Two novel neo-clerodane diterpenoids from Scutellaria barbata

Two novel neo-clerodane Diterpenoids, barbatellarines A (1) and B (2), were isolated from the whole Plants of Scutellaria barbata, along with the known compound scutebarbatine F (3). The chemical structures and relative stereochemistry of the isolated compounds were established by NMR (1D and 2D) and mass spectroscopic analyses. Compounds 2 and 3 were evaluated for in vitro cytotoxic activity against the HL-60 (human leukemia), MCF7 (human breast Cancer), and LLC (Lewis lung carcinoma) Cancer cell lines. Compound 2 exhibited weak cytotoxic activity against HL-60 cells, with an IC(50) value of 41.4microM.