A novel 13-membered spermidine macrocyclic alkaloid, (2R)-9-furoyl-2-phenyl-1,5,9-triazacyclotridecane-4,13-dione, named celacarfurine (1), was isolated from the roots of Tripterygium wilfordii. Its structure has been elucidated on the basis of NMR and MS data. To the best of our knowledge, 13-membered spermidine macrocyclic alkaloids were rarely reported natural products; moreover, the known ones were generally in the 2S configuration and there was none or only one amide carbonyl in the macrocycle. A (2R)-13-membered spermidine macrocyclic alkaloid containing two amide carbonyls in the macrocycle (celacarfurine) is reported here for the first time. Compound 1 showed statistically significant inhibitory effects on IL-1 beta secretion in LPS-induced rat primary synovial fibroblasts at 10 mu M.