Silver ion coordination countercurrent chromatography: Separation of β‐elemene from the volatile oil of Curcumae Rhizoma

Abstract

In this work, the antitumor constituent β-elemene was selectively separated from the volatile oil of the Curcumae Rhizoma by countercurrent chromatography with silver nitrate as selective reagent based on the formation of coordination complexes. A biphasic solvent system composed of n-hexane/methanol/water (2:1.5:0.5, v/v/v) was selected, in which 0.15 mol/L of silver nitrate was added to the aqueous phase. The aqueous phase was used as the stationary phase for separation of β-elemene by countercurrent chromatography after it was partially purified from the volatile oil by silica gel column chromatography. An enriched β-elemene fraction was obtained by silica gel column chromatography to improve the percentage of β-elemene from 16.5 to 46.1%. Subsequently, β-elemene was further purified from 445 mg of the partially purified sample of volatile oil by countercurrent chromatography with silver nitrate as a selective reagent, yielding 145 mg of β-elemene with greater than 99% purity, as determined by gas chromatography mass spectrometry. The recovery of β-elemene from the crude volatile oil through two steps was around 63.6%.

Nigella damascena L. Essential Oil—A Valuable Source of β-Elemene for Antimicrobial Testing

“…High-performance centrifugal partition chromatography (HPCPC) resulted in elution of β-elemene after 400 min [ 7 ], whereas our protocol enabled the elution of target compound in 70 min. Also, silver ion coordination high-speed counter-current chromatography resulted in higher elution time of β-elemene (over 80 min) [ 8 ] compared to our method. The differences in the elution time come from different separation conditions between these techniques (HPCCC vs. HPCPC or HSCCC; e.g., rotation speed, column volume, solvent system flow rate); however, they also come from the different essential oils used.…”

“…In both previously applied counter-current chromatographic techniques, C. Wenyuj in essential oil was used for β-elemene isolation. Because C. wenyujin essential oil contains a lot of constituents, Lu et al [ 8 ] introduced a silica gel column chromatography step before HSCCC separation. This enabled the removal of impurities and increased β-elemene content in the purified fraction [ 8 ].…”

“…Because C. wenyujin essential oil contains a lot of constituents, Lu et al [ 8 ] introduced a silica gel column chromatography step before HSCCC separation. This enabled the removal of impurities and increased β-elemene content in the purified fraction [ 8 ]. The two steps separation resulted in around 63% recovery [ 8 ].…”

“…This enabled the removal of impurities and increased β-elemene content in the purified fraction [ 8 ]. The two steps separation resulted in around 63% recovery [ 8 ]. The isolation protocol described in our study is more effective, since no purification step is required to obtain β-elemene with purity up to 96% and 80% yield.…”

“…Also, preparative gas chromatography with dimethylpolysiloxane or enantioselective cyclodextrin columns were applied [ 6 ]. Modern techniques based on the principle of liquid-liquid extraction (in which no losses of sample occurs), like high-performance centrifugal partition chromatography (HPCPC) [ 7 ] or high-speed counter-current chromatography (HSCCC) [ 8 ], were used to obtain β-elemene from plant material/essential oil as well. In our study the other modern technique based on the principle of liquid-liquid extraction, high performance counter-current chromatography (HPCCC), was applied, because it enables the achievement of a higher g level, and thus higher efficiency, compared to high-speed counter-current chromatography.…”