(+)-Limonene is a monoterpene that has been found in citrus oils and Cannabis and has diverse biological activities.^1,2,3,4 It is active against S. aureus, B. cereus, E. faecalis, E. coli, P. aeruginosa, K. pneumoniae, M. catarrhalis, and C. neoformans (MICs = 3-27 mg/ml).¹ In a human BGC-823 gastric cancer nude mouse orthotopic transplantation model, (+)-limonene inhibits tumor growth by 47.6% and reduces the number of metastases in the liver, peritoneum, and other organs when administered by gastric perfusion at a dose of 15 ml/kg.⁵ Dietary administration of (+)-limonene (5 and 10% in chow) reverses doxorubicin-induced decreases in glutathione (GSH) levels in rat kidney.³ (+)-Limonene is toxic to cockroaches and house flies (LD50s = 700 and 90 µg/insect, respectively).⁶ Formulations containing (+)-limonene have been used as flavoring and fragrance agents, in the treatment of gallstones, heartburn, and gastroesophageal reflux disorder, as well as in the control of insects and algae.