment of proanthocyanidins. Secondly, the enriched proanthocyanidins sample (EPS) was further fractionated by HSCCC with a two-phase solvent system ethyl acetate:n-butanol:water (9:1:10, v/v/v) using DPB mode. The flow rate of the two phases was 2.2 mL/min, the revolution speed was 900 rpm, the separation temperature was 30 °C and the detection wavelength was 280 nm. Finally, the structures of the three isolated proanthocyanidins were elucidated by spectroscopic methods and compared with published data.

RESULTS

Under the optimized conditions, 600 mg of the EPS with six continuous injections (100 mg/time) was fractionated, yielding 57 mg of prodelphinidin B3, 198 mg of procyanidin B3, and 162 mg of procyanidin B1, at purities of 97.2%, 98.1% and 97.3%, respectively.

CONCLUSIONS

The HSCCC separation method with CSL and DPB proved to be rapid, convenient and economical, constituting an efficient strategy for the isolation of proanthocyanidins.