Citrus limon, Citrus sinensis and C. sinensis grafted upon C. limon
Walking through an orchard of lemons and oranges at Amazonat in Brazil, one may not realize the species' long history. There are indications of early cultivation of lemon and citron in India, and of mandarins and possibly other citrus fruits in China (1). The sweet orange probably originated as a natural hybrid between the pummelo and mandarin, grown in China in mixed village gardens (1).
Citrus plants were eventually brought to Europe by the Arabs (2). Special houses called "orangeries", which can be seen as predecessors of greenhouses, were established in the fourteenth century for cultivating citrons and oranges in many parts of Europe (1). Citrus was successfully established in Brazil by the middle of the sixteenth century (1).
Citrus fruits are known to have several nutritional and medicinal properties. Oranges and lemons are high in minerals (potassium and calcium), and vitamins (especially vitamin C). Drinking orange juice prevented oxidative stress in rats by enhancing total antioxidant capacity and elevating liver antioxidant enzymes while modulating cardiovascular risk factors (3). Flavones derived from sweet orange peel have been shown to inhibit growth of human breast cancer cells (4). The essential oil of Citrus sinensis was found to have antifungal effects (5). Citrus juices such as those from lemon were furthermore found to have antibacterial activity (6). In another study, volatile extracts of two species of orange peel - Citrus sinensis (sweet orange) and Citrus aurantifolia (lime) - had insecticidal activity (7).
(1) Spiegel-Roy, P, Goldschmidt, EE (1996) Biology of Citrus, 230 p.
(2) Ferrao, JEM (1993) 2nd edition, The Adventure of Plants and the Portuguese Discoveries. EU: 247 p.
(3) Deyhim F, Lopez E, Gonzalez J, Garcia M, Patil BS (2006) Citrus juice modulates antioxidant enzymes and lipid profiles in orchidectomized rats. J Med Food. 9(3): 422-6
(4) Sergeev IN, Li S, Colby J, Ho CT, Dushenkov S (2006) Polymethoxylated flavones induce Ca(2+)-mediated apoptosis in breast cancer cells. Life Sci [Epub ahead of print]
(5) Sharma N, Tripathi A (2006) Effects of Citrus sinensis (L.) Osbeck epicarp essential oil on growth and morphogenesis of Aspergillus niger (L.) Van Tieghem. Microbiol Res [Epub ahead of print]
(6) Tomotake H, Koga T, Yamato M, Kassu A, Ota F. (2006) Antibacterial activity of citrus fruit juices against Vibrio species. J Nutr Sci Vitaminol (Tokyo) 52(2): 157-60
(7) Ezeonu FC, Chidume GI, Udedi SC (2001) Insecticidal properties of volatile extracts of orange peels. Bioresour Technol 76(3): 273-4