In Vitro Antiproliferative Properties and Flavanone Profiles of Six Grapefruit (Citrus paradisi Macf.) Cultivars

Recent studies suggest an inverse relationship between the intake of Citrus fruits and the incidence of cardiovascular diseases, stroke and different cancer types. Protective effects shown could be ascribed to the flavonoid content of Citrus fruits. A reversed-phase highperformance liquid chromatographic method was developed to determine the content of flavanone glycosides, which are the main flavonoids present in Citrus fruits. Fresh squeezed juices of six different grapefruit cultivars (Citrus paradisi Macf.) were analysed. In all grapefruit juices tested, we found total flavanone glycoside contents in the range from 33.93 to 44.97 mg/100 ml of juice; naringin was the main flavanone component (16.37-26.14 mg/100 ml of juice). To evaluate pharmacological activity and, in particular, inhibitory effects in vitro on proliferation and growth of cancer cells, the six freshly squeezed grapefruit juices were tested against K562 (human chronic myelogenous leukemia), NCI-H460 (human lung cancer) and MCF-7 (human breast adenocarcinoma) cell lines. Most of the tested grapefruit juices showed distinct antiproliferative activity against all three cancer cell lines; in particular ‘Ruby Red’ and ‘Foster’ grapefruit juices showed the best activity in inhibiting the growth of NCI-H460 and MCF-7 cell lines at 3% v/v (fresh juice volume diluted in cell culture medium).