Preparative separation of alkaloids from Gelsemium elegans Benth. using pH-zone-refining counter-current...

Area of Science:

• Phytochemistry
• Chromatographic Techniques
• Natural Product Chemistry

Background:

• Gelsemium elegans alkaloids exhibit significant therapeutic potential, including anti-tumor, analgesic, and anti-inflammatory properties.
• Traditional Chinese medicine utilizes G. elegans for treating chronic pain and skin ulcers.
• Existing methods for alkaloid separation from G. elegans are inefficient, time-consuming, and yield low recovery rates.

Purpose of the Study:

• To develop and validate an efficient method for separating and purifying major alkaloids from Gelsemium elegans.
• To assess the efficacy of pH-zone-refining counter-current chromatography (CCC) for this purpose.

Main Methods:

• Utilized pH-zone-refining counter-current chromatography (CCC) for alkaloid separation.
• Employed a two-phase solvent system: methyl tert-butyl ether (MtBE)/acetonitrile/water (3:1.5:4, v/v).
• Incorporated triethylamine (20 mM) as a retainer in the organic phase and hydrochloric acid (10 mM) as an eluter in the aqueous phase.

Main Results:

• Successfully isolated gelsemine (312 mg), koumine (420 mg), and gelsevirine (195 mg) from 1.5 g of crude G. elegans extract.
• Achieved high purities for the isolated alkaloids: gelsemine (94.8%), koumine (95.9%), and gelsevirine (96.7%), as determined by High-Performance Liquid Chromatography (HPLC).
• Confirmed the chemical identity of the isolated compounds using electrospray ionization-mass spectrometry (ESI-MS), ¹H NMR, and ¹³C NMR.

Conclusions:

• pH-zone-refining CCC is a highly effective and efficient technique for the separation and purification of major alkaloids from Gelsemium elegans.
• This advanced chromatographic method surpasses traditional techniques in terms of speed and recovery.
• The isolated alkaloids hold promise for further investigation into their therapeutic applications.