Antioxidant activities of Perilla frutescens against low-density lipoprotein oxidation in vitro and in human subjects.

Perilla (Perilla frutescens (L.) Britt.) is a popular food as well as a traditional medicine in Japan, China, and other Asian countries. The aim of this study was to investigate the inhibitory effects of perilla on low-density lipoprotein (LDL) oxidation in vitro and in human subjects. We compared the antioxidant activities of red perilla and green perilla. Both green and red perilla had high 1,1-diphenyl-2-picrylhydrazyl radical scavenging activities and were abundant in polyphenol compounds. In addition, the radical scavenging activity and polyphenol content of red perilla were higher than those of green perilla. Perilla dramatically inhibited azo-radical-induced LDL oxidation and endothelial-cell-mediated LDL oxidation in vitro. Moreover, red perilla significantly increased mRNA and protein expression levels of antioxidant enzymes in endothelial cells. We further examined the antioxidant effects against LDL in human subjects after the consumption of perilla extracts. After oral intake of red perilla, the subjects' LDL oxidation lag times were significantly longer than those before the intake. Furthermore, lipid peroxide formation and the electrophoretic mobility of LDL decreased markedly. These results suggested that perilla, especially the red variety, had high antioxidant activity and prevented the oxidation of LDL, which is a process strongly related to the development of atherosclerosis.