Cytotoxic Diterpenoids from Rabdosia japonica var. glaucocalyx

Abstract

The structures of two new diterpenoids [glaucocalyxin X(1) and glaucocalyxin F(2)] from the whole plant of Rabdosia japonica (Burm. f.) Hara var. glaucocalyx (Maxim.) Hara. were confirmed furthermore on the basis of ¹H-¹H COSY and NOESY spectrum, respectively. Compounds 1 and 2 were tested in vitro for their cytotoxicity against human tumour cell lines HL-60,6T-CEM, LOVO and A549. Compound 1 exhibited good cytotoxicity with IC₅₀ values of 3.16, 1.57,1.73 and 3.31 μg/mL, respectively. but compound 2 showed no activity against the above cancer cell lines with IC₅₀ values all higher than 100 μg/mL.