Eight eudesmane-type sesquiterpenes -phaeusmanes A-H (1-8) -isolated for the first time in this work, and four others (9-12) isolated for the first time from plants in this work, together with fourteen known eudesmane derivatives, were isolated from the rhizomes of Curcuma phaeocaulis. Their structures were elucidated by 1D and 2D NMR and CD spectroscopy and HRMS. Compound 8 is the first example of a nitrogen-containing eudesmane-type sesquiterpene isolated from the genus Curcuma. Furthermore, inhibitory effects of [a]5540 the isolated compounds on NO production in lipopolysaccharide-activated macrophages were evaluated. Compounds 1, 6, 10, 19, 22, and 24 showed strong inhibitory activities on NO production with IC 50 values of 3.2, 4.8, 1.2, 0.8, 3.8, and 0.8 μM, respectively. Preliminary structure-activity relationships for these compounds are proposed. A possible biogenetic pathway for nitrogen-containing eudesmane-type sesquiterpene 8 is postulated.www.eurjoc.org

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