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.