Sesquiterpenes from Atractylodes japonica and their Inhibitory Activities on Nitric Oxide Production in Macrophage RAW264.7 Cells

In this study, the dried rhizomes of Atractylodes japonica Koidz. were extracted with MeOH, suspended with water, and continuously partitioned with n-hexane, CHCl₃, EtOAc, and n-BuOH. Fourteen compounds were isolated from the n-hexane and CHCl₃ fractions using various chromatographic techniques. Chemical structures of twelve compounds were characterized by spectroscopic methods as sesquiterpenes including atractylenolide III (1), atractylenolide II (2), 8β-methoxyatractylenolide (3), 4,15-epoxy-8β-hydroxyasterolide (4), (3R)-3-hydroxyatractylenolide III (5), taenialactam B (6), 8-epiasterolide (7), eudesma-3,7(11)-dien-5,15-dihydroxy-8α,13-olide (8), 4(15)-eudesmene-1β,7,11-triol (9), 3-eudesmene-1β,7,11-triol (10), eudesm-7(11)-en-4-ol (11), and eudesm-4(15),7-diene-11-ol (12). The others were determined to be a polyacetylene and a steroid glycoside viz., atractylodiol (13) and daucosterol (14). Compounds 8 and 12 are reported for the first time from nature, compounds 5, 6, 9, and 10 are newly reported from Compositae, compound 7 is newly reported from Atractylodes genus, and compounds 3, 4, and 11 are reported for the first time from A. japonica.

The inhibition on LPS-induced NO production of the isolated compounds were measured using Griess assay in RAW264.7 cells. Among the compounds, compounds 2 and 10 showed higher activity in dose-dependent manner without cytotoxicity. Compound 2, not containing 8-hydroxy moiety, displayed higher inhibitory activity than compounds 1, 4, and 5 that contain the 8-hydroxy moiety.