Comparison of Anti‐diabetic Activities of Selected Phenolic Acids in Relation to Antioxidant Activities

Abstract

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.