Limonin may be used in assays to quantify limonin in citrus products. It may also be used in other assays as a control, standard, or competitor or in studies on the physiology, metabolism and biosynthesis of limonin.

Limonin is a triterpenoid aglycone that is a bitter principle of citrus fruits. It has anti-proliferative, proapoptotic activity on several cancer cell lines and inhibits azoxymethane-induced colon cancer in rats. It also inhibits HIV-1 replication in culturedf monocytes, macrophages, and mononuclear cells, perhaps by inhibition of HIV-1 protease activity.