The Effects of Oxidation on the Antithrombotic Properties of Tea Lipids Against PAF, Thrombin, Collagen, and ADP.

Alexandros Tsoupras,Karen Devaney,Jack Harrington,Rebecca Pienaar,Ronan Lordan,Stephanie Heaney,Anastasios Koidis,Ioannis Zabetakis

doi:10.3390/foods9040385

Alexandros Tsoupras, Karen Devaney + Show 6 more

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https://doi.org/10.3390/foods9040385

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Abstract

Tea provides health benefits, while oxidation is part of tea processing. The effect of oxidation on the antithrombotic properties of tea lipid extracts was evaluated for the first time. Total lipids (TL) extracted from fresh tea leaves and commercial tea powder, before and after 30–60 min of oxidation, were further fractionated into neutral lipids (NL) and polar lipids (PL). The antithrombotic bioactivities of tea TL, PL, and NL were assessed in human platelets against the inflammatory mediator platelet-activating factor. PL were further assessed against thrombin, collagen, and adenosine diphosphate, while their fatty acid composition was evaluated by GC-MS. PL exhibited the strongest antithrombotic effects against all platelet agonists and were rich in omega-3 polyunsaturated (ω3 PUFA) and monounsaturated (MUFA) fatty acids. A decline was observed in the antithrombotic activities, against all platelet agonists tested, for PL after 60 min of oxidation, and on their MUFA content, while their overall ω3 PUFA content and ω6/ω3 ratio remained unaffected. A synergistic effect between tea phenolic compounds and PL protects them against oxidation, which seems to be the rational for retaining the antithrombotic biofunctionalities of PL at a considerable favorable cardioprotective level, even after 60 min of tea oxidation. More studies are required to elucidate the mechanisms of the favorable synergism in tea PL extracts.

Highlights

Tea is brewed from the dried leaves of the plant Camellia sinensis and is one of the most widely consumed beverages in the world
* Results are expressed as IC50 values that reflect the inhibitory strength of each standard against platelet-activating factor (PAF), thrombin, collagen, adenosine diphosphate (ADP)-induced platelet aggregation and is expressed as mean values of μg of standard in the aggregometer cuvette that causes 50% of inhibition on thrombin, collagen, and ADP-induced aggregation of platelets in human platelet-rich plasma (hPRP) ± standard deviation (SD). # In the parentheses the IC50 values for each standard are expressed as μM concentration ± SD. ** Results are expressed as EC50 values that reflect the agonistic strength of each standard to induce aggregation of human platelets and is expressed as mean values of μM
The amounts of the phosphocholine standard (PCS) needed for platelet aggregation were at least one order of magnitude higher than those needed for inhibiting platelet aggregation, while this agonistic effect on human platelets was found to be at least three orders of magnitude lower than that of PAF

Summary

Introduction

Tea is brewed from the dried leaves of the plant Camellia sinensis and is one of the most widely consumed beverages in the world. 4000 bioactive chemical compounds, including polar lipids (PL) and their subclasses of glycolipids, phospholipids, essential fatty acids (FA), and polyphenols such as catechins [1,2,3,4,5,6,7,8]. Tea can be mainly categorized into three types depending on the level of tea polyphenol oxidation. These include green tea (nonoxidized), oolong tea (partially oxidized), and black tea (fully oxidized) [1,2,3]. Black tea contains bioactive derivatives of catechins such as theaflavins and thearubigins, which are favourably formed at the expense of catechins during oxidation processing [1,2,3]

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