New 2-isobutylmalates from the tubers of Bletilla striata and their potential anti-pulmonary fibrosis activities

Two new 2-isobutylmalates, named bletimalate C (1) and bletimalate D (2), together with eight known ones (3-10) were isolated from the tubers of Bletilla striata using various chromatographic methods. Their structures were elucidated with the aid of extensive spectroscopic data analyses and by comparison NMR data with those reported in literature. The anti-pulmonary fibrosis activity on TGF-beta 1-actived NIH/3T3 cells were evaluated for all isolates. Among them, compounds 1, 7 and 10 showed potential anti-pulmonary fibrosis effects with IC50 values of 22.16 +/- 1.18 mu M, 32.35 +/- 3.01 mu M and 19.52 +/- 4.05 mu M, respectively.