Limonoids occur naturally only in plant species of the Rutaceae and Meliaceae plant families (Manners, 2007). Limonoids are highly oxygenated modified triterpenes that are biosynthesized from the acetate–mevalonate pathway in citrus fruits (Roy & Saraf, 2006). They occur in significant amounts as aglycones and glycosides in seeds and fruit tissues. Citrus fruits contain approximately 36 limonoid aglycones and 17 limonoid glucosides (Hasegawa & Miyake, 1996). Major citrus species accumulate limonin, nomilin, obacunone, and deacetylnomilin. Limonoid aglycones that cause bitterness in numerous citrus fruits are converted into tasteless limonoid glucosides during fruit maturation first limonoid component identified as the bitter component of citrus seeds. Several other limonoid compounds such as obacunone, nomilin, obacunoic acid, isolimonic acid, deacetylnomilin, ichigan, isoobacunoic, and dictomnolide were also identified. Limonin and nomilin are the predominant limonoids of citrus fruit. Limonoids are grouped into aglycones and glucosides. Aglycones are bitter limonoid compounds in the peels of citrus fruits, while glucosides are tasteless components. Both aglycones and glucosides are present in citrus seeds, but fruit tissue contains only glucosides. More than 50 limonoid aglycones and glucosides have been identified from various Citrus species. Evidence from several in vivo, in vitro, and animal studies suggests that limonoids have anticancer properties and showed potent cytotoxic activities