Structures and Biomimetic Synthesis of Novel α‑Pyrone Polyketides of an Endophytic <i>Penicillium</i> sp. in <i>Catharanthus roseus</i>

Abstract

Novel polyketides, citreoviripyrone A (<b>1</b>) and B (<b>2</b>), known citreomontanin (<b>3</b>), and (−)-citreoviridin (<b>4</b>) were isolated from the mycelium of the endophytic fungus. The endophytic fungus, which belongs to the genus <i>Penicillium</i>, was separated from surface-sterilized healthy leaves of <i>Catharanthus roseus</i>. The structures of <b>1</b> and <b>2</b> were determined on the basis of NMR data, and <b>1</b> was characterized as an α-pyrone polyketide featuring bicyclo[4.2.0]octadiene. The biomimetic synthesis of <b>1</b> and <b>2</b> from <b>3</b> elucidated a plausible biosynthetic pathway. Both Zn(II)-type and NAD⁺-dependent histone deacetylase inhibitors significantly enhanced the production of <b>1</b> and <b>3</b>