Hydrosphere c18

The 90% (v/v) MeOH extract (10 mg/mL) from the AP extract incubated with or without the LAB strain was eluted using HPLC (JASCO system; JASCO Corporation) with an octadecylsilyl (ODS) C18 column (Hydrosphere C18, YMC, Kyoto, Japan; 5 μm, Φ = 6 mm, L = 250 mm) at 37°C. The column was equilibrated with water and eluted with the linear gradient method (0 to 100% acetonitrile) at a flow rate of 1.0 mL/min. Wavelengths of 210 nm were employed to detect elution of the sample. The injection volume was 10 μL.

Separation by analytical RP-HPLC was performed using the Shimadzu Prominence analytical HPLC system with an SPD-M20A diode array detector set at 220 nm, an autosampler, and LC Solutions software (Shimadzu Corp., Kyoto, Japan). The Hydrosphere C18 (5 μm, 12 nm, 150 × 4.6 I.D., YMC Co., Ltd., Kyoto, Japan) column was used with a temperature of 30 °C. The eluent was 20 mM Na₂HPO₄ buffer solution, pH adjusted to 2.8 with acetic acid. The flow rate was 1.0 mL/min. The injection volume was 20 μL. Calibration curves of quinic, citric, and malic acid were used for the quantification; concentration range was from 1 to 20 mg/mL.