With bioassay-guided fractionation, five new polyprenylated benzoylphloroglucinol derivatives, garcimultiflorone D (1), 18- hydroxygarcimultiflorone D (2), garcimultiflorone E (3), garcimultiflorone F (4), and isogarcimultiflorone F (5), and five known compounds, guttiferone E (6), guttiferone F (7), aristophenone A (8), isoxanthochymol (9), and morelloflavone (10), were isolated from the acetone extract of the twigs of Garcinia multiflora. The compounds were evaluated for their apoptotic effects against HeLa-C3 cells, which have been genetically engineered to produce a fluorescent biosensor capable of detecting caspase-3 activation. Compounds 1 and 3-9 activate caspase-3 in HeLa-C3 cells within 72 h after treatment at a concentration of 100 μM or lower. In particular, compounds 6, 8, and 9 showed strong apoptosis-inducing effects at a concentration of 25 μM. © 2010 The American Chemical Society and American Society of Pharmacognosy.