Biotransformation of Coumarins in Angelica gigas Nakai Root Extract and Their Inhibitory Effect on Acetylcholinesterase Activity

Abstract

Preliminary studies have shown that a methanol extract of the Angelica gigas Nakai (AG) root significantly inhibited acetylcholinesterase (AChE) activity. In this study, we present a biotransformation method of coumarins within the AG extract, which included decursin and nodakenin. Biotransformation of decursin to decursinol and nodakenin to nodakenetin was accomplished by a crude enzyme extract of Bifidobacterium sp. Int57 (Int57) and porcine esterase. After carrying out the biotransformation for 7 days, 88.8% of the decursin was converted to decursinol and the nodakenin was converted into nodakenetin, showing 2.1-fold increase of the nodakenetin. Moreover, the IC50 value of the biotransformed AG extract on the inhibition of AChE was 2.4-fold lower than that of the non-transformed AG extract. The cytotoxicity of the decursin present in AG was reduced due to the biotransformation into decursinol and the treatment of the nodakenin reduced the Aβ1-40 levels in SH-SY5Y cells. This study shows an efficient biotransformation of decursin and nodakenin in AG extract into decursinol and nodakenetin, respectively, which enhances the AChE inhibitory effect.