Gwanakosides A and B, 6-Deoxy-α-l-talopyranose-Bearing Aromatic Metabolites from a <i>Streptomyces</i> sp. and Coculture with <i>Pandoraea</i> sp.
Huynh TH, Lee J, Moon DH, Nguyen TQ, Son S, Hwang S, Du YE, Cui J, Jang JH, Nam SJ, Shin J, Jang J, Lee SK, Oh KB, Oh DC.
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).