Lipoic Acid Antagonizes Paraquat-induced Vascular Endothelial Dysfunction by Suppressing Mitochondrial Reactive Oxidative Stress

Paraquat (PQ) is a widely used herbicide in the agricultural field. The lack of an effective antidote is the significant cause of high mortality in PQ poisoning. Here, we investigate the antagonistic effects of alpha lipoic acid (α-LA), a naturally existing antioxidant, on PQ toxicity in human microvascular endothelial cells (HMEC-1). All the doses of 250, 500 and 1000 μM α-LA significantly inhibited 1000 μM PQ-induced cytotoxicity in HMEC-1 cells. α-LA pretreatment remarkably diminished the damage to cell migration ability, recovered the declined levels of the vasodilator factor nitric oxide (NO), elevated the expression level of endothelial nitric oxide synthases (eNOS), and inhibited the upregulated expression of vasoconstrictor factor endothelin-1 (ET-1). Moreover, α-LA pretreatment inhibited reactive oxygen species (ROS) generation, suppressed the damage to the mitochondrial membrane potential (Δ ) and mitigated the inhibition of adenosine triphosphate (ATP) production in HMEC-1 cells. These results suggested that α-LA could alleviate PQ-induced endothelial dysfunction by suppressing oxidative stress. In summary, our present study provides novel insight into the protective effects and pharmacological potential of α-LA against PQ toxicity in microvascular endothelial cells.