2.3. Determination of ginsenosides

Freeze-dried GP (5 g) was sonicated in 70% methanol for 2 h at room temperature. A round-bottom flask fitted with a cooling condenser was used to evaporate the methanol solution [16]. The extract obtained was evaporated using a rotary evaporator under vacuum at 60°C. The evaporated residue was dissolved in 100 mL of distilled water.

Levels of seven major ginsenosides were analyzed using the HPLC method [17], [18], [19]. The HPLC system consisted of a Dionex Summit HPLC (Dionex Corp., Sunnyvale, CA, USA) with a UV detector (UVD340U), a P680 pump, an autosampler, and a column oven (TCC100). A Capcell Pak column (C18 MG, 4.6 × 250 mm; Shiseido Co., Tokyo, Japan) was used. The detection wavelength was set at 203 nm, and the solvent flow rate was held constant at 1.0 mL/min. The column temperature was fixed at 25°C using a column oven. The mobile phase used for separation consisted of Solvent A (10% acetonitrile) and Solvent B (90% acetonitrile). The injection volume was 20 μL for analysis. Peak identifications were based on retention times and comparisons with injected standard samples. All values were calculated on a dry weight basis.