Antioxidant Activity in the Extracts Produced by Two-step Hot/hot-compressed Water Percolation from Japanese Cedar (<i>Cryptomeria japonica</i>) Leaf

Abstract

Japanese cedar (Cryptomeria japonica) is a forest tree species, and widely distributed in Japan. The lumber of Japanese cedar has been used for building materials, furniture, and traditional crafts, but the "leaf" is rarely used for practical applications. In this study, the physiological activity in the water extracts of Japanese cedar leaf which extracted by the two-step hot/hot-compressed water percolation evaluated by the in vitro assay and the experiment using human keratinocyte, HaCaT cells. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and total polyphenol concentration in 180 °C extract were significantly higher than those in 80 °C extract. Additionally, the suppressive effects of 180 °C water extract of Japanese cedar leaf on the cellular reactive oxygen species (ROS) level were more effective than that of 80 °C water extract in HaCaT cells. Therefore, it was indicated that the 180 °C water extracts of Japanese cedar leaf contained more antioxidant compounds than that of 80 °C water extract.