Polyketides and Alkaloids from the Marine-Derived Fungus Dichotomomyces cejpii F31-1 and the Antiviral Activity of Scequinadoline A against Dengue Virus

Abstract

In our continuous chemical investigation on the marine-derived fungus <i>Dichotomomyces cejpii</i> F31-1, two new polyketides dichocetides B-C (<b>1</b>, <b>2</b>), two new alkaloids dichotomocejs E-F (<b>3</b>, <b>4</b>), and three known fumiquinozalines: scequinadoline A (<b>5</b>), quinadoline A (<b>6</b>), and scequinadoline E (<b>7</b>) were discovered from the culture broth and the mycelium in the culture medium, by the addition of l-tryptophan and l-phenylalanine. Their chemical structures were established by one dimensional (1D), two dimensional (2D) nuclear magnetic resonance (NMR) and high resolution mass spectrometry (HR-MS) data. Among them, scequinadoline A (<b>5</b>) exhibited significant inhibitory activity against dengue virus serotype 2 production by standard plaque assay, equivalent to the positive control andrographlide. Scequinadoline A (<b>5</b>) possesses the potential for further development as a dengue virus inhibitor.