Binding characteristics of polyphenols as milk plasmin inhibitors

Abstract

BACKGROUND The potential use of polyphenols to improve the functional characteristics of dairy products has gained much attention. However, the effects of the polyphenols on naturally occurring enzymes in milk have not been studied extensively. Excess plasmin activity in dairy products might result in several quality defects. The objective of this study was to assess the ability of polyphenols to inhibit plasmin in milk using a molecular and kinetic approach. RESULTS Epicatechin gallate (ECG), epigallocatechin gallate (EGCG), quercetin (QUER), and myricetin (MYR) caused a significant decrease in plasmin activity by 60, 86, 65, and 90%, respectively. The inhibition rates were alleviated in the presence of milk proteins. EGCG, QUER, and MYR, exhibited noncompetitive inhibition against plasmin, whereas ECG caused a mixed‐type inhibition. A decrease in the random structure of plasmin upon the complex formation with ECG, EGCG, QUER, and MYR was found. The other phenolics that were evaluated did not cause any significant changes in plasmin conformation. The observed inhibitory phenolic‐plasmin interactions were dominated by H‐bonds and electrostatic attractions. Green tea extract (GTE) rich in catechins also inhibited plasmin activity in the milk. CONCLUSION Significant changes in the secondary structure of plasmin upon binding of ECG, EGCG, QUER, and MYR led to diminished plasmin activity both in the absence and presence of milk proteins. These flavonoids with promising plasmin inhibitory potential could be used in new dairy formulations leading to controlled undesired consequences of plasmin activity. © 2019 Society of Chemical Industry

The Enzymatic Digestion of Pomaces From Some Fruits for Value-Added Feed Applications in Animal Production

“…The ability of using enzymes with pomaces faces another hurdle that emerges from the unique ability of pomace bioactives [including polyphenols and tannins (Hemingway and Laks, 2012)] at certain concentration to influence (or even inactivate) the functionality of used enzymatic preparations either through specific or non-specific interactions (Martinez-Gonzalez et al, 2017;Yildirim-Elikoglu and Vural, 2019). Many reports showed the ability of certain polyphenolics to negatively influence the functions of natural or industrial enzymes in a similar fashion to their ability to negatively impact microbial growths (Gonçalves and Romano, 2017;Ramos-Pineda et al, 2019).…”

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