Abstract:The saponification conditions of the extract from Cucurbita moschata Duch. was optimized and its antioxidant activity in vitro was evaluated. On the basis of single factor experiment, the saponification solution concentration, saponification temperature and saponification time were optimized as the response factors. The Box-Behnken Center combination experiment principle was carried out by the three-factor and three-level design to optimize the saponification process of Cucurbita moschata Duch. lutein. After saponification, high performance liquid chromatography (HPLC) and mass spectrometry (MS) analysis were used to detect the purified Cucurbita moschata Duch. lutein, which was separated by silica gel column chromatography. The free lutein in Cucurbita moschata Duch. was evaluated by spectrophotometry comparing the scavenging ability of DPPH· and ·OH in vitro antioxidant activity. The optimum saponification condition for lutein ester in Cucurbita moschata Duch. extract was set as 33% saponification at 33 ℃ for 5.5 h. Under the optimal conditions, the yield of free lutein in Cucurbita moschata Duch. extract was 0.4175%, which was similar to the predicted value, revealing that the optimization process was stable and feasible. HPLC and MS analysis showed that the saponified product was lutein. After purification by silica gel column chromatography, the purity of free lutein significantly increased to 91.39%. The half-inhibitory concentration IC50 of DPPH· and ·OH in free lutein in Cucurbita moschata Duch. is 0.021 4 mg/mL and 0.038 3 mg/mL, respectively. It has high antioxidant activity and can be used as a good natural antioxidant.
