Abstract: | The lichen substance, 16-O-acetyl-leucotylic acid (1), was isolated from an acetone extract of Myelochroa aurulenta and found to exhibit antiproliferative activity against HL-60 human leukemia cells. This is the first report on its anti-leukemia activity (EC50=21 μM) which is greater than that of leucotylic acid (2) and the structurally related anti-tumor agent, betulinic acid (4). |