Induction of New Aromatic Polyketides from the Marine Actinobacterium through an OSMAC Approach.

Using the OSMAC (One Strain Many Compounds) approach, the actinobacterium , 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 (-), wherein five compounds were unprecedented as natural products (-). Specifically, compounds and showcased novel anthrone backbones, while compound displayed a distinctive tetralone structure. Additionally, compounds and presented an unusual naphtho [2,3-]furan-4(9)-one chromophore. Interestingly, the detection of all these novel compounds (-) 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 was facilitated by employing the mix--DP4 computational approach.