Piceatannol 3'-O-glucoside (Piceatannol-3'-O-β-D-glucopyranoside; PG) is a potent component of stilbenes, inhibits the activity of arginase I and II prepared from mouse liver and kidney lysates, respectively, in a dose-dependent manner. In human umbilical vein endothelial cells, incubation of Piceatannol 3'-O-glucoside markedly blocks arginase activity and increases nitrite and nitrate (NOx) production, as measured by Griess assay. In liver lysates, incubation of different concentrations of Piceatannol 3'-O-glucoside significantly decreases arginase I activity (75±5% at 1 µM, 72±7% at 3 µM, 62±1% at 10 µM) compared to untreated control (100±9%). In kidney lysates, the residual arginase activities after incubation of 1, 3 and 10 µM Piceatannol 3'-O-glucoside are 75±6, 74±5, and 53±8%, respectively. Arginase activity is measured in the presence of different concentration of Piceatannol 3'-O-glucoside (from 0 to 120 µM) using liver lysate and kidney lysate. The 50% inhibitory concentrations (IC50) are 11.22 µM for the liver lysate and 11.06 µM for kidney lysate. The values are obtained using the software of Graphpad prizm 4.0. Piceatannol 3'-O-glucoside inhibits arginase activity and increases NO production in HUVECs. Piceatannol 3'-O-glucoside inhibits lipoxygenase activity upto 66% at the concentration of 100 µM and IC50 value is 69 µM.