Determination of Lotus Leaf Alkaloids by Solid Phase Extraction Combined with High Performance Liquid Chromatography with Diode Array and Tandem Mass Spectrometry Detection

Abstract

Lotus (nelumbo) is a traditional Chinese medical herb, and alkaloids are responsible for its pharmaceutical activities. Therefore, a rapid, validated method to determine alkaloids in lotus leaves is useful for its quality control. The goal of this work was to develop and validate an analytical method for the identification and quantitation of the bioactive alkaloids of extracts from lotus leaf and classification of lotus germplasm based on alkaloid concentrations. Solid-phase extraction was used prior to high-performance liquid chromatography coupled with photodiode array detection at 272 nm and tandem electrospray ionization triple quadrupole mass spectrometry for analysis. Nuciferine and O-nornuciferine were the dominant compounds in lotus used for seed production and some used for flower production. However, anonaine, roemerine, and N-nornuciferine were abundant only in some lotus flowers. All the lotuses were classified into four groups by principal component analysis of alkaloid content: 10 flower and three seed lotuses characterized by high nuciferine and O-nornuciferine content; 12 flower lotuses with high N-nornuciferine, roemerine, and anonaine content; two flower lotuses with a relatively high content of all five alkaloids; and cultivars with a low alkaloid content and without dominant alkaloids.

Keywords:

• Alkaloids
• HPLC-MS
• Lotus germplasm
• PCA

Acknowledgments

This study was financially supported by The Knowledge Innovation Project of Chinese Academy of Sciences (No. KSCX2-EW-J-20). The authors thank Douglas D. Archbold (Department of Horticulture, University of Kentucky, USA) for his critical review of the manuscript.

Notes

Note: Numbers in parentheses represented cultivars. The underlined cultivars were studied in two consecutive years (2009–2010).

^a Correlation coefficients of each and total alkaloid content between two years. *, **, and ***, respectively, indicate significance at P < 0.05, P < 0.01, and P < 0.001.

^b There was no significant difference in each and total alkaloid contents, and in relative alkaloid content between 2009 and 2010 via Paired-Sample t Test at P < 0.05.