Pentaacetylquercetin is a pentaacetylated derivative of the flavonoid quercetin that has diverse biological activities, including antioxidant, anti-inflammatory, and anticancer properties. It scavenges 2,2-diphenyl-1-picrylhydrazyl (DPPH; ) radicals in vitro (IC50 = 3.74 μg/ml) and inhibits iron(II) chloride-induced lipid peroxidation in rat liver mitochondria (IC50 = 20.2 μg/ml). Pentaacetylquercetin inhibits LPS-induced increases in nitrite (IC50 = 8.7 μM) and PGE2 production, as well as inducible nitric oxide synthase (iNOS) and COX-2 levels, in RAW 264.7 cells when used at concentrations of 20 and 40 μM. It also inhibits the growth of HL-60, U937, and SK-MEL-1 cells (IC50s = 38, 25, and 58 μM, respectively).
