The four-year-old Michelia chapensis, M. platypetala, M. foveolata, and M. maudiae leaves were selected as experimental materials, and their ethanol extracts (light yellow liquid) were obtained by method of organic solvent extraction. The antioxidant components of extracts were initially identified by physical and chemical detection and UV scan. Moreover, the activities of anti-overoxidation for four samples on soybean oil were determined, and PA(phytic acid)and PG(propyl gallate)were contrasted. Besides, the regression models of first-order kinetics for soybean oil samples containing additives were fitted. Results showed that the extraction rate of M. chapensis was the highest (13.24%).The anti-overoxidation components of four samples were flavonoids. According to results of Pf (Oxidation Protection Factor) and determining values of MDA, we found that the capacity of anti-overoxidation for the extract from M. platypetala was the strongest(Pf value 1.25, MDA 0.456). The regression relationships for equations of first-order kinetics were significant. They were suitable to fit exponential function curves. The experiment provides scientific basis for the research and exploration of four Michelia species.
