To identify the optimal conditions of polyphenol extraction from Lagerstroemia specious and measure the antioxidational effects of polyphenol extract from Lagerstroemia specious. Orthogonal test were used to identify the optimal conditions .Hydroxyl radical clearing capacity of polyphenol extract from Lagerstroemia specious and its inhibitory effect on lipidoxidation were measured. The results are as follows: The alcohol concentration, ultrasonic power, and ultrasonic treatment time had significant effects on polyphenol extraction, and the optimizing conditions were 70% alcohol concentration,200W ultrasonic power, and 20minutes of ultrasonic treatment time. Both the clearing capacity of polyphenol extract from Lagerstroemia specious or hydroxyl radical and its inhibitory effect on lipidoxidation were very significant, and the EC50 were 2.8mg/ml and 0.3mg/ml respectively.The considerable extraction rate is achieved by applying the selected technology. polyphenol extraction from Lagerstroemia specious has more stronger antioxidational effects.
