The marine fungus Aspergillus versicolor was isolated from the inner tissue of the Red Sea green alga Halimeda opuntia. The fungus was identified by its morphology and 18s rDNA. Cultivation of this fungal strain led to a new metabolite named isorhodoptilometrin-1-methyl ether (1) along with the known compounds emodin (2), 1-methyl emodin (3), evariquinone (4), 7-hydroxyemodin 6,8-methyl ether (5), siderin (6), arugosin C (7), and variculanol (8). The structures were elucidated on the basis of NMR spectroscopic analysis and mass spectrometry. The biological properties of ethyl acetate extract and compounds 1-3 and 6-8 were explored for antimicrobial activity, anti-cancer activity and inhibition of Hepatitis C virus (HCV) protease.