Cytotoxic ent‐Kaurane Diterpenoids from Rabdosia Rubescens

Abstract

Abstract One new ( 1 ) and 11 reported ent ‐kaurane diterpenoids ( 2 – 12 ) were received from the ethanol extract of the air‐dried aerial parts of Rabdosia rubescens collected in Jiyuan. Their structures were determined in accordance with high resolution electrospray ionization mass spectroscopy, one dimensional (1D) and two‐dimensional (2D) NMR spectroscopy and the data published in the literature. The cytotoxic activity of these isolated compounds was assessed against SMMC‐7721, A‐549, H‐1299 and SW‐480 cancer cell lines. Compounds 2 – 6 revealed significant cytotoxic activity on lung cancer cell lines A549 with IC 50 values from 6.2 to 28.1 μM. Analysis of structure−activity relationship of these tested compounds indicated the carbonyl at C‐15 and hydroxy at C‐1 together could be crucial groups for inhibiting lung cancer cell lines A549 proliferation.