Anti-inflammatory and Antinociceptive Constituents of Atractylodes japonica Koidzumi

The rhizomes of many Atractylodes species, including Atractylodes chinensis Koidzumi, Atractylodes macrocephala Koidzumi, and Atractylodes japonica Koidzumi, are collectively termed Atractylodis Rhizoma. We prepared n-hexane extracts of the three species and evaluated their anti-inflammatory effects on lipopolysaccharide (LPS)-induced RAW 264.7 cells. Among all n-hexane extracts, those of A. japonica most strongly inhibited nitric oxide (NO) production in LPS-induced RAW 264.7 cells; five sesquiterpenes, atractylon, atractylenolide I, atractylenolide II, atractylenolide III, and 8-epiasterolid, were isolated from A. japonica. The phytochemical content of A. japonica was similar to those of A. chinensis and A. macrocephala. Moreover, the atractylon concentration was higher in A. japonica than in A. chinensis and A. macrocephala. Atractylon significantly inhibited NO and prostaglandin E₂ production as well as inducible NO synthase and cyclooxygenase-2 expression in LPS-induced RAW 264.7 cells. Atractylon (40 mg/kg) also significantly reduced the acetic-acid-induced writhing response, carrageenan-induced paw edema, and hot-plate latent pain response in mice. According to the results, A. japonica has anti-inflammatory and antinociceptive effects and atractylon is the major active component of A. japonica. Therefore, atractylon can be used as a bioactivity marker in A. japonica.