Antiproliferative Effect of Green Papaya on Lymphocytic Leukemic Cells

Numerous edible plants have been reported to interfere with the carcinogenic process, and therefore, the regular consumption of these plant products may reduce the risk of developing cancer. We investigated the effect of papaya fruit and leaves on the cell proliferation of Jurkat T-lymphocytic and Daudi B-lymphocytic leukemia cells. Cells were treated with aqueous or methanolic extracts from leaves, skin, pulp, and seeds from green papaya. The papaya fractions were tested for total phenolic content, total flavonoids content, and anti-oxidation activity using chemical assays. Cell proliferation was measured using a WST-1 assay. Our data indicate that methanol and water extracts of seeds and leaves contained higher concentrations of total phenolic compounds and higher anti-oxidation activity than that of extracts from skin and pulp. Both methanol and water extracts from leaves and skin potently inhibited the proliferation of leukemic Jurkat T-cells and Daudi B-cells. However, the effect was more potent on Jurkat T-cells, and the leaf extracts were more effective than that of skin extracts. None of the pulp or seed extracts showed inhibitory activity on leukemic cell proliferation. Although papaya leaves are not consumed as a food, leaf extracts have been used for the treatment of various conditions, including dengue and malaria fevers, gastric ulcers, low platelet counts, and cancers of the breast, lung, and cervix. Our data suggest that the consumption of papaya leaf extracts may also be beneficial in preventing and/or treating lymphocytic cancer. Isolation of active compounds from papaya leaves will also help in developing new drugs for cancer treatment.