From the leaves of Machilus japonica Sieb. et Zucc., four lignans were isolated; they have been found to be (+)-galbacin [1], (+)-galbelgin [2], (−)-licarin-B [4], and a new lignan, machilusin, whose structure can be described as [3a] or [3b].
The structures of two new sesquiterpene glycosides, pittosporanoside A1, and A2, isolated from the title plant were determined on the basis of chemical and spectral evidence and X-ray crystal structure analysis.
A new labile highly oxygenated sesquiterpene has been isolated from Neolitsea acciculata Koidz (Lauraceae, lnugashi in Japanese), and its structure determined by X-ray diffraction analysis.
Culcitiolides E-J (1-6), six new eremophilane-type sesquiterpenes, were isolated from the stem of Senecio culcitioides Sch. Bip. (Asteraceae). The structures were determined by detailed NMR spectral analysis. The inhibitory activities of these compounds against nuclear factor κB (NF-κB)-dependent gene expression were assessed. Culcitiolides E, H, and I potently inhibited NF-κB-induced gene expression at 20 µm.Key words Senecio culcitioides; eremophilane; culcitiolide; nuclear factor κB Senecio culcitioides Sch. Bip. is distributed throughout the Peruvian Andes in South America at an altitude of 4500-5000 m. S. culcitioides belongs to the family Asteraceae and has been used as a traditional folk medicine to treat cough, bronchitis and asthma.1-3) Nuclear factor κB (NF-κB) is a transcription factor and functions as a key regulatory element in inflammatory and immune responses and in cancer. During our search for new classes of inhibitors of NF-κB derived from natural products, we previously isolated culcitiolides A-D, eremophilane-type sesquiterpenoids from the stem of the previously uninvestigated plant S. culcitioides, and we showed that culcitiolides C and D are potent NF-κB inhibitors. 4) Our continuous effort to identify NF-κB inhibitors in S. culcitioides led to the isolation of six new eremophilane-type sesquiterpenoids exhibiting potent NF-κB inhibitory activity. Herein, we describe the isolation and structural elucidation of culcitiolides E-J and the evaluation of their inhibitory activities against NF-κB-dependent gene expression.
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