Rapid Isolation and Purification of the Antidepressants Mesembrine and Mesembrenone from Mesembryanthemum tortuosum

Abstract

Mesembryanthemum tortuosum is a medicinal plant that has traditionally been used as a mood enhancer, stress reducer, analgesic, anxiolytic, and even a narcotic. Its primary activity is attributed to mesembrine-type alkaloids, which have shown pharmacological and clinical promise as antidepressants and anxiolytics. Due to the limited availability and high cost of pure reference compounds, the aim of this study was to develop a rapid purification method for mesembrine and mesembrenone from
M. tortuosum. A simple acid-base partitioning of a dichloromethane extract was utilised as the initial partial purification step, directly followed by semi-preparative High-Performance Liquid Chromatography
(HPLC) as a final purification step. This reduced the number of purification steps compared to previously reported methods. Analytical quantities of mesembrenone and mesembrine (chemical structures confirmed by Nuclear Magnetic Resonance spectroscopy and Mass Spectrometry) were purified to approximately 98% purity (as determined by HPLC). The entire purification process, from extraction to the isolation of pure compounds, was completed in a relatively short period of just four hours. Ultimately, a rapid and simple method to purify the mesembrine-type alkaloids, mesembrine and mesembrenone, was developed, yielding sufficient quantities for use in analytical studies. This
provides a cost-effective approach to overcoming the scarcity of pure reference compounds for M. tortuosum.