Ionic liquid aqueous solvent-based microwave-assisted hydrolysis for the extraction and HPLC determination of myricetin and quercetin from Myrica rubra leaves.

An ionic liquid aqueous solvent-based microwave-assisted hydrolysis (ILAS-MAH) approach was proposed for the rapid extraction and accurate determination of myricetin and quercetin from Myrica rubra (M. rubra) leaves for the first time. The effects of the ionic liquid class and concentration, liquid-solid ratio, hydrolysis temperature and time were investigated to obtain the optimal ILAS-MAH conditions. The optimized conditions were 2.0 mol/L [bmin][HSO4] or 2.5 mol/L acidified [bmin]Br solution, liquid-solid ratio 30:1 (mL : g), hydrolysis temperature 70°C and hydrolysis time 10 min. Under these conditions, the recoveries of myricetin and quercetin were in the range of 86.3-107.3% with relative standard deviation lower than 5.8%. Compared with conventional heating hydrolysis and regular MAH, the proposed approach reduced hydrolysis time and improved yields. The mechanism of ILAS-MAH was also investigated.