Anti-inflammatory isocoumarins from the bark of Fraxinus chinensis subsp. rhynchophylla
A new isocoumarin (1) named fraxicoumarin was isolated from the bark of Fraxinus chinensis subsp. rhynchophylla along with three known compounds (2–4). The structure of the new compound was established by extensive spectroscopic studies and chemical evidence. The anti-inflammatory effects of the isolated compounds (1–4) on lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells were evaluated in vitro. Of the compounds tested, compounds 1 and 3 inhibited LPS-induced nitric oxide (NO) production in RAW 264.7 cells. Consistent with these findings, they also suppressed LPS-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the protein level in RAW 264.7 cells.