Three new eudesmane sesquiterpenoids and a new dimer from the aerial part of Salvia plebeia R. Br.

Four new compounds, including three eudesmane sesquiterpenoids (1-3) and a dimeric sesquiterpenoid lactone (4), were isolated from the aerial part of Salvia plebeia R. Br., together with two known eudesmanolides (5-6). Their structures were elucidated by extensive spectroscopic analysis including 1D and 2D NMR, HR-ESI-MS spectra. Antiproliferative activities of isolates against six human myeloid leukemia cell lines were evaluated, salplebeone D (1) and G (4) showed moderate inhibitory activity. In addition, compound 4 was a rare eudesmane sesquiterpenoid dimer obtained from this specie for the first time.