Screening for Aldose Reductase Inhibitory Activity of 92 Crude Drugs, and Isolation and Identification of Active Ingredients from Clove

Abstract

In order to explore new aldose reductase (AR) inhibitory substances, the H₂O, EtOH, and EtOAc extracts of 92 crude drugs were evaluated for the AR inhibitory activities. As a result, the H₂O, EtOH, and EtOAc extracts of clove showed relatively potent AR inhibitory activities. Phytochemical investigation of the H₂O extract of clove identified 10 flavonol derivatives 　(1－10), a chromone derivative (11), a sesquiterpene derivative (12), and an acetophenone derivative (13). Among the isolated compounds, 3 (rhamnocitrin) significantly inhibited AR activity with an IC₅₀ value of 0.57 μM, which is comparable to epalrestat used as the positive control.