Flavonoids in Grapefruit and Commercial Grapefruit Juices: Concentration, Distribution, and Potential Health Benefits

摘要

Florida is the main producer of grapefruit (Citrus parodist Macf.) in the world. Grapefruit provide not only the traditional nutrients (carbohydrates; proteins, vitamins, minerals), but also phytochemicals such as flavonoids, which are not essential for life, but may provide many health benefits. Flavanones are the dominant flavonoids, and account for about 98% of the total flavonoids hi grapefruit. Major flavanones in grapefruit are present as glycosides. In grapefruit, identified flavanone glycosides include didymin, dihydrokaempferol glucoside, eriocitrin, naringin, poncirin, hesperidin, neohesperidin, neoeriocitrin, narirutin, narirutin-4'-glucoside, naringin-6"-malonate (open form), and naringin-6"-malonate (closed form). Flavones or flavonolsfound in grapefruit include apigenin 6,8-di-C-glucoside, apigenin 7-(malonylapiosy)-glucoside, kaempferol glycoside, luteolin, myricetin, neodiosimin, quercetin, rutin, and rhoifolin. Reported polymethoxylated flavones in grapefruit include heptamethoxyflavone, nobiletin, and tangeretin. The presence of naringenin (an aglycone form of naringin and narirutin) in grapefruit remains controversial. Naringin is present at the highest concentration followed by narirutin, hesperidin, poncirin, neohesperidin, didymin, and quercetin. The presence and their concentrations of individual flavonoids vary with grapefruit variety, fruit tissue, juice extraction method, and geographic location. Flavonoids have been linked to many health benefits including antioxidant,anti-inflammatory, and anti-tumor activity. Grapefruit and grapefruit juice are a rich source of flavonoids, especially naringin. By consuming grapefruit and grapefruit juice, individuals not only will obtain essential nutrients but also will get health-beneficial flavonoids.