Abstract: Two new compounds 1-2 and four known compounds 3-6 were isolated from the fermentation broth of Streptomyces sp.HCCB11431 by using silica gel column chromatography and semi-preparative HPLC chromatography.They were identified as 3-(3-acetoxy-4-methoxy-5-methylphenyl)-2-aminopropanoic acid (1), 3-(3-acetoxy-4-hydroxyl-5-methyphenyl)-2-aminopropanoic acid (2), 2′-dexoyadenosine (3), Cytidine (4), Uridine (5), 2′-deoxycytidine (6) based on the date of IR,MS and NMR.All compounds exhibited cytotoxicity against breast cancer cell line MCF-7,pancreatic cancer cell line PANC-1 and prostatic cancer cell line Du145. Compounds 2-4 showedstrong inhibitory against MCF-7 with IC₅₀ values of 7.9,10.1 and 9.5 μg/mL,respectively.

Key words: Streptomyces sp.HCCB11431, cytotoxicity, metabolites