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

In our continuous chemical investigation on the marine-derived fungus F31-1, two new polyketides dichocetides B-C (, ), two new alkaloids dichotomocejs E-F (, ), and three known fumiquinozalines: scequinadoline A (), quinadoline A (), and scequinadoline E () 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 () exhibited significant inhibitory activity against dengue virus serotype 2 production by standard plaque assay, equivalent to the positive control andrographlide. Scequinadoline A () possesses the potential for further development as a dengue virus inhibitor.