Limonin is a highly oxygenated terpenoid which forms the core structure of the citrus limonoid metabolites found mostly in the seeds, fruits and peel tissues of citrus. Limonin was first isolated over 175 years ago. In Australia, limonin was isolated from the components of the tree, Acradenia euodiiformis (syn. Bosistoa euodiiformis), by Taylor, Ritchie and colleagues in 1975. Limonin has antiproliferative activity in the low micromolar range. Members of the group display numerous pharmacological activities, including anticancer, antimicrobial, antioxidant, antidiabetic, metabolic and insecticidal, among others. There is extensive research into liminoids to modulate the bitter principles of citrus for food and beverage products.