Pheophorbide a, a moiety of chlorophyll a, induces apoptosis in human lymphoid leukemia molt 4B cells.

The exposure of human lymphoid leukemia Molt 4B cells to pheophorbide a (PPB a), a moiety of chlorophyll a, led both to growth inhibition and induction of programmed cell death (apoptosis). The growth inhibition by PPB a was much stronger than that by chlorophyll a. Morphological change showing apoptotic bodies was observed in the Molt 4B cells treated with PPB a. The fragmentation by PPB a of DNA to oligonucleosomal-sized fragments, that are characteristics of apoptosis, was observed to be concentration- and time-dependent. These findings suggest that growth inhibition by PPB a of Molt 4B cells results from the induction of apoptosis and that PPB a, moiety of chlorophyll a, is essential for exertion of antitumor and apoptosis-inducing activity in these cells.