Find in Library

Using the OSMAC (One Strain Many Compounds) approach, the actinobacterium <i>Streptomyces griseorubiginosus</i>, derived from an unidentified cnidarian collected from a reef near Pointe de Bellevue in Réunion Island (France), was subjected to cultivation under diverse conditions. This endeavour yielded the isolation of a repertoire of 23 secondary metabolites (<b>1</b>–<b>23</b>), wherein five compounds were unprecedented as natural products (<b>19</b>–<b>23</b>). Specifically, compounds <b>19</b> and <b>20</b> showcased novel anthrone backbones, while compound <b>23</b> displayed a distinctive tetralone structure. Additionally, compounds <b>21</b> and <b>22</b> presented an unusual naphtho [2,3-<i>c</i>]furan-4(9<i>H</i>)-one chromophore. Interestingly, the detection of all these novel compounds (<b>19</b>–<b>23</b>) was exclusively achieved when the bacterium was cultured in FA-1 liquid medium supplemented with the epigenetic modifier γ-butyrolactone. The elucidation of the structural features of the newfound compounds was accomplished through a combination of HRESIMS, 1D and 2D NMR spectroscopy, as well as QM-NMR (Quantum Mechanical—Nuclear Magnetic Resonance) methods and by comparison with existing literature. Moreover, the determination of the relative configuration of compound <b>23</b> was facilitated by employing the mix-<i>J</i>-DP4 computational approach.