Studies on Extraction Technology and Antioxidant Activities Basis of Flavonoids from Zea Mays L.

OBJECTIVE To optimize conditions for the extraction of total flavonoids from Zea mays L.. To identify the structures of compounds from active fraction and to discuss the structure-activity relationship between flavonoids and antioxidant activities. METHODS Response surface methodology was used to optimize conditions for the extraction of total flavonoids from Z. mays. DPPH, ABTS and FRAP methods were used to test the antioxidant activities of different extracts. The relativities of the data were analyzed. D101 macroporous resin column was applied to isolate the extract. LC-MS was used to identify the compounds from the active fraction. The antioxidant activities of the flavonoids were tested. RESULTS The best extraction conditions were as follows:ethanol concentration was 65%, extraction time was 78 min and extraction temperature was 86℃. The content of total flavonoids could reach 2.35 mg·g^-1. It indicated that 60% ethanol fraction had the most content of total flavonoids after eluted from macroporous resin column. There was a significant positive correlation between total flavonoids content and antioxidant activity. What's more, seven flavonoids were identified from the active fraction. The antioxidant activity of six flavonoids were tested. The structure-activity relationship was discussed. CONCLUSION Response surface method is effective to optimize the extraction of total flavonoids from Z. mays. Flavonoids are the main antioxidant ingredients of Z. mays.