ObjectiveTo investigate the chemical constituents in the mycelia of an acidoduric streptomycetes.MethodsMultiple chromatographic methods were used to isolate and purify the constituents, and their chemical structures were identified by NMR, IR, and MS.The anti-inflammatory activities of four compounds were observed in rats with CⅡ-A-induced toe swelling experiments.ResultsFour compounds were identified: 8-(4-hydroxy-3, 5-di-methoxy phenyl)-2, 3-dimethoxy-1, 6-naphthalenediol (1),7, 4′-dihydroxy isoflavone (2), 5,7,4′-trihydroxyisoflavone (3), and 3,4,5-trihydroxybenzoic acid (4).Compound of 2, 3, and 4 could inhibit CⅡ-A-induced toe swelling in rats at 10 mg/(kg· d).ConclusionCompound 1 is a novel compound, and other compounds have been isolated from the acidoduric Streptosporangium sp. for the first time. Compounds 2, 3, and 4 possess anti-inflammatory activities.