A pentaacetylated derivative of quercetin with diverse biological activities; scavenges DPPH radicals in vitro (IC50 = 3.74 μg/ml); inhibits iron(II) chloride-induced lipid peroxidation in rat liver mitochondria (IC50 = 20.2 μg/ml); inhibits LPS-induced increases in nitrite production (IC50 = 8.7 μM) and PGE2 production, as well as iNOS and COX-2 levels, in RAW 264.7 cells at 20 and 40 μM; inhibits the growth of HL-60, U937, and SK-MEL-1 cells (IC50s = 38, 25, and 58 μM, respectively)