<jats:title>Abstract</jats:title><jats:p>One new diketopiperazine alkaloid amauromine B (<jats:bold>1</jats:bold>), along with three known meroterpenoids, austalide B (<jats:bold>2</jats:bold>), austalides N and O (<jats:bold>3</jats:bold> and <jats:bold>4</jats:bold>), and two known steroids (<jats:bold>5</jats:bold> and <jats:bold>6</jats:bold>), was isolated and identified from the culture broth of the fungus <jats:italic>Aspergillus terreus</jats:italic> 3.05358. Their structures were elucidated by extensive spectroscopic techniques, including 2D‐NMR and MS analysis, the absolute configuration of <jats:bold>1</jats:bold> was unambiguously established by single crystal X‐ray diffraction analysis. All the isolates were evaluated for their inhibitory effects on <jats:italic>α</jats:italic>‐glucosidase. Amauromine B (<jats:bold>1</jats:bold>) and austalide N (<jats:bold>3</jats:bold>) exhibited more potent <jats:italic>α</jats:italic>‐glucosidase inhibitory activities than the positive control acarbose.