Chemical Constituents Isolated from Bletilla striata and Their Inhibitory Effects on Nitric Oxide Production in RAW 264.7 Cells.

Bioassay-guided fractionation of the MeOH extract of the tubers of Bletilla striata led to the isolation of two new C-methylated flavan-3-ols, bletillanols A (1) and B (2), along with ten known compounds (3 - 12). Their structures were determined by using extensive spectroscopic analysis including 1D-, 2D-NMR, and circular dichroism data. All of the isolated compounds were tested for their inhibitory potential on the nitric oxide generation in LPS-stimulated RAW 264.7 cells.