Changes in flavonoid content and tyrosinase inhibitory activity in kenaf leaf extract after far-infrared treatment

초록

The tyrosinase inhibitory activity of ethanolic extract of kenaf (Hibiscus cannabinus L.) leaf was evaluated before and after subjecting it to far-infrared (FIR) irradiation. The main component of the extract was analyzed as kaempferitrin (kaempferol-3,7-O-alpha-dirhamnoside). Prior to FIR irradiation, no inhibitory activity of the extract was detected in a tyrosinase assay. However, after FIR irradiation for 1 h at 60 degrees C, significant tyrosinase inhibitory activity (IC(50) = 3500 ppm) was observed in it. In HPLC analysis, derhamnosylation products (kaempferol, afzelin, and alpha-rhamnoisorobin) were detected. The inhibitory activity may be due to the existence of derhamnosylation products. This study demonstrated that FIR irradiation can be used as a convenient tool for deglycosylation of flavonoid glycoside. (C) 2010 Elsevier Ltd. All rights reserved.

키워드