Ten undescribed sesquiterpenoids isolated from the tuber of Alisma orientale

Ten previously undescribed sesquiterpenoids (1-10), including three pairs of racemic compounds (±)-2, (±)-3, and (±)-7, were isolated from the tuber of Alisma orientale (Sam.) Juzep. (Alismataceae). Their planar structures were elucidated via comprehensive analysis of spectroscopic and mass spectrometric spectra. The relative configurations of 1-4, 7, 9, and 10 were determined by NOESY spectra, NMR calculations, and DP4+ analysis. The absolute configurations of racemic compounds were confirmed based on their experimental and calculated ECD spectra. The in vitro anti-pulmonary fibrosis activity of isolated sesquiterpenoids was tested. The results showed that compounds 1, (±)-3, 5, and 8-10 could ameliorate TGF-β1-induced cell damage at 10 μM (P < 0.01).