Phytochemical analysis of alkaloids from the Icelandic club moss Diphasiastrum alpinum

More than 500 species of club mosses grow all around the world, but only five of them are represented in Iceland: Lycopodium annotinum, Selaginella selaginoides, Diphasiastrum alpinum, Huperzia selago, and Lycopodium clavatum. Club mosses produce a range of secondary metabolites called lycopodium alkaloids and some of them in particular huperzine A have shown interesting anticholinesterease activity (1). The present study is a phytochemical analysis of Diphasiastrum alpinum (Lycopodium alpinum) collected in Iceland. Previous studies on D. alpinum described the isolation of four alkaloids: lycopodine, clavolonine, lycoclavine and des-N-methyl-α-obscurine (2), however our investigation has shown that it contains at least eight alkaloids. The aim of this study was to isolate and elucidate the structures of these alkaloids. The plant extract was subjected to usual fractionation, and structures of the purified alkaloids were determined by 2D NMR spectroscopy including COSY, NOESY, HSQC and HMBC. This resulted in isolation of eight alkaloids including the previously reported lycopodine and clavolonine. Three of the remaining alkaloids are lycopodane type structures with two acetyl groups not previously reported. Lycoclavine and des-N-methyl-α-obscurine found in earlier studies could not be detected in the Icelandic collection of D. alpinum.

Acknowledgements: The Icelandic Research Fund, The University of Iceland Research Fund, The Icelandic Research Fund for Graduate Students, and Th. Scheving Thorsteinsson Fund.

References: 1. Wang, et al. (2009)J. Neural Transm. 116: 457–465.

2. Miller, et al. (1971) Phytochemistry 10:1931–1934.