New Drimane Sesquiterpenoids from Tidestromia oblongifolia

From an acetone extract of the aerial parts of Tidestromia oblongifolia (Amaranthaceae), a new drimane sesquiterpenoid bearing an 11,12,13-trihydroxydrimene skeleton (1) as well as the 11,12 acetonide of 1 were isolated. Three known stigmastane triterpenoids were also isolated. Structures were elucidated with the aid of 1D and 2D NMR spectroscopic techniques. The absolute configuration of 1 was confirmed by single-crystal x-ray crystallography. This is the first report on phytochemical constituents from any plant of the genus Tidestromia and is the first report of the occurrence of drimanes in the Amaranthaceae.