ANTIOXIDANT, GALLIC ACID, INDUCES APOPTOSIS IN HL-60RG CELLS

Gallic acid, a naturally occurring plant phenol with antioxidative act ivity, was found to induce cell death in promyelocytic leukemia HL-60R G cells, although many antioxidants are well known to protect the cell from oxidative stress, Morphological and biochemical studies indicate d that the gallic acid-induced cell death is apoptosis. Flow cytometri c analysis revealed that the apoptosis was not triggered at st specifi c phase of the cell cycle and that 2 h exposure of gallic acid to HL-6 0RG cells was enough to induce apoptosis. The inhibitory assay suggest ed that gallic acid-induced cell. death was mediated by reactive oxyge n species such as hydrogen peroxide, superoxide anion in addition to C a2+ ion, calmodulin-dependent enzymes. Structure-activity analysis sug gests that gallic acid induces apoptosis in HL-60RG cells, depending o n its distinctive feature derived from the structure but not on its an tioxidative activity. (C) 1994 Academic Press, Inc.