Chemical investigation of the terrestrial Streptomyces sp. isolates GT2005/020 and ANK148 led to the isolation of two microbial furanone derivatives, 5-hydroxy-4-methylnaphtho[1,2-b]furan-3-one (1) and 4-hydroxy-5-methyl-furan-3-one (2), respectively, which have some similarity to quorum sensing molecules of the AI-2 type. In addition, the known compounds chalcomycin, ferulic acid, indole-3-acetic acid, uracil, thymine, 2'-deoxy-thymidin, monensin B (3), phencomycin, and 1-acetyl-beta-carboline were isolated. The structures of 1 and 2 were deduced from extensive studies of NMR (1D and 2D) and mass spectra. Additionally, the complete NMR shift assignments for monensin B (3) using H-H COSY, HMQC and HMBC experiments are reported here for the first time. We are describing the taxonomy and fermentation of the producing strains, the structure elucidation of the new metabolites and their bioactivity.