Anti-polyphenol oxidase properties of total flavonoids from young loquat fruits: inhibitory activity and mechanism

ABSTRACT

This study investigated anti-polyphenol oxidase activity and mechanism of purified total flavonoids (PTF) from young loquat fruits. PTF remarkably inhibited the activity of polyphenol oxidase (PPO) with an IC₅₀ value of 21.03 ± 2.37 μg/mL. Based on enzyme kinetics, PTF was found to be a potent, mixed-type, and reversible inhibitor of PPO. The fluorescence intensity of PPO was quenched by PTF through forming a PTF-PPO complex in a static procedure. Therefore, this study authenticated PTF as an efficient PPO inhibitor, which would contribute to their utilization in food industry.

Graphical Abstract

KEYWORDS:

• Polyphenol oxidase
• total flavonoids
• young loquat fruits
• inhibitory mechanism

Highlights

1. PTF is efficient, reversible, and mixed competitive inhibitors of PPO.

2. PTF has one binding site with PPO.

3. PTF induced conformational change of PPO.

Disclosure statement

Authors declare no conflict of interest.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by The Open Research Fund of Jiangsu Key Laboratory for Biomass Energy and Material (JSBEM202009), The Science and Technology Foundation of Suzhou (SNG201909) and The Foundation of Suzhou Academy of Agricultural Sciences (KJ(18)101).