Subcritical water extraction, identification and antiproliferation ability on HepG2 of polyphenols from lotus seed epicarp

In this study, polyphenols were extracted with subcritical water (SWE) from lotus seed epicarp. Based on single factor experiments, the extraction parameters were optimized by response surface methodology (RSM). Lotus seed epicarp polyphenols (LSEP) were purified by column chromatography (AB-8 macroporous resin) and identified by HPLC-ESI-MS. The antiproliferation ability of LSEP was also investigated. The optimal extraction parameters for the polyphenols were the temperature of 160℃, the time of 15 min, the liquid-solid ratio of 60 mL/g and the sodium bisulfite (NaHSO3) addition amount of 2‰ (W/V). Under these extraction conditions, the maximal yeild of LSEP was 88.72 mg of gallic acid equivalents (GAE) per 1 g dry weight (DW), significantly higher than that of hot water extraction (HWE). Ten polyphenols were identified and quantified. Total content of ten polyphenols was 896.604 mg/g in LSEP. This study also found that LSEP extracted by SWE has better antiproliferation ability on human hepatoma G2 (HepG2) cells than that of HWE.