Five new labdane diterpenes from Aster oharai

Five new labdane diterpenes (1-5) together with seven known diterpenes have been isolated from a methanol extract of the aerial parts of Aster oharai Five new structures were determined as 7alpha hydroperoxylabda 8(17),14 then 13(R) ol 4 O acetyl alpha L 6 deoxyidopyranoside (1) 7alpha hydroperoxylabda 8,14 then 13(R) ol 4 O acetyl alpha L 6 deoxyidopyranoside (2), labda 7,14 dien 13(R) ol 4 O acetyl alpha L rhamnopyranoside (3), labda 7 14 dien 13(R) ol-3 O acetyl alpha L rhamnopyranoside (4), and labda 7 14 dien 13(R) ol 2 O acetyl alpha L rhamnopyranoside (5), on the basis of spectroscopic methods Compound I showed moderate cytotoxicity against four cultured human tumor cell lines with ED50 values ranging from 11 to 7 7 mug/mL.