Studies on the Constituents of Viburnum Species. XIX. Six New Triterpenoids from Viburnum dilatatum THUNB.

Six new triterpenoids, viburnudienone B1 methyl ester (1), viburnudienone B2 methyl ester (2), viburnudienone H1 (3), viburnudienone H2 (4), viburnenone B1 methyl ester (5) and viburnenone B2 methyl ester (6), were isolated from the leaves of Viburnum dilatatum (Caprifoliaceae). Their structures were established by extensive spectroscopic studies.