# Electrospray–Mass Spectrometry-Guided Targeted Isolation of Indole Alkaloids from Leaves of Catharanthus roseus by Using High-Performance Countercurrent Chromatography

## TL;DR

Scientists isolated six major indole alkaloids from Catharanthus roseus leaves using a mass spectrometry-guided chromatography method.

## Contribution

A novel electrospray-mass spectrometry guided HPCCC method was developed for targeted isolation of indole alkaloids.

## Key findings

- Six indole alkaloids were successfully isolated and identified using NMR spectroscopy.
- The biphasic solvent system with trifluoroacetic acid improved separation efficiency.
- Electrospray mass spectrometry enabled real-time monitoring of metabolite recovery.

## Abstract

Electrospray mass spectrometry off-line profiling monitored the recovery of targeted indole alkaloids from a fortified crude extract of Catharanthus roseus (790 mg) using semi-preparative high-performance countercurrent chromatography (HPCCC) fractionation. Visualization of selected single-ion traces projected the HPCCC molecular weight elution profile. Experimental partition-ratio values KD and peak widths for detected metabolites were determined. Structural characterization of metabolites and co-elution effects were monitored in the scan range m/z 100–2000. In this study, the biphasic solvent system containing n-hexane–n-butanol–water with 0.5% ion-pair reagent trifluoro-acetic acid [1:1:2, v/v/v] was used based on partition ratio KD-value liquid chromatography–electrospray ionization–mass spectrometry (LC-ESI-MS) analysis prediction. The monitoring of target ions resulted in the isolation of six major concentrated indole alkaloids (akuammicine, catharanthine, perivine, vindoline, vindorosine, and 19R-vindolinine), which were fully elucidated by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy.