Radical Scavenging-Linked Anti-Adipogenic Activity of Aster scaber Ethanolic Extract and Its Bioactive Compound

Aster scaber is a wild vegetable cultivated in Korea and is known to contain phytochemicals with various biological activities. The potential antioxidant and anti-obesity effects of A. scaber and their mechanism are yet to be reported. We evaluated the total phenolic, flavonoid, and proanthocyanidin contents and oxygen radical absorbance capacity of A. scaber ethanolic extract (ASE), and analyzed the major phenolic compounds of ASE. Antioxidant activity was measured at the chemical level through 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power assay, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), and fluorescence recovery after photobleaching (FRAP) assay. In addition, it was measured in vitro through inhibition of Reactive oxygen species (ROS) production in 3T3-L1 adipocyte, and inhibition of lipid accumulation was also evaluated. ASE reduced the expression of enzymes involved in the production of ROS and increased the expression of antioxidant enzymes that reduce increased ROS levels. They also reduced the expression of adipogenesis transcription factors that regulate adipocyte differentiation in relation to ROS production, inhibited the expression of lipogenesis-related genes related to fat accumulation through AMP-activated protein kinase (AMPK) activity, and increased expression of lipolysis-related genes. Thus, ASE containing CGA (chlorogenic acid) inhibits ROS production in 3T3-L1 adipocytes, owing to its strong antioxidant activity, and inhibits lipid accumulation caused by oxidative stress. The extract can be used as a potential functional food material for reducing oxidative stress and obesity.