Three new serratane-type triterpenoids, japonicumins A -C (1 -3), as well as a unique, new C 13 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.
Introduction. -The plants of the genus Lycopodium are widely used as traditional Chinese herbal medicines for the treatments of arthritic pain, quadriplegia, dysmenorrhea, contusion, and other health problems [1] [2]. Previous chemical studies established the occurrence of alkaloids, serratenes, and flavones from this genus, some of them being biologically active [3 -11]. Serratenes are an unusual group of naturally occurring, pentacyclic triterpenes with a seven-membered central ring C, and they are well-known characteristic constituents of Lycopodium plants [5 -10]. Lycopodium japonicum THUNB., a species of this genus, is widely distributed in the Chinese provinces Guangdong, Guangxi, Yunnan, and Guizhou. It is commonly used as a traditional folk medicine [2], and has been reported to be a source of serratenes [5] [11].
During our search for biologically active secondary metabolites, we analyzed the acetone extract of J. japonicum and found four new compounds, japonicumins A -D (1 -4), together with the known serratane-type triterpenoid lycoclavanol (5) [12]. In this work, we report their isolation and structure elucidation.
Results and Discussion
. -Japonicumin A (1) was isolated as a colorless, optically active powder ([a] 25 D = À 1.3 (c = 0.57, MeOH)) with the molecular formula C 30 H 50 O 4 , as determined by positive-ion HR-ESI-MS ([M + Na] + at m/z 497 .3605; calc. 497.3606). The IR spectrum of 1 showed absorption bands characteristic of OH (3425) and CH 2 groups (2925 cm À1 ). The 1 H-NMR spectrum (Table 1) showed signals for six Me groups at tertiary C-atoms; and the 13 C-NMR spectrum (Table 2) exhibited signals for 30 C-atoms, including six quaternary ones (one olefinic), eight CH (three oxygenated, one olefinic), ten CH 2 (one oxygenated), and six Me groups. Comparison of the 1 H-and 13 C-NMR spectroscopic data of 1 with those of the known compound lycoclavanol (5) [12], which was also isolated in this study, showed that the two compounds are very similar. The only difference was the replacement of a CH 2 (12) signal © 2006 Verlag Helvetica Chimica Acta AG, Zürich
Experimental Part
General. Column chromatography (CC) was performed on silica gel (100 -200 mesh; Qingdao Marine Chemical, Inc., China) and silica gel H (10 -40 mm; Qingdao); fractions were monitored by TLC, and spots were visualized by spraying with 10% H 2 SO 4 in EtOH, followed by heating. UV Spectra: