Terrecyclic acid is a sesquiterpene originally isolated from A. terreus with antibiotic and anticancer activity. It is active against S. aureus, B. subtilis, and M. roseus (MICs = 25, 50, and 25 μg/ml, respectively). Terrecyclic acid induces a heat shock response, increases levels of reactive oxygen species (ROS), and inhibits NF-κB activity and cell growth in 3T3-Y9-B12 cells. In vivo, terrecyclic acid (0.1, 1, and 10 mg/ml) reduces the number of ascitic fluid tumor cells in a mouse model of P388 murine leukemia.