Inhibitory effects of L-3-phenyllacitc acid on the activity of mushnroom pholyphenol oxidase

Haiwei Ren,Nana Du,Binyun Zhang,Yingying Cao,Yonggang Wang,Wenguang Fan,Hui Tian,Xiaoqian Niu

doi:10.1590/fst.08420

Abstract

Polyphenol oxidase is the popular enzyme involved in fruit-vegetable browning and melanin synthesis. In the present paper, L-3-phenyllactic acid, a natural bacteriostatic substance, was investigated as an inhibitor of polyphenol oxidase. The results were demonstrated that the residual enzyme activity of polyphenol oxidase decreased gradually with the increase of the concentration of L-3-phenyllactic acid. The L and ΔE values of the reaction system increased gradually. The reversible mixed-type inhibition mode of L-3-phenyllactic acid was determined by Lineweaver Burk plot. At the same time, the results of fluorescence quenching demonstrated that L-3-phenyllactic acid was a quencher of polyphenol oxidase, and the molecular docking study provided the binding mode of L-3-phenyllactic acid and polyphenol oxidase at the molecular level. L-3-phenyllactic acid decreased the activity of polyphenol oxidase and browning of fresh-cut Agaricus Bosporus. This research first studied the inhibitory effect of L-3-phenyllactic acid on the activity of polyphenol oxidase, and would provide a theoretical foundation for the use of L-3-phenyllactic acid as anti-polyphenol oxidase agents.

Highlights

Polyphenol oxidase (PPO), a kind of multiple functional oxidases, which was usually founded in many organisms including animals, insects, plants and microorganisms (Li et al, 2009; Seo et al, 2003; Yin et al, 2011a)
It could be concluded that the amount of products in the reaction system in the certain reaction time were stable, and the addition of phenyllactic acid (PLA) reduced the amount of the products, and had no effect on the maximum absorption peak of the products
The fluorescence intensity of PPO decreased with increase of PPO concentrations, and the shift of the maximum peak was not significant. These results showed that PLA might interact with PPO, covered some color base of PPO and quenched the intrinsic fluorescence

Summary

Introduction

Polyphenol oxidase (PPO), a kind of multiple functional oxidases, which was usually founded in many organisms including animals, insects, plants and microorganisms (Li et al, 2009; Seo et al, 2003; Yin et al, 2011a). PPO is the key enzyme involved in melanin synthesis, determined the color of mammalian skin, hair and fruit-vegetable browning (Ciou et al, 2011; Li et al, 2010; Lee et al, 2015). When fruits and vegetables were damaged, the regional and localized distribution of the cells was destroyed, let the phenolic substances contact with polyphenol oxidase, they ware polymerized to brown pigments and accelerated the browning of fruits and vegetables (Ciou et al, 2011; Pan et al, 2011). After the treatment of fruits and vegetables, the monophenol was produced to melanin through non-enzymatic reaction in the catalysis of PPO (Ismaya et al, 2011), polymerized to brown pigments, accelerated the browning of fruits and vegetables. PPO was responsible for the reduction of the nutritional quality and market value of fruits and vegetables (Zhou et al, 2016)

Methods

Results

Conclusion