Japonicumins A–D: Four New Compounds from Lycopodium japonicum

Three new serratane‐type triterpenoids, japonicumins A–C ( 1 – 3 ), as well as a unique, new C₁₃ terpenoid, japonicumin D ( 4 ), were isolated from the dried whole plants of Lycopodium japonicum, together with the known compound lycoclavanol ( 5 ). Their structures were identified by extensive mass‐spectrometric and spectroscopic (especially 2D‐NMR) experiments. Compounds 1 – 5 exhibited no activity against human‐tumor A 549 cells.