Comprehensive study on the formation mechanism of highly bioactive compounds from Allium hookeri root using subcritical water and their antioxidant and anticancer effects

•Efficiency of subcritical water extraction on Allium hookeri root was investigated.•88 wt% extraction yield with high bioactivity was achieved at 160 °C for 30 min.•Simultaneous formation and extraction of Maillard reaction products was achieved.•Origin of antioxidant activities of the extracts was elucidated by correlation analysis.•Antiproliferative activities of the extract against two human cancer cells were examined.