The extracted GAs were subjected to reverse-phase C18-HPLC and were chromatographed on a 3.9 x 300 m Bondapak, C18 column (Waters Corp., USA) and eluted at 1.5 ml/min with the following gradient: 0-5 min, isocratic 28% methanol (MeOH) in 1% aqueous acetic acid; 5-35 min, linear gradient from 28 to 86% MeOH; 35 to 36 min, 86 to 100% MeOH; 36 to 40 min, isocratic 100% MeOH.