Curcumin and a Morus alba extract reduce pro-inflammatory effects of resistin in human endothelial cells

Resistin is a cytokine which plays an important role in cardiovascular disease by influencing systemic inflammation and endothelial activation. In human endothelial cells (HEC) it increases the expression of P‐selectin and fractalkine, and enhances monocyte adhesion by antioxidant mechanisms. This study investigated whether the natural antioxidants curcumin (CC) and an extract of Morus alba leaves (MA) have protective effects in resistin‐activated HEC. HEC were exposed to 100 ng/mL resistin for 6 and 18 h in the absence or presence of MA or CC and the expression of fractalkine and P‐selectin was determined by RT‐PCR and western blot. Intracellular accumulation of reactive oxygen species (ROS) was monitored by fluorimetry and NADPH oxidase activity by a lucigenin‐enhanced chemiluminescence assay. In addition, adhesion assays using the monocytic U937 cells were performed. The results showed that treatment of HEC exposed to resistin with MA and CC: (1) inhibited significantly P‐selectin and fractalkine expression, (2) inhibited the increase in the intracellular ROS level, (3) reduced NADPH activation and (4) reduced monocytes adhesion to HEC. The results indicate that MA and curcumin target resistin‐induced human endothelial activation partly via antioxidant mechanisms and suggest that they may represent therapeutic agents in vascular disease mediated by resistin. Copyright © 2011 John Wiley & Sons, Ltd.