Cytotoxic effects of Vitis labrusca (fox grape) whole juices on human tumor and non-tumor cells, in vitro
Cancer is a public health problem of increasing concern worldwide due to the growing increase in mortality rates. The identification of natural compounds with cytotoxic activity is important due to the ready availability and their ability to act effectively in reducing the incidence of cancer, without adverse side effects. Whole grape juice (Vitis labrusca) is often consumed by the population, which is an example of a product with a high content of bioactive compounds, such as flavonoids and resveratrol. To help determine the suitability of this natural product as a health aid, we evaluated the cytotoxic activity of organic and conventional whole grape juices, exposed or not to UV-C irradiation, on human liver tumor cells (HepG2/C3A) and on non-tumor lung cells (MRC-5), by the MTT assay (a colorimetric assay for assessing cell metabolic activity), for 24 and 48 h. All of the juices, at the highest concentrations (50-100 µL/mL), showed significant cytotoxic activity on HepG2/C3A cells, reducing cell proliferation from 78 to 47%, in relation to the control, especially, after 48 h of treatment. Both conventional grape juices had cytotoxic effects on MRC-5 cells at 24 h of treatment, but cell proliferation was reestablished after 48 h. Furthermore, organic grape juice stimulated the proliferation of this cell line, especially that produced from grape exposed to UV-C, possibly in consequence of the increased amount of antioxidants, such as anthocyanins, resveratrol and flavonoids in the fruits, which probably stimulated cell metabolism. This data supports the use of whole grape juice, due to it’s nutraceutical potential, mainly because of antioxidant activity, in particular organic juice, and our findings demonstrate the benefit of food production techniques that add nutritional value, such as post-harvest exposure to UV-C.