Antrodia camphorata is an endemic mushroom in Taiwan. This study was designed to screen anti-inflammatory compounds from the methanolic extract of the mycelium of A. camphorata on nitric oxide (NO) production in RAW 264.7 cells induced by polyinosinic-polycytidylic acid (poly I:C), a synthetic analog of double-stranded RNA (dsRNA) known to be present in viral infection. A combination of bioactivity-guided isolation with an NMR-based identification led to the isolation of 4-acetylantroquinonol B (1), along with seven compounds. The structure of new compounds (4 and 5) was elucidated by spectroscopic experiments, including MS, IR, and NMR analysis. The anti-inflammatory activity of all isolated compounds was assessed at non-cytotoxic concentrations. 4-Acetylantroquinonol B (1) was the most potent compound against poly I:C-induced NO production in RAW 264.7 cells with an IC50 value of 0.57 +/- 0.06 mu M.
