Eighteen new compounds named aspergones A–Q (1–17) and 6-O-demethylmonocerin (18), along with five known analogues (19–23), were isolated from the fermentation broth of Aspergillus sp. OUCMDZ-1583 associated with an unidentified marine sponge (XD10410) from the Xisha Islands of China. The structures, including the absolute configurations, were unambiguously elucidated by spectroscopic, X-ray crystallographic, chemical, and Mosher’s methods along with quantum ECD calculations. Compounds 1, 2, 5, 10, 11, 14–18, and 21–23 showed α-glucosidase inhibition with IC50 values of 2.36, 1.65, 1.30, 2.37, 2.70, 1.36, 1.54, 2.21, 2.26, 0.027, 1.65, 1.19 and 1.74 mM, respectively (with acarbose as the positive control; IC50 = 0.95 mM), among which compound 18 is 35 times more potent than acarbose. In addition, compounds 18 and 21 exhibited inhibitory activity against the influenza A (H1N1) virus with IC50 values of 172.4 and 175.5 μM, respectively (with ribavirin as the positive control; IC50 = 137.3 μM).
