Single-strain cultivation of a mountain soil-derived <i>Streptomyces</i> sp. GA02 and its coculture with <i>Pandoraea</i> sp. GA02N produced two aromatic products, gwanakosides A and B (<b>1</b> and <b>2</b>, respectively). Their spectroscopic analysis revealed that <b>1</b> is a new dichlorinated naphthalene glycoside and <b>2</b> is a pentacyclic aromatic glycoside. The assignment of the two chlorine atoms in <b>1</b> was confirmed by the analysis of its band-selective CLIP-HSQMBC spectrum. The sugars in the gwanakosides were identified as 6-deoxy-α-l-talopyranose based on <sup>1</sup>H-<sup>1</sup>H coupling constants, Rotating frame Overhauser enhancement spectroscopy (ROESY) NMR correlations, and chemical derivatization followed by spectroscopic and chromatographic analyses. The absolute configuration of <b>2</b>, whose production was enhanced approximately 100-fold in coculture, was proposed based on a quantum mechanics-based chemical shift analysis method, DP4 calculations, and the chemically determined configuration of 6-deoxy-α-l-talopyranose. Gwanakoside A displayed inhibitory activity against pathogenic bacteria, including <i>Staphylococcus aureus</i> (MIC = 8 μg/mL) and <i>Mycobacterium tuberculosis</i> (MIC<sub>50</sub> = 15 μg/mL), and antiproliferative activity against several human cancer cell lines (IC<sub>50</sub> = 5.6-19.4 μM).