Aspulvinone O is a biprenylated butyrolactone isolated from a strain of Paecilomyces by Chinese researchers in 2015. Aspulvinone O is a member of the larger aspulvinone family of secondary metabolites originally isolated from Aspergillus terreus by Seto and colleagues at Tohuku University, Japan, in 1973. Aspulvinone O exhibits antioxidant activity in the low micromolar range, via DPPH radical scavenging, and possesses antibiotic and cytotoxic activity.