A novel eremophilane dimer, named as fischelactone, and a new sesquiterpene lactam, eremophila-1(10),7(11),8-triene-12,8-lactam, along with ten known compounds, were isolated from the roots of Ligularia fischeri. Their structures were established by means of spectroscopic analyses (EI-MS, HR-ESI-MS, IR, and 1D-and 2D-NMR data) and X-ray diffraction study.

A new farnesene derivative, 7R*,10S*-epoxy-3E,5E-farnesadien-1,2,11-triol, along with eight known compounds was isolated from the aerial parts of Senecio cannabifolius. Their structures were established on the basis of spectroscopic methods.

NoteSesquiterpenoids are the characteristic secondary metabolites of the Asteraceae family.1) Some of them showed a wide range of biological and pharmacological properties including insect antifeedant,2) anti-inflammatory activity, 3) antibacterial activity, 4) antimalarial activity, 5) cytotoxicity, 6) and nuclear factor kB (NF-kB) inhibition activity 7) etc. The investigation of the structure diversities, structure-activity relationships and biosynthetic approaches of the sesquiterpenoid constitutes in traditional Chinese medicines to screen for cytotoxic leads to drug has been the principal subject of our researchs. 8,9) Ligularia fischeri (LEDEB.) TURCZ. (Asteraceae) has long been used as a folk medicine in China for the treatment of coughs, inflammations, jaundice, scarlet fever, rheumatoidal arthritis, and hepatic diseases.10) In the mid1970s, Japanese researchers initially isolated furanoeremophilane-type sesquiterpenoids from this plant for the first time.11) Subsequent phytochemical researches of this plant collected in different region have resulted in the isolation of many eremophilane-type lactones and norsesquiterpene derivatives. [12][13][14] Recently, we reported the structures of eremophilane dimers and an eremophilane lactam from this plant. 15,16) This paper describes the isolation and structure elucidation of two sesquiterpenoid-geranylhydroquinone hybrids, namely fischerisin A (1) and fischerisin B (2), isolated from the roots of L. fischeri. To the best of our knowledge, these two compounds represent a kind of unprecedented sesquiterpenoid derivative. In addition, the in vitro cytotoxicity of both compounds against cultured human oral epidermoid carcinoma (KB) and human breast cancer (MCF-7) cell lines was also evaluated. Results and DiscussionThe petroleum ether (60-90°C)-Et 2 O-CH 3 OH (1 : 1 : 1) extract of the root of L. fischeri was chromatographed on a silica gel column with a gradient of hexane-acetone as eluent. After the sequential purification, fischerisin A (1) and fischerisin B (2) were finally obtained from the part of hexane-acetone (10 : 1).Fischerisin A (1) During the course of screening natural sesquiterpenoids for new antitumor agents, two novel compounds, fischerisin A (1) and fischerisin B (2), were isolated from the roots of Ligularia fischeri. Their structures were elucidated by interpretation of their IR, high resolution-mass spectrometry (HR-MS), 1D-and 2D-NMR data. Fischerisin A and B are the first representatives of a novel sesquiterpenoid-geranylhydroquinone hybrid, and both compounds exhibited in vitro cytotoxicity against cultured human oral epidermoid carcinoma (KB) and human breast cancer (MCF-7) cell lines with IC 50 values of 9.7 and 10.2 m mM, and 9.8 and 17.8 m mM, respectively.