Protostane alisol derivatives from the rhizome of Alisma orientale

Abstract

Alisma orientalis is a well-known traditional Chinese medicine with diuretic, hypopietic, hypolipemic, and antiatherosclerotic activities. In the present study, we investigated triterpenoids from the rhizome of A. orientalis, identifying four new alisol derivatives, namely, Alismanol M (1), Alismanol Q (2), Alismanol O (3) and Alismanol P (4). The structures of these compounds were characterized using detailed spectroscopic analysis (UV, HRESIMS, 1D and 2D NMR data including HSQC, HMBC, 1H–1H COSY, and NOESY). These four new alisol derivatives were all protostane triterpenoids, belonging to a group of tetracyclic triterpenes. A 17, 23- or 20, 24-five-membered oxide ring is the primary structural characteristic of these alismanols (1–4). Furthermore, in vitro bioassays demonstrated that the isolated compounds could not inhibit nitric oxide production in LPS-induced macrophages.