Members of the class Actinobacteria have been extensively studied because of their ability to produce pharmaceutically useful compounds. In order to construct a natural product library for bioactivity screening, we isolated a diverse variety of actinomycetes from marine resources, including marine sponges and tunicates, and mangrove soils, as well as the conventionally utilized terrestrial soils. As a result, we discovered novel compounds such as the anti-influenza compound JBIR-68,1 promothiocin derivatives JBIR-83 and -84,2 naphthablin analogs JBIR-79 and -80,3 and new angucyclines JBIR-90, -91, -92, -93 and -116.4 Further screening resulted in the isolation of two new cytotoxic compounds, JBIR-76 (1) and JBIR-77 (2), in addition to the antioxidative naphthoquinone-like polyketide, designated JBIR-85,5 from the culture of Streptomyces sp. RI-77 obtained from a soil sample collected in Okinawa Prefecture, Japan. This paper describes the fermentation, isolation, structural elucidation and brief biological activities of 1 and 2.