Abstract: Two new isomeric modified tripeptides, aspergillamides C and D (compounds 1 and 2 ), together with fifteen known compounds (compounds 3 - 17 ), were obtained from the marine sponge-derived fungus Aspergillus terreus SCSIO 41008. The structures of the new compounds, including absolute configurations, were determined by extensive analyses of spectroscopic data (NMR, MS, UV, and IR) and comparisons between the calculated and experimental electronic circular dichroism (ECD) spectra. Butyrolactone I (compound 11 ) exhibited strong inhibitory effects against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with the IC₅₀ being 5.11 ± 0.53 μmol·L^-1, and acted as a noncompetitive inhibitor based on kinetic analysis.