Comparative immunomodulatory effect of scopoletin on tumoral and normal lymphocytes

Some coumarins possess enhancing effects on lymphocyte mitogen responsiveness. In this investigation, the activity of scopoletin, a coumarin that has been isolated from different plants and in this case specifically from T. cordata Mill., was evaluated. For this purpose, normal T lymphocytes and a hyperproliferative T lymphoma cell line were used. Scopoletin was found to exert a dual action on tumoral lymphocytes exhibiting both a cytostatic and a cytotoxic effect. These effects varied with the concentrations analysed and the time of cell incubation (EC(50): 251+/-15 microg/ml) and were associated to the induction of apoptosis. Scopoletin induced cell proliferation on normal T lymphocytes (Proliferation stimulation index: 1 microg/ml scopoletin: 1.26+/-0.1; 10 microg/ml scopoletin: 3+/-0.25; 100 microg/ml scopoletin: 1.86+/-0.08); this stimulatory action was found to be due to the interaction with kinase C (PKC) protein. These results indicate that scopoletin could be a potential antitumoral compound to be used for cancer treatment.