Phenolic acids, found in cereals, legumes, vegetables, and fruits, have various biological functions. We aimed to compare the antihypertensive potential of different phenolic acids by evaluating their ACE inhibitory activity and cytoprotective capacity in EA.hy926 endothelial cells. In addition, we explored the mechanism underlying the antihypertensive activity of sinapic acid. Of all the phenolic acids studied, sinapic acid, caffeic acid, coumaric acid, and ferulic acid significantly inhibited ACE activity. Moreover, gallic acid, sinapic acid, and ferulic acid significantly enhanced intracellular NO production. Based on the results of GSH depletion, ROS production, and MDA level analyses, sinapic acid was selected to study the mechanism underlying the antihypertensive effect. Sinapic acid decreases endothelial dysfunction by enhancing the expression of antioxidant-related proteins. Sinapic acid increased phosphorylation of eNOS and Akt in a dose-dependent manner. These findings indicate the potential of sinapic acid as a treatment for hypertension.

Dietary phenolic acids are antioxidants with diverse physiological functions that are beneficial for human health. Phenolic acids show anti‐mutagenesis and anti‐microbial activities and play a role in immune regulation in humans. The objective of this research work was to compare antioxidant and anti‐diabetic activities of selected 11 phenolic acids. 1,1‐Diphenyl‐2‐picrylhydrazyl (DPPH), 2,2‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) radical scavenging capacities, reducing power, α‐glucosidase inhibitory activity and glucose uptake in HepG2 cells were evaluated. The relation of antioxidant activities with anti‐diabetic activities was also investigated. Gallic acid showed significantly higher on DPPH and ABTS radical scavenging activities and reducing power followed by caffeic acid and sinapic acid. Caffeic acid among samples showed the highest α‐glucosidase inhibitory activity followed by gallic acid and coumaric acid. Glucose uptake was the highest in gallic acid and coumaric acid. Compared to the positive control (metformin), all the phenolic acids showed equivalent or more potent effects on the glucose uptake in HepG2 cells. However, low relationship was found between antioxidant capacity and anti‐diabetic activity. These results suggested that phenolic acids can be used as functional food ingredients or blood glucose regulators.