Chemical constituents from Alismatis Rhizoma and their anti-inflammatory activities in vitro and in vivo

Six new compounds, including a new compound with an unusual 2, 4, 6-cycloheptatrien ketone skeleton (1), two new diphenylpropanoid ethers (2, 3), a new protostane-type triterpenoid (4), two new norsesquiterpene (5a, 5b), and two new natural products (6, 7), together with eleven known compounds (8–18) were isolated from the aqueous extract of Alismatis Rhizoma (AR). Their structures were elucidated by a combination of 1D and 2D NMR (1H and 13C NMR, COSY, HSQC, HMBC, and NOESY), HRESIMS spectroscopic data, experimental and calculated electronic circular dichroism (ECD) spectra. Some of the compounds were evaluated for their inhibitory effects on nitric oxide (NO) production in LPS-induced RAW 264.7 cells. Two protostane-type triterpenoids, compounds 4 and 17, exhibited potent inhibitory activities with the IC50 values of 39.3 and 63.9 μM compared with indomethacin. In the meanwhile, their anti-inflammatory effects were also confirmed by acute inflammation model induced by CuSO4 in zebrafish.