Amino Acid-Directed Strategy for Inducing the Marine-Derived Fungus Scedosporium apiospermum F41–1 to Maximize Alkaloid Diversity

By feeding various amino acids to the marine fungus Scedosporium apiospermum F41–1, 22 diverse alkaloids, including 14 new compounds, were obtained. Scedapins A–E (1–5) possess a rare skeleton of a pyrazinoquinazolinedione and an imidazoindolone/indolone linked by a tetrahydrofuran ring. Scedapin C (3) is the first example of fumiquinazoline that contains an aminosulfonyl group. Their structures were determined by HRMS, NMR, ECD calculations and X-ray single-crystal diffraction analysis. The biosynthetic pathways of fumiquinazolines 1–18 were proposed. Scedapin C (3) and scequinadoline D (8) displayed significant antiviral activity against hepatitis C.