Cinnamaldehyde prevents endothelial dysfunction induced by high glucose by activating Nrf2.

Objective: It is well documented that hyperglycemia-induced oxidative stress is an important causative factor of endothelial dysfunction. Cinnamaldehyde (CA) is a key flavor compound in cinnamon essential oil that can enhance the antioxidant defense against reactive oxygen species (ROS) by activating NF-E2-related factor 2 (Nrf2), which has been shown to have a cardiovascular protective effect, but its role in endothelial dysfunction induced by high glucose is unknown.

Methods: Dissected male C57BL/6J mouse aortic rings and HUVECs were cultured in normal glucose(NG 5.5 mM) or high glucose(HG 30.0 mM) DMEM treatment with or without CA (10 µM).

Results: Treatment with CA protected the endothelium relaxation, inhibited ROS generation and preserved nitric oxide (NO) levels in the endothelium of mouse aortas treated with high glucose . CA up-regulated Nrf2 expression, promoted its translocation to the nucleus'and increased HO-1, NQO1, Catalase and Gpx1 expression under high glucose condition. The increased level of nitrotyrosine in HUVECs under high glucose was also attenuated by treatment with CA. Dihydroethidium (DHE) and DAF-2DA staining indicated that CA inhibited the ROS generation and preserved the NO levels in HUVECs, but these effects were reversed by Nrf2-siRNA in high glucose conditions.

Conclusions: Our results indicated that CA protected endothelial dysfunction under high glucose conditions and this effect was mediated by Nrf2 activation and the up-regulation of downstream target proteins. CA administration may represent a promising intervention in diabetic patients who are at risk for vascular complications.