Limonin is a limonoid, and a bitter, white, crystalline substance found in citrus and other plants. It is also known as limonoate D-ring-lactone and limonoic acid di-delta-lactone. Chemically, it is a member of the class of compounds known as furanolactones.
Limonin is a limonoid, an epoxide, a hexacyclic triterpenoid, a member of furans, an organic heterohexacyclic compound and a lactone. It has a role as a metabolite, an inhibitor and a volatile oil component.
Limonin is the bitter principle of citrus fruits which acts as a chemically-induced carcinogenesis inhibitor and HIV-1 replication inhibitor. While limonin does not possess any inherent antioxidant activity, it does show antinociceptive effects.