Study on Polyphenol Oxidase (PPO) Activity and Total Phenol Content of Docynia Indica

[Objectives] To study the polyphenol oxidase （PPO） activity and total phenol content of Docynia indica.[Methods]The tender branches and petioles of the medicinal and edible plant D. indica were used as experimental materials,and the annual changes of total phenol content and polyphenol oxidase （PPO） activity were analyzed.[Results] pH7. 0 was the optimum value of polyphenol oxidase activity in D. indica plants; the best substrate was catechol with the concentration of 0. 15 mol/L; the optimum temperature was 25℃.[Conclusions]The total phenol content of D. indica plants was the lowest in April,May and September of each year. The polyphenol oxidase activity of D. indica plants at flowering and fruiting stage was significantly higher than that at pre-flowering stage.