Obscurumines H–P, new Lycopodium alkaloids from the club moss Lycopodium obscurum

Seven new fawcettimine-type (1–7) and two new lycopodine-type (8 and 9) Lycopodium alkaloids, as well as 10 known compounds, were isolated from the club moss, Lycopodium obscurum L. The structures of obscurumines H–P (1–9) were determined based on high-resolution MS and 1D and 2D NMR data. Compounds 1 and 2 include a new skeleton that is formed via the linkage of C-9–N-2′, which is rarely present in Lycopodium alkaloids. The in vitro acetylcholinesterase (AChE) inhibitory activity assay showed that 5 exhibited weak anti-AChE activity with an IC50 value of 81.0 μM. Compound 8 exhibited inhibition of the secretion of IL-2 in phytohemagglutinin (PHA) and phorbol myristate acetate (PMA) stimulated Jurkat cells, and the IC50 value was 17.2 μM.

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