Total polyphenol of Anemarrhena asphodeloides ameliorates advanced glycation end products-induced endothelial dysfunction by regulation of AMP-Kinase

Objective: Anemarrhena asphodeloides Bunge is widely used in China for the treatment of diabetes and the polyphenol components are responsible for its anti-diabetic action. This study aimed to investigate the effect of total polyphenol of Anemarrhena asphodeloides (TPAA) on endothelial dysfunction and to elucidate underlying mechanisms. Methods: We stimulated endothelial cells with advanced glycation end products (AGEs) to establish the model of endothelial dysfunction in vitro and observed the effect of TPAA (10, 30, or 100 mu g/mL) on AMP-Kinase (AMPK) activation implicated in regulation of nitric oxide (NO) and endothelin-1 (ET-1) production. Meanwhile, nuclear factor-kappa B (NF-kappa B) activation, intracellular reactive oxygen species (ROS) production, mitochondrial membrane potential (Delta Psi m) and eNOS expression were investigated by western blot, fluorescence microscopy and real time-quantitative PCR analysis, respectively. Results: Total polyphenol of Anemarrhena asphodeloides enhanced AMPK phosphorylation and promoted the basal NO production along with the inhibition of ET-1 secretion in endothelial cells. TPAA inhibited NF-kappa B activation by attenuating p65 phosphorylation and suppressed ROS production, well demonstrating its action in inhibition of ROS-associated inflammation in the endothelium. Meanwhile, TPAA protected mitochondrial function and endothelial homeostasis against AGEs insult by restoring Delta Psi m and mRNA expression of eNOS. AGEs stimulation inhibited AMPK activation and induced the loss of NO production together with increased secretion of ET-1, but these changes were reversed by TPAA in a concentration-dependent manner. Compound C, an AMPK inhibitor, attenuated the effects of TPAA mentioned above, indicating the involvement of AMPK. Conclusions: Total polyphenol of Anemarrhena asphodeloides inhibited AGEs-induced ROS-associated inflammation and ameliorated endothelial dysfunction through beneficial regulation of AMPK activation.