One new diketopiperazine alkaloid amauromine B (1), along with three known meroterpenoids, austalide B (2), austalides N and O (3 and 4), and two known steroids (5 and 6), was isolated and identified from the culture broth of the fungus Aspergillus terreus 3.05358. Their structures were elucidated by extensive spectroscopic techniques, including 2D-NMR and MS analysis, the absolute configuration of 1 was unambiguously established by single crystal X-ray diffraction analysis. All the isolates were evaluated for their inhibitory effects on alpha-glucosidase. Amauromine B (1) and austalide N (3) exhibited more potent alpha-glucosidase inhibitory activities than the positive control acarbose. CI - Copyright (c) 2015 Verlag Helvetica Chimica Acta AG, Zurich.