Antineuroinflammatory and Antiproliferative Activities of Constituents from Tilia amurensis

As part of our ongoing search for bioactive constituents of natural Korean medicinal resources, we found in a preliminary study that the methanol (MeOH) extract from the trunks of Tilia amurensis RUPR. showed an inhibitory effect on nitric oxide (NO) production in an activated murine microglial cell line. A bioassay-guided fractionation and chemical investigation of the MeOH extract resulted in the isolation and identification of a new isoflavonoid glycoside, orobol 4'-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside (1) and 16 known compounds (2-17). The structure of the new compound was determined by spectroscopic methods, i.e., one-dimensional (1D) and two-dimensional (2D)-NMR techniques and high resolution (HR)-MS, and chemical methods. The antineuroinflammatory activities of the isolated compounds were determined by measuring NO levels in the medium using murine microglial BV-2 cells. Among them, 12 compounds, including compound 1 (most active with an IC50 value of 23.42 µM), inhibited NO production in lipopolysaccharide-stimulated BV-2 cells. Moreover, compounds 1-4 showed moderate antiproliferative activities against the SK-MEL-2 cell line, with IC50 values ranging from 12.31 to 19.67 µM.