Neosartoryadins A and B, Fumiquinazoline Alkaloids from a Mangrove-Derived Fungus <i>Neosartorya udagawae</i> HDN13-313

Neosartoryadins A (<b>1</b>) and B (<b>2</b>), both with a unique 6/6/6/5 quinazoline ring system connected directly to a 6/5/5 imidazoindolone ring, together with three biogenetically related compounds <b>3</b>–<b>5</b>, were isolated from the endophytic fungus <i>Neosartorya udagawae</i> HDN13-313. The absolute configurations of new compounds <b>1</b>–<b>4</b> were established. Compounds <b>1</b> and <b>2</b> displayed anti-influenza virus A (H1N1) activities with IC₅₀ values of 66 and 58 μM, respectively (ribavirin as positive control, IC₅₀ = 94 μM)