Two new compounds from rifamycin resistant mutant strain Streptomyces sp. HS-NF-1046R

Using silica gel column chromatography, gel chromatography and HPLC, we isolated secondary metabolites in fermentation broth of a rifamycin resistant mutation strain Streptomyces sp. HS-NF-1046R. Based on spectroscopic data, the chemical structures of three compounds were identified as 3-hydroxyl-2-N-propionyl-anthranilamide (1), 2,3-dihydro-8-hydroxy-2,2-dimethyl quinazolin-4-(1H)-one (2) and 2-aminobenzamide (3). Compounds 1 and 2, as new entities, were evaluated for cytotoxicity against A549, HepG2, HCT-116 and K562 cells using the SRB assay. Compounds 1 and 2 exhibited no cytotoxicity with IC₅₀ over 100 μmol·L^-1.