“…In order to check cell proliferation, MTT assay was carried out [ [32] , [33] , [34] , [35] ]. In a first test of cell viability, five concentrations of 6 PP (0.001, 0.01, 0.1, 1 and 10 μg/mL) were checked at 48 h p. i., and then we have chosen 0.1 μg/mL 6 PP for MTT test.…”